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Wind farms can affect local temperature - how the papers reported it

  • 30 Apr 2012, 09:09
  • Christian Hunt

Wind turbines might be affecting local weather and temperature, according to a new study in the Journal Nature Climate Change. But despite researchers' assurances that these are localised effects, some UK outlets have been suggesting this means wind farms are causing climate change.

Although getting detailed measurements of wind speed is usually high on the list of priorities around wind farms, taking the temperature around the turbines might seem more unusual. But measuring the effects of wind farms on local temperatures may have thrown up some interesting results.

Scientists examining temperature readings for an area in Texas that contains a large wind farm have found a "warming trend of up to 0.72◦ C per decade, particularly at night-time, over wind farms relative to nearby non-wind-farm regions". According to the researchers, the warming patterns they've observed closely match the distribution of wind farms.

This appears to be the first time anyone has used satellite data to measure the impacts of large wind farms on surface temperature. The researchers compared temperatures in the two years before 2,358 turbines were constructed with a two-year period after they had all been built. They noticed that after correcting for other causes of warming, the temperature around the site had increased.

So what is it about the wind turbines that might be causing the warming? The paper suggests it's probably due to higher wind speeds at night - which mean the wind turbines are more active, and have a bigger effect on their environment.

What effect is that? Changes in temperature are "very probably" caused by changes in local windspeed and turbulence due to the turbines, the researchers say. Modelling studies have already suggested that wind farms can noticeably affect local weather. But the authors of this paper are careful to point out that these findings are still a bit sketchy and that understanding of the exact way in which turbines interact with their environment is still developing - you can read more on this in a Q and A with them.

One of the researchers is Dr Somnath Roy who led a previous study looking at the same effect around a wind farm in California. Anti-wind outlets pounced on that earlier paper, ignoring the work's focus on local effects to claim it showed that wind farms increase climate change - here in the Daily Mail:

"They have long been championed as a way to combat global warming by creating clean energy.

"But wind farms can actually alter the climate according to a new study by a group of American scientists.

"The team from the University of Illinois found that daytime temperatures around wind farms can fall by as much as 4C, while at night temperatures can increase."

As we noted when the article came out the earlier research did conclude that wind turbines lower temperatures in the region of the turbines a bit in the day and raise it a bit at night by moving air around, it didn't suggest that wind turbines were warming the planet up or otherwise causing climate change.

In response, Roy told the Guardian

My Proceedings of the National Academy of Sciences paper is on local-scale processes where we find that windfarms may make the nights warmer and days cooler in their immediate vicinity. Climate change is a longer-term phenomenon involving process that operate at larger spatial scales…My expertise is in small-scale (what we call atmospheric boundary layer and/or mesoscale) processes, not climate.

You might hope that this time around the distinction between local weather effects and global climate change would be more carefully noted.

For the most part, the press have reported the study pretty straightforwardly - with plenty of coverage apparently just based on the press release. Reuters writes that the study may "[cast] a shadow over the long-term sustainability of wind power", but doesn't explain why.

The Daily Mail writes a fairly sane and sensible interpretation of the study, giving it an accurate and normal headline in the paper, and then climate sexes it up for an online audience. 

In print, the reasonably straightforward reporting of the paper is titled: Wind farms link to rising temperatures could have detrimental impact on wildlife and weather, say scientists. Online, the headline is a punchier "Wind farms make climate change WORSE: Turbines actually heat up local areas". Strictly speaking it's accurate, but given the localised nature of the effect also misleading.

Meanwhile, the front page of today's Telegraph carries a piece entitled: "Wind farms linked to climate change". The online headline is  " Wind farms can cause climate change, finds new study". It goes on to say:

"Wind farms can cause climate change, according to new research that shows for the first time the new technology is already pushing up temperatures."

Fox News, on the other hand, pulls no punches with: New research finds wind farms cause global warming.

Has something changed since the last paper came out? And are the researchers campaigning against new wind farms? Still no, although they argue for better systems to measure how turbines might affect different elements of local weather and climate systems. The Guardian talked to one of the authors of the letter, who said:

... that his results could not be used as an justification for blocking new wind farms. "The warming might have positive effects," he said. "Furthermore, this study is focused only on one region and for only 9 years. Much more work is needed before we can draw any conclusion."

And is it possible to say wind farms cause climate change? The authors say not:

"Overall, the warming effect reported in this study is local and is small compared to the
strong background year-to-year land surface temperature changes. Very likely, the wind turbines do not create a net warming of the air and instead only re-distribute the air's heat near the surface, which is fundamentally different from the large-scale warming effect caused by increasing atmospheric concentrations of greenhouse gases."

*Updated on 30 April 2012 at 15.15 to include Q&A answers

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