Increased rainfall over time would certainly cause a lot of damage in some regions. But it might have some benefits as well. Some climate models have shown dry areas of the earth getting even drier as the world warms. Frank Wentz's study discussed previously, however, suggested not only that rainfall would be higher than expected in wet areas, but that it would be higher than expected in dry areas as well. If this hypothesis is true, drought-plagued regions like the American Southwest might finally get enough water in a warmer world.8 More generally, increased rainfall might be good for crops. This outcome is especially likely because plants use CO2 as a nutrient, and because higher temperatures might mean a longer growing season as frosts occur later and thaws earlier. Add together more water, more CO2, and less frost, and altogether global warming might be "beneficial to agriculture" in many parts of the world, according to David Archer.9
More controversial is the suggestion that rainfall might actually help reduce global warming. A few scientists, such as Richard Lindzen of MIT, argue that the increased cloud cover associated with more precipitation may reflect light from the sun, creating a negative feedback loop and reducing the impact of climate change. These arguments, however, "have been widely challenged," according to reporter Alan Prendergast.10 For instance, James Hansen of the Goddard Institute for Space Studies has argued based on measurements from ice-core samples that past climate changed more quickly than Lindzen's theories suggest. Hansen called Lindzen's theory "simply wrong."11
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