Adapted from S. Levitus et al., Geophys. Res. Letts.; © AGU 2012

ScienceShot: No Letup in World's Warming

Global warming contrarians remind the public that the world has not warmed all that much, if at all, during the past decade or so. But that's the atmosphere. Oceanographers with their thermometers in Earth's biggest reservoir of heat—the world's ocean—report in a paper to be published in Geophysical Research Letters that greenhouse warming has in fact been proceeding apace the past decade, not to mention the past half century. Ninety-three percent of the heat trapped by increasing greenhouse gases goes into warming the ocean, not the atmosphere. So taking the ocean's temperature is the most comprehensive way to monitor global warming. A group of National Oceanic and Atmospheric Administration scientists has revised and updated their decade-old compilation of temperature measurements from the upper 2000 meters of the world's ocean. Its store of heat (red line with error bars) steadily increased over the past 20 years. And the upper ocean has warmed so much in the past 50 years that its added heat would be enough to warm the lower atmosphere by about 36°C (thankfully a physically impossible feat).

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