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Global Warming Alters Gardening Map17 May 2012
The US Department of Agriculture has released a new gardening map, and it reflects the impact of global warming. While gardeners already know this, one can now see the global weather phenomenon's impact on a nationwide garden map, the Plant Hardiness Zone Map. The map splits the US into 13 areas using each area's lowest annual temperature. The map helps farmers and gardeners pick out which crops can survive the cold of winter. Many gardeners are familiar with the map since a version of it is often printed in the back of seed packages.
Each region crept up approximately half a zone since the previous version of the map was published in 1990. This creep up in zones represents a five degree rise in average minimum temperatures. Some regions even experienced temperature increases of as much as ten degrees. Although the USDA does acknowledge some of the map's changes are due to global warming, the agency says that some of the zone changes are due to the map's use of more climate data. Using the additional years of climate data, the new map is more accurate than its 1990 version.