Saturday, January 21, 2017

125,000 years of ocean warming in 50 years: What does it mean for sea levels?

[Christian Science Monitor] What do Boston, Miami, and New Orleans have in common? All three may be almost completely underwater someday, if the results of a recent research paper are accurate.
The last time surface ocean temperatures were as warm as they are today, sea levels were 20 to 30 feet higher, according to findings published Friday in the journal Science. Using data from a wide range of locations, the study was able to measure regional temperature changes and concluded that recent models may be underestimating warming trends.
Earth’s climate features cyclical ice ages, when temperatures drop and ice sheets spread, causing ocean levels to fall. We currently enjoy the mild climate of what’s known as an “interglacial period,” when warmer temperatures melt ice, raising the seas. To better understand how our climate may develop in the future, experts consider the last interglacial period, 129,000 years ago, to be of great importance.
Getting a snapshot of what was going on so long ago isn’t easy, but scientists have a few tricks up their sleeves, such as measuring the makeup of ancient ice cores. This study used the composition of plankton shells (which depends on surface temperature) found in ocean sediments from 83 sites worldwide to compare our current interglacial period to the last one.
While it took a tipping of the planet’s axis 125,000 years to raise ocean temperatures by 0.9 degrees F., as The Los Angeles Times explained, current conditions have seen similar warming in less than 50, the paper found. Read More