Wednesday, February 01, 2012

Warming Wednesdays: A windy future

To minimize harm to birds, future wind farms may consist of a "forest" of stalks. Discovery News. H/t Time Goes By.

In the Anthropocene, even renewable technologies may have unsettling climate effects. That's what happens when we use our human technological capacity to alter the planet's balance -- something we are doing and will continue to do whether we want to or not, barring a massive human die-off.

Think adoption of wind power couldn't possibly mess with the climate? Not so according to New Scientist.

In 2010, Somnath Baidya Roy at the University of Illinois in Urbana-Champaign reported that wind farms affect their local climate. Long-term data from a wind farm at San Gorgonio, California, confirmed his earlier model predictions: surface temperatures behind the wind turbines were higher than in front during the night, but as much as 4 °C lower by day.

Roy thinks the turbulence created by the turbines sucks air down from above. During the day, when the hottest air is usually near the surface, this has a cooling effect. At night, when the air near the ground may be colder than that above, it can have a warming effect.

These effects could be minimised by placing wind farms in areas where there's already a lot of turbulence. But we might not want to minimise them. "Some of these effects are actually welcome for agricultural reasons," says Cristina Archer at the University of Delaware in Newark, who studies wind power. Strategically placed wind farms might keep crops cool in summer and reduce the risk of frost in other seasons. Farmers in California and Florida already use wind machines to fight frost by pulling down warmer air.

Do offshore wind farms affect sea surface temperatures and evaporation rates? Could these local effects add up to produce significant regional or even global effects? Perhaps. Winds obviously play a major role in climate. Slowing or altering wind patterns will alter the movement of heat and water around the planet, and thus temperature and rainfall.

It might seem inconceivable that humans could have a significant effect on the wind, but we may already be doing so. While wind speeds over the oceans are increasing, surface winds over Europe, Asia and North America have slowed by up to 15 per cent on average since 1979.

Go read it all.

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