Planting zones are retreating north all over the country, but the United States Department of Agriculture (USDA) won’t state the obvious: the shift is a rock solid indicator of climate change.
On Wednesday, the USDA released a new plant hardiness zone map, which contours the nation according to average annual lowest winter temperatures. The new zones analyze these temperatures for the period 1976-2005, updating a 1990 version of the map, which covered 1974-1986.
Interactive map: USDA upgrades Plant Hardiness Zone MapAlthough these zones, which serve as a guide to the kinds of plants that can grow, have shifted north in most areas, USDA shied away from making a climate change connection.“The map is not a good instrument for determining climate change,” said Kim Kaplan, a spokeswoman for the USDA’s Agricultural Research Service. “It’s not that there hasn’t been global climate change it’s that the map isn’t a good (vehicle) for demonstrating it.”
USDA’s line of reasoning in perplexing. Climate data are used in USDA’s analysis and the northward jog in planting zones is fully consistent with other data and indicators that establish warming of the coldest temperatures in the U.S. (and most locations globally).
Read the rest at The Washington Post | Capital Weather GangNew USDA plant zones clearly show climate change
By Jason Samenow
(h/t Kevin Fathi via email)