Global Warming Thawing The Arctic Alaskan Glaciers Offer Scary Preview, Scientists Report
Unprecedented temperature increases are thawing huge swaths of the Arctic, including Alaska, offering an alarming preview of what global warming could do to the rest of the world, scientists reported Thursday.
“The Arctic is a harbinger - a canary in the mine shaft - of global warming,” said Jonathan Overpeck, coordinator of a U.S.-Canadian government-sponsored study of climate in the far North. “It’s scary.”
The study found average temperatures in the Arctic have increased by approximately 3 degrees Fahrenheit since 1840 and might rise by many times that amount in coming years. Up until 1920, the increase was due to natural causes, the scientists said, but since then, air pollution from various causes has made the difference.
The report, to be published in today’s edition of Science magazine, is based on 10 years of work by a team of government and university scientists.
They collected data from tree rings, ice cores, lake and ocean sediments and other evidence of climate change from more than two dozen sites in Alaska, Canada, Greenland, Scandinavia and Siberia. Results were similar everywhere.
In northern Alaska, the warming already is shrinking glaciers, swallowing up roads, buckling airport runways and thawing the permafrost, the frozen tundra supporting much of the state’s infrastructure. Sea-ice is melting and vegetation and wildlife are moving northward and up onto higher terrain, seeking cooler climes.
“If you want to see climate change, go to Alaska,” said Paul Dresler, leader of a global-change monitoring group at the Department of the Interior. He was attending another conference on the subject here this week.
“It’s weird what’s happening in Alaska,” agreed Brian Henry, chairman of the Northwest Council on Climate Changes.
Overpeck said his report is the most detailed study to date of the effects of climate change on a single portion of the world. He said the results tend to confirm the predictions of computer climate models that the impact of global warming should be most severe in the far north and far south.
These models have been criticized as inaccurate and misleading by global warming skeptics. At a congressional hearing Thursday, one such skeptic, Rep. Dana Rohrabacher, RCalif., a member of the House Science Committee, called global warming “baloney.”
Overpeck, a climate expert at the National Oceanic and Atmospheric Administration (NOAA), attributed the temperature increase between 1840 and 1920 to natural causes - not human activities. During that period, there was increased radiation from the sun and fewer volcanic eruptions to shade and cool the land, he said.
But since 1920, humans have been pouring greenhouse gases - mostly carbon dioxide and methane from factories, automobiles and farms - into the atmosphere, trapping much of the sun’s heat that previously escaped from the Earth.
Human factors account for about half the warming, Overpeck said, and in the future, they will be more important than natural causes.
Some cooling occurred in the 1950s and 1960s, thanks to a renewed burst of volcanic activity, but the upward march has since resumed.