True climate science denier, David Roberts (formerly with Grist) has authored another truly vapid article for Vox …
The 2 key points that climate skeptics miss
Updated by David Roberts on December 11, 2015
Arguments between climate skeptics (or whatever the hell we’re calling them now) and their opponents very frequently devolve into hypertechnical squabbles over particular scientific issues like sea surface temperatures or Milankovitch cycles (don’t ask).
Generally speaking, this is a Bad Thing. Technical scientific disputes are of limited interest the general public — especially technical disputes litigated with great partisan venom. A discussion dominated by such disputes just causes most people to tune out entirely. What’s more, it creates the illusion that the validity of climate science hinges on how these squabbles are resolved. It doesn’t.
Mr. Roberts actually denied the scientific method prior to making his first point. Science is the process of formulating systematic explanations for observations (hypotheses) and then testing and upholding or falsifying those hypotheses. Science is not about formulating slogans that non-scientists can “tune in” to.
1) Climate science represents a convergence of evidence
Why do so many scientists and scientific organizations accept that climate change is real, human-caused, and dangerous?
It’s not because of any single line of evidence or any one prediction. Rather, says Shermer, “there is a convergence of evidence from multiple lines of inquiry — pollen, tree rings, ice cores, corals, glacial and polar ice-cap melt, sea-level rise, ecological shifts, carbon dioxide increases, the unprecedented rate of temperature increase — that all converge to a singular conclusion.” Scientists call this sort of convergence of independent lines of evidence “consilience.” Biologist E.O. Wilson wrote a very good book about it.
Mr. Roberts appears to think that the initial observations are the test of the hypothesis. If he knew the least little bit about the scientific method, he would grasp the fact that his version of consilience is nothing more than plain silliness. In the oil patch, we refer to this sort of consilience as “arm waving.”
The “consilience” of rising atmospheric CO2 and various bits of evidence of warming over the past 500 years does not converge on the conclusion that rising CO2 is the cause of the warming. This is what the scientific method dictates that you have to test and verify. Platitudes (citations of Arhenius) are not tests. The claim that CO2 is a greenhouse gas; therefore increasing atmospheric concentrations should cause unquantified warming – is not a test… It isn’t even a scientific hypothesis.
A scientific hypothesis would go something like this…
A doubling of atmospheric CO2 from 280 to 560 ppmv will cause the bulk temperature of the lower atmosphere to rise by 3.5 (±1.5) °C .
Then, climate scientists (whatever the hell we’re calling them now) would devise methods of testing this hypothesis. Since, as Admiral Titley pointed out in his Senate testimony, “There is no Planet B”… Without a control planet, we can pretty well rule out an empirical experiment. The only way to test the hypothesis is to observe changes in atmospheric CO2 and temperature over time and see how well (or poorly) the changes conform to the hypothesis.
With nearly 30 years of climate model failures under their belts, climate scientists (whatever the hell we’re calling them now) now have ample data with which to test such a hypothesis.
- The troposphere has not warmed as fast as almost all climate models predict.
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. For the time period before 2005, the models were forced with historical values of greenhouse gases, volcanic aerosols, and solar output. After 2005, estimated projections of these forcings were used. If the models, as a whole, were doing an acceptable job of simulating the past, then the observations would mostly lie within the yellow band. For the first two plots (Fig. 1 and Fig 2), showing global averages and tropical averages, this is not the case. Only for the far northern latitudes, as shown in Fig. 3, are the observations within the range of model predictions.
Fig. 1. Global (80S to 80N) Mean TLT Anomaly plotted as a function of time. The thick black line is the observed time series from RSS V3.3 MSU/AMSU Temperatures. The yellow band is the 5% to 95% range of output from CMIP-5 climate simulations. The mean value of each time series average from 1979-1984 is set to zero so the changes over time can be more easily seen. Note that after 1998, the observations are likely to be below the simulated values, indicating that the simulation as a whole are predicting too much warming.
The models have not only been wrong, they are getting “wronger” over time…
Global mean surface temperature over the past 20 years (1993–2012) rose at a rate of 0.14 ±0.06 °C per decade (95% confidence interval)1. This rate of warming is significantly slower than that simulated by the climate models participating in Phase 5 of the Coupled Model Intercomparison Project (CMIP5).
The inconsistency between observed and simulated global warming is even more striking for temperature trends computed over the past fifteen years (1998–2012). For this period, the observed trend of 0.05 ±0.08 °C per decade is more than four times smaller than the average simulated trend of 0.21 ±0.03 °C per decade (Fig. 1b). It is worth noting that the observed trend over this period — not significantly different from zero — suggests a temporary ‘hiatus’ in global warming2–4. The divergence between observed and CMIP5-simulated global warming begins in the early 1990s, as can be seen when comparing observed and simulated running trends from 1970–2012 (Fig. 2a and 2b for 20-year and 15-year running trends, respectively).The evidence, therefore, indicates that the current generation of climate models (when run as a group, with the CMIP5 prescribed forcings) do not reproduce the observed global warming over the past 20 years, or the slowdown in global warming over the past fifteen years.
The “consilience” is that the Earth’s climate is far less sensitive to CO2 than has been assumed by climate scientists (whatever the hell we’re calling them now).
Mr. Roberts’ first point was actually semi-reasonable compared to his second point.
Burden of Proof Fallacy
2) Climate “skepticism” does not
For [climate] skeptics to overturn the consensus, they would need to find flaws with all the lines of supportive evidence and show a consistent convergence of evidence toward a different theory that explains the data. … This they have not done.
I’m not sure the disengaged public understands this: Climate skepticism is not an alternative theory. The climate skeptic community is a hodgepodge, a farrago of theories and conspiracies that range all over the map, from sunspots to adjustments in particular temperature data sets to hoaxes by scientists greedy for grant money. There’s no shared alternative framework, just a fixed certainty that the consensus must be wrong.
If the mainstream scientific consensus on anthropogenic climate change is wrong, then we’ll need some other theory that makes sense of present-day changes and harmonizes with data from historical record. Climate skeptics have offered no such theory. Where climate change science is fecund, climate skepticism is moribund, merely destructive.
The burden of proof is not on skeptics of a scientific hypothesis. The burden of proof rests with its proponents to demonstrate that it systematically explains the observations. Mr. Roberts once again confuses the observations with actual tests of the hypothesis. He bizarrely thinks that the AGW hypothesis is upheld unless skeptics can disprove the observations and produce a replacement hypothesis. Science had never worked this way. Science cannot work this way. Politics do work this way. Logical fallacy is to a politician, what an Brunton Compass is to a geologist.
An Example of Scientific Consilience
: the linking together of principles from different disciplines especially when forming a comprehensive theory
The climate models…
The spectrally sound climate reconstructions…
What was the climate doing before 1880? Just about the same thing it has been doing since 1880…
Pretty well all of the [spectrally] consistent (non-hockey stick) reconstructions yield the same conclusion…
If we take Moberg and Ljungqvist back to the year zero, we can clearly see another characteristic of the Late Holocene climate: A millennial scale cycle with a period of ~1,000 years and amplitude of ~0.5 °C.
These cycles even have names…
These cycles have been long recognized by Quaternary geologists…
Fourier analysis of the GISP2 ice core clearly demonstrates that the millennial scale climate cycle is the dominant signal in the Holocene (Davis & Bohling, 2001). It is pervasive throughout the Holocene (Bond et al., 1997).
The industrial era climate has not changed in any manner inconsistent with the well-established natural millennial scale cycle. Assuming that the ice core CO2 is reliable, the modern rise in CO2 has had little, if any effect on climate…
While the climate may have warmed by 0.2 to 0.4 °C more than what might be expected to occur in a 100% natural warming phase of the millennial cycle, all of the apparent excess warming may very well be due to resolution differences between the instrumental and proxy data…
The sea level data…
A Geological Perspective of Recent Sea Level RiseAll of the estimated sea level rise since 1700 is represented by the light blue blob and dark blue line inside the black oval. Sea level isn’t doing anything now that it wasn’t already doing before All Gore invented global warming. And Holocene sea level changes have been insignificant relative to the Holocene transgression…Figure 1. Sea 1evel rise since the late Pleistocene from Tahitian corals, tide gauges and satellite altimetry.
Figure 2. Northern Hemisphere temperature, atmospheric CO2 and sea level since 1700 AD.
We can adapt to this without breaking a sweat…
Figure 3. Projected sea level rise through 2100 AD.
Particularly since sea level rose just as fast from 1931-1960 as it has risen since 1985…
Figure 4. Paracyclical sea level rise since 1931.
Glaciers and sea ice…
The “small glaciers” of Glacier National Park, Montana may have not existed during the Holocene Climatic Optimum (HCO). The geological evidence suggests that they formed about 7,000 years ago as the Earth’s climate began to cool after the HCO.
History of Glaciers in Glacier National Park
The history of glaciation within current Glacier National Park boundaries spans centuries of glacial growth and recession, carving the features we see today. Glaciers were present within current Glacier National Park boundaries as early as 7,000 years ago but may have survived an early Holocene warm period (Carrara, 1989), making them much older. These modest glaciers varied in size, tracking climatic changes, but did not grow to their Holocene maximum size until the end of the Little Ice Age (LIA) around A.D. 1850. While they may not have formed in their entirety during the LIA, their maximum perimeters can be documented through mapping of lateral and terminal moraines. (Key, 2002) The extent and mass of these glaciers, as well as glaciers around the globe, has clearly decreased during the 20th century in response to warmer temperatures.
Climate reconstructions representative of the Glacier National Park region extend back multiple centuries and show numerous long-duration drought and wet periods that influenced the mass balance of glaciers (Pederson et al. 2004). Of particular note was an 80-year period (~1770-1840) of cool, wet summers and above-average winter snowfall that led to a rapid growth of glaciers just prior to the end of the LIA. Thus, in the context of the entire Holocene, the size of glaciers at the end of the LIA was an anomaly of sorts. In fact, the large extent of ice coverage removed most of the evidence of earlier glacier positions by overriding terminal and lateral moraines.
“Mapping of lateral and terminal moraines” clearly demonstrates that the maximum extent of the glaciers was reached during the Little Ice Age (LIA). If “in the context of the entire Holocene, the size of glaciers at the end of the LIA was an anomaly,” how can the current reduced extent be an anomaly? Is there some ideal extent? Something between the LIA maximum and the current extent?
The glaciers of Mt Ranier National Park may date back to the last Pleistocene glaciation, but they also exhibit a similar variability to those of Glacier National Park…
The size of glaciers on Mount Rainier has fluctuated significantly in the past. For example, during the last ice age, from about 25,000 to about 15,000 years ago, glaciers covered most of the area now within the boundaries of Mount Rainier National Park and extended to the perimeter of the present Puget Sound Basin.
Geologists can determine the former extent of glaciers on Mount Rainier by mapping the outline of glacial deposits and by noting the position of trimlines, the distinct boundaries between older and younger forests or between forests and pioneering vegetation. Geologists determine the age of some of the deposits by noting the age of the oldest trees and lichens growing on them and the degree of weatherring on boulders. Between the 14th century and AD 1850, many of the glaciers on Mount Rainier advanced to their farthest went down-valley since the last ice age. Many advances of this sort occurred worldwide during this time period known to geologists as the Little Ice Age. During the Little Ice Age, the Nisqually Glacier advanced to a position 650 feet to 800 feet down-valley from the site of the Glacier Bridge, Tahoma and South Tahoma Glaciers merged at the base of Glacier Island, and the terminus of Emmons Glacier reached within 1.2 miles of the White River Campground.
Retreat of the Little Ice Age glaciers was slow until about 1920 when retreat became more rapid. Between the height of the Little Ice Age and 1950, Mount Rainier’s glaciers lost about one-quarter of their length. Beginning in 1950 and continuing through the early 1980’s, however, many of the major glaciers advanced in response to relatively cooler temperatures of the mid-century. The Carbon, Cowlitz, Emmons, and Nisqually Glaciers advanced during the late 1970’s and early 1980’s as a result of high snowfalls during the 1960’s and 1970’s. Since the early-1980’s and through 1992, however, many glaciers have been thinning and retreating and some advances have slowed, perhaps in response to drier conditions that have prevailed at Mount Rainier since 1977.
The Mt. Ranier glaciers also seem to have reached their maximum Holocene extent during the Little Ice Age.
Guess what other ice feature appears to have also reached its maximum Holocene extent during the Little Ice Age?
McKay et al., 2008 demonstrated that the modern Arctic sea ice cover is anomalously high and the Arctic summer sea surface temperature is anomalously low relative to the rest of the Holocene…
Modern sea-ice cover in the study area, expressed here as the number of months/year with >50% coverage, averages 10.6 ±1.2 months/year… Present day SST and SSS in August are 1.1 ± 2.4 8C and 28.5 ±1.3, respectively… In the Holocene record of core HLY0501-05, sea-ice cover has ranged between 5.5 and 9 months/year, summer SSS has varied between 22 and 30, and summer SST has ranged from 3 to 7.5 8C (Fig. 7).
And even the carbon dioxide data…
Had atmospheric CO2 simply followed the preindustrial trajectory, it very likely would have reached 315-345 ppmv by 2010…
Oddly enough, plant stomata-derived CO2 reconstructions indicate that CO2 levels of 315-345 ppmv have not been uncommon throughout the Holocene…
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 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…
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.
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.
Brad Plummer’s recent piece in the Washington Post featured a graph that caught my eye…
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.
I get a CO2 level of 560 ppmv, comparable to the IPCC SRES B2 emissions scenario…
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.
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…
- 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.
All converge on one conclusion: The Earths’s climate is not behaving any differently now, than it was over the previous 10,000 years. Anthropogenic CO2 emissions have not significantly affected the bulk temperature of the atmosphere.
This is true consilience.