The United States National Oceanic and Atmospheric Administration (NOAA) satellites that keep buzzing around the earth have what are called Advanced Very High Resolution Radiometer (AVHRR) sensors with a thermal infrared channel.

This portion of the light spectrum can sense as heat what human eyes cannot see and has recorded temperature trends for the icy continent from 1982 to 2004.

The picture below from the NASA website indicates areas where temperatures generally increased during that period, and blue shows where temperatures predominantly decreased. This image shows trends in “skin temperatures” – temperatures from roughly the top millimeter of the land or sea surface—not air temperatures.

The NASA scientists are cautious folk. They summarise their findings in this way and give an appropriate warning about using the data:

Antarctica has been showing some interesting heating and cooling trends over the past 20+ years. Even though the interior of Antarctica is generally cooling, the coastlines (particularly in the western hemisphere) seem to be warming. This data is skin-depth temperatures derived from the thermal IR channel of historical AVHRR data.

Please note, these are preliminary findings and there are errors associated with these trends. Scientists are currently working on ways of minimizing these errors to more precisely determine these trends.

NASA reports the area of strongest cooling appears at the South Pole, and the region of strongest warming lies along the Antarctic Peninsula. In some instances, bright red spots or streaks along the edge of the continent show where icebergs calved or ice shelves disintegrated, meaning the satellite began seeing warmer ocean water where there had previously been ice. One example of this is the bright red line along the edge of the Ross Ice Shelf.

NASA poses the question: Why is Antarctica getting colder in the middle when it’s warming up around the edge?

One possible explanation is that the warmer temperatures in the surrounding ocean have produced more precipitation in the continent’s interior, and this increased snowfall has cooled the high-altitude region around the pole. Another possible explanation involves ozone. Ozone in the Earth’s stratosphere absorbs ultraviolet radiation, and absorbing this energy warms the stratosphere.

Loss of UV-absorbing ozone may have cooled the stratosphere and strengthened the “polar vortex,” a pattern of spinning winds around the South Pole. The vortex acts like an atmospheric barrier, preventing warmer, coastal air from moving in to the continent’s interior. A stronger polar vortex might explain the cooling trend in the interior of Antarctica.

Now in these times of concern about a shrinking Artic ice cap caused by global warming not much has been heard about this finding of increasing snow falls at the other end of the globe. The NOAA scientists clearly do not want to waste their time defending a charge of heresy and have not cranked up their publicity machine.

But if the idea that the hole in the ozone layer may be stopping the oceans of the earth from drowning Tuvalu by adding ice to the Antarctic that is being taken away from the Arctic, cast your eye on these two images of the ozone layer.

The graphic on the left is of NASA’s ozone hold watch for September 1982 and the one on the right for September 2004. For a description of what it all means click here but in summary the darker the blue the bigger the ozone shortage.

You might want to thank the Chinese and the Indians too for ensuring that last year’s ozone hole in the polar region of the Southern Hemisphere broke records for area and depth. According to Paul Newman, atmospheric scientist at NASA’s Goddard Space Flight Center, Greenbelt, Md. From September 21 to 30 2006, the average area of the ozone hole was the largest ever observed, at 10.6 million square miles. If the stratospheric weather conditions had been normal, the ozone hole would be expected to reach a size of about 8.9 to 9.3 million square miles.

As the New York Times reported earlier this week, an unusually cold Antarctic winter, rather than the rise in the use of refrigerants, may have caused the sudden expansion but “it has refocused attention on the ozone layer, which protects people and other animals as well as vegetation from the sun’s harmful ultraviolet rays. Now, the world’s atmospheric scientists are concerned that the air-conditioning boom sweeping across Asia could lead to more serious problems in the future.”

Or perhaps, although the Times did not say it, to an even colder Antarctic this September with yet more snow and ice than ever before.

Peter Fray

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