http://www.sciencedaily.com/re...
Science daily (.com) published an article Sept 13th about some cliams by Dr. Nir Krakauer, (assistant professor of civil engineering in The City College of New York's Grove School of Engineering) .
Prof seems conviced that the recent USXDA update of hardiness zones (usually 1/2 Zone warmer) underestimates recent warming. USDA averaged annual minimus over 30-yearsm (1976-2005). Since the warming has speeded up over those 30 years (and in the 6-7 years since 2006), Krakauer uses a mthod that gives more weight to recent years than it does to the 1980s an 1990s.
His map predicts that next winter in the continental US will be 1.5 to 3 degrees warmer than the latrest USDA Zones predict.
It will be interesting to see who's right. For one thing, if the last 10 year's trend is really a trend and not a long-lasting fluctuation, it probably menas we are now in a period of rapid climate change, not just random variation. I'm betgting that way: there have been too many records broken too consistently just in the last 2-3 years to seem "random".
So zone-pushing gardeners may have an easier time of it. As long as you live more than 10-15 feet above current sea level!