Wednesday, December 20, 2006

This town don’t look good in snow: The National Arbor Day Foundation’s national map is still more evidence that global warming is creeping up on us. In 1990, Washington, D.C., was essentially at the climactic Mason-Dixon Line, separating South from North. No longer. You might say that the South has its final revenge, between stealing Americans away from Northern cities to live in the eerie eternal paradise of the Sunbelt, and then foisting its climate on the rest of us. Global warming means we’re losing the remnants of the ancient price Persephone paid. I kid you not, you can now grow southern magnolias in parts of Michigan, and it looks like Chicago jumped up a zone, and Minneapolis two (viz., the change map):

In a revised map of “hardiness zones” — bands of similar temperatures where similar trees are likely to grow in winter — the foundation reclassified the entire Washington area in the same zone as parts of North Carolina and Texas. In 1990, the region was on the border of northern and southern growing zones, but a foundation official said that has changed after 15 years of balmy winter weather.

The foundation’s findings provide a window into the local effects of climate change, scaled down to lawn level. Colorado blue spruce and hemlock, at home in the cold, might have a harder time. Crape myrtles and camellias will have it easier.


But at the Botanic Garden, [U.S. Botanic Garden curator Bill] McLaughlin had mixed feelings. He was glad to find that such species as the needle palm or the yaupon, a holly native to areas farther south, could be raised more easily. But then, he said, he thought of the impact on the species that belong here: native plants that might find their growing seasons shifted, their life cycles out of sync with pollinating insects, if warming trends continued to affect them.

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