What is causing sea levels to rise? As the water in the oceans warms along with the earth it expands and sea level rises. More important, as the earth warms, glacial ice melts, water flows into the ocean, and sea level rises. The especially large bodies of ice in Antarctica and Greenland account for nearly half of the earth’s water that is not already in the ocean.
How quickly will sea levels rise? In the last 130 years sea level has risen about 18 cm but it’s not clear how fast glaciers will melt in the future. The IPCC predicts from 80 to 130 cm by 2100. but so far IPCC models have underestimated the rate of sea level rise. James Hansen and 16 co-authors recently published a discussion paper warning that sea levels could rise by 5 meters in the next 50 years. When all the ice in Antarctica and Greenland melts, sea level will rise by about 65 meters.
How bad is that? The costs of ocean inundations during storms on coastal cities is already huge – think of the costs of recovering from Hurricane Sandy in New York. The costs of infrastructure proposed to protect vulnerable cities is likewise huge. The human cost will be even greater – hundreds of millions of people will be displaced and the climate refugees who survive will need to move somewhere.
What else might go wrong? Some recent models predict that the rapid melting in Antarctica and Greenland may cause the Gulf Stream to dramatically change course causing extreme disruption to climate all along its route.
What can we do about it? Besides moving inland and building dykes, only an aggressive move away from fossil fuel based energy will slow this down.
Here are some reference articles that give more background on the issue of Sea Level Rise.
- Why sea level is rising and how much it will continue
- Antarctica is melting
- Greenland is melting
- This World Bank study details the impacts of rising sea level
- A video clip showing the effects of rising sea level on Norfolk, Virginia
- The reality of the impacts of other climate change factors
- A big picture view of Global Warming and Climate Change
- State of the Cryosphere
- James Hansen’s recent paper
- National Geographic Interactive Map