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Changes in Hardiness Zones

Arbor Day Foundation

This animation illustrates how the hardiness zones for plants have changed between 1990 and 2006 based data from 5,000 National Climatic Data Center cooperative stations across the continental United States.

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Teaching Tips | Science | Pedagogy | Technical Details

Teaching Tips

  • This would be a good tool to introduce the idea that climate warming affects society in various ways.

About the Content

  • Hardiness zones are determined by the coldest wintertime temperature expected in a given location. The actual low temperature could be higher or lower than that specified by the hardiness zone.
  • The Arbor Day Foundation determined a need for a new hardiness zone map and used NOAA data to create the newer 2006 map http://www.arborday.org/media/zonechanges2006.cfm.
  • The US Department of Agriculture continues to use the map they generated in 1990.
  • A related map shows where the largest changes from 1990 to 2006 have occurred: http://www.arborday.org/media/map_change.cfm.
  • Comments from expert scientist: The changes of the hardiness zones in the U.S. are consistent with the phenolgy changes reported in the scientific literature.

About the Pedagogy

  • Comparing the 1990 and 2006 US Hardiness Zones gives students a good idea of how tangibly the climate in the continental US has warmed over 15 years.
  • Emphasizing why gardeners and farmers rely on the hardiness zone maps can help explain their relevance.

Technical Details/Ease of Use

  • When the user presses "play" there is a visible shift in the hardiness zone from 1990 to 2006. When the user presses "difference," the shifts across zones are highlighted.
  • There is some commentary about these maps in the press release - http://www.arborday.org/media/zonechanges2006.cfm
  • A high-resolution version of this map is available for download.
Entered the Collection: October 2013 Last Reviewed: September 2016

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