Six months ago today, Super-storm Sandy devastated a large section of the northeastern United States. The flooding caused by its record storm surge was a heart-wrenching example of the dangers posed by rising sea levels.
Storm surge is the rise in sea height that occurs during an intense storm like a hurricane or nor’easter. Its baseline is local sea level. So, as sea levels rise, storm surges are able to reach further inland. This is a serious problem for coastal communities around the world.
According to climate scientists, the average global sea level has risen about eight inches since 1880. This may not sound like a lot, but it is a significant amount when you consider it is spread out across all of the world’s oceans. That said, sea levels are not rising evenly across the planet. Recent studies have found that certain areas, such as the East Coast of the US, are experiencing faster rates of sea level rise than others. New York Harbor, for example, has seen its water level increase by more than a foot in the past century.
Sea level rise has two main drivers. They are thermal expansion – a process in which water expands as it warms – and the melting of massive amounts of land based ice, such as glaciers and ice sheets. Both are the result of rising global temperatures.
In the future, sea levels are expected to continue rising as our atmosphere warms. Estimates of how much vary from four inches to two feet above current levels by 2050. This wide range reflects uncertainty in the amount of future greenhouse gas emissions, subsequent warming, and rate of ice melt. What is certain, however, is that the frequency and magnitude of storm surge flooding will increase as sea levels rise.