Monday, September 19, 2011

A possible explanation

Deep oceans can mask global warming for decade-long periods

Here's a good, succinct report on modelling that indicates the deep oceans indeed may be absorbing the "missing heat" that Trenberth wrote about famously in his "Climategate" email.

To track where the heat was going, Meehl and colleagues used a powerful software tool known as the Community Climate System Model, which was developed by scientists at NCAR and the Department of Energy with colleagues at other organizations. Using the model's ability to portray complex interactions between the atmosphere, land, oceans, and sea ice, they performed five simulations of global temperatures.

The simulations, which were based on projections of future greenhouse gas emissions from human activities, indicated that temperatures would rise by several degrees during this century. But each simulation also showed periods in which temperatures would stabilize for about a decade before climbing again. For example, one simulation showed the global average rising by about 2.5 degrees Fahrenheit (1.4 degrees Celsius) between 2000 and 2100, but with two decade-long hiatus periods during the century.

During these hiatus periods, simulations showed that extra energy entered the oceans, with deeper layers absorbing a disproportionate amount of heat due to changes in oceanic circulation. The vast area of ocean below about 1,000 feet (300 meters) warmed by 18% to 19% more during hiatus periods than at other times. In contrast, the shallower global ocean above 1,000 feet warmed by 60% less than during non-hiatus periods in the simulation.

"This study suggests the missing energy has indeed been buried in the ocean," Trenberth says. "The heat has not disappeared, and so it cannot be ignored. It must have consequences."


I wonder if work is being done on measurements to confirm it?

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