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 Average Annual Global Number of People Flooded under Three Emissions Scenarios

Warm water takes up more space than the same weight of cold water. As the earth grows warmer, ocean waters expand, and the melting of glacial ice adds to the rise in sea level.

When researchers use computer models to create scenarios about how the climate might change and how this change will affect people, they must make assumptions about human behavior. Different assumptions give different results. In this graph, red represents conditions if no efforts are made to reduce carbon dioxide emissions. Blue represents stabilization of carbon dioxide levels at 750 ppm (parts per million, or parts of carbon dioxide per million parts of atmosphere sampled). That's almost three times the pre-industrial concentration of about 280 ppm. Green represents stabilization of carbon dioxide levels at 550 ppm. Gray represents no climate change.

If no efforts are made to reduce carbon dioxide emissions, researchers at the Hadley Centre for Climate Prediction and Research estimate that sea level will rise by about 40 cm (about 15 inches) by 2080. Notice that under all three scenarios, the effect of sea level rise is different for each continent. The effects of climate change will be felt differently in different areas.



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Average Annual Global Number of People Flooded under Three Emissions Scenarios

Average Annual Global Number of People Flooded under Three Emissions Scenarios - One consequence of increasing temperatures is rising sea levels—which leads to flooding of coastal areas. This graph shows computer projections of the average number of people flooded each year in the 2080s in five vulnerable continental regions. The colors on the graph correspond to different assumptions about the concentration of carbon dioxide in the atmosphere as a result of human activity. Source: Robert Nicholls, Flood Hazard Research Centre, Middlesex University



 questions about the data

question I heard that a giant ice sheet recently broke off the coast of Antarctica. Did that cause sea level to rise?

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 research connection  

Information from many sources can contribute to an understanding of how sea level may change. Coastal scientists generally agree that sea level during the last interglacial period was over 6 meters (about 20 feet) higher than it is today. The earth’s temperature during the interglacial period was only slightly warmer than it is today. This suggests that factors other than the ones considered in this model may affect sea level changes.


 related sites  

Environmental Protection Agency (EPA)/Future Climate - This section of the EPA’s Global Warming site discusses possible sea level changes.

Sea Level and Climate - This fact sheet from the U.S. Geological Survey describes geological evidence for past sea level changes.

University of New England - A press release describing research that indicates sea level has changed frequently and drastically over the last 6,000 years.

Global Climate Highlights - A daily summary of major events and anomalies in the world’s weather.
 


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