Melting ice threatens sea-level rise

WASHINGTON – Already the Earth is shaking beneath melting ice as rising temperatures threaten to shrink polar glaciers and raise sea levels around the world.

By the end of this century, Arctic readings could rise to levels not seen in 130 000 years, when the oceans were several feet higher than now, according to new research appearing in Friday’s issue of the journal Science. Even now, giant glaciers lubricated by melting water have begun causing earthquakes in Greenland as they lurch toward the ocean, other scientists report.In principal findings: * At the current warming rate, Earth’s temperature by 2100 will probably be at least four degrees warmer than now, the Arctic at least as warm as it was 130 000 years ago, reports a research group led by Jonathan T Overpeck of the University of Arizona.* Computer models indicate that warming could raise the average temperature in parts of Greenland above freezing for multiple months and could have a substantial impact on melting of the polar ice sheets, says a second paper by researchers led by Bette Otto-Bliesner of the National Centre for Atmospheric Research.Melting could raise sea level one to three feet over the next 100 to 150 years, she said.* A team led by Goeran Ekstroem of Harvard University reported an increase in “glacial earthquakes”, which occur when giant rivers of ice – some as big as New York’s Manhattan Island – move suddenly as meltwater eases their path.The sudden movement causes the ground to tremble.Otto-Bliesner and Overpeck also worked together, studying ancient climate and whether modern computer climate models correctly reflect those earlier times.That allowed them to use the models to look at possible future conditions.”Although the focus of our work is polar, the implications are global,” Otto-Bliesner said.”These ice sheets have melted before and sea levels rose.The warmth needed isn’t that much above present conditions.”According to the studies, increases in greenhouse gases in the atmosphere over the next century could raise Arctic temperatures as much as 2,6 to 4,4? C.The warming could raise global sea levels by up to 6,6 metres this century.”People often think of glaciers as inert and slow-moving, but in fact they can also move rather quickly,” Ekstroem said.- Nampa-APEven now, giant glaciers lubricated by melting water have begun causing earthquakes in Greenland as they lurch toward the ocean, other scientists report.In principal findings: * At the current warming rate, Earth’s temperature by 2100 will probably be at least four degrees warmer than now, the Arctic at least as warm as it was 130 000 years ago, reports a research group led by Jonathan T Overpeck of the University of Arizona.* Computer models indicate that warming could raise the average temperature in parts of Greenland above freezing for multiple months and could have a substantial impact on melting of the polar ice sheets, says a second paper by researchers led by Bette Otto-Bliesner of the National Centre for Atmospheric Research.Melting could raise sea level one to three feet over the next 100 to 150 years, she said.* A team led by Goeran Ekstroem of Harvard University reported an increase in “glacial earthquakes”, which occur when giant rivers of ice – some as big as New York’s Manhattan Island – move suddenly as meltwater eases their path.The sudden movement causes the ground to tremble.Otto-Bliesner and Overpeck also worked together, studying ancient climate and whether modern computer climate models correctly reflect those earlier times.That allowed them to use the models to look at possible future conditions.”Although the focus of our work is polar, the implications are global,” Otto-Bliesner said.”These ice sheets have melted before and sea levels rose.The warmth needed isn’t that much above present conditions.”According to the studies, increases in greenhouse gases in the atmosphere over the next century could raise Arctic temperatures as much as 2,6 to 4,4? C.The warming could raise global sea levels by up to 6,6 metres this century.”People often think of glaciers as inert and slow-moving, but in fact they can also move rather quickly,” Ekstroem said.- Nampa-AP