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Sunday, March 15, 2009

Sea Level Rise Due to Global Warming Poses Threat to NYC

Global warming is expected to cause the sea level along the northeastern U.S. coast to rise almost twice as fast as global sea levels during this century, putting New York City at greater risk for damage from hurricanes and winter storm surge, according to a new study led by a Florida State University researcher.

Jianjun Yin, a climate modeler at the Center for Ocean-Atmospheric Prediction Studies (COAPS) at Florida State, said there is a better than 90 percent chance that the sea level rise along this heavily populated coast will exceed the mean global sea level rise by the year 2100. The rising waters in this region -- perhaps by as much as 18 inches or more -- can be attributed to thermal expansion and the slowing of the North Atlantic Ocean circulation because of warmer ocean surface temperatures.

Yin and colleagues Michael Schlesinger of the University of Illinois at Urbana-Champaign and Ronald Stouffer of Geophysical Fluid Dynamics Laboratory at Princeton University are the first to reach that conclusion after analyzing data from 10 state-of-the-art climate models, which have been used for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report. Yin's study, "Model Projections of Rapid Sea Level Rise on the Northeast Coast of the United States," will be published online March 15 in the journal Nature Geoscience.

"The northeast coast of the United States is among the most vulnerable regions to future changes in sea level and ocean circulation, especially when considering its population density and the potential socioeconomic consequences of such changes," Yin says. "The most populous states and cities of the United States and centers of economy, politics, culture and education are located along that coast."

The researchers found that the rapid sea-level rise occurred in all climate models whether they depicted low, medium or high rates of greenhouse-gas emissions. In a
medium greenhouse-gas emission scenario, the New York City coastal area would see an additional rise of about 8.3 inches above the mean sea level rise that is expected around the globe because of human-induced climate change.

Thermal expansion and the melting of land ice, such as the Greenland ice sheet, are expected to cause the global sea-level rise. The researchers projected the global sea-level rise of 10.2 inches based on thermal expansion alone. The contribution from the land ice melting was not assessed in this study due to uncertainty.

Considering that much of the metropolitan region of New York City is less than 16 feet above the mean sea level, with some parts of lower Manhattan only about 5 feet above the mean sea level, a rise of 8.3 inches in addition to the global mean rise would pose a threat to this region, especially if a hurricane or winter storm surge occurs, Yin says.

Potential flooding is just one example of coastal hazards associated with sea-level rise, Yin said, but there are other concerns as well. The submersion of low-lying land, erosion of beaches, conversion of wetlands to open water and increase in the salinity of estuaries all can affect ecosystems and damage existing coastal development.

Although low-lying Florida and Western Europe are often considered the most vulnerable to sea level changes, the northeast U.S. coast is particularly vulnerable because the Atlantic meridional overturning circulation (AMOC) is susceptible to global warming. The AMOC is the giant circulation in the Atlantic with warm and salty seawater flowing northward in the upper ocean and cold seawater flowing southward at depth. Global warming could cause an ocean surface warming and freshening in the high-latitude North Atlantic, preventing the sinking of the surface water, which would slow the AMOC.

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1 Comments:

Blogger Bhuvan Chand said...

Combating climate change may not be a question of who will carry the burden but could instead be a rush for the benefits, according to new economic modeling presented at “Climate Change: Global Risks, Challenges & Decisions” hosted by the University of Copenhagen.

Contrary to current cost models for lowering greenhouse gas emissions and fighting climate change, a group of researchers from the University of Cambridge conclude that even very stringent reductions of can create a macroeconomic benefit, if governments go about it the right way.

“Where many current calculations get it wrong is in the assumption that more stringent measures will necessarily raise the overall cost, especially when there is substantial unemployment and underuse of capacity as there is today”, explains Terry Barker, Director of Cambridge Centre for Climate Change Mitigation Research (4CMR), Department of Land Economy, University of Cambridge and a member of the Scientific Steering Committee of the Congress.

8:47 AM  

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