Conveniently, or rather inconveniently, the media often misinterprets scientific findings to produce seductive headlines such as: “Wind Farms Cause Global Warming” or “Wind Farms are Warming the Earth, researchers say”. These extravagant claims have been triggered by a recent study by Zhou et al., (2012). This study looks at surface temperature changes in west-central Texas, where four of the world’s largest wind farms are located. This is the first study of its kind and has raised significant questions relating to local and regional impacts of wind farms.
The study uses MODIS satellite data for the 2003-2011 period. The first three years of data (2003-2005) are prior to large-scale production of turbines in the area and are thus used to represent the period with the least impacts. The last three years of data (2009-2011) represent the case with the most likely impacts. Regional mean warming rates were removed from the study period.
The authors’ choice of wording in parts of the paper can be troubling. For example, they claim their results show a significant warming ‘trend’. ‘Trend’ is a bold word to use when analysing a data set that is only 9 years long. They also state that this warming ‘trend’ of up to 0.72°C is occurring ‘per decade’ – again, extrapolating these changes to a ‘per decade’ occurrence is, in my opinion, a brash conclusion from less than 10 years of data.
Aside from these criticisms the results indicate a significant warming change over south-central Texas wind farms and, on average, the warming is stronger and better coupled with wind farms during (summer) night-time vs. (summer and winter) daytime. The authors explain that this warming is most likely caused by turbines enhancing the vertical mixing of the near surface Atmospheric Boundary Layer (ABL). In other words, the turbines tend to stir up the cool night-time surface air that usually settles low to the ground. Also, the stronger wind speeds in the summer and at night-time likely drive wind turbines to generate more electricity and turbulence, resulting in a stronger night-time warming effect during the summer.
The lead scientist, Liming Zhou made it clear in an open Q&A that,
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 redistribute the air’s heat near the surface (the turbine itself does not generate any heat), which is fundamentally different from the large-scale warming effect caused by increasing atmospheric concentrations of greenhouse gases due to the burning of fossil fuels.
This statement is greatly contrasted by online columns such as The Bluefield Daily Telegraphwhere the author states, “This data suggests that wind farms have a greater warming effect than the fossil fuel sources they are intended to replace”. Ughh!
While articles written in Fox News and the Telegraph bring up some interesting points and present a relatively succinct summary of the Zhou et al. paper, their headlines essentially fuel the skeptics and confuse everyone else.
Initially, I was infuriated with the numerous deceptive headlines responding to this article. However, upon further google searching, I was pleasantly surprised to see the prominent responses to this frenzy of misguided headlines: Yahoo News – ‘Study: Texas Wind Farms Not Causing Global Warming’, Christian Science Monitor – ‘Don’t believe the headlines. Wind farms do not cause ‘global’ warming’, and The Washington Post– ‘No, wind farms are not causing global warming’.
In the end, the battle of media botchery vs. informed discussions of scientific findings continues.