TCS Daily

Calving and Sobs

By Sallie Baliunas - May 31, 2002 12:00 AM

There are a lot of headlines about weird weather these days. And many of those stories often blame human-made global warming for the wacky weather events. As a result, it would be difficult even for a reasonable person not to conclude that human fossil-fuel use has transformed the natural weather to something wholly dastardly and 'unnatural.'

However, from a scientific standpoint, the earth's weather always yields extraordinary events - that is one of the hallmarks of earthly weather. For example, one newsy weather oddity occurred in the usually snowless desert kingdom of Saudi Arabia. In January this year, eight inches of snow fell in northern and central Arabia (despite the fact that the residents had prayed for rain; still, precipitation - liquid or ice - is precipitation). But it does snow there every few decades or so. Unusual? Yes. Resutling from fossil fuel use? Scientifically unproven.

What's new is the sociology of reporting weather events, built on the technology of rapid telecommunication and incredible scientific instruments that download digital imagery of space-age weather data, so essential to the study of weather. The new sociology includes blather reporting so acutely displayed recently with another snow and ice event we've been following closely (and one that's troubling for many): the calving of ice in Antarctica.

Two large icebergs calved from the Ross Ice Shelf early in May and were caught in the act by the instruments of the U.S. Defense Meteorological Satellite Program. Almost immediately, headline-hunters could be found frothing about iceberg digital imagery and human-made global warming. The "Antarctic ice melt poses worldwide threat" blared one story from Reuters (May 15, 2002). The article asserted that the rate of ice breakup in Antarctica "is alarming scientists, who blame global warming." Another article (Reuters, May 10, 1002) quoted "a global warming expert at the National Environmental Trust" who stated that glaciers are "a canary in the coal mine for the global warming trend."

Some perspective - and history -- is badly needed. Antarctica is a continent sitting on the South Pole. At the rim of the continent lie the exposed edges of the landmass, but the continent has been predominantly snow and ice covered for perhaps 40 million years. To understand the climate of Antarctica before then, we have to consider that the continents shift slowly but widely over the surface of the earth over tens of millions of years.

Around 240 million years ago, in the geologic period called the Mesozoic, Antarctica was part of the large supercontinent called Gondwana. Stretching nearly from the North to South Poles, Gondwana included nearly every major landmass except southern China and Malaysia. During this period -- which was a period of great warmth -- dinosaurs rose to ascendancy in the kingdom of life. The giant reptiles stomped the earth for over 180 million years. At that time, Antarctica was not located dead south, and was not the ice-draped continent it is today. Gradually continental drift tore the continents apart, isolating Antarctica, which now sits atop the South Pole in her icy glory.

And over long periods of time Antarctica's ice has dramatically changed. The ice is very dynamic, so abrupt changes commonly occur as the ice responds to earth's ever-changing climate. We are more sensitized to even small changes - like iceberg calving - owing to astonishing satellite imagery broadcast to our homes.

After the first flurry of hysterical press accounts about the calving, there appeared some refreshingly scientific headlines and stories detailing the facts. A press release from the National Science Foundation (May 23, 2002) describes the original data and the current scientific analysis that led to the scary stories mentioned above. As it turns out, media-hype overshadows the facts. The NSF release states that the iceberg events were a "natural 'calving' process" that "is part of a natural cycle in which ice shelves grow and then calve icebergs over geological time scales."

Moreover, any link between the human-made increase in the air's carbon dioxide content and global warming cannot be demonstrated by the calving events. The rapid rise in the air's carbon dioxide content occurred in the last three decades. Yet the iceberg calving "brings the Ross Ice Shelf to roughly the size it was in 1911, when members of British explorer Robert Falcon Scott's party first mapped it," according to NSF. The point is that through most of the 20th century the ice grew, then finally calved, independent of the air's concentration of greenhouse gases. That's the natural, dynamic process of complex Antarctic ice.


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