Oceans storing heat

The oceans are becoming a repository for almost all of Earth’s excess heat, driving up sea levels and threatening coastlines, according to a leaked draft of the most comprehensive United Nations report addressing climate science.

Temperatures in the shallowest waters rose by more than 0.1 degree Celsius (0.18 degree Fahrenheit) a decade for the 40 years through 2010, the study found. Average sea levels have increased worldwide by about 19 centimeters (7.5 inches) since 1901 and researchers said it’s “very likely” the system of ocean currents that includes the Gulf Stream will slow in the coming decades.

The findings are detailed in a 2,200-page report that will guide UN envoys as they devise a new treaty to fight climate change by 2015. It was obtained by Bloomberg from a person with official access to the report who declined to be further identified because it hasn’t been published. The UN declined to comment.

“The Earth is absorbing more heat than it is emitting back into space, and nearly all this excess heat is entering the oceans and being stored there,” the report’s authors wrote. “Changes have been observed in ocean properties of relevance to climate during the past 40 years, including temperature, salinity, sea level, carbon, pH and oxygen.”

It’s “extremely likely” mankind is responsible for more than half of the observed temperature rises since the 1950s and it’s “virtually certain” the global rate of sea-level rise has accelerated over the past two centuries, according to the summary document. Those main points are little changed from an earlier version that was leaked by the blogger Alec Rawls on the website www.stopgreensuicide.com in December.

The latest version of the summary includes a lower forecast for temperature rise from 2016 through 2035 of 0.3 degrees to 0.7 degrees Celsius, compared with 0.4 degrees to 1 degree in last year’s version. Both versions conclude that there’s “very high confidence” the Greenland Ice Sheet has lost mass and “high confidence” the same has happened to the Antarctic Ice Sheet. The two ice sheets contain more than 99 percent of the planet’s freshwater ice, according to the National Snow & Ice Data Center.