Weatherdem's Weblog

Bridging climate science, citizens, and policy

Plants Demonstrate How Climate Has Already Changed


The USDA recently released new plant hardiness zones – updating maps from 1990.  While some areas look different just because finer details were possible, there are clearly significant differences between the maps that are due to longer growing seasons and warmer nights at the bookends of the growing season.  Those shifts in plant hardiness are an obvious manifestation of shifts that have already occurred in the climate.  More shifts will continue to become apparent in the years ahead.

Where did most of the changes occur?  As the comparison map below shows, at higher latitudes and higher altitudes – in the same locations that have warmed the most to date.


Figure 1. Comparison of the 1990 and 2012 USDA Plant Hardiness Zone Maps. Image credit: USDA and Arbor Day Foundation.

Look at the northern tier and the Rocky Mountains.  Shifts from Zone 3 to 4 up north and from Zone 4 to 5 and Zone 5 to 6 throughout the Rocky Mountains are most apparent.  Other changes can also be seen in smaller regions across the country.

The plants are simply responding to the changes in the climate.  No cosmic rays or long solar minimum precipitated these changes.  Readers should keep a simple fact in mind: these shifts are in response to the climate forcing leading up to the 1980s.  These shifts do not yet represent the forcing of the past 30 years.  How different will the maps of 2100 look?


4 thoughts on “Plants Demonstrate How Climate Has Already Changed

  1. Excellent graphic. The disappearance of much Zone 3 from States bordering Canada seems most obvious. Hansen warned this was coming in Storms of my Grandchildren – and that it will eventually separate fertile soils from areas where crops can be grown and, because population growth goes on, its a doubly-whammy less food can be grown for more people.

    How I hope these revelations about the Heartland Institute will be a game-changer – that the general public will now wake up to the fact that environmental skepticism has not been in the public interest (Peter Jacques).

    • Good observations.

      Call me cynical, but I don’t think the Heartland Institute flap will change much of anybody’s opinion on the topic. It hardly made news and I think a substantial portion of the bite will be taken out of the document release now that Gleick has admitted to a serious lapse in ethics. I don’t think that should be the case, but as with anything else, public perception is a fickle and ever-changing thing.

      • I really hope you’re wrong about the HI. Gleick has sacrificed his career in order to get this information in the public domain and, when you read the documents, you can understand why he momentarily mislaid his moral compass. But, as many have said, investigative journalists do this sort of thing every day. The HI’s intended indoctrination of children (independently confirmed by the Wosjic or whatever his name is) is absolutely outrageous. Therefore the general public really should be outraged…

  2. Pingback: Como Perder Peso En Una Semana

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