New federal estimates say global sea levels could rise faster than previously thought, and the rise may be even worse in many coastal regions of the United States. A new report, written by scientists with several federal agencies and universities, says that under a worst-case scenario, climate change could raise the oceans an average of more than 8 feet by 2100, about 20 inches more than a previous federal estimate published in 2012. The best case now projected would be an average of about a foot.- Inside Climate News
The six scenarios are based on United Nations models of future greenhouse gas emissions, depending on whether countries rapidly slash pollution or continue burning fossil fuels as usual. The authors determined that the worst-case rise of more than 8 feet has only a 0.1 percent chance of occurring by 2100, even under a business-as-usual emissions scenario, but a rise of more than 1.5 feet is near certain with high emissions. The increase in the estimates for global sea rise was partly due to new research on the Antarctic ice sheet, which is melting faster and appears to be more fragile than previously estimated, suggesting that some of the more pessimistic scenarios are increasingly likely.
Sea levels have already risen by more than 8 inches globally since 1880, with 3 inches coming since 1993. Tidal flooding "has increased by an order of magnitude over the past several decades," the report says, "turning it from a rare event into a recurrent and disruptive problem."
"Even if society sharply reduces emissions in the coming decades," the authors write, "sea level will most likely continue to rise for centuries."