Do you doubt climate change?

It generally seems pretty abstract. Sure, it's warm this December, but some years are colder, some warmer than others. I remember more snow when I was a kid, but then, everything was better when I was a kid!

Here's the reality, though: The National Arbor Day Foundation has just "re-issued" the USDA's plant hardiness zone map, and it shows the real impact of global warming. Here in Carroll County, I've always figured us to be a 6 to 6.5. Now, we're clearly a 7. That's a big difference on a scale of 10.

Look your zone up here. The USDA, too, is revising its map, but hasn't released it yet.

As reported in the New York Times: "Cameron P. Wake, a research associate professor at the Climate Change Research Center at the University of New Hampshire, said that winter temperatures in the Northeast have increased an average of 4.3 degrees over the last 30 years."

It's good news and bad news for us gardeners. On the good side, barring the inevitable cold snap, we can shave a week or two off our earliest safe planting times, and get a week or two more out of the season. And it means we can grow some varieties that previously were too risky.

On the minus side, less cold means more insects overwintering, less successful kill-off of harmful disease-causing bacteria and fungi such as apple scab, and more vigorous growth of invasive species including poison ivy, Japanese honeysuckle and English ivy. For us allergy sufferers, too, it means exponential growth in the release of pollen — 10x as much from ragweed as in the old, cold days.

I've always felt that good, long freezes are critical in our area to keep the plant cycles viable (from a human perspective, to serve our needs, of course) and also to kill off germs that make us sick.

So, we'll see how the rosemary does — that should be a good test. We'll know in the Spring.