USA National Phenology Network exists to document just these sorts of changes: - "Phenology, which is derived from the Greek word phaino meaning to show or appear, is the study of periodic plant and animal life cycle events that are influenced by environmental changes, especially seasonal variations in temperature and precipitation driven by weather and climate."
What are some of the implications of the shifting Hardiness Zones? Like hunters taking aim on a passing bird, today's teachers may be tempted to take a "lead" on where the zones will end up amid the planted species lifespan, and have their students plant more southerly-adapted tree species, counting on the isopleths continuing to move northward at a regular pace. The problem is, that in "leading" this way, for example, needed pollinators may not move in synchrony. So, tree planting may end up a game of "pin the tail on the donkey" with a Hardiness Zone map the target.
Fast thinkers will see the uncertainties for agriculture. That had best be left for another post.
Perhaps some biologist will log on with a comment to pull me out of this melancholy, pointing out some compensating factors that I have missed. Hopefully, he'll reafirm the revelation that I had as a young adult, that the Pasque Flower will bloom two weeks prior to the apple blossoms opening, forever more setting off childhood searches for asparagus. Otherwise, I had better not meet any Climate Skeptics in the garden store this spring.
Image credit: Pasque Flower, on Wikipedia