The new version of the map includes 13 zones, with the addition for the first time of zones 12 (50-60 degrees F) and 13 (60-70 degrees F). U.S. Department of Agriculture hide caption

toggle caption U.S. Department of Agriculture

Altering the upper atmosphere could block enough sunlight to offset the warming effects of climate change and protect food crops. But what are the risks? iStockphoto hide caption

toggle caption iStockphoto

Prepare to see this more often, even in usually cooler climes, the experts say. Elaine Thompson/AP hide caption

toggle caption Elaine Thompson/AP

GED = gross external damages from pollution.

Environmental Accounting for Pollution hide caption

toggle caption Environmental Accounting for Pollution

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