| Farmers' and home gardeners' jobs are about to get more difficult. Most of us have relied on two main clues to decide when to plant in the spring: experience and the USDA planting zone map. That second one has just been revised: thank you climate change. From the Washington Post notes that the USDA is being coy about drawing conclusions, but others are not: “The map is not a good instrument for determining climate change,” said Kim Kaplan, a spokeswoman for the USDA’s Agricultural Research Service. “It’s not that there hasn’t been global climate change it’s that the map isn’t a good (vehicle) for demonstrating it.”
USDA’s line of reasoning in perplexing. Climate data are used in USDA’s analysis and the northward jog in planting zones is fully consistent with other data and indicators that establish warming of the coldest temperatures in the U.S. (and most locations globally).
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Seth Borenstein spoke with David Wolfe, a professor of plant and soil ecology at Cornell, who agreed USDA is being “too cautious” in laying off the climate change connection. “At a time when the ‘normal’ climate has become a moving target, this revision of the hardiness zone map gives us a clear picture of the ‘new normal,’” Wolfe said.
The Washington Post has a cool interactive map - it's impossible to include here, but go to the site - that compares the old map to the new one. It clearly shows differences in Alabama and other states. Now, at first glance, you might wonder why this is a big deal. A longer growing season means more food, right? No. Because there are a LOT more variables involved: rainfall, heat, plant disease, and insect infestations: - Rain: The hotter is it, the more rain you need - or maybe an expensive irrigation system. The Texas Drought Project has information about what happens during wide scale droughts. People have begun to speculate that the situation in Texas isn't in fact a "drought," but creeping desertification.
- Heat: Warmer isn't necessarily better. Yes, earlier planting means we can get those tomatoes & cucumbers in the ground, but it also tends to portend a long, hot summer. Some plants can't withstand it.
- Disease: A lot of disease problems in the South come from hot, muggy weather that encourages fungal infections. A little more heat and less moisture helps with that - however, too much heat and drought stresses plants and makes them more susceptible to other problems.
- Pests: Good, long cold snaps in the winter do more than drive up our heating bills: they kill insects burrowed down in the soil. Warm winters often lead to armies of voracious squash bugs, Japanese beetles, and other pests in the summer garden.
A longer growing season doesn't necessarily mean more food. It could mean less. It could mean that your favorite type of tomato or melon are no longer suited to your area. It could mean a lot of things and the longer we keep denying the reality of what is happening, the harder it will be to adapt and deal with new realities. We can't wish climate change away and we probably can't stop it. But we have got to start seriously trying to slow it and develop strategies to adapt to it. Everyone. Even home gardeners. |
