Warming trend may redraw botanical map of U.S.

Using data from the National Oceanic and Atmospheric Administration, the Arbor Day map indicates that many bands of the country are a full zone warmer, and a few spots are two zones warmer, than they were in 1990, when the map was last updated.

Atlanta, which was in Zone 7 in 1990, is now in Zone 8, along with the rest of northern Georgia. That means that areas in the northern half of the state where the average low temperature was zero to 10 degrees are now in a zone where the average low is 10 to 20 degrees. A scientific consensus has concluded that this warming trend has largely been caused by the human production of heat-trapping gases.