Answer to Jon Chambers

Jonathan Chambers

Hey Mid. Received the below from a friend of a friend. Went on line to refute this but all the articles say a 1.4 degree change in temperature is a bad thing. Starts a Little Ice Age.

Anything you can offer to concretely snuff this guy?

Climate change is cyclical. I agree 100%. Ice ages come and go. If you follow this thought process though, the data since the industrial revolution has us coming out of an ice age faster amd more drastically than ever. Climate deniers are my favorite kinds of Republicans

He already snuffed himself better than I could.  His ignorance appears to be manifest.

We are still in an “ice age.” We are just fortunate enough to be living in an interglacial stage known as the Holocene.  Geologically speaking, this is an “ice age”… We’ve been in an ice age since the beginning of the Oligocene (~30 MYA)…


(Older is to the right.)

This particular ice age period (the Quaternary) has been particularly cold. Over the most recent ~2 million years, glacial maxima have had periods of ~100,000 years, punctuated by brief (15-40 KY) interglacial stages. The last glacial maximum occurred about 20,000 years ago.

We are currently in an interglacial stage known as the Holocene. It began about 10,000 years ago and peaked during the Holocene Climatic Optimum (4,000 to 7,000 years ago). Based on analyses of the Milankovitch cycles, some people think the Holocene will be a long interglacial stage. In which case, we have about 30,000 years of balmy weather remaining. If this is a typical interglacial, we only have about 5,000 years left. Even then, it will take thousands of years for the ice to build up and advance across Canada. Places like Chicago might still have 50,000 years remaining to plan on how to deal with a mile-high sheet of ice bulldozing its way south across the Midwest.

Like all other significant biomass features on Earth, humans do affect natural processes. We amplify some processes and attenuate others. Some studies have suggested that AGW has already staved off a decline into the next glacial stage (Ruddiman). Others have suggested that AGW will delay or even prevent the next glacial stage. I think it might delay it by a few centuries, maybe even more than 1,000 years; but it can’t prevent it. The greenhouse effect can’t trap heat that never arrived from the Sun. Atmospheric CO2 remained elevated long after Sangamonian (Eemian, MIS 5) interglacial stage began cooling toward the last glacial maximum..

When insolation declines, less solar energy reaches the Earth and there is less heat for CO2 and other GHG’s to trap. Holocene insolation peaked during the Holocene Climatic Optimum…


(Older is to the left.)

Insolation has been declining since the Holocene Climatic Optimum. While we still can benefit from episodic periods of millennial scale warming, the long-term trend is toward the inevitable next deep freeze.

We came out of the most recent glacial stage at the end of the Pleistocene (~10,000 yrs ago).

The Holocene has been a heck of a lot more stable than the preceding Pleistocene glacial episode (the x-axes of next three graphs are denominated in calendar years – Today is to the right)…

But it has been far from stable…

The end-Pleistocene deglaciation was far more drastic than any climatic change in the Holocene, including the industrial revolution (AKA Anthropocene).  The Earth’s climate has generally been warming since 1600 AD, the coldest part of a period known as the Little Ice Age (LIA).  The LIA is part of a naturally occurring millennial scale climate oscillation which has dominated Holocene climate change and was quite possibly the coldest phase of the Holocene since the 8.2 KYA Cooling Event. The LIA was characterized by maximum glacial advances and the most extensive sea ice coverage since the onset of the Neoglaciation (end of the Holocene Climatic Optimum).


The Little Ice Age.may have been the coldest climatic period of the past 8,200 years.

While volcanic forcing may have played a role in the coldness of the LIA, it was clearly a.cyclical cooling event. Much, if not all, of the warming since the late 16th century is clearly part of a millennial climate cycle.

All of the “global warming” from ~1600 AD through 2000 AD barely brought the climate back to “normal.”

There is nothing anomalous about recent warming unless you fraudulently splce high frequency instrumental data onto low frequency proxy reconstructions (AKA Hockey Sticks).

The following is a composite of several different posts I have written on the subject.  Hopefully it’s not too disjointed.

The rate of warming since ~1978 was no different than the rate of warming from ~1910 to 1945…

The recent warming was totally nonanomalous relative to changes of the prior 2,000 years…

Which were unrelated to atmospheric CO2 concentrations…

The Late Holocene climate has been characterized by millennial scale cycle with a period of ~1,000 years and amplitude of ~0.5 °C.

Figures 7 & 8. Both Moberg and Ljungqvist clearly demonstrate the millennial scale climate cycle.

These cycles even have names…


Figure 9. Ljungqvist with climatic period nomenclature.

These cycles have been long recognized by Quaternary geologists…


Figure 10. The millennial scale climate cycle can clearly be traced back to the end of the Holocene Climatic Optimum and the onset of the Neoglaciation.

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).


Figure 11. The Holocene climate has been dominated by a millennial scale climate cycle.

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…


Figure 12. Why would CO2 suddenly start driving climate change in the 19th century?

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…


Figure 13. Ljungqvist demonstrates that the modern warming has not unambiguously exceeded the range of natural variability. The bold black dashed line is the instrumental record. I added The red lines to highlight the margin of error.

According to Ljungqvist…

The amplitude of the reconstructed temperature variability on centennial time-scales exceeds 0.6°C. This reconstruction is the first to show a distinct Roman Warm Period c. AD 1-300, reaching up to the 1961-1990 mean temperature level, followed by the Dark Age Cold Period c. AD 300-800. The Medieval Warm Period is seen c. AD 800–1300 and the Little Ice Age is clearly visible c. AD 1300-1900, followed by a rapid temperature increase in the twentieth century. The highest average temperatures in the reconstruction are encountered in the mid to late tenth century and the lowest in the late seventeenth century. Decadal mean temperatures seem to have reached or exceeded the 1961-1990 mean temperature level during substantial parts of the Roman Warm Period and the Medieval Warm Period. The temperature of the last two decades, however, is possibly higher than during any previous time in the past two millennia, although this is only seen in the instrumental temperature data and not in the multi-proxy reconstruction itself.

[…]

The proxy reconstruction itself does not show such an unprecedented warming but we must consider that only a few records used in the reconstruction extend into the 1990s. Nevertheless, a very cautious interpretation of the level of warmth since AD 1990 compared to that of the peak warming during the Roman Warm Period and the Medieval Warm Period is strongly suggested.

[…]

The amplitude of the temperature variability on multi-decadal to centennial time-scales reconstructed here should presumably be considered to be the minimum of the true variability on those time-scales.

Ljungqvist is recommending caution in comparing the modern instrumental record to the older proxy reconstructions because the proxy data are of much lower resolution. The proxy data are showing the “minimum of the true variability on those time-scales.” The instrumental data are depicting something closer to actual variability. Even then, the instrumental record doesn’t exceed the margin of error for the proxy data during the peak of the Medieval Warm Period. With a great deal of confidence, perhaps even 67%, it can be concluded that at least half, perhaps all, of the modern warming is the result of quasi-periodic natural climate fluctuations (AKA cycles).

Ljungqvist said that “the temperature since AD 1990 is, however, possibly higher than during any previous time in the past two millennia if we look at the instrumental temperature data spliced to the proxy reconstruction.” The dashed red curve is the instrumental data set…

The instrumental data always show faster (higher amplitude) temperature variations than the proxy reconstructions…

Many multi-decadal periods have warmed at 7-13 times the background rate.  Many 100-yr periods of warming and cooling exceeded the 10,000 year average.

The pronounced spike at 62-65 years on this power spectrum means almost any 100-yr period has a far greater rate and magnitude of warming or cooling than the 10,000-yr average…

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