Monday, February 8, 2010

Global Warming in Antarctica?

Several people have asked me about the 'warm' weather that I experienced, and whether this was due to global warming. Others have asked about my photos of liquid water (e. g. above). Is this due to global warming? Did I see global warming in Antarctica?

I've hesitated to answer these questions here, because these are not simple ones. However, with the caveat that I am NOT an expert on climatology, let me tell you what I know.

The evidence for global warming is very clear.

The carbon dioxide levels in the atmosphere have risen to levels far beyond anything seen at least since the last Ice Age, and very probably for the last 400,00 years. For the purposes of considering the future of humanity, I don't think that we need to go any further back. This increase is clearly due to human activity.

Global temperatures are rising, and the last 50 years have been the warmest in centuries. There are many many places where one can compare photos of glaciers taken 50-100 years ago with recent photos; the differences are dramatic. A quick google search found examples from Glacier National Park, elsewhere in North America , and even from Africa's Mt. Kilamanjaro. One can debate temperature trends, the effect of heat islands, etc., but it is clear that these glaciers have formed over long periods, and are now rapidly disappearing. Further, they are far from cities or other local heat sources.

These examples are all from the Northern hemisphere or equatorial region (Mt. Kilamanjaro is 3 degrees south of the Equator). In Antarctica, the evidence is less dramatic, but there are clear signs of thinning glaciers.

Of course, one can find contrary evidence. In McMurdo, I heard a talk about exploring the dry valleys; the speaker pointed out one location where there is now apparently much more ice than in 1904, when Scott visited the site. On balance, however, there is much more evidence for global warming than against it.

That said, what I observed was not evidence of glacial warming. The temperatures during my visit were well within the expected range. The water pools were not anomalies; the snow around McMurdo always melts on hot summer days, forming small freshwater pools. Global warming is real, but one needs careful, long-term study to observe the effects - one visit to an area is not enough.

Anybody who wants to learn more about global warming should visit the website of the International Panel on Climate Change (IPCC). Their reports (available on the website) discuss an enormous volume of climatological data drawn from many sources. Notwithstanding an occasional gaffe, their carefully worded conclusions represent the views of the vast majority of climate scientists.

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