May 27, 2005

Antarctic Ice: A Global Warming Snow Job?

Climate scientists have long suspected that warming the oceans around a very cold continent is likely to dramatically increase snowfall. Consider Antarctica. It’s plenty chilly, dozens of degrees below freezing, and it’s surrounded by water. The warmer the water, the greater the evaporation from its surface, and, obviously, the more moisture it contributes to the local atmosphere.

So, when this moisture gets swirled up by a common cyclone, do you think it’s going to fall as rain in Antarctica?

A recent study, no shocker to real climatologists (but perhaps to climate doomsayers), demonstrates this simple physics. It appears in the latest SciencExpress, and it shows that the vast majority of the Antarctic landmass is rapidly gaining ice and snow cover.

Obviously this moisture comes from the sea. And, being deposited in solid form on the land-way-down-under, this lowers the earth’s sea level.

Like we said, this should shock no climatologist. But consider the “profession” of environmental journalism, which ran these headlines just one teensy month ago:

“Antarctic glaciers shrink” –The Baltimore Sun, April 22, 2005

“Study shows Antarctic glaciers shrinking” –Associated Press, April 22, 2005

“Vanishing glaciers: Antarctica’s big melt” –The Australian, April 23, 2005

“New study points to big melt in Antarctica” – Sci-Tech Today, April 22, 2005

“Antarctic glaciers in mass retreat” –, April 21, 2005

“Antarctic glaciers at risk of global warming” – All Headline News, April 22, 2005

“Antarctic glaciers are getting smaller faster” –The Times On-line, April 22, 2005

“Shrinking glaciers confirm the worst” –New Scientist, April 27, 2005

Suddenly the tune has changed:

“As climate shifts, Antarctic ice sheet is growing” –Los Angeles Times, May 20, 2005

“Scientists link global warming to Antarctic’s ice cap’s growth” –Chicago Tribune, May 20, 2005

“Antarctica ice cap thickens” –Pittsburgh Post Gazette, May 20, 2005

“Warming is blamed for Antarctic’s weight gain” –New York Times, May 20, 2005

“Ice sheet confounds climate theory” – The Telegraph, May 20, 2005

“Antarctica ice cap thickens, slowing rise in sea levels” – Pioneer Press, May 20, 2005

Recent climate changes have led to a fairly large warming trend in the region around the Antarctic Peninsula—the spit of land the stretches from the Antarctic mainland towards the southern tip of South America. In this region, comprising about 2% of the entirety of Antarctica, significant changes associated with rising temperatures are being observed—floating ice shelves are breaking up, glaciers are shrinking, seal species are moving in, grasses, tiny shrubs and mosses are thriving, etc. By most accounts, transitioning from a relatively barren, frozen landscape to a warmer, less frozen one would seem to be a positive development, as this change presents a growing opportunity for increased species richness and diversity. But, in today’s world, dominated by an eagerness to demonstrate how human activities are impacting the innocent “natural” species of the world, all change is bad.

The fact is that the vast majority of global warming stories that have come out of Antarctica are based upon observations and events on and around the Peninsula. This isn’t surprising as it conforms to my theory of “Predictable Distortion” recently published in my book Meltdown. Indeed, the number of stories about Antarctic melting is roughly in inverse proportion to the percentage of the Antarctic continent that they pertain to (and thus their global significance). For instance, most of Antarctica has actually been cooling for the past couple of decades (see here for more details). And now comes word that the snow and ice cover over large portions of Antarctica has been increasing, leading to a drawdown of global sea level.

In their SciencExpress article, Curt Davis (University of Missouri-Columbia) and his collaborators used satellite radar altimetry measurements from 1992 to 2003 to determine that, on average, the elevation of about 8.5 million square kilometers of the Antarctic interior has been increasing (Figure 1). The increasing elevation was then linked to increases in snowfall, which was translated into a mass gain of 45 ± 7 billion tons per year, tying up enough moisture to lower sea level by 0.12 ± 0.02 millimeters per year.

(The study region covered about 70% of the total ice sheet area–the satellites couldn’t “see” all the way to the South Pole due to orbital constraints, and the altimetry doesn’t work well in areas of rough terrain such as along the coastline).

Antarctic Ice Trends

Figure 1. Rate of elevation change (cm/yr) from 1992 to 2003 as determined by satellite altimetry measurements (from Davis et al., 2005).

This 0.12 millimeters is a very fortuitous number. In 2000, NASA iceman William Krabill grabbed global headlines by claiming that melting in the world’s other big icebox—Greenland—was raising sea level by 0.13 millimeters annually. In blackjack, this would be called a “push,” and everybody would get to keep their money. (Global warming obviously isn’t “21”, is it?)

It seems perfectly logical that a warming of the Southern Oceans (as opposed to most of the Antarctic continent proper where temperatures have been decreasing) has led to higher levels of atmospheric moisture that eventually precipitates out over Antarctica. The authors caution though, that from their work alone, it is impossible to tell whether the observed snowfall increases are from natural climate variations or from a human-induced global warming.

Just for the hey of it, assume the increased snow cover is because of anthropogenic global warming. That would be more evidence it that the global climate system has more checks and balances in it than the U.S. Constitution, something as obvious as this planet’s propensity to sustain life for three billion years.

Cook, A.J. et al., 2005. Retreating Glacier Fronts on the Antarctic Peninsula over the Past Half-Century. Science, 308, 541-544.

Davis, C.H., et al., 2005. Snowfall-driven growth in East Antarctic ice sheet mitigates recent sea-level rise. SciencExpress, May 19, 2005.

Krabill, W., et al., 2000, Greenland Ice Sheet: High Elevation Balance and Peripheral Thinning, Science, 289, 428–430.

Michaels, P.J., 2004. Meltdown: The Predictable Distortion of Global Warming by Scientists, Politicians and the Media. Cato Books, Washington DC. 272pp.

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