shark
Image: UNIVERSITY OF WASHINGTON

As evidence for global warming accumulates, predictions concerning its effects are growing in scope and magnitude. Two separate presentations made at the annual meeting of the American Association for the Advancement of Science this past weekend in Boston demonstrated the range of global warming's possible consequences, from a boom in the shark population in Alaskan waters to a sharper rise in sea level than previously estimated.

According to Vince Gallucci of the University of Washington, the combined effects of a periodic swing in weather called the Pacific Decadal Oscillation and global warming may be making Alaskas Prince William Sound more hospitable to local sharks. Meanwhile, Galucci notes, the number of pinnipeds, such as seals and sea lions, has decreased. In fact, Pacific sleeper sharks, which are capable of growing to 24 feet, and the much smaller salmon sharks have replaced the pinnipeds as the second-most efficient predators in the area, behind orcas.

Perhaps even more significant, the very waters these creatures swim in could rise much higher than recently predicted. After analyzing the melting rate of glaciers on the western coast of Alaska and northern Canada, Mark Meier and Mark Dyurgerov of the University of Colorado at Boulder have concluded that forecasts made last year by the Intergovernmental Panel on Climate Change (IPCC) failed to take into account an acceleration in glacial and ice cap melting that began in 1988. Since then, Meier says, the rate of ice loss has doubled. He notes that the Alaskan and Canadian glaciers are important because they currently account for about half of the rate of global ice loss, yet they make up only about one sixth of total glacial ice area. In contrast to the IPCCs prediction that glacial melting will elevate sea levels by 0.16 to 0.36 feet, the new calculations indicate that that figure should be 0.65 feet or more. Although this might not seem large, Meier notes that a one-foot rise in sea level typically corresponds to a loss of 100 feet of beach. A rise of one meter, he adds, would flood half of Bangladesh, displacing 100 million people.