John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
More than half of the Northern Hemisphere's surface water is currently hotter than the historical average.
Human-generated greenhouse gas emissions aren't just causing more-sweltering weather inland. They're also turning the ocean's surface waters as tepid as a public pool's pee-filled kiddie area. Abnormally warm seas are certainly the case this year, with more than half of the oceans in the Northern Hemisphere being recorded as hotter than average.
The visualization folks at NOAA have posted this model of the briny aberration with these notes:
Analysis from NOAA satellites shows that sea surface temperatures in September 2014 were well above normal. In fact, 60% of the Northern Hemisphere ocean surface was 0.5°C or more above the 1981-2010 average. Only 5% of the Northern Hemisphere ocean surface was cooler than -0.5°C below normal. This image, also available in NOAA View, shows areas warmer than normal colored in red and areas cooler than normal colored in blue.
Here's the key; note the high-temperature anomalies along both coasts of the U.S., in Canada's Hudson Bay, all around Alaska and in the Siberian Sea, and in northeast Russia:
While surface waters are getting warmer, the bottom of the ocean has stayed the same cold temperature since 2005. That complicates one theory for why global warming has slowed in the past decade: that the bottom half of the ocean is sucking up the planet's excess heat and storing it like a reservoir. Here's a NASA scientist explaining what that means, and doesn't mean, for our understanding of climate change:
Scientists at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, analyzed satellite and direct ocean temperature data from 2005 to 2013 and found the ocean abyss below 1.24 miles (1,995 meters) has not warmed measurably. Study coauthor Josh Willis of JPL said these findings do not throw suspicion on climate change itself.
"The sea level is still rising," Willis noted. "We're just trying to understand the nitty-gritty details."