re: #25 researchok

Terrific article.

Global warming is real, of course. Any look at the changes in growing maps/zones over the last 50 years makes that clear.

As to whether or not warming is man made or a natural shift in climate is the real question.

Does it? I’m not aware of any shifts in our Midwestern region, and I’ve run across some older climatic zone maps. Also, 50 years ago and earlier there was a thriving citrus industry in northern Florida and even southern Georgia; it’s gone now, as the frost line has pushed southward. I don’t think citrus is grown much north of Tampa these days. One would have expected the opposite: a northward migration of the citrus industry, which is severely constrained by the occurrence of frost.

Also, there have been several different climatic zone rating systems used over time, and there have been changes in the methodology used to compile them even within a given system.

I’d be interested if you have references to the use of climate zone maps as evidence for climate change. I looked into this a few years ago, and found the situation difficult to untangle owing to shifts in methodology, and where corrections could be applied they seemed to suggest a very stable mapping without much shift over time.