Miocene (~20 MYA) lizards, preserved in amber, “identical to their modern cousins.”

July 28, 2015

Truly amazing…

Ancient lizards in amber amaze scientists
Tuesday, 28 July 2015 Stuart Gary
ABC

A community of lizards from the Caribbean, preserved for 20 million years in amber, have been found to be identical to their modern cousins, say researchers.

This suggests the different niches inhabited by the lizards have – incredibly – changed little over the past 20 million-year, report the team, in this week’s Proceedings of the National Academy of Sciences.

[…]

http://www.abc.net.au/science/articl…28/4279562.htm

I guess the Gorebots are wrong about climate change endangering lizards

(Older is to the right.)

Gavin says the funniest things…

June 5, 2015

NOAA temperature record updates and the ‘hiatus’

Filed under:

— gavin @ 4 June 2015

In a new paper in Science Express, Karl et al. describe the impacts of two significant updates to the NOAA NCEI (née NCDC) global temperature series. The two updates are: 1) the adoption of ERSST v4 for the ocean temperatures (incorporating a number of corrections for biases for different methods), and 2) the use of the larger International Surface Temperature Initiative (ISTI) weather station database, instead of GHCN. This kind of update happens all the time as datasets expand through data-recovery efforts and increasing digitization, and as biases in the raw measurements are better understood. However, this update is going to be bigger news than normal because of the claim that the ‘hiatus’ is no more. To understand why this is perhaps less dramatic than it might seem, it’s worth stepping back to see a little context…

Global temperature anomaly estimates are a product, not a measurement

The first thing to remember is that an estimate of how much warmer one year is than another in the global mean is just that, an estimate. We do not have direct measurements of the global mean anomaly, rather we have a large database of raw measurements at individual locations over a long period of time, but with an uneven spatial distribution, many missing data points, and a large number of non-climatic biases varying in time and space. To convert that into a useful time-varying global mean needs a statistical model, good understanding of the data problems and enough redundancy to characterise the uncertainties. Fortunately, there have been multiple approaches to this in recent years (GISTEMP, HadCRUT4, Cowtan & Way, Berkeley Earth, and NOAA NCEI), all of which basically give the same picture.

[…]

The ‘hiatus’ is so fragile that even those small changes make it disappear

[…]

– See more at: http://www.realclimate.org/index.php/archives/2015/06/noaa-temperature-record-updates-and-the-hiatus/#sthash.B1t4pbWO.dpuf

If “the ‘hiatus’ is so fragile that even those small changes make it disappear,” the underlying trend must also be fragile, if small data fudges are the difference between hiatus and the road to AGW calamity.

In the meantime…

Anatomy of a Collapsing Paradigm

March 18, 2015

Paradigm:

A framework containing the basic assumptions, ways of thinking, and methodology that are commonly accepted by members of a scientific community.

Paradigm Shift:

These examples point to the third and most fundamental aspect of the incommensurability of competing paradigms. In a sense that I am unable to explicate further, the proponents of competing paradigms practice their trades in different worlds. One contains constrained bodies that fall slowly, the other pendulums that repeat their motions again and again. In one, solutions are compounds, in the other mixtures. One is embedded in a flat, the other in a curved, matrix of space. Practicing in different worlds, the two groups of scientists see different things when they look from the same point in the same direction. Again, that is not to say that they can see anything they please. Both are looking at the world, and what they look at has not changed. But in some areas they see different things, and they see them in different relations one to the other. That is why a law that cannot even be demonstrated to one group of scientists may occasionally seem intuitively obvious to another. Equally, it is why, before they can hope to communicate fully, one group or the other must experience the conversion that we have been calling a paradigm shift. Just because it is a transition between incommensurables, the transition between competing paradigms cannot be made a step at a time, forced by logic and neutral experience. Like the gestalt switch, it must occur all at once (though not necessarily in an instant) or not at all.

–Thomas Kuhn, 1962. The Structure of Scientific Revolutions. Vol. II, No. 2 p. 150

What is the current paradigm?

  • Human activities, primarily carbon dioxide emissions, have been the primary cause of the observed global warming over the past 50 to 150 years.
  • The atmospheric carbon dioxide concentration had stabilized between 270 and 280 ppmv early in the Holocene and had remained in that range prior to the mid-19th century when fossil fuels became the primary energy source of the Industrial Revolution.
  • Anthropogenic carbon dioxide emissions are causing the atmospheric concentration to rise at a dangerously rapid pace to levels not seen in 100’s of thousands to millions of years.
  • The climate sensitivity to a doubling of pre-industrial carbon dioxide concentration “is likely to be in the range of 2 to 4.5°C with a best estimate of about 3°C, and is very unlikely to be less than 1.5°C,” possibly even much higher than 4.5°C.
  • Immediate, deep reductions in greenhouse gas emissions are necessary in order to stave off catastrophic climate change.
  • The scientific consensus regarding this paradigm is overwhelming (~97%).

Why is the paradigm collapsing?

  • There has been no increase in the Earth’s average surface temperature since the late 20th century.
  • Every measure of pre-industrial carbon dioxide, not derived from Antarctic ice cores, indicates a higher and more variable atmospheric concentration.
  • The total lack of predictive skill in AGW climate models.
  • An ever-growing body of observation-based studies indicating that the climate sensitivity is in the range of 0.5 to 2.5°C with a best estimate of 1.5 to 2°C, and is very unlikely to be more than 2°C.
  • Clear evidence that the dogmatic insistence of scientific unanimity is at best highly contrived and at worst fraudulent.

The paradigm is collapsing primarily due to the fact that the climate appears to be far less sensitive to changes in atmospheric carbon dioxide concentrations than the so-called scientific consensus had assumed.

One group of scientists has steadfastly resisted the carbon dioxide-driven paradigm: Geologists, particularly petroleum geologists. As Kuhn wrote,

“Practicing in different worlds, the two groups of scientists see different things when they look from the same point in the same direction. Again, that is not to say that they can see anything they please. Both are looking at the world, and what they look at has not changed. But in some areas they see different things, and they see them in different relations one to the other. That is why a law that cannot even be demonstrated to one group of scientists may occasionally seem intuitively obvious to another.”

Petroleum geologists tend to be sedimentary geologists and sedimentary geology is essentially a combination of paleogeography and paleoclimatology. Depositional environments are defined by physical geography and climate. We literally do practice in a different world, the past. Geologists intuitively see Earth processes as cyclical and also tend to look at things from the perspective of “deep time.” For those of us working the Gulf of Mexico, we “go to work” in a world defined by glacioeustatic and halokinetic processes and, quite frankly, most of us don’t see anything anomalous in recent climate changes.

So, it should come as little surprise that geoscientists have consistently been far more likely to think that modern climate changes have been driven by overwhelmingly natural processes…

APEGA is the organization responsible for certifying and licensing professional geoscientists and engineers in Alberta, Canada.

This study is very interesting because it analyzes the frames of reference (Kuhn’s “different worlds”) in which opinions are formed. Skeptical geologists are most likely to view climate change as overwhelmingly natural. Skeptical engineers are more likely to view it as a matter of economics or fatalism. The cost of decarbonization would far outweigh any benefits and/or would have no measurable effect on climate change.

The Obsession With Consensus

In nearly 40 years as an Earth Scientist (counting college), I have never seen such an obsession with consensus. In geology, there are many areas in which there are competing hypotheses; yet there is no obsession with conformance to a consensus.

The acceptance of plate tectonics was a relatively new thing when I was a student. This paradigm had only recently shifted from the geosynclinal theory to plate tectonics. We still learned the geosynclinal theory in Historical Geology and it still has value today. However, I don’t ever recall papers being published claiming a consensus regarding either theory.

Most geologists think that granite is an igneous rock and that petroleum is of organic origin. Yet, the theories of granitization and abiogenic hydrocarbon formation are not ridiculed; nor are the adherents subjected to “witch hunts.”

One of the most frequent methods of attempting to quantify and justify the so-called consensus on climate change has been the abstract search (second hand opinions). I will only bother to review one of these exercises in logical fallacy, Cook et al., 2013.

Second Hand Opinions.

These sorts of papers consist of abstract reviews. The authors’ then tabulate their opnions regarding whether or not the abstracts support the AGW paradgm. As Legates et al., 2013 pointed out, Cook defined the consensus as “most warming since 1950 is anthropogenic.” Cook then relied on three different levels of “endorsement” of that consensus and excluded 67% of the abstracts reviewed because they neither endorsed nor rejected the consensus.

The largest endorsement group was categorized as “implicitly endorses AGW without minimizing it.” They provided this example of an implied endorsement:

‘…carbon sequestration in soil is important for mitigating global climate change’

Carbon sequestration in soil, lime muds, trees, seawater, marine calcifers and a whole lot of other things have always been important for mitigating a wide range of natural processes. I have no doubt that I have implicitly endorsed the so-called consensus based on this example.

The second largest endorsement group was categorized as “implicitly endorses but does not quantify or minimize.” Pardon my obtuseness, but how in the heck can one explicitly endorse the notion that “most warming since 1950 is anthropogenic” without quantification? This is the exmple Cook provided:

‘Emissions of a broad range of greenhouse gases of varying lifetimes contribute to global climate change’

Wow! I contributed to Romney for President… Yet most of his campaign warchest didn’t come from me. By this subjective standard, I have probably explicitly endorsed AGW a few times.

No Schist, Sherlock.

One of the most frequent refrains is the assertion that “climate scientists” endorse the so-called consensus more than other disciplines and that the level of endorsement is proportional to the volume of publications by those climate scientists. Well… No schist, Sherlock! I would bet a good bottle of wine that the most voluminous publishers on UFO’s are disproportionately more likely to endorse Close Encounters of the Third Kind as a documentary. A cursory search for “abiogenic hydrocarbons” in AAPG’s Datapages could lead me to conclude that there is a higher level of endorsement of abiogenic oil among those who publish on the subject than among non-publishing petroleum geologists.

These exercises in expertise cherry-picking are quite common. A classic example was Doran and Kendall Zimmerman, 2009. This survey sample was limited to academic and government Earth Scientists. It excluded all Earth Scientists working in private sector businesses. The two key questions were:

1. When compared with pre-1800s levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?

2. Do you think human activity is a significant contributing factor in changing mean global temperatures?

I would answer yes to #1 and my answer to #2 would depend on the meaning of “human activity is a significant contributing factor.” If I realized it was a “push poll,” I would answer “no.”

Interestingly, economic geologists and meteorologists were the most likely to answer “no” to question #2…

The two areas of expertise in the survey with the smallest percentage of participants answering yes to question 2 were economic geology with 47% (48 of 103) and meteorology with 64% (23 of 36).

The authors derisively dismissed the opinions of geologists and meteorologists…

It seems that the debate on the authenticity of global warming and the role played by human activity is largely nonexistent among those who understand the nuances and scientific basis of long-term climate processes.

No discipline has a better understanding the “nuances” than meteorologists and no discipline has a better understanding of the “scientific basis of long-term climate processes” than geologists.

The authors close with a “no schist, Sherlock” bar chart:

The most recent example of expertise cherry-picking was Stenhouse et al., 2014.

The 52% consensus among the membership of the American Meteorological Society was explained away as being due to “perceived scientific consensus,” “political ideology,” and a lack of “expertise” among non-publishing meteorologists and atmospheric scientists…

While we found that higher expertise was associated with a greater likelihood of viewing global warming as real and harmful, this relationship was less strong than for political ideology and perceived consensus. At least for the measure of expertise that we used, climate science expertise may be a less important influence on global warming views than political ideology or social consensus norms. More than any other result of the study, this would be strong evidence against the idea that expert scientists’ views on politically controversial topics can be completely objective.

Finally, we found that perceiving conflict at AMS was associated with lower certainty of global warming views, lower likelihood of viewing global warming as human caused, and lower ratings of predicted harm caused by global warming.

So… Clearly, 97% of AMS membership would endorse the so-called consensus if they were more liberal, more accepting of unanimity and published more papers defending failed climate models.  No schist, Sherlock!

What, exactly, is a “climate scientist”?

35 years ago climatology was a branch of physical geography. Today’s climate scientists can be anything from atmospheric physicists & chemists, mathematicians, computer scientists, astronomers, astrophysicists, oceanographers, biologists, environmental scientists, ecologists, meteorologists, geologists, geophysicists, geochemistry to economists, agronomists, sociologists and/or public policy-ologists.

NASA’s top climate scientist for most of the past 35 years, James Hansen, is an astronomer. The current one, Gavin Schmidt, is a mathematician.

It seems to me that climate science is currently dominated by computer modelers, with little comprehension of the natural climate cycles which have driven climate change throughout the Holocene.

Climate scientist seems to be as nebulous as Cook’s definition of consensus.

What is the actual consensus?

The preliminary results of the AMS survey tell us all we need to know about the former…

89% × 59% = 52%… A far cry from the oft claimed 97% consensus.

Based on BAMS definition, global warming is happening. So, I would be among the 89% who answered “yes” to question #1 and among the 5% who said the cause was mostly natural.

When self-described “climate scientists” and meteorologists/atmospheric scientists are segregated the results become even more interesting…

Only 45% of meteorologists and atmospheric scientists endorse the so-called consensus. When compared to the 2009, American Geophysical Union survey, the collapsing paradigm sticks out like a polar vortex…

In reality, about half of relevant scientists would probably agree that humans have been responsible for >50% of recent climate changes.  And there might even be a 97% consensus that human activities have contributed to recent climate changes.

However, there really isn’t any scientific consensus if it is defined this way:

So… Why is there such an obsession with a 97% consensus?  My guess is that it enables such demagoguery.

Science Lessons for Secretary of State John F. Kerry

March 16, 2015

Secretary of State John F. Kerry’s recent remarks on climate change at the Atlantic Council were so scientifically illiterate that I find it difficult to believe that he managed to barely get a D in geology at Yale University.  As a US citizen and geoscientist, I feel it is my patriotic and professional duty to provide Secretary Kerry with a few complimentary science lessons.

Let’s start with some basics

So stop for a minute and just think about the basics. When an apple falls from a tree, it will drop toward the ground. We know that because of the basic laws of physics. Science tells us that gravity exists, and no one disputes that. Science also tells us that when the water temperature drops below 32 degrees Fahrenheit, it turns to ice. No one disputes that.

So when science tells us that our climate is changing and humans beings are largely causing that change, by what right do people stand up and just say, “Well, I dispute that” or “I deny that elementary truth?” And yet, there are those who do so.

http://m.state.gov/md238829.htm

Well Mr. Secretary… The Theory of Gravity can be empirically tested with such repeatability that it has become a Law and can be expressed with a simple equation… It can even be tested and  confirmed on the Moon…

The freezing point of water (phase transition) can also be empirically tested and demonstrated with ample repeatability. However, the freezing point of water is not always 32°F. The freezing point is dependent on both temperature and pressure….

We do not accept gravity and phase transition because science tells us to. We accept these things because they can be empirically tested, repeatedly confirmed and form the bases of solid scientific theories.

Science tells us that climate has always changed and always will be changing. While the radiative forcing effect of CO2 is kind of in the same ballpark as the freezing point of water, the notion that humans are the primary cause of recent climate changes is nothing but a hypothesis which has failed almost every empirical test. This is why many scientists do not accept that this is “settled science.”

From Remote Sensing Systems [with my commentary]:

Over the past decade, we have been collaborating with Ben Santer at LLNL (along with numerous other investigators) to compare our tropospheric results with the predictions of climate models. Our results can be summarized as follows:

  • Over the past 35 years, the troposphere has warmed significantly. The global average temperature has risen at an average rate of about 0.13 degrees Kelvin per decade (0.23 degrees F per decade).[All of the warming occurred in one step-shift in the late 1990’s.]
  • Climate models cannot explain this warming if human-caused increases in greenhouse gases are not included as input to the model simulation.[Only because climate models are programmed to do so. The models are programmed with very high sensitivities to CO2. Then they are paramaterized (fudged) with assumptions about albedo effects of past anthropogenic aerosol emissions in order to retrocast past temperature changes. The climate models almost totally fail to incorporate cloud albedo effects and natural climate oscillations.This is why they lack predictive skill.
  • The spatial pattern of warming is consistent with human-induced warming. See Santer et al 2008, 2009, 2011, and 2012 for more about the detection and attribution of human induced changes in atmospheric temperature using MSU/AMSU data.[Yep. Most of the warming is occurring at night and in the coldest air masses in the Northern Hemisphere.]

But….

  • The climate has not warmed as fast as almost all climate models predict.

[Because the models lack predictive skill.]

To illustrate this last problem, we show several plots below. Each of these plots has a time series of TLT temperature anomalies using a reference period of 1979-2008. In each plot, the thick black line is the measured data from RSS V3.3 MSU/AMSU Temperatures. The yellow band shows the 5% to 95% envelope for the results of 33 CMIP-5 model simulations (19 different models, many with multiple realizations) that are intended to simulate Earth’s Climate over the 20th Century.

[…]

[…]

http://www.remss.com/research/climate

RSS shows no warming since 1997…

In fairness, the models have demonstrated precision. They precisely miss the mark to the high side…

The first modern AGW model from 1988 has essentially proven that the climate is relatively insensitive to increasing atmospheric CO2. Subsequent models have confirmed that the hypothesis is wrong…

James Hansen, formerly of NASA-GISS, first proved that AGW was wrong 27 years ago. 

Back in 1988, he published a climate model that, when compared to his own temperature data, substantially disproves AGW…

GISTEMP has tracked the Hansen scenario in which a green utopia was achieved more than a decade ago.

Hansen’s model used an equilibrium climate sensitivity (ECS) of 4.2°C per doubling of pre-industrial CO2. The IPCC “consensus” is 3.0°C. Numerous recent papers have demonstrated that the ECS is less than 2.0°C. T

“Scenario B” might be the most relevant prediction because CH4 and CFC’s have followed closest to the “C” trajectory, while CO2 has tracked “A”.

Since CO2 tracked “A”, CH4 and CFC’s tracked “C” and temperature tracked below “C”… The atmosphere is far less sensitive to CO2 than Hansen modeled… The atmosphere was essentially insensitive to the ~50ppmv rise in CO2 over the last 24 years.

The following CMIP5 model was parameterized (fudged) to accurately retrocast HadCRUT4 from 1950-2004.

Within eight years, the observed temperature is on the verge of dropping out of the lower error band.

This model from Kaufmann et al., 2011 simulated natural and anthropogenic (primarily CO2) forcing mechanisms from 1999-2008. Natural forcing won by a score of 3-1.

A plot of the Wood for Trees Temperature Index on 12 years worth of IPCC model suites demonstrates that the AGW hypothesis has demonstrated no predictive skill in nearly 30 years of testing…

On to basic math and reading skills

Now folks, we literally do not have the time to waste debating whether we can say “climate change.” We have to talk about how we solve climate change. Because no matter how much people want to bury their heads in the sand, it will not alter the fact that 97 percent of peer-reviewed climate studies confirm that climate change is happening and that human activity is largely responsible.

Well Mr. Secretary… The SkepSci bloggers who claimed the bogus 97% consensus don’t even assert that “97 percent of peer-reviewed climate studies confirm that climate change is happening and that human activity is largely responsible.”

 The fact.is that less than 1% “of peer-reviewed climate studies confirm that climate change is happening and that human activity is largely responsible.”

Now for a bit of history

Just look around you. Fourteen of the fifteen warmest years on record in all of history have occurred since 2000, in all of recorded history. Last year was the warmest of all. And I think if you stop and think about it, it seems that almost every next year becomes one of the hottest on record.

Wrong again, Mr. Secretary. While it is possible that “fourteen of the fifteen warmest years on record (since about 1850) have occurred since 2000″… “all of recorded history” goes back a bit farther than that.  Recorded history goes back a time long before this 2,000 year climate reconstruction…

ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/ljungqvist2010/ljungqvist2010.txt

And now back to basic science

It’s not particularly complicated. I don’t mean to sound haughty, but think about it for a minute. Life on Earth would not exist without a greenhouse effect. That is what has kept the average temperature up, until recently, at 57 degrees Fahrenheit, because there is this greenhouse effect. And it was called the greenhouse effect because it does exactly what a greenhouse does. When the sun pours in and bounces off at a different angle, it goes back up at a different angle. That can’t escape, and that warms things – a very simple proposition.

Don’t worry Mr. Secretary… You don’t sound haughty. You sound like a guy who got a D in geology and would have gotten an F in physics.

Neither a greenhouse nor the greenhouse effect rely on the Law of Reflection or Snell’s Law… Nor does the greenhouse effect even behave like a greenhouse…

The greenhouse effect refers to circumstances where the short wavelengths of visible light from the sun pass through a transparent medium and are absorbed, but the longer wavelengths of the infrared re-radiation from the heated objects are unable to pass through that medium. The trapping of the long wavelength radiation leads to more heating and a higher resultant temperature.

[…]

A major part of the efficiency of the heating of an actual greenhouse is the trapping of the air so that the energy is not lost by convection. Keeping the hot air from escaping out the top is part of the practical “greenhouse effect”, but it is common usage to refer to the infrared trapping as the “greenhouse effect” in atmospheric applications where the air trapping is not applicable.

http://hyperphysics.phy-astr.gsu.edu…mo/grnhse.html

Summary

The laws and theories of gravity and phase transition are not even remotely analogous to the fatally flawed AGW hypothesis.

97% of peer-reviewed climate studies do not conclude that humans are largely to blame for recent climate changes.

There is no evidence that 14 of the last 15 years are the warmest in all of recorded history.

A greenhouse works by retarding convective cooling.  The greenhouse effect works by retarding radiative cooling.  Secretary Kerry’s lack of scientific literacy will work by retarding our economy.

Ice Cores vs. Plant Stomata Collection

March 9, 2015

INTRODUCTION

Anyone who has spent any amount of time reviewing climate science literature has probably seen variations of the following chart…

A record of atmospheric CO2 over the last 1,000 years constructed from Antarctic ice cores and the modern instrumental data from the Mauna Loa Observatory suggest that the pre-industrial atmospheric CO2 concentration was a relatively stable ~275ppmv up until the mid 19th Century. Since then, CO2 levels have been climbing rapidly to levels that are often described as unprecedented in the last several hundred thousand to several million years.

Ice core CO2 data are great.  Ice cores can yield continuous CO2 records from as far back as 800,000 years ago right on up to the 1970’s.  The ice cores also form one of the pillars of Enviromarxist Junk Science: A stable pre-industrial atmospheric CO2 level of ~275ppmv.  The Antarctic ice core-derived CO2 estimates are inconsistent with just about every other method of measuring pre-industrial CO2 levels.

Three common ways to estimate pre-industrial atmospheric CO2 concentrations (before instrumental records began in 1959) are:

1) Measuring CO2 content in air bubbles trapped in ice cores.

2) Measuring the density of stomata  in plants.

3) GEOCARB (Berner et al., 1991, 1999, 2004): A geological model for the evolution of atmospheric CO2 over the Phanerozoic Eon.  This model is derived from “geological, geochemical, biological, and climatological data.”  The main drivers being tectonic activity, organic matter burial and continental rock weathering.

ICE CORES

The advantage to the ice core method is that it provides a continuous record of relative CO2 changes going back in time 800,000  years, with a resolution ranging from annual in the shallow section to multi-decadal in the deeper section.  Pleistocene-age ice core records seem to indicate a strong correlation between CO2 and temperature; although the delta-CO2 lags behind the delta-T by an average of 800 years…

PLANT STOMATA

Stomata are microscopic pores found in leaves and the stem epidermis of plants.  They are used for gas exchange.  The stomatal density in some C3 plants will vary inversely with the concentration of atmospheric CO2.  Stomatal density can be empirically tested and calibrated to CO2 changes over the last 60 years in living plants.  The advantage to the stomatal data is that the relationship of the Stomatal Index and atmospheric CO2 can be empirically demonstrated…

When stomata-derived CO2 (red) is compared to ice core-derived CO2 (blue), the stomata generally show much more variability in the atmospheric CO2 level and often show levels much higher than the ice cores…

Plant stomata suggest that the pre-industrial CO2 levels were commonly in the 360 to 390ppmv range.

GEOCARB

GEOCARB provides a continuous long-term record of atmospheric CO2 changes; but it is a very low-frequency record…

The lack of a long-term correlation between CO2 and temperature is very apparent when GEOCARB is compared to Veizer’s d18O-derived Phanerozoic temperature reconstruction.  As can be seen in the figure above, plant stomata indicate a much greater range of CO2 variability; but are in general agreement with the lower frequency GEOCARB model.

DISCUSSION

Ice cores  and GEOCARB provide continuous long-term records; while plant stomata records are discontinuous and limited to fossil stomata that can be accurately aged and calibrated to extant plant taxa.  GEOCARB yields a very low frequency record, ice cores have better resolution and stomata can yield very high frequency data.  Modern CO2 levels are unspectacular according to GEOCARB, unprecedented according to the ice cores and not anomalous according to plant stomata.  So which method provides the most accurate reconstruction of past atmospheric CO2?

The problems with the ice core data are 1) the air-age vs. ice-age delta and 2) the effects of burial depth on gas concentrations.

The age of the layers of ice can be fairly easily and accurately determined.  The age of the air trapped in the ice is not so easily or accurately determined.  Currently the most common method for aging the air is through the use of “firn densification models” (FDM).  Firn is more dense than snow; but less dense than ice.  As the layers of snow and ice are buried, they are compressed into firn and then ice.  The depth at which the pore space in the firn closes off and traps gas can vary greatly… So the delta between the age of the ice and the ago of the air can vary from as little as 30 years to more than 2,000 years.

The EPICA C core has a delta of over 2,000 years.  The pores don’t close off until a depth of 99 m, where the ice is 2,424 years old.  According to the firn densification model, last year’s air is trapped at that depth in ice that was deposited over 2,000 years ago.

I have a lot of doubts about the accuracy of the FDM method.  I somehow doubt that the air at a depth of 99 meters is last year’s air.  Gas doesn’t tend to migrate downward through sediment… Being less dense than rock and water, it migrates upward.  That’s why oil and gas are almost always a lot older than the rock formations in which they are trapped.  I do realize that the contemporaneous atmosphere will permeate down into the ice… But it seems to me that at depth, there would be a mixture of air permeating downward, in situ air, and older air that had migrated upward before the ice fully “lithified”.

A recent study (Van Hoof et al., 2005) demonstrated that the ice core CO2 data essentially represent a low-frequency, century to multi-century moving average of past atmospheric CO2 levels.

Van Hoof et al., 2005. Atmospheric CO2 during the 13th century AD: reconciliation of data from ice core measurements and stomatal frequency analysis. Tellus (2005), 57B, 351–355.

It appears that the ice core data represent a long-term, low-frequency moving average of the atmospheric CO2 concentration; while the stomata yield a high frequency component.

The stomata data routinely show that atmospheric CO2 levels were higher than the ice cores do.  Plant stomata data from the previous interglacial (Eemian/Sangamonian) were higher than the ice cores indicate…

The GEOCARB data also suggest that ice core CO2 data are too low…

The average CO2 level of the Pleistocene ice cores is 36ppmv less than GEOCARB…

Recent satellite data (NASA AIRS) show that atmospheric CO2 levels in the polar regions are significantly less than in lower latitudes…

“AIRS can observe the concentration of carbon dioxide in the mid-troposphere, with 15,000 daily observations, pole to pole, all over the globe, with an accuracy of 1 to 2 parts per million and a horizontal surface resolution of 1 by 1 degree. The monthly map at right allows researchers to better observe variations of carbon dioxide at different latitudes and during different seasons. Image credit: NASA” http://www.nasa.gov/topics/earth/agu/airs-images20091214.html

“AIRS data show that carbon dioxide is not well mixed in Earth’s atmosphere, results that have been validated by direct measurements. The belt of carbon dioxide concentration in the southern hemisphere, depicted in red, reaches maximum strength in July-August and minimum strength in December-January. There is a net transfer of carbon dioxide from the northern hemisphere to the southern hemisphere. The northern hemisphere produces three to four times more human produced carbon dioxide than the southern hemisphere. Image credit: NASA” http://www.nasa.gov/topics/earth/agu/airs-images20091214.html

So… The ice core data should be yielding lower CO2 levels than the Mauna Loa Observatory and the plant stomata.

Kouwenberg et al., 2005 found that a “stomatal frequency record based on buried Tsuga heterophylla needles reveals significant centennial-scale atmospheric CO2 fluctuations during the last millennium.”

Plant stomata data show much greater variability of atmospheric CO2 over the last 1,000 years than the ice cores and that CO2 levels have often been between 300 and 340ppmv over the last millennium, including a 120ppmv rise from the late 12th Century through the mid 14th Century.  The stomata data also indicate higher CO2 levels than the Mauna Loa instrumental record; but a 5-point moving average ties into the instrumental record quite nicely…

A survey of historical chemical analyses (Beck, 2007) shows even more variability in atmospheric CO2 levels than the plant stomata data since 1800…

WHAT DOES IT ALL MEAN?

The current “paradigm” says that atmospheric CO2 has risen from ~275ppmv to 388ppmv since the mid-1800’s as the result of fossil fuel combustion by humans. Increasing CO2 levels are supposedly warming the planet…

However, if we use Moberg’s (2005) non-Hockey Stick reconstruction, the correlation between CO2 and temperature changes a bit…

Moberg did a far better job in honoring the low frequency components of the climate signal.  Reconstructions like these indicate a far more variable climate over the last 2,000 years than the “Hockey Sticks” do.  Moberg also shows that the warm up from the Little Ice Age began in 1600, 260 years before CO2 levels started to rise.

As can be seen below, geologically consistent reconstructions like Moberg and Esper are in far better agreement with “direct” paleotemperature measurements, like Alley’s ice core reconstruction for Central Greenland…

What happens if we use the plant stomata-derived CO2 instead of the ice core data?

We find that the ~250-year lag time is consistent. CO2 levels peaked 250 years after the Medieval Warm Period peaked and the Little Ice Age cooling began and CO2 bottomed out 240 years after the trough of the Little Ice Age. In a fashion similar to the glacial/interglacial lags in the ice cores, the plant stomata data indicate that CO2 has lagged behind temperature changes by about 250 years over the last millennium. The rise in CO2 that began in 1860 is most likely the result of warming oceans degassing.

While we don’t have a continuous stomata record over the Holocene, it does appear that a lag time was also present in the early Holocene…

Once dissolved in the deep-ocean, the residence time for carbon atoms can be more than 500 years. So, a 150- to 200-year lag time between the ~1,500-year climate cycle and oceanic CO2 degassing should come as little surprise.

CONCLUSIONS

  • Ice core data provide a low-frequency estimate of atmospheric CO2 variations of the glacial/interglacial cycles of the Pleistocene.  However, the ice cores seriously underestimate the variability of interglacial CO2 levels.
  • GEOCARB shows that ice cores underestimate the long-term average Pleistocene CO2 level by 36ppmv.
  • Modern satellite data show that atmospheric CO2 levels in Antarctica are 20 to 30ppmv less than lower latitudes.
  • Plant stomata data show that ice cores do not resolve past decadal and century scale CO2 variations that were of comparable amplitude and frequency to the rise since 1860.

Thus it is concluded that:

  • CO2 levels from the Early Holocene through pre-industrial times were highly variable and not stable as the ice cores suggest.
  • The carbon and climate cycles are coupled in a consistent manner from the Early Holocene to the present day.
  • The carbon cycle lags behind the climate cycle and thus does not drive the climate cycle.
  • The lag time is consistent with the hypothesis of a temperature-driven carbon cycle.
  • The anthropogenic contribution to the carbon cycle since 1860 is minimal and inconsequential.

Note:  Unless otherwise indicated, all of the climate reconstructions used in this article are for the Northern Hemisphere.

BIBLIOGRAPHY

Wagner et al., 1999. Century-Scale Shifts in Early Holocene Atmospheric CO2 Concentration. Science 18 June 1999: Vol. 284. no. 5422, pp. 1971 – 1973.

Berner et al., 2001. GEOCARB III: A REVISED MODEL OF ATMOSPHERIC CO2 OVER
PHANEROZOIC TIME. American Journal of Science, Vol. 301, February, 2001, P. 182–204.

Kouwenberg et al., 2004. APPLICATION OF CONIFER NEEDLES IN THE RECONSTRUCTION OF HOLOCENE CO2 LEVELS. PhD Thesis. Laboratory of Palaeobotany and Palynology, University of Utrecht.

Esper et al., 2005. Climate: past ranges and future changes. Quaternary Science Reviews 24 (2005) 2164–2166.

Kouwenberg et al., 2005. Atmospheric CO2 fluctuations during the last millennium reconstructed by stomatal frequency analysis of Tsuga heterophylla needles. GEOLOGY, January 2005.

Van Hoof et al., 2005. Atmospheric CO2 during the 13th century AD: reconciliation of data from ice core measurements and stomatal frequency analysis. Tellus (2005), 57B, 351–355.

Rundgren et al., 2005. Last interglacial atmospheric CO2 changes from stomatal index data and their relation to climate variations. Global and Planetary Change 49 (2005) 47–62.

Jessen et al., 2005.  Abrupt climatic changes and an unstable transition into a late Holocene Thermal Decline: a multiproxy lacustrine record from southern Sweden. J. Quaternary Sci., Vol. 20(4) 349–362 (2005).

Beck, 2007.  180 Years of Atmospheric CO2 Gas Analysis by Chemical Methods. ENERGY & ENVIRONMENT. VOLUME 18 No. 2 2007.

Loulergue et al., 2007. New constraints on the gas age-ice age difference along the EPICA ice cores, 0–50 kyr. Clim. Past, 3, 527–540, 2007.

DATA SOURCES

CO2

Etheridge et al., 1998. Historical CO2 record derived from a spline fit (75 year cutoff) of the Law Dome DSS, DE08, and DE08-2 ice cores.

NOAA-ESRL / Keeling.

Berner, R.A. and Z. Kothavala, 2001. GEOCARB III: A Revised Model of Atmospheric CO2 over Phanerozoic Time, IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2002-051. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.

Kouwenberg et al., 2005. Atmospheric CO2 fluctuations during the last millennium reconstructed by stomatal frequency analysis of Tsuga heterophylla needles. GEOLOGY, January 2005.

Lüthi, D., M. Le Floch, B. Bereiter, T. Blunier, J.-M. Barnola, U. Siegenthaler, D. Raynaud, J. Jouzel, H. Fischer, K. Kawamura, and T.F. Stocker. 2008. High-resolution carbon dioxide concentration record 650,000-800,000 years before present. Nature, Vol. 453, pp. 379-382, 15 May 2008. doi:10.1038/nature06949.

Royer, D.L. 2006. CO2-forced climate thresholds during the Phanerozoic. Geochimica et Cosmochimica Acta, Vol. 70, pp. 5665-5675. doi:10.1016/j.gca.2005.11.031.

TEMPERATURE RECONSTRUCTIONS

Moberg, A., et al. 2005. 2,000-Year Northern Hemisphere Temperature Reconstruction. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2005-019. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.

Esper, J., et al., 2003, Northern Hemisphere Extratropical Temperature Reconstruction, IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2003-036. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.

Mann, M.E. and P.D. Jones, 2003, 2,000 Year Hemispheric Multi-proxy Temperature Reconstructions, IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series #2003-051. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.

Alley, R.B.. 2004. GISP2 Ice Core Temperature and Accumulation Data. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series #2004-013. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.

VEIZER d18O% ISOTOPE DATA.  2004 Update.

Tom Van Hoof, an actual plant physiologist and author of numerous peer-reviewed papers on plant stomata made these comments…

Tom van Hoof on December 28, 2010 at 6:48 am
As one of the “stomata: people and author ofd the cited Tellus paper, I want to draw attention to one of the most interesting outcomes of our research. That is that for the past thousand years the stomata records seem to match with respect to timing to two Antarctic ice core records which are not often cited…. Matching variabilities between ice cores of such resolution has not been achieved yet… well, ice core people claim that they reproduce their flat liners, but if you zoom into detail the small fluxes never match wit respect to timing… The lone fact that stomata data of the USA and Europe have the same timing of a CO2 wiggle which has also been recorded (but with a much lower amplitude) in two Antarctic ice cores is evidence enough that Co2 variability has been larger in the past millennium then assumed. If the variability would have been as small as the ice cores tell us, plant would hav e never ever picked this signal up on two different continents on another hemisphere.

Tom van Hoof on December 28, 2010 at 11:46 pm
@ David Middleton… well actually for the somewhat older stomata data ( I focussed on the past 1000 yrs but my colleages on the whole Holocene) there are Greenland iced-core records which match pretty well… However, we can’t use them for publictions as the ice community officially redrew them as soon as the Antarctic records became available.. they claimed the records are contaminated by too much dust in the ice….

Furthermore I want to mention that we fully understand there are uncertainties with the stomata data. what bothers me is that for our records the scientific community focusses on these uncertainties in exact prediction while all the flaws and errors in ice data are ignored… furthermore it is quite amusing for me as a biologist to read the papers where physicists try to attack the proxies by playing plant physiologist…. I am very surprised the scientific community does not have a very warm welcome for new innovative techniques when those techniques put question marks at established ideas.., I always learned that these discussions are the fundamental backbone for science… therefore my hope that climate science will ever become a fullgrown scientific discipline is lost as long as politics (read funding) keeps intermingling

Tom van Hoof on January 11, 2011 at 8:24 am
To come back on questions about the validity of Stomatal index (read, NOT stomatal density) as a CO2 proxy…

We use an index value between the number of leaf stomata and the number of epidermis cells called the stomatal index instead of just the number of stomata per leafarea as some people tned to do, the reason for thsi is that indeed drought can have an influence on stomatal density, but only through the mechanism on epidermal cell expansion… By using the stomatal index the response of leaf anatomy to changes in water availability are covered, temperature itself has almost no influence on leaf anatomy, only if you would change the annual average temperature 10 of degrees celcius as is done in soem experiments… but this is not comparable with a natural situation… So basically using this index proxy we are pretty sure we are looking at CO2 levels… how big they are is something different… calibration is difficult as it relies on historical CO2 data…

The amount of noise, we choose not to put all sorts of high tech statistical tricks over our data so we are very open about our data, in my opinion noise reduction is possible when more leaves are counted….

Quote:

Ice Core Resolution

The so-called consensus will continue overestimating CO2 forcing until they accept the fact that ice core temperature estimates are at least an order of magnitude of higher resolution than ice core CO2 estimates. The ever-growing volume of peer-reviewed research on the relationship between plant stomata and CO2 will eventually force a paradigm shift.

Wagner et al., 1999. Century-Scale Shifts in Early Holocene Atmospheric CO2 Concentration. Science 18 June 1999: Vol. 284 no. 5422 pp. 1971-1973…

In contrast to conventional ice core estimates of 270 to 280 parts per million by volume (ppmv), the stomatal frequency signal suggests that early Holocene carbon dioxide concentrations were well above 300 ppmv.

[…]

Most of the Holocene ice core records from Antarctica do not have adequate temporal resolution.

[…]

Our results falsify the concept of relatively stabilized Holocene CO2 concentrations of 270 to 280 ppmv until the industrial revolution. SI-based CO2 reconstructions may even suggest that, during the early Holocene, atmospheric CO2 concentrations that were .300 ppmv could have been the rule rather than the exception.

The ice cores cannot resolve CO2 shifts that occur over periods of time shorter than twice the bubble enclosure period. This is basic signal theory. The assertion of a stable pre-industrial 270-280 ppmv is flat-out wrong.

McElwain et al., 2001. Stomatal evidence for a decline in atmospheric CO2 concentration during the Younger Dryas stadial: a comparison with Antarctic ice core records. J. Quaternary Sci., Vol. 17 pp. 21–29. ISSN 0267-8179…

It is possible that a number of the short-term fluctuations recorded using the stomatal methods cannot be detected in ice cores, such as Dome Concordia, with low ice accumulation rates. According to Neftel et al. (1988), CO2 fluctuation with a duration of less than twice the bubble enclosure time (equivalent to approximately 134 calendar yr in the case of Byrd ice and up to 550 calendar yr in Dome Concordia) cannot be detected in the ice or reconstructed by deconvolution.

Not even the highest resolution ice cores, like Law Dome, have adequate resolution to correctly image the MLO instrumental record.

Kouwenberg et al., 2005. Atmospheric CO2 fluctuations during the last millennium reconstructed by stomatal frequency analysis o fTsuga heterophylla needles . Geology; January 2005; v. 33; no. 1; p. 33–36…

The discrepancies between the ice-core and stomatal reconstructions may partially be explained by varying age distributions of the air in the bubbles because of the enclosure time in the firn-ice transition zone. This effect creates a site-specific smoothing of the signal (decades for Dome Summit South [DSS], Law Dome, even more for ice cores at low accumulation sites), as well as a difference in age between the air and surrounding ice, hampering the construction of well-constrained time scales (Trudinger et al., 2003).

Stomatal reconstructions are reproducible over at least the Northern Hemisphere, throughout the Holocene and consistently demonstrate that the pre-industrial natural carbon flux was far more variable than indicated by the ice cores.

Wagner et al., 2004. Reproducibility of Holocene atmospheric CO2 records based on stomatal frequency. Quaternary Science Reviews. 23 (2004) 1947–1954…

The majority of the stomatal frequency-based estimates of CO 2 for the Holocene do not support the widely accepted concept of comparably stable CO2 concentrations throughout the past 11,500 years. To address the critique that these stomatal frequency variations result from local environmental change or methodological insufficiencies, multiple stomatal frequency records were compared for three climatic key periods during the Holocene, namely the Preboreal oscillation, the 8.2 kyr cooling event and the Little Ice Age. The highly comparable fluctuations in the paleo-atmospheric CO2 records, which were obtained from different continents and plant species (deciduous angiosperms as well as conifers) using varying calibration approaches, provide strong evidence for the integrity of leaf-based CO2 quantification.

The Antarctic ice cores lack adequate resolution because the firn densification process acts like a low-pass filter.

Van Hoof et al., 2005. Atmospheric CO2 during the 13th century AD: reconciliation of data from ice core measurements and stomatal frequency analysis. Tellus 57B (2005), 4…

AtmosphericCO2 reconstructions are currently available from direct measurements of air enclosures in Antarctic ice and, alternatively, from stomatal frequency analysis performed on fossil leaves. A period where both methods consistently provide evidence for natural CO2 changes is during the 13th century AD. The results of the two independent methods differ significantly in the amplitude of the estimated CO2 changes (10 ppmv ice versus 34 ppmv stomatal frequency). Here, we compare the stomatal frequency and ice core results by using a firn diffusion model in order to assess the potential influence of smoothing during enclosure on the temporal resolution as well as the amplitude of the CO2 changes. The seemingly large discrepancies between the amplitudes estimated by the contrasting methods diminish when the raw stomatal data are smoothed in an analogous way to the natural smoothing which occurs in the firn.

The derivation of equilibrium climate sensitivity (ECS) to atmospheric CO2 is largely based on Antarctic ice cores. The problem is that the temperature estimates are based on oxygen isotope ratios in the ice itself; while the CO2 estimates are based on gas bubbles trapped in the ice.

The temperature data are of very high resolution. The oxygen isotope ratios are functions of the temperature at the time of snow deposition. The CO2 data are of very low and variable resolution because it takes decades to centuries for the gas bubbles to form. The CO2 values from the ice cores represent average values over many decades to centuries. The temperature values have annual to decadal resolution.

Ice Core Resolution

The highest resolution Antarctic ice core is the DE08 core from Law Dome.

Law Dome DE08 Ice Core: Reconstruction of 1969 AD depositional layer. Modified after Fischer, H. A Short Primer on Ice Core Science. Climate and Environmental Physics, Physics Institute, University of Bern.

The IPCC and so-called scientific consensus assume that it can resolve annual changes in CO2. But it can’t. Each CO2 value represents a roughly 30-yr average and not an annual value.

If you smooth the Mauna Loa instrumental record (red curve) and plant stomata-derived pre-instrumental CO2 (green curve) with a 30-yr filter, they tie into the Law Dome DE08 ice core (light blue curve) quite nicely…

The deeper DSS core (dark blue curve)has a much lower temporal resolution due to its much lower accumulation rate and compaction effects. It is totally useless in resolving century scale shifts, much less decadal shifts.

The IPCC and so-called scientific consensus correctly assume that resolution is dictated by the bubble enclosure period. However, they are incorrect in limiting the bubble enclosure period to the sealing zone. In the case of the core DE08 they assume that they are looking at a signal with a 1 cycle/1 yr frequency, sampled once every 8-10 years. The actual signal has a 1 cycle/30-40 yr frequency, sampled once every 8-10 years.

30-40 ppmv shifts in CO2 over periods less than ~60 years cannot be accurately resolved in the DE08 core. That’s dictated by basic signal theory. Wagner et al., 1999 drew a very hostile response from the so-called scientific consensus. All Dr. Wagner-Cremer did to them, was to falsify one little hypothesis…

In contrast to conventional ice core estimates of 270 to 280 parts per million by volume (ppmv), the stomatal frequency signal suggests that early Holocene carbon dioxide concentrations were well above 300 ppmv.

[…]

Our results falsify the concept of relatively stabilized Holocene CO2 concentrations of 270 to 280 ppmv until the industrial revolution. SI-based CO2 reconstructions may even suggest that, during the early Holocene, atmospheric CO2concentrations that were >300 ppmv could have been the rule rather than the exception (⁠23⁠).

I merged the data from six peer-reviewed papers on stomata-derived CO2 to build this Holocene reconstruction…

Northern Sweden (Finsinger et al., 2009), Northern Spain (Garcia-Amorena, 2008), Southern Sweden (Jessen, 2005), Washington State USA (Kouwenberg, 2004), Netherlands (Wagner et al., 1999), Denmark (Wagner et al., 2002).

The plant stomata pretty well prove that Holocene CO2 levels have frequently been in the 300-350 ppmv range and occasionally above 400 ppmv over the last 10,000 years.

The incorrect estimation of a 3°C ECS to CO2 is almost entirely driven the assumption that preindustrial CO2 levels were in the 270-280 ppmv range, as indicated by the Antarctic ice cores.

The plant stomata data clearly show that preindustrial atmospheric CO2 levels were much higher and far more variable than indicated by Antarctic ice cores. Which means that the rise in atmospheric CO2 since the 1800’s is not particularly anomalous and at least half of it is due to oceanic and biosphere responses to the warm-up from the Little Ice Age.

Kouwenberg concluded that the CO2 maximum ca. 450 AD was a local anomaly because it could not be correlated to a temperature rise in the Mann & Jones, 2003 reconstruction.

As the Earth’s climate continues to not cooperate with their models, the so-called consensus will eventually recognize and acknowledge their fundamental error. Hopefully we won’t have allowed decarbonization zealotry to bankrupt us beforehand.

Until the paradigm shifts, all estimates of the pre-industrial relationship between atmospheric CO2 and temperature derived from Antarctic ice cores will be wrong… Because the ice core temperature and CO2 time series are of vastly different resolutions. And until the “so-called consensus” gets the signal processing right, Professor Nordhaus will continue to get it wrong.

References

Alley, R.B. 2000. The Younger Dryas cold interval as viewed from central Greenland.Quaternary Science Reviews 19:213-226.

Davis, J. C. and G. C. Bohling. The search for patterns in ice-core temperature curves. 2001. Geological Perspectives of Global Climate Change, AAPG Studies in Geology No. 47, Gerhard, L.C., W.E. Harrison,and B.M. Hanson.

Finsinger, W. and F. Wagner-Cremer. Stomatal-based inference models for reconstruction of atmospheric CO2 concentration: a method assessment using a calibration and validation approach. The Holocene 19,5 (2009) pp. 757–764

Fischer, H. A Short Primer on Ice Core Science. Climate and Environmental Physics, Physics Institute, University of Bern.

Garcıa-Amorena, I., F. Wagner-Cremer, F. Gomez Manzaneque, T. B. van Hoof, S. Garcıa Alvarez, and H. Visscher. 2008. CO2 radiative forcing during the Holocene Thermal Maximum revealed by stomatal frequency of Iberian oak leaves. Biogeosciences Discussions 5, 3945–3964, 2008.

Jessen, C. A., Rundgren, M., Bjorck, S. and Hammarlund, D. 2005. Abrupt climatic changes and an unstable transition into a late Holocene Thermal Decline: a multiproxy lacustrine record from southern Sweden. J. Quaternary Sci., Vol. 20 pp. 349–362. ISSN 0267-8179.

Kaufmann, R. K., H. Kauppi, M. L. Mann, and J. H. Stock (2011), Reconciling anthropogenic climate change with observed temperature 1998-2008, Proceedings of the National Academy of Sciences, PNAS 2011 : 1102467108v1-4.

Kouwenberg, LLR. 2004. Application of conifer needles in the reconstruction of Holocene CO2 levels. PhD Thesis. Laboratory of Palaeobotany and Palynology, University of Utrecht.

Kouwenberg, LLR, Wagner F, Kurschner WM, Visscher H (2005) Atmospheric CO2 fluctuations during the last millennium reconstructed by stomatal frequency analysis of Tsuga heterophylla needles. Geology 33:33–36

Ljungqvist, F.C.2009. Temperature proxy records covering the last two millennia: a tabular and visual overview. Geografiska Annaler: Physical Geography, Vol. 91A, pp. 11-29.

Ljungqvist, F.C. 2010. A new reconstruction of temperature variability in the extra-tropical Northern Hemisphere during the last two millennia. Geografiska Annaler: Physical Geography, Vol. 92 A(3), pp. 339-351, September 2010. DOI: 10.1111/j.1468-0459.2010.00399.x

Mann, M.E., Z. Zhang, M.K. Hughes, R.S. Bradley, S.K. Miller, S. Rutherford, and F. Ni. 2008. Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia. Proceedings of the National Academy of Sciences, Vol. 105, No. 36, September 9, 2008. doi:10.1073/pnas.0805721105

McElwain et al., 2001. Stomatal evidence for a decline in atmospheric CO2 concentration during the Younger Dryas stadial: a comparison with Antarctic ice core records. J. Quaternary Sci., Vol. 17 pp. 21–29. ISSN 0267-8179

Rundgren et al., 2005. Last interglacial atmospheric CO2 changes from stomatal index data and their relation to climate variations. Global and Planetary Change 49 (2005) 47–62.

Van Hoof et al., 2005. Atmospheric CO2 during the 13th century AD: reconciliation of data from ice core measurements and stomatal frequency analysis. Tellus 57B (2005), 4

Wagner F, et al., 1999. Century-scale shifts in Early Holocene CO2 concentration. Science284:1971–1973.

Wagner F, Aaby B, Visscher H, 2002. Rapid atmospheric CO2 changes associated with the 8200-years-B.P. cooling event. Proc Natl Acad Sci USA 99:12011–12014.

Wagner F, Kouwenberg LLR, van Hoof TB, Visscher H, 2004. Reproducibility of Holocene atmospheric CO2 records based on stomatal frequency. Quat Sci Rev 23:1947–1954

A Brief History of Atmospheric Carbon Dioxide Record-Breaking

Guest Post by David Middleton

The World Meteorological Organization (Why do I always think of Team America: World Police whenever “World” and “Organization” appear in the same title?) recently announced that atmospheric greenhouse gases had once again set a new record.

Greenhouse gases reach another new record high!

Records are made to be broken

I wonder if the folks at the WMO are aware of the following three facts:

1) The first “record high” CO2 level was set in 1809, at a time when cumulative anthropogenic carbon emissions had yet to exceed the equivalent of 0.2 ppmv CO2?

Figure 1. The Original CO2 “Hockey Stick.” CO2 emissions data from Oak Ridge National Laboratory’s Carbon Dioxide Information Analysis Center (CDIAC). The emissions (GtC) were divided by 2.13 to obtain ppmv CO2.

2) From 1750 to 1875, atmospheric CO2 rose at ten times the rate of the cumulative anthropogenic emissions…

Figure 2. Where, oh where, did that CO2 come from?

3) Cumulative anthropogenic emissions didn’t “catch up” to the rise in atmospheric CO2 until 1960…

Figure 3. It took humans over 100 years to “catch up” to nature.

The emissions were only able to “catch up” because atmospheric CO2 levels stalled at ~312 ppmv from 1940-1955.

The mid-20th century decline in atmospheric CO2

The highest resolution Antarctic ice cores I am aware of come from Law Dome (Etheridge et al., 1998), particularly the DE08 core. Over the past decade, the Law Dome ice core resolution has been improved through denser sampling and the application of frequency enhancing signal processing techniques (Trudinger et el., 2002 and MacFarling Meure et al., 2006). Not surprisingly, the higher resolution data are indicating more variability in preindustrial CO2 levels.

Plant stomata reconstructions (Kouwenberg et al., 2005, Finsinger and Wagner-Cremer, 2009) and contemporary chemical analyses (Beck, 2007) indicate that CO2 levels in the 1930′s to early 1940′s were in the 340 to 400 ppmv range and then declined sharply in the 1950’s. These findings have been rejected by the so-called scientific consensus because this fluctuation is not resolved in Antarctic ice cores. However, MacFarling Meure et al., 2006 found possible evidence of a mid-20th Century CO2 decline in the DE08 ice core…

The stabilization of atmospheric CO2 concentration during the 1940s and 1950s is a notable feature in the ice core record. The new high density measurements confirm this result and show that CO2 concentrations stabilized at 310–312 ppm from ~1940–1955. The CH4 and N2O growth rates also decreased during this period, although the N2O variation is comparable to the measurement uncertainty. Smoothing due to enclosure of air in the ice (about 10 years at DE08) removes high frequency variations from the record, so the true atmospheric variation may have been larger than represented in the ice core air record. Even a decrease in the atmospheric CO2 concentration during the mid-1940s is consistent with the Law Dome record and the air enclosure smoothing, suggesting a large additional sink of ~3.0 PgC yr-1 [Trudinger et al., 2002a]. The d13CO2 record during this time suggests that this additional sink was mostly oceanic and not caused by lower fossil emissions or the terrestrial biosphere [Etheridge et al., 1996; Trudinger et al., 2002a]. The processes that could cause this response are still unknown.

[11] The CO2 stabilization occurred during a shift from persistent El Niño to La Niña conditions [Allan and D’Arrigo, 1999]. This coincided with a warm-cool phase change of the Pacific Decadal Oscillation [Mantua et al., 1997], cooling temperatures [Moberg et al., 2005] and progressively weakening North Atlantic thermohaline circulation [Latif et al., 2004]. The combined effect of these factors on the trace gas budgets is not presently well understood. They may be significant for the atmospheric CO2 concentration if fluxes in areas of carbon uptake, such as the North Pacific Ocean, are enhanced, or if efflux from the tropics is suppressed.

From about 1940 through 1955, approximately 24 billion tons of carbon went straight from the exhaust pipes into the oceans and/or biosphere.

Figure 4. Oh where, oh where did all that carbon go?

If oceanic uptake of CO2 caused ocean acidification, shouldn’t we see some evidence of it? Shouldn’t “a large additional sink of ~3.0 PgC yr-1″ (or more) from ~1940–1955 have left a mark somewhere in the oceans? Maybe dissolved some snails or a reef?

Had atmospheric CO2 simply followed the preindustrial trajectory, it very likely would have reached 315-345 ppmv by 2010…

Figure 5. Natural sources probably account for 40-60% of the rise in atmospheric CO2 since 1750.

Oddly enough, plant stomata-derived CO2 reconstructions indicate that CO2 levels of 315-345 ppmv have not been uncommon throughout the Holocene…

Figure 6. CO2 from plant stomata: Northern Sweden (Finsinger et al., 2009), Northern Spain (Garcia-Amorena, 2008), Southern Sweden (Jessen, 2005), Washington State USA (Kouwenberg, 2004), Netherlands (Wagner et al., 1999), Denmark (Wagner et al., 2002).

So, what on Earth could have driven all of that CO2 variability before humans started burning fossil fuels? Could it possibly have been temperature changes?

CO2 as feedback

When I plot a NH temperature reconstruction (Moberg et al., 2005) along with the Law Dome CO2 record, it sure looks to me as if the CO2 started rising about 100 years after the temperature started rising…

Figure 7. Temperature reconstruction (Moberg et al., 2005) and Law Dome CO2 (MacFarling Meure et al., 2006)

The rise in CO2 from 1842-1945 looks a heck of a lot like the rise in temperature from 1750-1852…

Figure 8. Possible relationship between temperature increase and subsequent CO2 rise.

The correlation is very strong. A calculated CO2 chronology yields a good match to the DE08 ice core and stomata-derived CO2 since 1850. However, it indicates that atmospheric CO2 would have reached ~430 ppmv in the mid-12th century AD.

Figure 9. CO2 calculated from Moberg temperatures (dark blue curve), Law Dome ice cores (magenta curve) and plant stomata (green, light blue and purple squares).

The mid-12th century peak in CO2 is not supported by either the ice cores or the plant stomata. The correlation breaks down before the 1830’s. However, the same break down also happens when CO2 is treated as forcing rather than feedback.

CO2 as forcing

If I directly cross plot CO2 vs. temperature with no lag time, I get a fair correlation with the post DE08 core (>1833) data and no correlation at all with pre-DE08 core (<1833) data…

Figure 10. Temperature and [CO2] have a moderate correlation since ~1833; but no correlation at all before 1833.

If I extrapolate out to about 840 ppmv CO2, I get about 3 °C of warming relative to 275 ppmv. So, I get the same amount of warming for a tripling of preindustrial CO2 that the IPCC says we’ll get with a doubling.

Figure 11. CO2 from the Law Dome DE08 core plotted against Moberg’s NH temperature reconstruction.

Based on this correlation, the equilibrium climate sensitivity to a doubling of preindustrial CO2 is ~1.5 to 2.0 °C. But, the total lack of a correlation in the ice cores older than DE08 is very puzzling.

Ice core resolution and the lack a CO2-temperature coupling before 1833

Could the lack of variability in the older (and deeper) cores have something to do with resolution? The DE08 core is of far higher resolution than pretty well all of the other Antarctic ice cores, including the deeper and older DSS core from Law Dome.

Figure 12. The temporal resolution of ice cores is dictated by the snow accumulation rate.

The amplitude of the CO2 “signal” also appears to be well-correlated with the snow accumulation rate (resolution) of the ice cores…

Figure 13. Accumulation rate vs. CO2 for various ice cores from Antarctica and Greenland.

Could it be that snow accumulation rates significantly lower than 1 m/yr simply can’t resolve century-scale and higher frequency CO2 shifts? Could it also be that the frequency degradation is also attenuating the amplitude of the CO2 “signal”?

If the vast majority of the ice cores older and deeper than DE08 can’t resolve century-scale and higher frequency CO2 shifts, doesn’t it make sense that ice core-derived CO2 and temperature would appear to be poorly coupled over most of the Holocene?

Why is it that the evidence always seems to indicate that the IPCC’s best case scenario is the worst that can happen in the real world?

Brad Plummer’s recent piece in the Washington Post featured a graph that caught my eye…

Figure 14. The IPCC’s mythical scenarios. I think the shaded area represents the greentopian range.

It appears that a “business as usual” (A1FI) will turn Earth into Venus by 2100 AD.

But, what happens if I use real data?

Let’s assume that the atmospheric CO2 level will rise along an exponential trend line until 2100.

Figure 15. CO2 projected to 560 ppmv by 2100.

I get a CO2 level of 560 ppmv, comparable to the IPCC SRES B2 emissions scenario…

Figure 16. IPCC emissions scenarios.

So, business as usual will likely lead to the same CO2 level as an IPCC greentopian scenario. Why am I not surprised?

Assuming all of the warming since 1833 was caused by CO2 (it wasn’t), 560 ppmv will lead to about 1°C of additional warming by the year 2100.

Figure 17. Projected temperature rise derived from Moberg NH temperature reconstruction and Law Dome DE08 ice core CO2.
Projected Temp. Anom. = 2.6142 * ln(CO2) – 15.141

How does this compare with the IPCC’s mythical scenarios? About as expected. The worst case scenario based on actual observations is comparable to the IPCC’s best case, greentopian scenario…

Figure 18. Projected temperature rise derived from Moberg NH temperature reconstruction and Law Dome DE08 ice core CO2 indicates that the IPCC’s 2°C “limit” will not be exceeded.

Conclusions

  • Atmospheric CO2 concentration records were being broken long before anthropogenic emissions became significant.
  • Atmospheric CO2 levels were rising much faster than anthropogenic emissions from 1750-1875.
  • Anthropogenic emissions did not “catch up” to atmospheric CO2 until 1960.
  • The natural carbon flux is much more variable than the so-called scientific consensus thinks it is.
  • The equilibrium climate sensitivity (ECS) cannot be more than 2°C and is probably closer to 1°C.
  • The worst-case scenario based on the evidence is comparable to the IPCC’s most greentopian, best-case scenario.
  • Ice cores with accumulation rates less than 1m/yr are not useful for ECS estimations.

The ECS derived from the Law Dome DE08 ice core and Moberg’s NH temperature reconstruction assumes that all of the warming since 1833 was due to CO2. We know for a fact that at least half of the warming was due to solar influences and natural climatic oscillations. So the derived 2°C is more likely to be 1°C. Since it is clear that about half of the rise from 275 to 400 ppmv was natural, the anthropogenic component of that 1°C ECS is probably less than 0.7°C.

The lack of a correlation between temperature and CO2 from the start of the Holocene up until 1833 and the fact that the modern CO2 rise outpaced the anthropogenic emissions for about 200 years leads this amateur climate researcher to concluded that CO2 must have been a lot more variable over the last 10,000 years than the Antarctic ice core indicate.

Appendix I: Another Way to Look at the CO2 growth rate

In Figure 15 I used the Excel-calculated exponential trend line to extrapolate the MLO CO2 time series to the end of this century. If I extrapolate the emissions and assume 55% of emissions remain in atmosphere, I get ~702 ppmv by the end of the century, with an additional 0.6°C of warming. A total warming of 2.5°C above “preindustrial.” Even this worse than worst case scenario results in about 1°C less warming than the A1B reference scenario. It falls about mid-way between A1B and the top of the greentopian range.

Appendix II: CO2 Records, the Early Years

Whenever CO2 records are mentioned or breathtaking pronouncements like, “Carbon dioxide at highest level in 800,000 years” are made, I always like to take a look at those “records” in a geological context. The following graphs were generated from Bill Illis’ excellent collection of paleo-climate data.

Greenhouse gases reach another new record high! Or did they? The “Anthropocene” doesn’t look a heck of a lot different than the prior 25 million years… Apart from being a lot colder.

The “Anthropocene’s” CO2 “Hockey Stick” looks more like a needle in a haystack from a geological perspective. And it looks to me as if Earth might be on track to run out of CO2 in about 25 million years.

One of my all-time favorites! Note the total lack of correlation between CO2 and temperature throughout most of the Phanerozoic Eon.

In the following bar chart I grouped CO2 by geologic period. The Cambrian through Cretaceous are drawn from Berner and Kothavala, 2001 (GEOCARB), the Tertiary is from Pagani, et al. 2006 (deep sea sediment cores), the Pleistocene is from Lüthi, et al. 2008 (EPICA C Antarctic ice core), the “Anthropocene” is from NOAA-ESRL (Mauna Loa Observatory) and the CO2 starvation is from Ward et al., 2005.

“Anthropocene” CO2 levels are a lot closer to the C3 plant starvation (Ward et al., 2005) range than they are to most of the prior 540 million years.

[SARC ON] I thought about including Venus on the bar chart; but I would have had to use a logarithmic scale. [SARC OFF]

Appendix III: Plant Stomata-Derived CO2

The catalogue of peer-reviewed papers demonstrating higher and more variable preindustrial CO2 levels is quite impressive and growing. Here are a few highlights:

Wagner et al., 1999. Century-Scale Shifts in Early Holocene Atmospheric CO2 Concentration. Science 18 June 1999: Vol. 284 no. 5422 pp. 1971-1973

In contrast to conventional ice core estimates of 270 to 280 parts per million by volume (ppmv), the stomatal frequency signal suggests that early Holocene carbon dioxide concentrations were well above 300 ppmv.

[…]

Most of the Holocene ice core records from Antarctica do not have adequate temporal resolution.

[…]

Our results falsify the concept of relatively stabilized Holocene CO2 concentrations of 270 to 280 ppmv until the industrial revolution. SI-based CO2 reconstructions may even suggest that, during the early Holocene, atmospheric CO2 concentrations that were .300 ppmv could have been the rule rather than the exception.

The ice cores cannot resolve CO2 shifts that occur over periods of time shorter than twice the bubble enclosure period. This is basic signal theory. The assertion of a stable pre-industrial 270-280 ppmv is flat-out wrong.

McElwain et al., 2001. Stomatal evidence for a decline in atmospheric CO2 concentration during the Younger Dryas stadial: a comparison with Antarctic ice core records. J. Quaternary Sci., Vol. 17 pp. 21–29. ISSN 0267-8179…

It is possible that a number of the short-term fluctuations recorded using the stomatal methods cannot be detected in ice cores, such as Dome Concordia, with low ice accumulation rates. According to Neftel et al. (1988), CO2 fluctuation with a duration of less than twice the bubble enclosure time (equivalent to approximately 134 calendar yr in the case of Byrd ice and up to 550 calendar yr in Dome Concordia) cannot be detected in the ice or reconstructed by deconvolution.

Not even the highest resolution ice cores, like Law Dome, have adequate resolution to correctly image the MLO instrumental record.

Kouwenberg et al., 2005. Atmospheric CO2 fluctuations during the last millennium reconstructed by stomatal frequency analysis of Tsuga heterophylla needles. Geology; January 2005; v. 33; no. 1; p. 33–36…

The discrepancies between the ice-core and stomatal reconstructions may partially be explained by varying age distributions of the air in the bubbles because of the enclosure time in the firn-ice transition zone. This effect creates a site-specific smoothing of the signal (decades for Dome Summit South [DSS], Law Dome, even more for ice cores at low accumulation sites), as well as a difference in age between the air and surrounding ice, hampering the construction of well-constrained time scales (Trudinger et al., 2003).

Stomatal reconstructions are reproducible over at least the Northern Hemisphere, throughout the Holocene and consistently demonstrate that the pre-industrial natural carbon flux was far more variable than indicated by the ice cores.

Wagner et al., 2004. Reproducibility of Holocene atmospheric CO2 records based on stomatal frequency. Quaternary Science Reviews. 23 (2004) 1947–1954…

The majority of the stomatal frequency-based estimates of CO 2 for the Holocene do not support the widely accepted concept of comparably stable CO2 concentrations throughout the past 11,500 years. To address the critique that these stomatal frequency variations result from local environmental change or methodological insufficiencies, multiple stomatal frequency records were compared for three climatic key periods during the Holocene, namely the Preboreal oscillation, the 8.2 kyr cooling event and the Little Ice Age. The highly comparable fluctuations in the paleo-atmospheric CO2 records, which were obtained from different continents and plant species (deciduous angiosperms as well as conifers) using varying calibration approaches, provide strong evidence for the integrity of leaf-based CO2 quantification.

The Antarctic ice cores lack adequate resolution because the firn densification process acts like a low-pass filter.

Van Hoof et al., 2005. Atmospheric CO2 during the 13th century AD: reconciliation of data from ice core measurements and stomatal frequency analysis. Tellus 57B (2005), 4…

Atmospheric CO2 reconstructions are currently available from direct measurements of air enclosures in Antarctic ice and, alternatively, from stomatal frequency analysis performed on fossil leaves. A period where both methods consistently provide evidence for natural CO2 changes is during the 13th century AD. The results of the two independent methods differ significantly in the amplitude of the estimated CO2 changes (10 ppmv ice versus 34 ppmv stomatal frequency). Here, we compare the stomatal frequency and ice core results by using a firn diffusion model in order to assess the potential influence of smoothing during enclosure on the temporal resolution as well as the amplitude of the CO2 changes. The seemingly large discrepancies between the amplitudes estimated by the contrasting methods diminish when the raw stomatal data are smoothed in an analogous way to the natural smoothing which occurs in the firn.

The derivation of equilibrium climate sensitivity (ECS) to atmospheric CO2 is largely based on Antarctic ice cores. The problem is that the temperature estimates are based on oxygen isotope ratios in the ice itself; while the CO2 estimates are based on gas bubbles trapped in the ice.

The temperature data are of very high resolution. The oxygen isotope ratios are functions of the temperature at the time of snow deposition. The CO2 data are of very low and variable resolution because it takes decades to centuries for the gas bubbles to form. The CO2 values from the ice cores represent average values over many decades to centuries. The temperature values have annual to decadal resolution.

The highest resolution Antarctic ice core is the DE08 core from Law Dome.

The IPCC and so-called scientific consensus assume that it can resolve annual changes in CO2. But it can’t. Each CO2 value represents a roughly 30-yr average and not an annual value.

If you smooth the Mauna Loa instrumental record (red curve) and plant stomata-derived pre-instrumental CO2 (green curve) with a 30-yr filter, they tie into the Law Dome DE08 ice core (light blue curve) quite nicely…

The deeper DSS core (dark blue curve) has a much lower temporal resolution due to its much lower accumulation rate and compaction effects. It is totally useless in resolving century scale shifts, much less decadal shifts.

The IPCC and so-called scientific consensus correctly assume that resolution is dictated by the bubble enclosure period. However, they are incorrect in limiting the bubble enclosure period to the sealing zone. In the case of the core DE08 they assume that they are looking at a signal with a 1 cycle/1 yr frequency, sampled once every 8-10 years. The actual signal has a 1 cycle/30-40 yr frequency, sampled once every 8-10 years.

30-40 ppmv shifts in CO2 over periods less than ~60 years cannot be accurately resolved in the DE08 core. That’s dictated by basic signal theory. Wagner et al., 1999 drew a very hostile response from the so-called scientific consensus. All Dr. Wagner-Cremer did to them was to falsify one little hypothesis…

In contrast to conventional ice core estimates of 270 to 280 parts per million by volume (ppmv), the stomatal frequency signal suggests that early Holocene carbon dioxide concentrations were well above 300 ppmv.

[…]

Our results falsify the concept of relatively stabilized Holocene CO2 concentrations of 270 to 280 ppmv until the industrial revolution. SI-based CO2 reconstructions may even suggest that, during the early Holocene, atmospheric CO2 concentrations that were >300 ppmv could have been the rule rather than the exception (⁠23⁠).

The plant stomata pretty well prove that Holocene CO2 levels have frequently been in the 300-350 ppmv range and occasionally above 400 ppmv over the last 10,000 years.

The incorrect estimation of a 3°C ECS to CO2 is almost entirely driven the assumption that preindustrial CO2 levels were in the 270-280 ppmv range, as indicated by the Antarctic ice cores.

The plant stomata data clearly show that preindustrial atmospheric CO2 levels were much higher and far more variable than indicated by Antarctic ice cores. Which means that the rise in atmospheric CO2 since the 1800’s is not particularly anomalous and at least half of it is due to oceanic and biosphere responses to the warm-up from the Little Ice Age.

Kouwenberg concluded that the CO2 maximum ca. 450 AD was a local anomaly because it could not be correlated to a temperature rise in the Mann & Jones, 2003 reconstruction.

As the Earth’s climate continues to not cooperate with their models, the so-called consensus will eventually recognize and acknowledge their fundamental error. Hopefully we won’t have allowed decarbonization zealotry to bankrupt us beforehand.

Until the paradigm shifts, all estimates of the pre-industrial relationship between atmospheric CO2 and temperature derived from Antarctic ice cores will be wrong, because the ice core temperature and CO2 time series are of vastly different resolutions. And until the “so-called consensus” gets the signal processing right, they will continue to get it wrong.

References

Anklin, M., J. Schwander, B. Stauffer, J. Tschumi, A. Fuchs, J.M. Barnola, and D. Raynaud. 1997. CO2 record between 40 and 8kyr B.P. from the Greenland Ice Core Project ice core.Journal of Geophysical Research 102:26539-26545.

Barnola et al. 1987. Vostok ice core provides 160,000-year record of atmospheric CO2.
Nature, 329, 408-414.

Berner, R.A. and Z. Kothavala, 2001. GEOCARB III: A Revised Model of Atmospheric CO2 over Phanerozoic Time, American Journal of Science, v.301, pp.182-204, February 2001.

Boden, T.A., G. Marland, and R.J. Andres. 2012. Global, Regional, and National Fossil-Fuel CO2 Emissions. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A. doi 10.3334/CDIAC/00001_V2012

Etheridge, D.M., L.P. Steele, R.L. Langenfelds, R.J. Francey, J.-M. Barnola and V.I. Morgan. 1998. Historical CO2 records from the Law Dome DE08, DE08-2, and DSS ice cores. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.

Finsinger, W. and F. Wagner-Cremer. Stomatal-based inference models for reconstruction of atmospheric CO2 concentration: a method assessment using a calibration and validation approach. The Holocene 19,5 (2009) pp. 757–764

Fischer, H. A Short Primer on Ice Core Science. Climate and Environmental Physics, Physics Institute, University of Bern.

Garcıa-Amorena, I., F. Wagner-Cremer, F. Gomez Manzaneque, T. B. van Hoof, S. Garcıa Alvarez, and H. Visscher. 2008. CO2 radiative forcing during the Holocene Thermal Maximum revealed by stomatal frequency of Iberian oak leaves. Biogeosciences Discussions 5, 3945–3964, 2008.

Illis, B. 2009. Searching the PaleoClimate Record for Estimated Correlations: Temperature, CO2 and Sea Level. Watts Up With That?

Indermühle A., T.F. Stocker, F. Joos, H. Fischer, H.J. Smith, M. Wahlen, B. Deck, D. Mastroianni, J. Tschumi, T. Blunier, R. Meyer, B. Stauffer, 1999, Holocene carbon-cycle dynamics based on CO2 trapped in ice at Taylor Dome, Antarctica. Nature 398, 121-126.

Jessen, C. A., Rundgren, M., Bjorck, S. and Hammarlund, D. 2005. Abrupt climatic changes and an unstable transition into a late Holocene Thermal Decline: a multiproxy lacustrine record from southern Sweden. J. Quaternary Sci., Vol. 20 pp. 349–362. ISSN 0267-8179.

Kouwenberg, LLR. 2004. Application of conifer needles in the reconstruction of Holocene CO2 levels. PhD Thesis. Laboratory of Palaeobotany and Palynology, University of Utrecht.

Kouwenberg, LLR, Wagner F, Kurschner WM, Visscher H (2005) Atmospheric CO2 fluctuations during the last millennium reconstructed by stomatal frequency analysis of Tsuga heterophylla needles. Geology 33:33–36

Ljungqvist, F.C.2009. Temperature proxy records covering the last two millennia: a tabular and visual overview. Geografiska Annaler: Physical Geography, Vol. 91A, pp. 11-29.

Ljungqvist, F.C. 2010. A new reconstruction of temperature variability in the extra-tropical Northern Hemisphere during the last two millennia. Geografiska Annaler: Physical Geography, Vol. 92 A(3), pp. 339-351, September 2010. DOI: 10.1111/j.1468-0459.2010.00399.x

Lüthi, D., M. Le Floch, B. Bereiter, T. Blunier, J.-M. Barnola, U. Siegenthaler, D. Raynaud, J. Jouzel, H. Fischer, K. Kawamura, and T.F. Stocker. 2008. High-resolution carbon dioxide concentration record 650,000-800,000 years before present. Nature, Vol. 453, pp. 379-382, 15 May 2008. doi:10.1038/nature06949

MacFarling Meure, C., D. Etheridge, C. Trudinger, P. Steele, R. Langenfelds, T. van Ommen, A. Smith, and J. Elkins (2006), Law Dome CO2, CH4 and N2O ice core records extended to 2000 years BP, Geophys. Res. Lett., 33, L14810, doi:10.1029/2006GL026152.

McElwain et al., 2001. Stomatal evidence for a decline in atmospheric CO2 concentration during the Younger Dryas stadial: a comparison with Antarctic ice core records. J. Quaternary Sci., Vol. 17 pp. 21–29. ISSN 0267-8179

Moberg, A., D.M. Sonechkin, K. Holmgren, N.M. Datsenko and W. Karlén. 2005.
Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data. Nature, Vol. 433, No. 7026, pp. 613-617, 10 February 2005.

Morice, C.P., J.J. Kennedy, N.A. Rayner, P.D. Jones (2011), Quantifying uncertainties in global and regional temperature change using an ensemble of observational estimates: the HadCRUT4 dataset, Journal of Geophysical Research, accepted.

Pagani, M., J.C. Zachos, K.H. Freeman, B. Tipple, and S. Bohaty. 2005. Marked Decline in Atmospheric Carbon Dioxide Concentrations During the Paleogene. Science, Vol. 309, pp. 600-603, 22 July 2005.

Rundgren et al., 2005. Last interglacial atmospheric CO2 changes from stomatal index data and their relation to climate variations. Global and Planetary Change 49 (2005) 47–62.

Smith, H. J., Fischer, H., Mastroianni, D., Deck, B. and Wahlen, M., 1999, Dual modes of the carbon cycle since the Last Glacial Maximum. Nature 400, 248-250.

Trudinger, C. M., I. G. Enting, P. J. Rayner, and R. J. Francey (2002), Kalman filter analysis of ice core data 2. Double deconvolution of CO2 and δ13C measurements, J. Geophys. Res., 107(D20), 4423, doi:10.1029/2001JD001112.

Van Hoof et al., 2005. Atmospheric CO2 during the 13th century AD: reconciliation of data from ice core measurements and stomatal frequency analysis. Tellus 57B (2005), 4

Wagner F, et al., 1999. Century-scale shifts in Early Holocene CO2 concentration. Science284:1971–1973.

Wagner F, Aaby B, Visscher H, 2002. Rapid atmospheric CO2 changes associated with the 8200-years-B.P. cooling event. Proc Natl Acad Sci USA 99:12011–12014.

Wagner F, Kouwenberg LLR, van Hoof TB, Visscher H, 2004. Reproducibility of Holocene atmospheric CO2 records based on stomatal frequency. Quat Sci Rev 23:1947–1954

Ward, J.K., Harris, J.M., Cerling, T.E., Wiedenhoeft, A., Lott, M.J., Dearing, M.-D., Coltrain, J.B. and Ehleringer, J.R. 2005. Carbon starvation in glacial trees recovered from the La Brea tar pits, southern California. Proceedings of the National Academy of Sciences, USA 102: 690-694.

Stomata Notes

Ferdinand Engelbeen says:September 30, 2011 at 8:30 am

[…]

I don’t want to go back to 274 ppmv (LIA), but 280 ppmv during the Medieval Warm Period was not that bad.

[…]

Decadal- centennial- and millennial-scale fluctuations in atmospheric CO2 from 270-360 ppmv have been the norm throughout the Holocene. The natural source-sink ratio is far more variable than indicated by the ice cores. This was occurring long before man ever discovered how to burn things.

Wagner et al., 1999. Century-Scale Shifts in Early Holocene Atmospheric CO2 Concentration. Science 18 June 1999: Vol. 284 no. 5422 pp. 1971-1973…

In contrast to conventional ice core estimates of 270 to 280 parts per million by volume (ppmv), the stomatal frequency signal suggests that early Holocene carbon dioxide concentrations were well above 300 ppmv.

[…]

Most of the Holocene ice core records from Antarctica do not have adequate temporal resolution.

[…]

Our results falsify the concept of relatively stabilized Holocene CO2 concentrations of 270 to 280 ppmv until the industrial revolution. SI-based CO2 reconstructions may even suggest that, during the early Holocene, atmospheric CO2 concentrations that were .300 ppmv could have been the rule rather than the exception.

Fig. 1 from Wagner et al., 1999

The ice cores cannot resolve CO2 shifts that occur over periods of time shorter than twice the bubble enclosure period. This is basic Nyquist Sampling Theorem. The assertion of a stable pre-industrial 270-280 ppmv is flat-out wrong.

McElwain et al., 2001. Stomatal evidence for a decline in atmospheric CO2 concentration during the Younger Dryas stadial: a comparison with Antarctic ice core records. J. Quaternary Sci., Vol. 17 pp. 21–29. ISSN 0267-8179…

It is possible that a number of the short-term fluctuations recorded using the stomatal methods cannot be detected in ice cores, such as Dome Concordia, with low ice accumulation rates. According to Neftel et al. (1988), CO2 fluctuation with a duration of less than twice the bubble enclosure time (equivalent to approximately 134 calendar yr in the case of Byrd ice and up to 550 calendar yr in Dome Concordia) cannot be detected in the ice or reconstructed by deconvolution.

Not even the highest resolution ice cores, like Law Dome, have adequate resolution to correctly image the MLO instrumental record.

Kouwenberg et al., 2005. Atmospheric CO2 fluctuations during the last millennium reconstructed by stomatal frequency analysis ofTsuga heterophylla needles . Geology; January 2005; v. 33; no. 1; p. 33–36…

The discrepancies between the ice-core and stomatal reconstructions may partially be explained by varying age distributions of the air in the bubbles because of the enclosure time in the firn-ice transition zone. This effect creates a site-specific smoothing of the signal (decades for Dome Summit South [DSS], Law Dome, even more for ice cores at low accumulation sites), as well as a difference in age between the air and surrounding ice, hampering the construction of well-constrained time scales (Trudinger et al., 2003).

Stomatal reconstructions are reproducible over at least the Northern Hemisphere, throughout the Holocene and consistently demonstrate that the pre-industrial natural carbon flux was far more variable than indicated by the ice cores.

Fig. 3 from Kouwenberg et al., 2005

Wagner et al., 2004. Reproducibility of Holocene atmospheric CO2 records based on stomatal frequency. Quaternary Science Reviews. 23 (2004) 1947–1954…

The majority of the stomatal frequency-based estimates ofCO 2 for the Holocene do not support the widely accepted concept of comparably stable CO2 concentrations throughout the past 11,500 years. To address the critique that these stomatal frequency variations result from local environmental change or methodological insufficiencies, multiple stomatal frequency records were compared for three climatic key periods during the Holocene, namely the Preboreal oscillation, the 8.2 kyr cooling event and the Little Ice Age. The highly comparable fluctuations in the paleo-atmospheric CO2 records, which were obtained from different continents and plant species (deciduous angiosperms as well as conifers) using varying calibration approaches, provide strong evidence for the integrity of leaf-based CO2 quantification.

The Antarctic ice cores lack adequate resolution because the firn densification process acts like a low-pass filter.

Van Hoof et al., 2005. Atmospheric CO2 during the 13th century AD: reconciliation of data from ice core measurements and stomatal frequency analysis. Tellus 57B (2005), 4…

AtmosphericCO2 reconstructions are currently available from direct measurements of air enclosures in Antarctic ice and, alternatively, from stomatal frequency analysis performed on fossil leaves. A period where both methods consistently provide evidence for natural CO2 changes is during the 13th century AD. The results of the two independent methods differ significantly in the amplitude of the estimated CO2 changes (10 ppmv ice versus 34 ppmv stomatal frequency). Here, we compare the stomatal frequency and ice core results by using a firn diffusion model in order to assess the potential influence of smoothing during enclosure on the temporal resolution as well as the amplitude of the CO2 changes. The seemingly large discrepancies between the amplitudes estimated by the contrasting methods diminish when the raw stomatal data are smoothed in an analogous way to the natural smoothing which occurs in the firn.

Any estimate of the pre-industrial relationship between atmospheric CO2 and temperature derived from Antarctic ice cores is wrong… Because the ice core temperature and CO2 time series have vastly different resolutions.

It is physically impossible for Law Dome to have a resolution better than 60 years. The differential between the ice age and gas age is at least 30 years…

Mixing of air from the ice sheet surface to the sealing depth is primarily by molecular diffusion. The rate of air mixing by diffusion in the firn decreases as the density increases and the open porosity decreases with depth. Etheridge et al. (1996) determined the sealing depth at DE08 to be 72 m where the age of the ice is 40±1 years; at DE08-2 to be 72 m depth and 40 years; and at DSS to be 66 m depth and 68 years. For more details on dating the Law Dome ice cores and sealing densities, please refer to Etheridge et al. (1996).

Historical CO2 Records from the Law Dome DE08, DE08-2, and DSS Ice Cores

Ice cores cannot resolve CO2 shifts that occur over time periods less than twice the bubble enclosure time. That is basic Nyquist Sampling Theorem.

At the time the cores were taken, the sealing depth ranged from 66-72 m at an ice age of 40-68 years. None of those cores have the resolution to properly image the MLO instrumental record.

Ferdinand Engelbeen says:

October 1, 2011 at 1:32 am

David Middleton says:

September 30, 2011 at 6:59 pm

You can’t recover higher frequencies than you put into the ground. The Nyquist frequency is equivalent to two-times the bubble enclosure period.

Agreed, but the bubble enclosure period in the high accumulation Law Dome cores is only 8 years starting at 72 m depth. Thus any continuous change of 16 years above the accuracy limits (1.2 ppmv, 1 sigma) can be detected in the ice core. For the lower accumulation third Law Dome core, the closure period is 21 years, thus any frequency of longer than 40 years would be detected. In the case of the MWP-LIA change, the frequency is ~1000 years, thus no problem to detect the change in CO2 between the MWP and LIA, which was about 6 ppmv. That means that it is highly unlikely that the variability seen in stomata data is real, anyway the higher average CO2 levels are impossible, as the ice core data are filtering out the higher frequencies, but filtering doesn’t change the average…

I’m sorry, Ferdinand, but you are totally wrong…

The enclosed air at any depth in the ice has a mean age, (aa), that is younger than the age of the host ice layer (ai), from which the air is extracted. The difference (δa) equals the time (Ts) for the ice layer to reach a depth (ds), where air becomes sealed in the pore space, minus the mean time (Td) for air to mix down the depth. The mean air age is thus

aa = ai + δa = ai + Ts – Td

where ages are dates A.D.

Mixing of air from the ice sheet surface to the sealing depth is primarily by molecular diffusion. The rate of air mixing by diffusion in the firn decreases as the density increases and the open porosity decreases with depth. Etheridge et al. (1996) determined the sealing depth at DE08 to be 72 m where the age of the ice is 40±1 years; at DE08-2 to be 72 m depth and 40 years; and at DSS to be 66 m depth and 68 years. For more details on dating the Law Dome ice cores and sealing densities, please refer to Etheridge et al. (1996).

Historical CO2 Records from the Law Dome DE08, DE08-2, and DSS Ice Cores

Aa = Ai + δa = Ai + Ts – Td

δa = Ts – Td

Aa = Mean air age

Ai = Ice age at extraction depth

Ts = Time for ice to reach sealing depth

Td = Time for air to mix down to sealing depth

DE08 205

Ai=      1939

Aa=     1969

δa=      30

Ts=      40

Td=     10

d=        72

The bubble enclosure time is 4 times the time for the air to mix down to the sealing depth.  Every point in the DE08, DE08-2 and DSS cores is approximately a 30-yr moving average of annual CO2 concentrations.  The highest frequency recoverable is equivalent to a 30-yr period.  The Nyquist frequency at Law Dome is equivalent to a period of 60-yr.

Law Dome cannot resolve CO2 shifts that occur over periods of less than 60 years.  That is an absolute immutable fact.

David Middleton says:
October 2, 2011 at 6:53 am

David you are confusing between mean gas age of the air enclosed in the ice and gas age distribution within that enclosed air.

At sealing depth of 72 meter, the air is starting to be sealed from the atmosphere. At that moment the average gas age is only 10 years older than in the atmosphere, while the ice age is already 40 years. The gas age distribution at that moment is mainly +/- 3 years, be it with a relative long tail of older gas ages. Then it takes about 8 years to close all bubbles. That means that the average gas age now goes up at the same pace as the ice age, thus the mean gas age now is 18 years and because of less and less sealing bubbles left, the gas age distibution then is less than 8 years + the gas age distribution at sealing start depth, that makes about 11 years for the main age distibution, with relative smaller leads and longer tails of younger and older air, see Fig 11 in:
http://courses.washington.edu/proxies/GHG.pdf

The bubble enclosure time is 4 times the time for the air to mix down to the sealing depth.

Here you are mistaken: there is no bubble enclosure until 72 m depth and all air is fully enclosed at 83 m depth, that is about 8 years (with 1.2 m ice equivalent precipitation at Law Dome). Thus the bubble enclosure time is less than the mix down time of the air in the firn.
The bubble enclosure time and gas age distribution in the bubbles have nothing to do with the mean gas age or ice age or ice age – gas age difference, only with temperature and the static pressure caused by precipitation.

Ferdinand,

You are totally 100% wrong.

Sintering begins when the snow is buried to a depth sufficient to compact its density to 0.55 kg/l (~9 m at DE08).  The bubbles begin to close off at ~.70 kg/l (~60 m at DE08) and are completely sealed off at a density of ~0.84 kg/l (72 m at DE08).  At the time the core was drilled (1987), the relatively open mixing interval was from the surface down to ~60 m (“1954″ ice layer).  The sealing interval was from 60-72 m (1954 down to 1946).  Even though the sealing interval only spanned 8 ice years, it contained a 30-yr blend of gases because it took that interval ~30 years to be buried to a depth sufficient to achieve sealing density.

At the time of deposition of the “1969” ice layer in the DE-08 core, the top of sealed ice was at an approximate depth of 72 m at the “1929” layer.  The sealing interval in 1969 was from the “1937” layer down to the “1929” layer.  From the 1969 surface down to the “1937” layer the firn was permeable.  During the 10 years that the 1969 air mixed down to the “1939” layer, the 1929-1937 interval sealed completely off.

The air trapped at the “1939” ice layer was a mixture of 1939-1969 air.  The mean age of that air was not 1969, as asserted by Etheridge et al.; the mean air age was no younger than 1954.  It was actually older than 1954 because the firn/ice becomes less permeable with depth.

Law Dome DE08 Ice Core: Reconstruction of 1969 AD depositional layer. Modified after Fischer, H. A Short Primer on Ice Core Science. Climate and Environmental Physics, Physics Institute, University of Bern.

Fischer, H. A Short Primer on Ice Core Science. Climate and Environmental Physics, Physics Institute, University of Bern.

Once again, it is physically impossible for the DE08 or DE08-2 cores to resolve CO2 shifts that occur over periods of less than 60 years; and it is impossible for the DSS core to resolve CO2 shifts of shorter duration than 116 years.  Below 120 m in the DSS core, the resolution may actually even be much worse than 116 years.  There is a pronounce decline in the sampling rate below 120 m.  There is a linear decline from 0.74 m/yr to 0.27 m/yr from 116.9 m down to 523.6 m.

The linear nature of the trend means that this is most likely due to compaction, rather than accumulation rate.  If the sampling rate decline is due to compaction, it would only have a minimal effect on resolution.  If it’s due to accumulation rate, then the resolution below 120 m could be as poor as ~500 years.

Bender, M., T. Sowers & E. Brook. Gases in Ice Cores. Proc. Natl. Acad. Sci. USA.  Vol. 94, pp. 8343–8349, August 1997. Colloquium Paper

The most extensive study of the preindustrial CO2 concentration of air and its anthropogenic rise is that of Etheridge et al. (17). Their results are based largely on studies of the DE 08 ice core, from Law Dome, Antarctica (66° 43′ S, 113° 12′ E; elevation 1,250 m). The high accumulation rate, about 1.2 myyr, and warm annual temperature (-19°C) at the site of this core (which causes the closeoff depth to be relatively shallow) allow time to be resolved exceptionally well. Etheridge et al. (17) estimate the gas age–ice age difference to be only 30 yr and the duration of the bubble closeoff process to be 8 yr.

Neftel A, Oeschger H, Staffelbach T, Stauffer B. 1988. CO2 record in the Byrd ice core 50 000–5000 years BP. Nature 331: 609–611.

Because the enclosure process acts as a low pass filter, the CO2 record stored in the ice bubbles of polar ice archive is a smoothed record of the atmospheric CO2 concentration.  In the Byrd core the air is enclosed between 60 and 80 m below the surface (m.b.s.) and the duration of the enclosure is ~50 yr during the Holocene.

[…]

Oscillations of the atmospheric CO2 concentration with a period corresponding to twice the enclosure time, 2T would be attenuated to 40% in the ice and would be reinstalled to 82% of the orginal value after the deconvolution procedure.  For oscillations corresponding to the duration of the ecclosure time, the percentages would be 8.5% for the CO2 record in ice and 18% for the reconstructed record by the deconvolution procedure.  Faster changes are suppressed and cannot be seen in either the ice or reconstructed by deconvolution.

Trudinger, C. M., I. G. Enting, P. J. Rayner, and R. J. Francey (2002), Kalman filter analysis of ice core data 2. Double deconvolution of CO2 and δ13C measurements, J. Geophys. Res., 107(D20), 4423, doi:10.1029/2001JD001112.

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, 4423, 24 PP., 2002
doi:10.1029/2001JD001112

Kalman filter analysis of ice core data 2. Double deconvolution of CO2 and δ13C measurements

C. M. Trudinger

CSIRO Atmospheric Research, Aspendale, Victoria, Australia

I. G. Enting

CSIRO Atmospheric Research, Aspendale, Victoria, Australia

P. J. Rayner

CSIRO Atmospheric Research, Aspendale, Victoria, Australia

R. J. Francey

CSIRO Atmospheric Research, Aspendale, Victoria, Australia

A new method for deconvolving ice core CO2 and δ13CO2 measurements to estimate net CO2 uptake by the terrestrial biosphere and the oceans has been developed. The method, which uses the Kalman filter, incorporates statistical analysis into the calculation. This allows a more rigorous analysis of CO2 variability than the usual deconvolution method. The Kalman filter method estimates uncertainties on the deduced fluxes as part of the calculation. The deconvolution method is applied to the Law Dome CO2 and δ13C ice core record. The calculation suggests that natural variability in CO2 fluxes may be as large as 1 GtC yr−1 (GtC is gigatonnes carbon, 1 Gt = 1015 g) on the timescale of just less than a decade. The Law Dome CO2 measurements show a slight decrease in CO2 around the 1940s. Analysis with the carbon cycle model and a numerical model of firn processes suggests that about 3 GtC yr−1 uptake (mostly oceanic) is required in the 1940s to match the ice core measurements. The estimates of variation in the terrestrial biospheric flux between 1950 and 1980 from the double deconvolution calculation are in very good agreement with an independent estimate of the global terrestrial flux from a climate-driven ecosystem model.

Published 19 October 2002.

MacFarling Meure, C., D. Etheridge, C. Trudinger, P. Steele, R. Langenfelds, T. van Ommen, A. Smith, and J. Elkins (2006), Law Dome CO2, CH4 and N2O ice core records extended to 2000 years BP, Geophys. Res. Lett., 33, L14810, doi:10.1029/2006GL026152.

GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L14810, 4 PP., 2006
doi:10.1029/2006GL026152

C. MacFarling Meure

Marine and Atmospheric Research, Commonwealth Scientific and Industrial Research Organisation, Aspendale, Victoria, Australia

D. Etheridge

Marine and Atmospheric Research, Commonwealth Scientific and Industrial Research Organisation, Aspendale, Victoria, Australia

C. Trudinger

Marine and Atmospheric Research, Commonwealth Scientific and Industrial Research Organisation, Aspendale, Victoria, Australia

P. Steele

Marine and Atmospheric Research, Commonwealth Scientific and Industrial Research Organisation, Aspendale, Victoria, Australia

R. Langenfelds

Marine and Atmospheric Research, Commonwealth Scientific and Industrial Research Organisation, Aspendale, Victoria, Australia

T. van Ommen

Department of the Environment and Heritage, Australian Antarctic Division, and Antarctic Climate and Ecosystems CRC, Hobart, Tasmania, Australia

A. Smith

Australian Nuclear Science and Technology Organisation, Menai, New South Wales, Australia

J. Elkins

NOAA, Earth System Research Laboratory, Boulder, Colorado, USA

New measurements of atmospheric greenhouse gas concentrations in ice from Law Dome, Antarctica reproduce published Law Dome CO2 and CH4 records, extend them back to 2000 years BP, and include N2O. They have very high air age resolution, data density and measurement precision. Firn air measurements span the past 65 years and overlap with the ice core and direct atmospheric observations. Major increases in CO2, CH4 and N2O concentrations during the past 200 years followed a period of relative stability beforehand. Decadal variations during the industrial period include the stabilization of CO2 and slowing of CH4 and N2O growth in the 1940s and 1950s. Variations of up to 10 ppm CO2, 40 ppb CH4 and 10 ppb N2O occurred throughout the preindustrial period. Methane concentrations grew by 100 ppb from AD 0 to 1800, possibly due to early anthropogenic emissions.

Received 26 February 2006; accepted 16 May 2006; published 21 July 2006.

The stabilization of atmospheric CO2 concentration during the 1940s and 1950s is a notable feature in the ice core record. The new high density measurements confirm this result and show that CO2 concentrations stabilized at 310–312 ppm from ~1940–1955. The CH4 and N2O growth rates also decreased during this period, although the N2O variation is comparable to the measurement uncertainty. Smoothing due to enclosure of air in the ice (about 10 years at DE08) removes high frequency variations from the record, so the true atmospheric variation may have been larger than represented in the ice core air record. Even a decrease in the atmospheric CO2 concentration during the mid-1940s is consistent with the Law Dome record and the air enclosure smoothing, suggesting a large additional sink of ~3.0 PgC yr-1 [Trudinger et al., 2002a]. The d13CO2 record during this time suggests that this additional sink was mostly oceanic and not caused by lower fossil emissions or the terrestrial biosphere [Etheridge et al., 1996; Trudinger et al., 2002a]. The processes that could cause this response are still unknown.

[11] The CO2 stabilization occurred during a shift from persistent El Niño to La Niña conditions [Allan and D’Arrigo, 1999]. This coincided with a warm-cool phase change of the Pacific Decadal Oscillation [Mantua et al., 1997], cooling temperatures [Moberg et al., 2005] and progressively weakening North Atlantic thermohaline circulation [Latif et al., 2004]. The combined effect of these factors on the trace gas budgets is not presently well understood. They may be significant for the atmospheric CO2 concentration if fluxes in areas of carbon uptake, such as the North Pacific Ocean, are enhanced, or if efflux from the tropics is suppressed.

Fig. 2 from MacFarling Meure, et al., 2006

Bandwidth, Sample Rate, and Nyquist Theorem

Bandwidth describes the frequency range in which the input signal can pass through the analog front end with minimal amplitude loss – from the tip of the probe or test fixture to the input of the ADC. Bandwidth is specified as the frequency at which a sinusoidal input signal is attenuated to 70.7% of its original amplitude, also known as the -3 dB point. The following figure shows the typical input response for a 100 MHz high-speed digitizer.


Figure 2

For example, if you input a 1 V, 100 MHz sine wave into high-speed digitizer with a bandwidth of 100 MHz, the signal will be attenuated by the digitizer’s analog input path and the sampled waveform will have an amplitude of approximately 0.7 V.

It is recommended that the bandwidth of your digitizer be 3 to 5 times the highest frequency component of interest in the measured signal to capture the signal with minimal amplitude error (bandwidth required = (3 to 5)*frequency of interest). The theoretical amplitude error of a measured signal can be calculated from the ratio of the digitizer’s bandwidth in relation to the input signal frequency (R).


Figure 4

For example, the error in amplitude when measuring a 50 MHz sinusoidal signal with a 100 MHz high-speed digitizer, which yields a ratio of R=2, is approximately 10.5%.

Another important topic related to bandwidth is rise time. The rise time of an input signal is the time for a signal to transition from 10% to 90% of the maximum signal amplitude and is inversely related to bandwidth by the following formula, based on the one pole model, R-C limited input response.


Figure 5

This means that the rise time of a 100 MHz digitizer input path is 3.5 ns. It is recommended that the rise time of the digitizer input path be 1/3 to 1/5 the rise time of the measured signal to capture the signal with minimal rise time error. The theoretical rise time measured (Trm) can be calculated from the rise time of the digitizer (Trd) and the actual rise time of the input signal (Trs).


Figure 6

For example, the rise time measurement when measuring a signal with 12 ns rise time with a 100 MHz digitizer is approximately 12.5 ns.

Nyquist Theorem: Sample rate > 2 * highest frequency component (of interest) of the measured signal

The Nyquist theorem states that a signal must be sampled at a rate greater than twice the highest frequency component of the signal to accurately reconstruct the waveform; otherwise, the high-frequency content will alias at a frequency inside the spectrum of interest (passband). An alias is a false lower frequency component that appears in sampled data acquired at too low a sampling rate. The following figure shows a 5 MHz sine wave digitized by a 6 MS/s ADC. The dotted line indicates the aliased signal recorded by the ADC and is sampled as a 1 MHz signal instead of a 5 MHz signal.


Figure 8: Sine Wave Demonstrating the Nyquist Frequency

The 5 MHz frequency aliases back in the passband, falsely appearing as a 1 MHz sine wave. To prevent aliasing in the passband, you can use a lowpass filter to limit the frequency of the input signal or increase your sampling rate.

Diffusion Confusion

The concept of gas diffusion in ice cores can be a confusing topic.

The age of the layers of ice can be fairly easily and accurately determined. The age of the air trapped in the ice is not so easily or accurately determined. Currently the most common method for aging the air is through the use of “firn densification models” (FDM). Firn is more dense than snow; but less dense than ice. As the layers of snow and ice are buried, they are compressed into firn and then ice. The depth at which the pore space in the firn closes off and traps gas can vary greatly… So the delta between the age of the ice and the age of the air can vary from as little as 30 years to more than 2,000 years.

The DE08 core from Law Dome core has a delta of 30 years. When the core was drilled in 1992 pores didn’t close off until a depth of 83 m, in ice that formed in 1939. According to the firn densification model, air from 1969 was trapped at that depth in ice that was deposited in 1939.  It doesn’t seem reasonable to assume that “1969” air was trapped at 83 m in “1939” ice  It seems to me that at depth, there would be a mixture of air permeating downward, in situ air, and older air that had migrated upward before the ice fully “lithified.” The air trapped in the 1939 layer should be a blend of air from 1909 to 1969.  At the time that the 1939 layer was deposited, the ice crystals above 1909 would not have “lithified” yet.  In 1939, the air within the interstitial pore space would be a mixture of 1909 to 1939 air.  By the time the 1969 layer was deposited and the 1939 layer “lithified,” the air at the 1939 layer would have been a blend of 1909 to 1969 air.

Here are a schematic diagrams of the two models…

Fig. 1) Schematic diagram of DE08 firn densification model.

Fig. 2) Schematic diagram of DE08 geological model.

Read the rest of this entry »

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Miami Beach, Florida topographic maps from 1950 and 1994.(USGS).

Miami Beach, Florida topographic maps from 1950 and 1994.(USGS).

Miami Beach topographic maps for 1950 and 1994. Note that the 5' elevation contour has not shifted (USGS).

Miami Beach topographic maps for 1950 and 1994. Note that the 5′ elevation contour has not shifted (USGS).

Miami Beach, Florida topographic maps for 1994 and 2012. The 2012 map has no 5' contour because it has a 10' contour interval. However, it is abundantly obvious that Florida is not being inundated.

Miami Beach, Florida topographic maps for 1994 and 2012. The 2012 map has no 5′ contour because it has a 10′ contour interval. However, it is abundantly obvious that Florida is not being inundated.

Topographic profile A-A'. The NOAA sea level trend has been plotted at.the same vertical scale.

Topographic profile A-A’. The NOAA sea level trend has been plotted at.the same vertical scale.


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