From Terra Pass

We thought you'd be interested in this information as you plan for spring and summer:

New USDA Plant Hardiness Zone Map released

In January the USDA released an updated Plant Hardiness Zone Map (PHZM). The PHZM splits the county in multiple climate zones and is used by gardeners to determine what plants will thrive in their location. The new map represents the first update since 1990 and is designed specifically to provide greater detail to the internet user. The map was created using GIS technology, and therefore is much more complete and accurate than the previous PHZM.

To the casual observer the map creates a compelling case for climate change, as each zone is now about half-a-zone warmer than previous version. The USDA, however, cautions against this conclusion. This map only incorporates 30 years of weather data, rather than 50 – 100 years of data needed to establish climate trends; furthermore, this map was created with more sophisticated mapping methods. So we can’t really compare it against previous versions. It is important to note, however, that according to NOAA, the top 10 warmest years on record have been since 1990, and this data is captured in the new PHZM map.

A better map for looking at warming trends in relation to plant hardiness comes from a map published in 2006 by The Arbor Day Foundation. They used the same techniques as the PHZM, and created a compelling animated graphic showing what the changes look like over time. The graphic shows warmer zones migrating north from 1990 to 2006, and here the change seems pretty significant...

Interesting stat:  " the top 10 warmest years on record have been since 1990, and this data is captured in the new PHZM map."

The economic changes, following these weather changes, could be staggering.