Supreme irony: wind farms can cause atmospheric warming, finds a new study

NOTE: An update has been added below, using the press release that came out today after the news stories yesterday.

While ironic that something designed to reduce CO2 emissions (and presumably warming)is actually producing warming around it, this isn’t really any big surprise. Orchardists and vineyard operators in California have been using motor driven wind turbines to elevate local temperatures to save crops from frost for over half a century. What is different here is the scale of nighttime warming, large enough to be visible on MODIS satellite imagery thanks to large scale wind farms.

Dr. Roger Pielke Sr. and associates have been doing research along these lines for quite some time, and has this summary on some recent research.

From Louise Gray in the Telegraph:

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

Usually at night the air closer to the ground becomes colder when the sun goes down and the earth cools. But on huge wind farms the motion of the turbines mixes the air higher in the atmosphere that is warmer, pushing up the overall temperature.

Satellite data over a large area in Texas, that is now covered by four of the world’s largest wind farms, found that over a decade the local temperature went up by almost 1C as more turbines are built. This could have long term effects on wildlife living in the immediate areas of larger wind farms. It could also affect regional weather patterns as warmer areas affect the formation of cloud and even wind speeds.

Full story here:

http://www.telegraph.co.uk/earth/earthnews/9234715/Wind-farms-can-cause-climate-change-finds-new-study.html

Here’s the paper:

Zhou, Liming, Yuhong Tian, Somnath Baidya Roy, Chris Thorncroft, Lance F. Bosart and Yuanlong Hu 2012: Impacts of wind farms on land surface temperature. Nature Climate Chnage. doi:10.1038/nclimate1505

And the abstract (bold mine):

The wind industry in the United States has experienced a remarkably rapid expansion of capacity in recent years and this fast growth is expected to continue in the future. While converting wind’s kinetic energy into electricity, wind turbines modify surface–atmosphere exchanges and the transfer of energy, momentum, mass and moisture within the atmosphere. These changes, if spatially large enough, may have noticeable impacts on local to regional weather and climate.

Here we present observational evidence for such impacts based on analyses of satellite data for the period of 2003–2011 over a region in west-central Texas, where four of the world’s largest wind farms are located. Our results show a significant warming trend of up to 0.72 °C per decade, particularly at night-time, over wind farms relative to nearby non-wind-farm regions. We attribute this warming primarily to wind farms as its spatial pattern and magnitude couples very well with the geographic distribution of wind turbines.

h/t to WUWT reader Andrew Kissling

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UPDATE: 4/30/12:30PM PST  The press release came out this morning, including this image:

Temperature Differences near Wind Farms

This graph shows the night-time land surface temperature differences near wind farms between 2010 and 2013. Credit: Liming Zhou et al., Nature Climate Change

Here’s the PR:

National Science Foundation

Scientists find night-warming effect over large wind farms in Texas

Wind turbines interact with atmospheric boundary layer near the surface

		IMAGE:Wind farms are numerous in parts of Texas; scientists report new results on their effects.Click here for more information.

Large wind farms in certain areas in the United States appear to affect local land surface temperatures, according to a paper published today in the journal Nature Climate Change.

The study, led by Liming Zhou, an atmospheric scientist at the State University of New York- (SUNY) Albany, provides insights about the possible effects of wind farms.

The results could be important for developing efficient adaptation and management strategies to ensure long-term sustainability of wind power.

“This study indicates that land surface temperatures have warmed in the vicinity of large wind farms in west-central Texas, especially at night,” says Anjuli Bamzai, program director in the National Science Foundation’s (NSF) Division of Atmospheric and Geospace Sciences, which funded the research.

“The observations and analyses are for a relatively short period, but raise important issues that deserve attention as we move toward an era of rapid growth in wind farms in our quest for alternate energy sources.”

		IMAGE:This graph shows the night-time land surface temperature differences near wind farms between 2010 and 2013.Click here for more information.

Considerable research has linked the carbon dioxide produced by burning fossil fuels with rising global temperatures.

Consequently, many nations are moving toward cleaner sources of renewable energy such as wind turbines. Generating wind power creates no emissions, uses no water and is likely “green.”

“We need to better understand the system with observations, and better describe and model the complex processes involved, to predict how wind farms may affect future weather and climate,” said Zhou.

There have been a growing number of studies of wind farm effects on weather and climate, primarily using numerical models due to the lack of observations over wind farms.

As numerical models are computationally intensive and have uncertainties in simulating regional and local weather and climate, said Zhou, remote sensing is likely the most efficient and effective way to study wind farm effects over larger spatial and longer temporal scales.

To understand the potential impact of wind farms on local weather and climate, Zhou’s team analyzed satellite-derived land surface temperatures from regions around large wind farms in Texas for the period 2003-2011.

The researchers found a night-time warming effect over wind farms of up to 0.72 degrees Celsius per decade over the nine-year-period in which data were collected.

Because the spatial pattern of warming mirrors the geographic distribution of wind turbines, the scientists attribute the warming primarily to wind farms.

The year-to-year land surface temperature over wind farms shows a persistent upward trend from 2003 to 2011, consistent with the increasing number of operational wind turbines with time.

		IMAGE:Wind farms dot the horizon in Lubbock County and other Texas areas.Click here for more information.

“This warming effect is most likely caused by the turbulence in turbine wakes acting like fans to pull down warmer near-surface air from higher altitudes at night,” said Somnath Baidya Roy of the University of Illinois at Urbana-Champaign, a co-author of the paper.

While the warming effect reported is local and small compared to the strong background year-to-year land surface temperature variation, the authors believe that this work draws attention to an important scientific issue that requires further investigation.

“The estimated warming trends only apply to the study region and to the study period, and thus should not be interpolated into other regions, globally or over longer periods,” Zhou said. “For a given wind farm, once there are no new wind turbines added, the warming effect may reach a stable level.”

The study represents a first step in exploring the potential of using satellite data to quantify the possible effects of the development of big wind farms on weather and climate, said Chris Thorncroft of SUNY-Albany, a co-author of the paper.

“We’re expanding this approach to other wind farms,” said Thorncroft, “and building models to understand the physical processes and mechanisms driving the interactions of wind turbines and the atmosphere boundary layer near the surface.”

Other authors of the paper include Lance Bosart at SUNY-Albany, Yuhong Tian of NOAA, and Yuanlong Hu at Terra-Gen Power LLC in San Diego, Calif.