Global Sea Levels Projected To Rise Faster Than Expected
Pastor Dale Morgan
Global Sea Levels Projected To Rise Faster Than Expected*
Under that scenario, regional sea levels could rise by up to a meter
(yard), and once the greenhouse gas effect is factored in, the increase
could be as much as two meters, which could expose London and New York
to potentially "devastating storm surges," Stefan Rahmstorf, professor
of ocean physics at Potsdam University said.
by Staff Writers
Chicago (AFP) Dec 15, 2006
Global warming may raise sea levels faster than previously expected this
century, said a study released Thursday that suggests the impact of
climate change on the oceans may have underestimated. The study says
rising temperatures could boost sea levels by as much as 1.4 meters (4.6
feet) by 2100, almost twice the rate previously forecast, increasing the
flood risk in low-lying areas, and the threat of storm surges to cities
such as New York and London.
Climatologists so far agree that sea levels will increase 9-88
centimeters (4-35 inches) over 1990 levels by the end of the century,
but in the paper published in the journal Science, a German researcher
suggests the range could be much higher, 50-140 centimeters (20-55 inches).
Stefan Rahmstorf, professor of ocean physics at Potsdam University, said
current working assumptions are unreliable because the computer models
that generated them significantly underestimate the rise in sea levels
already seen.
"In the past 40 years, sea levels have increased about 50 percent more
than the climate models predicted. That tells us that we haven't
understood the problem of rising sea levels yet," said Rahmstorf.
Current computer models used by the Intergovernmental Panel on Climate
Change, an UN-sponsored body that advises policymakers on the effects of
climate change, considers a number of factors including thermal
expansion and the effect of melting ice sheets.
For his analysis, Rahmstorf examined the relationship between rising sea
levels and increases in global average near-surface air temperatures. He
concluded that the rate of increase in sea levels was proportional to
rising temperatures and accounted for the changes seen in the 20th century.
Rahmstorf said the higher range has serious implications, not just for
low-lying areas which have already been identified as global
warming-related flood risks, but also for some major cities in the
Western hemisphere.
In a study published last year, Rahmstorf and his team at the Potsdam
Institute for Climate Impact Research argued that global warming could
increase sea levels in the North Atlantic by shutting down or weakening
an ocean current called the overturning circulation or conveyor belt.
Under that scenario, regional sea levels could rise by up to a meter
(yard), and once the greenhouse gas effect is factored in, the increase
could be as much as two meters, which could expose London and New York
to potentially "devastating storm surges," Rahmstorf said.
At the very least, Rahmstorf says his study shows just how wide the
margin of error is when it comes to forecasting climate-related change
in sea levels.
"The fact that we get such different estimates using different methods
shows how uncertain our sea level forecasts still are."
Source: Agence France-Presse