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A 2000-Year History of Climate Change in Alaska
Volume 7, Number 49: 8 December 2004

We have heard a lot of late about Alaska and other parts of the Arctic experiencing temperatures that are without precedent over the last one to two millennia, along with all sorts of calls for the United States to repent (of its usage of fossil fuels) and thereby return the climate of the planet back to what it was like before the Great Flood (of CO2 into the atmosphere). But are we really that powerful, in terms of what some people claim we have done to earth's climate in the past and what they say we can do about it in the future?

In an important study that appeared a few years ago in the Proceedings of the U.S. National Academy of Sciences, Hu et al. (2001) addressed this question by noting that "knowledge of natural climatic variability is essential for evaluating possible human impacts on recent and future climate changes." Hence, as they continue, they say they "conducted multiproxy geochemical analyses of a sediment core from Farewell Lake in the northwestern foothills of the Alaska Range," obtaining what they describe as "the first high-resolution quantitative record of Alaskan climate variations that spans the last two millennia." So what did they find?

The team of five scientists say their results "suggest that at Farewell Lake SWT [surface water temperature] was as warm as the present at AD 0-300 [during the Roman Warm Period], after which it decreased steadily by ~3.5C to reach a minimum at AD 600 [during the depths of the Dark Ages Cold Period]." From that point in time, they say "SWT increased by ~3.0C during the period AD 600-850 and then [during the Medieval Warm Period] exhibited fluctuations of 0.5-1.0C until AD 1200." Completing their narrative, they say that "between AD 1200-1700, SWT decreased gradually by 1.25C [as the world descended into the depths of the Little Ice Age], and from AD 1700 to the present, SWT increased by 1.75C," the latter portion of which warming initiated the Modern Warm Period.

In commenting on these findings, Hu et al. remark that "the warmth before AD 300 at Farewell Lake coincides with a warm episode extensively documented in northern Europe ? whereas the AD 600 cooling is coeval with the European 'Dark Ages'." They also say that "the relatively warm climate AD 850-1200 at Farewell Lake corresponds to the Medieval Climatic Anomaly, a time of marked climatic departure over much of the planet." And they say that "these concurrent changes suggest large-scale teleconnections in natural climatic variability during the last two millennia, likely driven by atmospheric controls."

Noting that "20th-century climate is a major societal concern in the context of greenhouse warming," Hu et al. conclude by reiterating that their record "reveals three time intervals of comparable warmth: AD 0-300, 850-1200, and post-1800," and they say that "these data agree with tree-ring evidence from Fennoscandia, indicating that the recent warmth is not atypical of the past 1000 years," in unmistakable contradiction of those who claim that it is.

The great importance of these observations resides in the fact that they testify to the reality of the non-CO2-induced millennial-scale oscillation of climate [see Climate Oscillations (Millennial Variability) in our Subject Index] that brought the world, including Alaska, significant periods of warmth comparable to, or in some cases actually greater than, that of the present some 1000 years ago, during the Medieval Warm Period, and some 1000 years before that, during the Roman Warm Period. These earlier periods of warmth were unquestionably not caused by elevated atmospheric CO2 concentrations (which were 100 ppm less during those periods than they are today), nor were they due to elevated concentrations of any other greenhouse gases; they were manifestly due to something else, which fact makes it very clear that the warmth of today could be due to that same "something else" as well.

To rant and rave, as climate alarmists do, about what's been happening in Alaska and other parts of the Arctic over the past few decades and claim, without reservation, that it is the result of CO2-induced global warming is unconscionable, especially when hard scientific evidence such as that provided by Hu et al. - and many others (see our Subject Index for much, much more) - has been around for years. It is clearly not science that is fueling the fervor for fossil fuel abandonment, it is politics, pure and simple ? or perhaps we should say politics not so pure and not so simple.

Sherwood, Keith and Craig Idso

Reference
Hu, F.S., Ito, E., Brown, T.A., Curry, B.B. and Engstrom, D.R. 2001. Pronounced climatic variations in Alaska during the last two millennia. Proceedings of the National Academy of Sciences, USA 98: 10,552-10,556.