November 15, 2007
Antarctica – a vast territory whose sea-ice growth in winter effectively doubles its size to envelop an area three times that of Canada – is the world’s coldest continent by far, its permanent ice sheet regulating the Antarctic atmosphere. It is also the world’s windiest and driest continent by far, and its highest by far, with a mean elevation of 2,300 metres.
It is also the world’s most remote continent, its least explored and least understood.
Not until 1998, with the advent of new technologies and improved scientific understanding, did human knowledge “allow the question of the global relevance of Antarctica to be explored in detail for the first time,” stated David Bromwich of the Byrd Polar Research Center at Ohio State University. A decade ago, Dr. Bromwich was embarking on a major research project for the National Science Foundation to begin to understand this frozen continent, which is the primary heat sink in the global climate system, and “plays a central role in global climate variability and change.”
His mission, in part, dealt with the science of global warming, which could not be settled until Antarctica gave up its mysteries. “The validity of global change scenarios remains controversial,” he said at the time.
A decade later, despite accumulating research, the validity of climate change scenarios continues to be controversial, and the unknowns surrounding the role of Antarctica continue to overwhelm the little that’s known. As Dr. Bromwich reported earlier this year at the annual meeting of the American Association for the Advancement of Science at San Francisco, “It’s hard to see a global-warming signal from the mainland of Antarctica right now.”
Dr. Bromwich presented his findings shortly after the United Nations Intergovernmental Panel on Climate Change came out with new findings in February that pointed to catastrophic consequences if mankind didn’t change its ways. The science is settled, the IPCC indicated, its global models reliable.
Yet Dr. Bromwich found that the global models that the IPCC relies on are at odds with his own findings. Antarctica’s temperatures during the late 20th century did not climb as global climate models predicted.
“The best we can say right now is that the climate models are somewhat inconsistent with the evidence that we have for the last 50 years from continental Antarctica,” he stated, adding that “We’re looking for a small signal that represents the impact of human activity and it is hard to find it at the moment.”
A 2006 study by Dr. Bromwich and others, published in the journal Science, again found the accepted climate-change models to be wrong. According to those models, snowfall in Antarctica should have been increasing. Instead, the study found, there has been no statistically significant increase in the snowfall trend over the past 50 years. Instead, snowfall patterns in Antarctica varied widely from year to year and decade to decade. Dr. Bromwich’s findings – considered to be the most precise record of Antarctic snowfall yet – also point to the need for decades of more data from satellites to determine Antarctica’s patterns.
Complex computer modelling is notoriously unreliable, yet there are exceptions. One is the model that helped save the life of Ronald Shemenski, a physician stationed at the U.S. South Pole Station in April, 2001. Dr. Shemenski, who had developed a life-threatening pancreatic infection, needed to be airlifted in a season of high winds, extreme cold and near 24-hour darkness, when plane travel doesn’t normally occur. The unprecedented rescue effort succeeded, thanks to the aircrew of Canada’s Kenn Borek Air Ltd., who flew a Twin Otter in and out of the South Pole, and Dr. Bromwich’s model, which helped predict the best time for the perilous rescue effort.
“The forecast model used to predict air-craft-landing conditions at the South Pole for the rescue was optimized specifically for Antarctic conditions,” Dr. Bromwich explains. “The model was only run for short periods, about two days at a time,” to approximate the time required for the rescue mission.
The optimization for Antarctic conditions also succeeds where global models fail. “Global climate models that are having some trouble at predicting the long-term behaviour [over decades] of Antarctic near-surface temperatures are not optimized for the unique atmospheric conditions over Antarctica, probably the most pristine place on Earth,” he elaborates. “The primary reason is connected with cloud formation. The global models treat the clouds like those in mid-latitudes, whereas they are very different in reality.”
That global models fare poorly in remote parts of the world doesn’t surprise him. “These are global models and shouldn’t be expected to be equally exact for all locations,” he explains, adding that “until the global models get the polar regions right, they won’t get the global climate right either.”
Lawrence Solomon is executive director of Energy Probe and the Urban Renaissance Institute.
CV OF A DENIER
David Bromwich is head of the Polar Meteorology Group of the Byrd Polar Research Center and Professor in the Atmospheric Sciences Program at the Department of Geography of Ohio State University. He is president of the International Commission on Polar Meteorology, the chair of the Polar DAAC Advisory Group, a member of the Arctic Climate System Study Working Group on Reanalysis, and a past member of the National Academy of Sciences, Committee on Geophysical and Environmental Data. The author or co-author of numerous papers, he received his PhD in meteorology from the University of Wisconsin, Madison, in 1979.