Thursday, December 12, 2013
The image shows potential storm flooding along the shorelines of Portland and South Portland if sea levels were to rise one meter or 3.3 feet. Some scientists say melting glaciers could increase sea levels at least one meter by the end of this century. The flooding shown here assumes a 2.6 foot storm surge in addition to the higher sea level. source: Clean Air-Cool Planet
John Ewing/Staff Photographer... October 21, 2009...Scientists discuss the faster than expected melting of glaciers in Greenland and the potential impacts in Maine at conference held at the Gulf of Maine Research Institute in Portland. Dr. Gordon Hamilton, a research professor at UMO speaks about his experiences and research in Greenland.
PORTLAND — Greenland's glaciers are melting and falling into the ocean far faster than expected just five years ago, which means higher sea levels and more coastal flooding than expected here, researchers from the universities of Maine and New Hampshire said Wednesday.
''A whole series of changes have started to take place in Greenland (that) lead us to believe we can expect a much larger sea level rise,'' said Gordon Hamilton, a research associate professor at the University of Maine's Climate Change Institute. And, Hamilton said, ''we're going to see a lot of this sea level rise come a lot sooner than we thought.''
A few years ago, scientists forecast a 1- to 2-foot rise in sea levels by 2100. Hamilton and others now foresee at least a 3.3-foot rise in this century.
Scientists have said such a rise would cause more flooding and damaging erosion in Maine, especially during storms. That could threaten buildings, roads and sewage treatment plants, as well as recreational beaches and wildlife habitat.
Hamilton and Mark Fahnestock, a research associate professor at the University of New Hampshire, spoke Wednesday about their findings during expeditions to the east and west coasts of Greenland, including several trips this summer. Their presentation, one of several planned for cities along the East Coast this fall, was sponsored by Clean Air-Cool Planet, a Portsmouth, N.H.-based advocacy group.
The emerging science from Greenland adds urgency to legislation pending in the U.S. Senate to create a national cap-and-trade system to slow greenhouse gas emissions, said Clean Air-Cool Planet's president, Rafe Pomerance.
''The policy makers need to know about the change in the fate of the world's coastlines,'' Pomerance said. ''This change in the ice sheets we're seeing now is a powerful, powerful piece of information.''
Hamilton has been studying glaciers on the east coast of Greenland, visiting several times a year and using GPS instruments and satellite images to track the frozen rivers as they slowly carry snow and ice from Greenland's interior and dump them into the ocean.
Fahnestock has been doing similar research on the west coast of Greenland. Both researchers, along with many others who are studying the Greenland ice sheet, have been documenting the same accelerated melting trend. It began around 2005, after what was considered a mild warming period in the region.
''These glaciers are far more responsive to small warmings than we might have anticipated,'' Hamilton said. Changes are taking place ''in a few years. It is not decades. It is not a century.''
Sea level rise, which has been measured at a slow rate along the Maine coast for centuries, has been caused primarily by melting polar ice and by thermal expansion -- ocean water has more volume as it warms.
Now, Greenland's glaciers are pushing huge icebergs into the sea at two to three times the pace they did before 2005, the scientists said.
''Once you put an iceberg into the ocean, it's like putting ice cubes into your cocktail: The volume is larger,'' Hamilton said. ''These are large glaciers. You make one change and you're having a global effect. Each one of those puts 40 or 50 gigatons of ice into the ocean each year.''
The ice on Greenland is as much as 2 miles thick at its center and contains enough water to raise the level of the world's oceans 23 feet, although scientists aren't predicting melting on anywhere near that scale.
While Hamilton and Fahne-stock said they can't predict exactly how much ice will flow into Greenland's coastal waters or how much it will raise the ocean's sea levels, they said they expect the trend to continue.
''We have great confidence that this trend is very strong, and very strongly negative,'' said Fahnestock. ''What we know is, the glaciers are very responsive'' to warming.
The scientists also are trying to understand other signs of change that appear to be affecting the rate of sea level rise.
Hamilton, for example, said he recently measured deep reservoirs of water beneath the glaciers. Warmer ocean water appears to be flowing into the deep fjords, melting the glaciers from the bottom and adding lubrication that may be helping to speed their advance to the sea, he said.
Scientists also now believe that the additional fresh water coming off Greenland may change the Gulf Stream, causing warmer water to pool up along the East Coast. And, because warmer water expands, that could add somewhat to the rise of sea levels.
''It turns out, the northeastern United States is even more at risk than just about anywhere else on the world's coasts,'' Hamilton said.
That's not to say the Northeast will see the biggest effects. In Bangladesh, for example, hundreds of millions of people live at or near sea level, so it doesn't matter so much if sea levels rise 1, 2 or 5 meters, Hamilton said.
''They only care about the first meter, or half a meter.''
Maine has adopted coastal development rules anticipating a 2-foot rise in sea levels in this century, although officials have said they are monitoring scientific reports about the acceleration of polar melting.
Saco and other communities around Saco Bay, meanwhile, are forming a regional planning group to prepare for rising sea levels. And a statewide task force is expected to report back to the Legislature in February with recommendations for preparing for coastal flooding and erosion and other effects of climate change.
Staff Writer John Richardson can be contacted at 791-6324 or at:
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