The Clear Effects of Global Warming

05.21.08
Sobering words from an ecologist at Monterey Bay Aquarium’s Sustainable Foods Institute.
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Giant invasive weeds that can withstand massive doses of herbicide, swarms of alien insects, cows that stop giving milk…

I’m not talking sci-fi here. Addressing the Monterey Bay Aquarium’s Sustainable Foods Institute last week, David W. Wolfe, a professor of plant ecology at Cornell University, painted the most vivid picture I’ve encountered of what agriculture will be like if the current rate of global warming continues.

Wolfe first gave some concrete examples of how change is already occurring. The National Arbor Day Foundation’s Plant Hardiness Zone Map, relied upon by farmers, horticulturalists, and gardeners to determine the length of growing seasons, has changed dramatically over the last 15 years, with vast areas of the country becoming one or even two zones warmer than they were in 1990, as these maps make startlingly clear.

And you don’t need maps or detailed computer modeling to see that we are in the midst of sweeping climate change. Just step outside and look at the flowers. According to Wolfe, researchers have found that apples are blooming eight days, grapes six days, and lilacs four days earlier than they did historically.

And if the present trends continue? Wolfe pointed out that the country will get 10.5 to 14 degrees warmer by the end of this century, unless we change our greenhouse-gas-emitting ways. To provide an idea of the difference 10 degrees can make, he pointed out that we have warmed up less than that amount over the past 10,000 years—which goes back to a time when much of the country was under glaciers.

Other changes we can expect:

· Kudzu, a fast-growing vine that engulfs trees, utility poles, and abandoned cars and buildings in the South, will move into the Northeast.

· Noxious weeds thrive on higher levels of carbon dioxide and become resistant to herbicide. In one experiment on Canadian thistles, it took three times as much herbicide to control those in a carbon-dioxide-rich environment than those in today’s environment.

· Due to heat stress, cattle will give less milk.

· California will lose its cherry crop due to heat. The cotton pink bollworm, a serious pest now confined to southern reaches of the state, will move north, infesting the entire Central Valley. California’s fine wines will decline in quality.

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