A recent study published in the September 4 issue of Science magazine is yet another indicator that the Arctic is in crisis. A team of scientists found that temperatures in the Earth’s vast northernmost region – which includes the Arctic Ocean and parts of Alaska, Canada, Russia, Greenland, and the Scandinavian countries in Northern Europe – have reversed a long-term cooling trend and are now the warmest they’ve been in at least 2,000 years.
The study’s authors include the renowned Darrell S. Kaufman, of the School of Earth Sciences and Environmental Sustainability at Northern Arizona University, and David Schneider of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado.
The Arctic cooling period had lasted for 2,000 years and was reversed during the 20th century, with four of the five warmest decades in the region occurring between 1950 and 2000.
Moreover, the warmest decade was from 1999 to 2008, with Arctic temperatures averaging 2.5 degrees Fahrenheit higher than would have been expected if the cooling trend had continued, said Kaufman, the study’s lead author.
According to the study, the 2,000-year cooling trend was largely the result of a “wobble” in Earth's rotation that has been increasing the distance between the sun and Earth and decreasing Arctic summer sunshine. (The Earth is approximately 600,000 miles further from the sun during the Northern Hemisphere summer solstice than it was in 1 B.C.)
Kaufman stated that the recent warming trend is directly correlated to a continuing buildup of human-induced greenhouse gases in the atmosphere. And, according to Professor Gifford Miller of CU-Boulder's Institute for Arctic and Alpine Research, a study co-author, greenhouse gases began "overriding" the natural cooling period in the middle of the last century.
Scientists previously had determined that the Arctic is warming more rapidly than anywhere else on Earth, a phenomenon called “Arctic amplification.” And a report published earlier this year by the Obama Administration’s U.S. Climate Change Science Program (CCSP) concluded that warming in the Arctic will continue at a rapid pace in the coming decades given human-induced changes in Earth's atmosphere.
In a classic example of nature’s remorseless feedback loops, warmer temperatures in the northernmost regions are causing the permafrost to thaw. The decomposing soil, in turn, is releasing vast quantities of methane, one of the most virulent greenhouse gases, thus further exacerbating warming.
Methane has a global warming potential (GWP) far greater than carbon dioxide, meaning it is more effective as a greenhouse gas. Over a 20-year time span – viewed by experts such as Stan Rhodes of Scientific Certification Systems as a more relevant timeframe for analysis rather than the standard 100-year timeframe used by the Intergovernmental Panel on Climate Change (IPCC) – methane has a GWP 72 times greater than carbon dioxide. Everyone focuses on carbon dioxide as the issue, but methane, pound for pound, is far worse. And it’s relentlessly spewing into the Arctic air.
Why care? According to NCAR’s Schneider, "… the Arctic, perhaps more than any other region on Earth, is facing dramatic impacts from climate change … greenhouse gases from human activities are overwhelming the Arctic's natural climate system." Study co-author Miller stated that impacts will include loss of land-based snow and ice, thus adding to sea-level rise. Rising ocean waters pose a grave threat to island and coastal communities worldwide.
In addition, scientists were startled to discover earlier this year that Arctic sea ice is thinning to a much greater extent than previously anticipated. The decreased sea ice, in turn, causes increased absorption of the sun’s heat by the increasingly exposed ocean water.
Finally, the region’s remarkable temperature increases could hasten a disturbing possibility known to researchers as “abrupt climate change.” This is generally described as nature’s point of no return, i.e., when even reducing greenhouse gas emissions would have no effect on runaway, nonlinear global climate shifts.
Sources for this article include the following: September 4 issue of Science magazine; an article by Rachel Zurer in the Fall 2009 issue terrain magazine, “Climate Change May Be Abrupt – and Unstoppable”; Stan Rhodes of Scientific Certification Systems; the web site, EurekAlert; and, a September 3 University of Colorado press release.
See future articles in Climate Change Update for more information regarding the Arctic in crisis and abrupt climate change.
No comments:
Post a Comment