Revised SCAR report highlights ozone depletion, tropical influences on Antarctica
Posted June 14, 2013
West Antarctica remains the most climatically dynamic region of the southernmost continent, which continues to be largely shielded from the effects of global warming thanks to the persistence of the ozone hole. But that’s likely to change before the end of the century.
That’s among some of the key points to the most recent update of a landmark report released in 2009 by the Scientific Committee on Antarctic Research (SCAR) . The latest Antarctic Climate Change and the Environment (ACCE) report was published last month in the journal Polar Record.
“Antarctic science moves very fast, and by the time we got 2012, we thought it was appropriate to have an update to identify the key advances since our original report,” said John Turner , a scientist with the British Antarctic Survey and chair of the ACCE expert group for SCAR, an international organization that promotes and coordinates scientific research in Antarctica.
Turner said in a brief video statement posted on YouTube that the scientific community has reached consensus on a number of issues, such as the fact that West Antarctica is contributing “significantly” to sea-level rise. In particular, the retreat of Pine Island Glacier, an area under intense study in recent years, accounts for about 10 percent of total glacial melt into the ocean, he said.
The original 555-page report focused attention on the effect of ozone depletion, which has caused the stratosphere to cool. The stratosphere is the layer of atmosphere above the troposphere, which is closest to the Earth. [See previous article — State of the Antarctic: New SCAR report shows continent undergoing major changes.]
However, the ocean around the continent and regions to the north are warming. The temperature differential has intensified westerly winds around the Southern Ocean by 15 to 20 percent, effectively shielding much of the continent from the intrusion of warmer air originating in lower latitudes.
The updated ACCE report noted that ozone-depleting substances in that stratosphere are decreasing by 1 percent per year. By mid-century, springtime ozone levels are expected to recover significantly, with stratospheric concentrations of ozone predicted to return to pre-1980s levels year-round by the end of the 21st century.
In effect, Antarctica’s added protection from warmer temperatures thanks to those intensified westerly winds might dissipate should the circulation patterns also return to pre-1980s levels.
Photo Credit: Dr. Paul Ponganis/Antarctic Photo Library
The SCAR report says populations of emperor penguins in East Antarctica are in decline.
The report also takes into account more recent research that suggests that warming across parts of the Antarctic Peninsula and West Antarctica, particularly during certain months of the year, is being influenced by warmer sea surface temperatures in the tropical Pacific. [See previous articles — Temperatures rise in the fall: Study suggests tropics to blame for warming during autumn months and Heat wave: UW scientists suggest Pacific Ocean contributes to West Antarctic warming.]
The update ACCE report also highlighted changes in the marine ecosystem, such as the shift of both phytoplankton and bacterioplankton from larger to smaller species, which may affect food availability for grazing animals.
Populations of Adélie and gentoo penguins continue to decline in some regions, along with numbers of emperor penguins in East Antarctica. Researchers have also documented a shift in the range of Southern elephant seals from north to south.
More than 25 experts from 15 institutions across the world contributed to the latest report, including five scientists from the United States whose research is supported, in part, by the National Science Foundation.