The melting ice sheet this century in Greenland is a bigger threat to major U.S. coastal cities than previously believed, according to a new government study.

Research released Friday by the National Center for Atmospheric Research found that if Greenland's ice melts at a moderate or high rate, ocean circulation may cause sea levels off the northeast coast of North America to rise by about 12 to 20 inches (30-50 centimeters) more than in other coastal areas by the year 2100. The region includes the New York, Boston and Halifax coastlines.

Scientists considered three scenarios in the study, including where the melt rate increases by 7 percent per year (as it has in recent years), an increase of 3 percent or 1 percent annually. The study findings of sea level rise were based on Greenland's ice melting alone.

In March, a study in Nature Geoscience warned that warmer temperatures could raise sea levels of the Northeast by about 8 inches more than the average global sea level rise but it did not include the additional impact of Greenland's ice.

Major northeastern cities are directly in the path of the greatest rise, NCAR scientist Aixue Hu, the lead author said today in a statement.

The research builds on recent reports that have found that the sea level rise is associated with global warming and could adversely affect North America. The study was funded by the U.S. Department of Energy and by NCAR's sponsor, the National Science Foundation. It was conducted by scientists at NCAR, the University of Colorado at Boulder, and Florida State University.

The U.S. House of Representatives will decide later this year if it will pass broad legislation to combat climate change. The House is considering a climate bill called the American Clean Energy and Security Act that aims to cut greenhouse gas emissions by 17 percent below 2005 levels by the year 2020. The emissions have been blamed for global warming.

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