Saturday, January 24, 2009

From the Little Ice Age to today -rates of climate change

Much of the media coverage of the changing climate relates to the changes in glacier size, and their relative retreat over the past four decades. In the last Saturday post, I quoted the overwhelming scientific evidence for the presence of a global Little Ice Age (LIA) as documented by Jean Grove.

What I would now like to do is show, through the work of Syun-Ichi Akosafu, of the International Arctic Research Center, that the transition from the LIA to today began long before the considerations of Global Warming and carbon dioxide forcings were much thought of, and, with the backing of the solid science that has documented these changes, that these changes have very little sensitivity to the purported effects of increased carbon dioxide levels. Further I would underline his comment that it is not possible to study climate change without long-term data – considering long term to be not 60 years or even 600, but rather the periodicity of climate changes over the last 3000 years. And that requires archaeological information as well as that of proxies alone, particularly as it relates to those that live in the Arctic regions.

In beginning let me note that as the global temperature, over the last decade, has refused to follow the predicted path of those who espouse global warming, so the period over which average temperatures are defined to denote the trend in climate has been extended, from three, to five, to ten, to the latest fifteen year averages. Let us, for the sake of scientific honesty, decide that five years is a reasonable period over which to define a mean, and then move into the discussion.

Akosafu begins by showing that, if we plot this 5-year mean over the past 140 years, then the trend can be divided into a steadily increasing part (the black line) with, superimposed upon it variations that he calls natural, but that will be examined and discussed as we work through the paper.

Figure 1. Global temperature change, shown as a 5-year average and defined by the overall trend, and the variations thereon. (Akosafu Fig 1e).

Given the whole debate about global warming and carbon dioxide levels, it is appropriate to also include his figure 2, which shows the change in both over the last 150 odd years,
Figure 2. Global temperature (5-year smoothing) plotted with CO2 levels

By comparing temperature records from Vardo, in Norway, with the ice core data from Severnaya Zemlya, he shows that the two can be correlated, and then uses the ice core data to show that the temperature it records has been rising since about 1780. This is then correlated with data from coral studies on the island of Guam that similarly show a temperature rise, which started around 1800. The paper ties this date to changes in the time that ice freezes over lakes and rivers, and when it melts. The conclusion is visibly evident that there has been a change, and that it dates back to around 1800.

However much of the response to mention of both an MWP and an LIA has suggested that the events were localized to Western Europe. Now Grove showed through quotations from numerous papers that this was not true, and Akosafu equally strongly refutes that argument with data from both Peru and China,
Figure 3. Oxygen isotope values translated into temperature variations for both China and Peru over the past 400 years (Akosafu Fig 4c)

While many folk seem to prefer to rely purely on the scientific numbers derived from proxy values, I feel that information from contemporary historical documents can be equally or more valid. Thus the reports of cooler summers between 1550 and 1750, which led to deaths because of the poor harvests, and thus famine, provide information that should not be ignored.

The generality of that condition, and the global evidence of a change to a warming trend after about 1800 is well documented. It is this evidence, and the timing of the start of global warming, that shows that it is a natural, rather than an anthropomorphic change. Anecdotal information, such as the fact that Permafrost formed during the LIA around Fairbanks is only now starting to thaw, does not define the depths of the cold that many places saw and he points out (Figure 6a) that for those many places around the globe, the average temperature in the 1700s was considerably below that modeled by Mann et al, in their famous “hockey stick” paper that formed such a central theme to the IPCC report of 2001. In fact he quotes a table from the NRC 2006 report on global temperatures that confirms, with half-a-dozen plots, that temperature started rising somewhere around 1800. He rightly asks the question that, if CO2 levels did not start rising significantly until 1946, what was the cause of the earlier rise?

If, in fact, one examines the trend of temperature rise from 1800 to 1900 and then from 1900 to 2000 and subtracts the rate of change in existence before carbon dioxide effects are postulated to have occurred, then one finds the pre-existing rate to have been 0.5 degC/100 years following 1800. With the IPCC claim of a temperature rise of 0.6 degC/100 years, then the difference due to CO2 initially appears to be 0.1degC/100 years.

Now if the drop in temperature during the LIA was a total of 1.5degC, such a rate would bring us “back” to date only 1degC. And there are records that suggest that the MWP was, in fact, warmer than today’s temperatures. This, however, only deals with the “black line” portion of Figure 1. Akasofu now looks at the variations around that trend, namely what is referred to as the “multi-decadal oscillation.” This can be seen, in Figure 1, to be an oscillation, but to those anxious to prove Global Warming, it is this oscillation above the underlying trend, coincident with the rise in CO2 levels, that is the marker to our future doom.

However, as an initial point, it should be noted that the nature of oscillations is that, after swinging one way in periodic mode, they then start to swing back. And the phase of the oscillation, as seen from Figure 1, is such as to suggest that the return should begin around 2000 – as it did. This variation is around 0.15degC /10 years, and cycles, as shown, around the mean growth.

Studying the changes that this warming is inducing, Akasofu looks in more detail at the actual specificity of occurrences, rather than the generality. Consider, for example, the reduction in the Arctic ice cap. This is not a uniform contraction, which one might anticipate if the cause were a universal warming, but rather is maximized along the Siberian coast, where the currents from the North Atlantic – under the driving force of the North Atlantic Oscillation (NAO)- have accelerated the melt. The characteristics of that melt – the ice is melting from the bottom, rather than the top, confim that it is a water current related phenomenon, rather than a surface temperature caused result.

In earlier posts I have commented on the retreat of the glacier at Glacier Bay in Alaska, and will take the opportunity of pasting his illustration of this, so that I can refer back to it later. You will note that it shows the glacier retreating to its greatest extent, before 1860.
Figure 4. Glacial retreat at Glacier Park

Similar plots are presented for the Franz Josef Glacier in New Zealand, and the Gangotri Glacier in the Himalayas, as well as the advance and retreat of the glaciers in the west-central Alps.

As I pointed out, when discussing Bangladesh, Akasofu also does an evaluation of the rise in sea levels over the last hundred years, and notes that while the average has been some 1.7 mm/year in recent years, rather than increasing, as one would expect with the glaciers melting, and the ocean warming, in fact the rate has dropped below 1.4 mm/year.

Hidden now, in the heart of the paper, lies some of the more damaging evidence against the modeling of Climate Change that is presumed by so many to be accurately predicting our future.

In the post that induced my departure from The Oil Drum, and as Akasofu confirms, Greenland, as a whole has not been warming in the same mode as the majority of the Arctic regions. When, however, the IPCC Arctic group were asked to run their models to hindcast the behavior of the Arctic regions over the past fifty years, the IPCC models were nowhere near accurate in their predictions of what actually occurred.
Figure 5. IPCC prediction vs reality (on the left)

Further, because the IPCC only focuses on the period following 1975 they neglect the changes in the Greenland ice sheet that occurred during the 1920-1940 period which were substantially greater in magnitude than those now occurring, but which could not have been caused by GHG. And, this after all being an Arctic Research Center, they also point out, contrary to MSM reports that the actual temperature of the permafrost has stopped rising, and in fact the methane levels “off-gassed” have decreased, since about 2000.

I will forego discussion of what might cause the larger cyclic variation (the MWP – LIA cycle) to another time.

So there you have it, to those willing to do "due diligence" on the changes in climate over the past two centuries, the evidence is substantial that the fears so assiduously heightened in the media, are not, in fact, based on fact. We'll get into the MWP and earlier parts of the cycle, in future posts.

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