The researchers' field camp on the Greenland Ice Sheet receives additional supplies. Principal investigator Joel Harper of the University of Montana says it is more plausible to expect sea level to rise about a meter by the end of this century, rather than several meters, as some scientists have theorized. "A rise in sea level of 0.8 to 2 meters is still a very serious business, especially for the millions of third-world people who live within a meter of sea level," Harper said.

Credit: Joel Harper, University of Montana.

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Time-lapse sequence of the calving terminus of Columbia Glacier, Prince William Sound, Alaska. Sequence covers the period 15 May -16 August 2007, and shows the interaction between down-slope flow and iceberg calving at the ocean-ending glacier ice cliff.

Credit: Copyright 2008 by James Balog/Extreme Ice Survey
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The researchers collect radar data to document meltwater movement on the Greenland Ice Sheet. Glaciers add water to the sea through surface melt and by "calving" icebergs. Surface melting of ice cannot alone cause multiple meters of sea level rise by 2100. The marine-terminating glaciers would also need to speed up and discharge an increased number of icebergs into the ocean. The researchers estimated what flow conditions would have to exist for Greenland to raise the sea level by large amounts (2 and 5 meters) in the next century and then asked whether those conditions might reasonably occur.

Credit: Joel Harper, University of Montana

The researchers' field camp on the Greenland Ice Sheet. Considering all major sources of sea level rise, including water and ice discharged from Greenland, Antarctica, smaller glaciers and ice caps, and the thermal expansion of water as ocean basins warm, the researchers' most likely estimate of roughly 3 to 6 feet by 2100 is still potentially devastating to huge tracts of low lying coastal areas. "A rise in sea level of 0.8 to 2 meters is still a very serious business, especially for the millions of third-world people who live within a meter of sea level," Harper said.

Credit: Joel Harper, University of Montana

Principal investigator Joel Harper makes measurements on water flow through snow on the Greenland Ice Sheet. Glaciers add water to the sea through surface melt and by "calving" icebergs. Surface melting of ice cannot alone cause multiple meters of sea level rise by 2100. The marine-terminating glaciers would also need to speed up and discharge an increased number of icebergs into the ocean. The researchers estimated what flow conditions would have to exist for Greenland to raise the sea level by large amounts (2 and 5 meters) in the next century, and then asked whether those conditions might reasonably occur.

Credit: Joel Harper, University of Montana

The researchers' findings were published in the Sept. 5, 2008, issue of Science magazine.

Credit: Copyright AAAS 2008