How Popular Coverage of Melting Arctic Sea Ice Overlooks Relevant Long-term Research
by the Greening Earth Society (December 9, 2002)

[OBJECTIVE SCIENCE.COM] On December 8^th both The New York Times and the Los Angles Times carried major articles in their Sunday editions about the latest measurements of a shrinking area of Arctic sea ice and how global warming is to blame despite its relatively small extent. Even AOL climbed on the bandwagon on its homepage. What all of this coverage fails to mention is the strong likelihood that this year's ice extent probably is not much different than that of summers earlier in the 20^th century at a time before there could possibly have been much of a human contribution to the concentration of carbon dioxide to the atmosphere, which is cited as the driver of climate change.

This spate of popular coverage of climate change completely ignores an extremely important analysis of Arctic ice and temperatures by Igor Polykov and other published in the November 18^th edition of EOS, the official scientific journal of the American Geophysical Union. It hardly will come as a surprise to those who've followed popular media coverage of the climate change issue that Polyakov and his fellow researchers found something that doesn't jibe with the conclusion trumpeted by both of the Times newspapers and AOL/Time-Warner.

Data cited in the newspaper articles is from summer 2002. It was released by scientists recently convened in San Francisco for the annual meeting of the American Geophysical Union. What that data shows is how the areal coverage of ice in the Arctic Ocean last summer reached its smallest value since satellite measurements began in 1978. It's more than a little interesting that satellite measurements are dismissed when it comes to measuring global temperature because of their relatively short record when compared with surface temperature data. In this instance, there are records of much longer duration. Polyakov's history goes back a hundred years further and shows how the current situation is not at all unusual.

Every climatologist worth their sea-salt knows this summer wasn't at all unusual because the Arctic was as warm (or warmer) than it is now, some seven decades ago. Figure 1 is from the EOS article. It clearly captures the warmth of decades early in the 20^th century. According to Polykov and his fellow researchers.:

With regard to sea ice:

Note those statements: The high-latitude temperature increase was stronger in the late 1930s to early 1940s than in recent decades and long-term trends are small and generally insignificant. How could the American Geological Union have missed this point? And if they could, how did both The New York Times and the Los Angeles Times?

How does Polyakov's data compare with the models used by the United Nations Intergovernmental Panel on Climate Change? In fact, the researchers address this point, specifically. In referring directly to those models they write, "The maximum simulated warming is in the central Arctic, while the observations do not provide evidence of amplified high-latitude warming."

Both newspapers point out that there is a strong relationship between the areal extent of Arctic sea ice and the area's atmospheric circulation patterns. Since the mid-1960s, the circulation pattern gradually has trended away from one which supports a lot of sea ice (one with lower temperatures and less wind) and toward a pattern that is not conducive to ice build-up, when warmer and stormier weather infiltrates the region. Such conditions have the effect of lowering the amount of summer ice because they break it up, disperse and melt it.

The atmospheric circulation patterns go through natural oscillations. While the 1980s and 1990s favored relatively small ice amounts, opposite conditions dominated the late 1950s and early 1960s. In the warmer early part of the 20^th century, the circulation pattern favored open water.

Because it is spherical, earth has two ice-covered poles. What's happening in the South is opposite of what's going on in the North. Figure 2 shows the satellite-derived sea ice extent for both poles. Notice that while the Arctic sea ice has been declining, Antarctic sea ice has been increasing.

What is one left with when all the data are considered? The Arctic is almost as warm as it was seventy years ago. As result, Arctic ice recently has diminished. But, as Polyakov et al. show, the long-term changes are "generally statistically insignificant". But there's more ice in Antarctica. What's the global evidence for global warming in that?
 

Figure 1. Solid line: Six-year running means of Arctic temperature from Polyakov et al. The dashed line represents annual temperatures. Clearly the 1930s, at a time before changes in the greenhouse effect could have caused much warming were as warm or warmer than today.
 

Figure 2. Trend in sea ice extent in the Arctic (top) and Antarctic (bottom). Figure taken from http://polynya.gsfc.nasa.gov/seaice_projects.html#image10.

Reference

Polyakov, I, et al., 2002. Trends and Variations in Arctic Climate Systems. EOS, Transactions, American Geophysical Union, Vol. 83, 547-548.

-- Reprinted from Greening Earth Society at www.CO2andClimate.org
 

Back to Objective Science Home