Sea Levels May Rise 2.3 Meters Per Degree Of Global Warming
By Countercurrents.org
16 July, 2013
Countercurrents.org
Greenhouse gases emitted today might raise sea level significantly for centuries to come, said an international study. The study was conducted for the Potsdam Institute for Climate Impact Research (PIK). Researchers from Germany, the US, Spain, Canada and Austria contributed to the research.
"Each degree of global warming is likely to raise sea level by more than 2 meters in the future," said the Germany-based PIK in a statement.
According to the study published on July 15, 2013 in the Proceedings of the National Academy of Sciences journal, thermal expansion of the ocean and melting mountain glaciers are the most important factors causing sea-level change today. During the 20th century, sea level rose by about 0.2 meters, and it is projected to rise by significantly less than two meters by 2100 even by strongest scenarios considered.
Within the next two millennia the Greenland and Antarctic ice sheets will be the dominant contributors in the sea level rise. Half of the sea level rise might come from ice loss in Antarctica, which is currently contributing less than 10 percent to the global sea-level rise. Greenland will add another 25 percent to the total sea-level rise, said the team.
The thermal expansion of the oceans' water, currently the largest component of sea-level rise, will contribute about 20 percent. The contribution from mountain glaciers will decline to less than 5 percent, mostly because many of them will shrink to a minimum, added the team.
"CO2, once emitted by burning fossil fuels, stays an awful long time in the atmosphere. Consequently, the warming it causes also persist," said Anders Levermann, lead author of the study.
"The problem is: once heated out of balance, they simply don't stop," he said.
"It is inevitable and therefore highly relevant for almost everything we build along our coastlines, for many generations to come," he said.
A Reuters/guardian.co.uk report on July 15, 2013 said:
Levermann said his study was the first to examine evidence from climate history and combine it with computer simulations of contributing factors to long-term sea-level increases: thermal expansion of oceans, the melting of mountain glaciers and the melting of the Greenland and Antarctic ice sheets.
"We're confident that our estimate is robust because of the combination of physics and data that we used," Levermann told Reuters. "We think we've set a benchmark for how much sea levels will rise along with temperature increases."
"In the past there was some uncertainty and people haven't known by how much," Levermann said. "We're saying now, taking everything we know, that we've got a robust estimate of 2.3 meters of rising sea per degree of warming."
"Continuous sea-level rise is something we cannot avoid unless global temperatures go down again," Levermann said. "Our results indicate that major adaptation at our coastlines will be necessary. It's likely that some currently populated regions can't be protected in the long run."
The Reuters/guardian.co.uk report added:
David Vaughan, head of the Ice2sea project to narrow down uncertainties about how melting ice will swell the oceans, has said sea levels would rise by between 16.5 and 69 cm under a scenario of moderate global warming this century.
Vaughan told Reuters the biggest impact rising seas will have is that storms will be more destructive in the near future.
"It's not about chasing people up the beach or the changing shape of coastlines," he said. "The big issue is how the storms will damage our coasts and how often they occur. That'll increase even with small levels of sea rise in coming decades."
Governments wish to limit global warming under 2 degrees compared to pre-industry times. In the latest round of UN climate change negotiations, a concrete process towards a new global agreement on battling against the global challenge has been made. The agreement, which is supposed to include elements of emission cutting, adaptation, financial and technology transferring, is scheduled to be made in 2015 and come in to force in 2020.
Global average surface temperatures have risen by 0.8C since the industrial revolution and the IPCC has said temperatures are likely to be 0.4 to 1.0C warmer from 2016-35 than in the two decades to 2005. Sea levels rose by 17cm last century and the rate has accelerated to more than 3mm a year, according to the IPCC.
A third of the current rise is from Antarctica and Greenland. Some scientific studies have projected sea level rise of up to 2 metres by 2100, a figure that would swamp large tracts of land from Bangladesh to Florida.
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