Are Polar Bears Dying?Commentary by H. Sterling Burnett
May 15, 2006
A new study by Dr. David Legates, Delaware's State Climatologist and director of the University of Delaware's Center for Climatic Research, throws cold water on the claim that global warming threatens to cause the extinction of polar bears.
As part of his study titled Climate Science: Climate Change and its Impacts, expected at press time to be released in April of this year, Legates reviewed assertions by environmental alarmists that global warming is causing an unnatural increase in Arctic temperatures, posing a threat to the thickness and extent of sea ice required by polar bears. In particular, Legates examined claims made in the Arctic Climate Impact Assessment (Arctic Assessment), an international project of the Arctic Council--an intergovernmental forum consisting of representatives from eight Arctic nations and six groups representing indigenous peoples.
After careful review, Legates found the Arctic Assessment claims of an impending, human-induced arctic meltdown are "not supported by the evidence."
The Arctic Assessment claimed Arctic air temperature trends provide an early and strong indication of global warming causing polar ice caps and glaciers to melt. However, Legates points out that current research suggests this conclusion is unwarranted.
For example, coastal stations in Greenland are experiencing a cooling trend, and average summer air temperatures at the summit of the Greenland Ice Sheet have decreased at the rate of 4º F (2.2º C) per decade since measurements began in 1987.
Arctic Russia Cooling
In addition, observes Legates, the Arctic Assessment ignored a relatively recent long-term analysis of records from coastal stations in Russia.
Russian coastal station records of both the extent of sea ice and the thickness of fast ice (ice fixed to the shoreline or seafloor) extending back 125 years show significant variability over 60- to 80-year periods. Moreover, the maximum air temperature they report for the twentieth century was in 1938, when it was nearly 0.4º F (0.2º C) warmer than the air temperature for 2000. According to Legates, the Russian observations do "not support [claims of] amplified warming in Polar Regions predicted by general circulation models."
Earth Warmer Before
Legates also points out that even if warming was happening, research shows such warming has occurred before, as ice cores from Baffin Island and sea core sediments from the Chukchi Sea (north of the Bering Straight between Alaska and Russia) show.
For example, in Alaska the onset of a climatic shift--a warming--in 1976-1977 ended a multi-decade trend of cold in the middle of the twentieth century. This simply returned temperatures to those experienced in the early years of the century.
Warming a Minor Factor
According to the Arctic Assessment, human-caused warming in the Arctic will necessarily lead to decreased sea ice extent and thickness. However, Legates notes air temperature is only one of the factors that dictate sea ice coverage and thickness.
When the Arctic is relatively calm, for example, it is easier for sea ice to form. Sea ice is then moved around the Arctic by the force of the wind. During stormy periods, surface winds churn the water and move existing ice, making it more difficult for sea ice to form.
Reinforcing that point, Legates highlights a study commissioned by Canada's Department of Fisheries and Oceans, which concluded, "the possible impact of global warming appears to play a minor role in changes to Arctic sea ice." According to Legates, the "Canadian study concluded that changing wind patterns are the primary cause of changing sea ice distributions. Moreover, the response of sea ice in the Antarctic has been quite different--while it has decreased in the Arctic, it has remained relatively constant (or even increased slightly) in the Antarctic since 1978."
Bear Population Steady
The Arctic Assessment concludes, "global warming could cause polar bears to go extinct by the end of the century by eroding the sea ice that sustains them." This is misleading, Legates finds, because, as discussed above, Arctic air temperatures were as high as present temperatures in the 1930s and polar bears survived.
According to the World Wildlife Fund, about 20 distinct polar bear populations currently exist, accounting for approximately 22,000 polar bears worldwide. Of those distinct populations only two, representing about 16.4 percent of the total population, are decreasing. At the same time, 10 populations representing approximately 45.4 percent of the total population are stable, and 2 populations representing about 13.6 percent of the total number of polar bears are increasing. The status of the remaining populations is unknown.
"This [the Arctic Assessment] is nothing more than a poorly designed attempt to implement the Kyoto Protocol through the back door," said Peyton Knight, director of environmental and regulatory affairs at the National Center for Public Policy Research. "You don't list endangered species based on speculative predictions," said Knight; "you list them because there are small numbers of the species and the numbers are in fact dwindling. This is not called the 'someday-might-possibly-become-endangered-if-our-speculative-claims-prove-true' list."