An updated map that will likely be familiar to anyone who has planted a packet of seeds was presented today by the U.S. Department of Agriculture (USDA). This is the first new version of Plant Hardiness Zone Map since 1990.
The government is "catching up with what the plants themselves have known for years now: The globe is warming and it is greatly influencing plants," Stanford University biology professor Terry Root told the Associated Press.
The map has "greater accuracy and detail" according to a USDA press release, thanks in part to 30-years of temperature data. The map also shows America's climate is changing.
Compared to the 1990 version, zone boundaries in this edition of the map have shifted in many areas. The new map is generally one 5-degree Fahrenheit half-zone warmer than the previous map throughout much of the United States.
Overall, the map generally shows warmer winter low temperatures than the 1990 map. "It reflects a new reality: The coldest day of the year isn't as cold as it used to be, so some plants and trees can now survive farther north," AP reports.
"People who grow plants are well aware of the fact that temperatures have gotten more mild throughout the year, particularly in the wintertime," said Boston University biology professor Richard Primack. "There's a lot of things you can grow now that you couldn't grow before."
He stand the giant fig tree in his suburban Boston yard stands as an example: "People don't think of figs as a crop you can grow in the Boston area. You can do it now."
But, is this evidence of climate change? Not necessarily according to the USDA. The USDA states this map is not a comment on climate change, USA Today reports.
"Across the country, people will be seeing where there are some changes," says Catherine Woteki, undersecretary of Agriculture. "There is some shifting in zones, but this we attribute to using new average minimum temperatures. We do not think the plant hardiness zone methodology is appropriate for making comments on climate change."
Still "scientific data shows that the world is getting warmer, with potentially adverse consequences for farmers worldwide," reports Bloomberg News. So, who are you going to believe? Me or your lying eyes?
"If you want to look at what might be the most politically correct thing, you can say something's happening," Vermont gardening consultant Charlie Nardozzi told USA Today. "But the climate is changing. Spring is coming sooner and lasting longer. Fall lasts longer, and overall the weather is so much more erratic now."
The revised Plant Hardiness Zone Map will be useful to people other than gardeners and farmers, according to the USDA.
The USDA Risk Management Agency uses the USDA plant hardiness zone designations to set some crop insurance standards. Scientists use the plant hardiness zones as a data layer in many research models such as modeling the spread of exotic weeds and insects.
Research has found that noxious weeds thrive with increased concentrations of CO2 that are a cause of global warming. A 2008 study by Lewis Ziska, a USDA researcher, found that weeds grow the best in hotter, urban test plots, which has frightening implications. "Weeds already cost U.S. farmers about 12 percent of their harvest, exacting an estimated annual loss of $33 billion." Changing the environment to better suit weeds may cause them to thrive. "Ziska says that he worries about mankind's ability to feed itself in a fast-changing future."
Climate change may also make insect-borne diseases harder to control.
"Climate change is not going to invent any new diseases; it's going to make controlling existing diseases harder," said Diarmid Campbell-Lendrum, head of the climate change team at the World Health Organization's headquarters. "We've been describing the links between climate change and health for quite a long time."
A milder climate is also allowing insect pests to ravage areas that have been protected in the past by their cold winters. All across the western United States, the mountain pine beetle is destroying pine forests making them undesirable for timber or tourist destinations and this, in turn, hurting the U.S. economy.
A warming America is the "new normal" that all Americans, not just gardeners and farmers need to now face. The reality is that our climate is changing.