Karl Popper and Antarctic Ice
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THERE IS YET ANOTHER IMPORTANT QUESTION to be asked. Suppose Antarctica were gaining mass. What would that tell us about global warming? It turns out that modeling the expected impact of global warming on Antarctic ice is at least as complicated as the empirical measurements. There are a number of factors to consider, some of which we have already mentioned, and it is quite difficult to figure out which of them will have the biggest impact.
The most obvious effect, and the one that makes the argument so intuitively compelling, is direct melting. However, it is perhaps the least important. The Antarctic is very cold, so it would take a lot of warming to raise temperatures such that they are frequently above freezing. In addition, unlike the Arctic it is surrounded by a lot of water, which serves to dampen the effect of global warming. Because of this, direct melting would not be a very important factor [See Jacobs 1992].
A much more important factor is the amount of precipitation in the atmosphere. Increased temperatures mean that more water evaporates from the oceans. Since the Antarctic is surrounded by oceans (again, unlike the Arctic), this means that there will be a huge increase in the amount of water vapor in the air, and thus a similar increase in the amount of precipitation. As the Antarctic is nearly always below freezing, this precipitation will fall in the form of snow which will eventually compact into ice, increasing the total mass of the Antarctic Ice Sheet. This is the mechanism that causes the increase in thickness that the Davis team found [Davis 2005].
Also important, however, are the complicated coastal dynamics that are observed in the Thomas study [Thomas 2004]. It is entirely possible that increased temperatures would weaken ice shelves and increase glacial flow, causing more ice to fall into the sea. The GRACE studies suggest this explanation for their data.
The Intergovernmental Panel on Climate Change, which is collection of experts from around the world, reflects this difficulty. In their Third Assessment Report, published in 2001, they projected that “The Antarctic ice sheet is likely to gain mass because of greater precipitation” [IPCC 2001]. This projection has the apparently paradoxical result that an increase of mass would be confirmation of global warming, not a refutation of it! However, they were criticized for failing to take coastal dynamics into account, and the Fourth Assessment Report in 2007 contains no firm projections, and instead offers a brief section stating merely that the impact of global warming on Antarctic ice is unclear [IPCC 2007].
What then is the status of this supposed refutation of global warming? Simply this: It is unclear whether and to what extent Antarctica is gaining ice, and it is unclear what we ought to expect if global warming is true. This is far from the simple Popperian falsification. It is a complex scientific issue, where none of the facts can be taken for granted.
BUT PERHAPS THERE IS YET A DEEPER QUESTION. If the facts and the predictions were both more clear, would this mean that global warming was disproven? It would not. This is only one tiny example from a small part of the overall climate debate. There are discussions in the literature that are vastly more complicated than this, covering issues such as methods for measuring historical temperatures, ways to measure the albedo of various substances, the effect of global warming on ocean currents, the carbon cycle and the percentage of carbon emissions that are retained by the atmosphere, the impact of methane and other greenhouse gases beyond carbon dioxide, the effects of cloud cover and water vapor, and many, many others. I have taken us on an abbreviated tour of one of the smallest back alleys in the city of climate science. The debate is far bigger than any one claim, and reducing it to a small set of talking points does the scientific community a great disservice.
Though I am sure my own opinion shows through, the point of this paper is not to argue for or against global warming itself. Instead, I hope to have shown that the public understanding of science is simplistic at best, and grossly distorted at worst. Reducing a scientific question to a matter of political debate strips it of meaning, and turns it into a caricature of itself. If we are to face the issues that the twenty-first century will bring us, then we must learn to grapple with scientific questions on their own terms, with a little modesty and a great deal of patience for nuance. Science refuses to be reduced to a talking point, and we must understand that if we are to have any chance of finding the truth.
