Tuesday, January 26, 2016

Ocean Warming Makes Floods Worse

[Scientific American] Floodwaters that washed icy brine into streets and homes along the eastern seaboard during Saturday’s blizzard reached heights in some places not experienced since Hurricane Sandy. “I just hope it isn’t a sign of things to come,” Pam Bross told a local newspaper as she mopped up the market she operates on a New Jersey street not normally reached by storm surges.
With tides and storm surges inching upward and inward, worsening floods are harbingers of even soggier times ahead. As the weekend’s winter storm hurtles across the Atlantic Ocean, bringing its flood risks to Europe, new research is pointing to an outsized role that ocean warming has been playing in raising sea levels — a problem normally associated with melting land ice.
Water expands as it heats up, and oceans have been absorbing most of the heat trapped by greenhouse gases released by fossil fuel burning, deforestation and animal farming. A new study blames expansion of warming waters for as much sea level rise from 2002 through 2014 as the melting of all the glaciers and the Greenland and Antarctic ice sheets combined.
“Satellite observations show that sea level rise over the last decade is explained, by about 50 percent, by thermal expansion,” said Roelof Rietbroek of the University of Bonn, who led the research, which was published Monday in Proceedings of the National Academy of Sciences.
The team of scientists led by Rietbroek concluded that thermal expansion caused seas to rise globally during the 12 years studied by about two-thirds of an inch, with ice melt and other factors contributing to an overall rise of twice that amount.
“We were surprised to find such high rates for the thermosteric contribution,” Rietbroek said. “Previous studies from hydrographic data indicated smaller signals, mostly confined in the upper ocean.” Read More