Rising sea levels will be localized

When you hear about global warming and sea levels rising, the projections are often cast in universal terms, e.g. “Scientists estimate that sea levels will rise between 0.8 m and 2 m by 2100.” This map, released by NASA’s Jet Propulsion Laboratory, illustrates that contrary to popular belief, sea level rise is not uniform, and indeed has been and will be much more severe in localized areas. At significant risk are the low-lying coral atolls and islands in the Pacific, where the impact of climate change is already taking a huge toll. The president of the Republic of Palau, Tommy Remengesau Jr., spoke at recent meeting of the U.S. Coral Reef Task Force and warned: “We are the window of what will eventually be happening to the rest of the world” (as reported by the Honolulu Star Bulletin).

When discussing the rising sea level, it is imperative that we consider the global picture rather than flatten the debate into statistical averages. Otherwise, it will be far too easy to discount the crisis, as The Telegraph UK has done in this headline: “An Inconvenient Truth exaggerated sea level rise.” The human and ecological cost is far too high.

Here’s a more detailed description of the above satellite image from NASA’s Earth Observatory:

Warming water and melting land ice have raised global mean sea level 4.5 centimeters (1.7 inches) from 1993 to 2008. But the rise is by no means uniform. This image, created with sea surface height data from the Topex/Poseidon and Jason-1 satellites, shows exactly where sea level has changed during this time and how quickly these changes have occurred.

It’s also a road map showing where the ocean currently stores the growing amount of heat it is absorbing from Earth’s atmosphere and the heat it receives directly from the Sun. The warmer the water, the higher the sea surface rises. The location of heat in the ocean and its movement around the globe play a pivotal role in Earth’s climate.

Light blue indicates areas in which sea level has remained relatively constant since 1993. White, red, and yellow are regions where sea levels have risen the most rapidly—up to 10 millimeters per year—and which contain the most heat. Green areas have also risen, but more moderately. Purple and dark blue show where sea levels have dropped, due to cooler water.

The dramatic variation in sea surface heights and heat content across the ocean are due to winds, currents and long-term changes in patterns of circulation. From 1993 to 2008, the largest area of rapidly rising sea levels and the greatest concentration of heat has been in the Pacific.

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