‘Cool farms’ mask the extent of global warming – earth – 14 August 2007 – New Scientist Environment
Whereas urban development generates pockets of hot air, irrigated fields tend to cool things down, they say – and there is evidence that the effects have been felt in California for over a century.
In areas of intensive irrigation, such as the Central Valley in California, US, these “cool farms” have counteracted global warming, say Céline Bonfils and David Lobell of the Lawrence Livermore National Laboratory in California. But they warn that a reduction in irrigation could spell the end of the relief that these regions have enjoyed. Pakistan and China have become huge irrigators over the past 50 years, but the growth of irrigated areas is slowing down.