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Wednesday, February 12, 2014

An Evil Wind Blows

Although I am a global warming skeptic, I have cited to articles that try to rationally support global warming. In that vein, the New Scientist reports on a theory that tries to explain the pause in global warming because of changes in wind patterns:
Over the past 20 years, the trade winds that gust westwards across the Pacific have soared to unprecedented strengths. The strongest winds are now twice as powerful. 
These winds are far in excess of anything climate models predicted and have not been considered in global temperature projections. So Matthew England from the University of New South Wales in Sydney, Australia, and colleagues decided to see what would happen if the actual wind levels were factored into the models. 
They discovered that five years of powerful trade winds was enough to spin up powerful ocean currents that buried the warm surface water, bringing cooler water to the surface. Those cooler waters produced exactly the warming hiatus observed. "The missing wind can account for the hiatus in its entirety," says England. 
Last year Yu Kosaka and Shang-ping Xie of the Scripps Institution of Oceanography in California showed that the cool surface waters in the Pacific could explain the hiatus (Nature, doi.org/rcp). 
But until now, nobody knew why those waters were so cool. "This provides a mechanism," says Kosaka. 
So why are the winds so strong? One reason may be a repeating pattern in the weather called the Interdecadal Pacific Oscillation (IPO). In its current state, the IPO should produce stronger winds and cool surface waters, says England. "But the models capture less than half the magnitude at best," he says. 
... England says the winds will inevitably return to normal. When that happens, the heat will quickly escape to the atmosphere. Since the warm water is buried only about 125 metres deep, the result could be very rapid warming. 
Exactly when that will happen is difficult to predict, but if the hiatus follows the pattern of the IPO, it may only last another five or six years, England says.

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