In a question-and-answer session, Carson said accuracy in weather forecasting is still limited to about three to 10 days — “beyond that, you might as well look at the Farmer’s Almanac.

“But we’ve got sensors now in the South Pacific, and we know west coast weather will be affected by what happens a couple of weeks earlier in the South Pacific. We have weather and climate models that can tell Californians to hold water in dams because it’s going to be hot and dry. We’re getting enough resolution that people can make plans.

“There are climate change maps floating about, forecastsing changes in the hydrology cycle — how much water you get and when — that look pretty ugly in terms of extended drought for some places, like Texas and Oklahoma. On the other hand, things for Mississippi actually might look fairly good.

“In terms of climate sensitivity, high value crops such as avocados in San Diego will continue to be grown unless water becomes prohibitively expensive. But if Imperial Valley farmers can make more money selling their water to cities, we might see some of their cotton or shift to Mississippi or other areas.”

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Even though climate change models don’t show big losses or gains for the U.S. as a whole, Carson says, “There are big losses or gains for certain regions. You could see the Corn Belt move north. Canadians do quite well agriculturally under climate change.”

If climate change is rapid, he says, “We could see more extinction of animals and plants; if it’s slow, there could be more adaptation to the change. The speed with which it happens is pretty much the primary determinant on land.”

But there are there are some big uncertainties associated with ocean warming. “A big worry is giant methane deposits on the bottom of the oceans; if they were to significantly heat up in the climate change process, it could be pretty catastrophic.”

Carbon sequestration proposals come up lacking economically, Carson says.

“I’ve never seen a carbon sequestration project that looked like it made any economic sense. With all the discoveries of natural gas driving those prices down, it doesn’t make any economic sense to sequester carbon.

“As natural gas prices drop, we’ll see power plants across the country converting from coal to natural gas. There are some carbon sequestration projects out there, but about all they’ve shown is that they’re very expensive. With the amount of energy it takes to sequester carbon, it doesn’t look like sequestration works with cheap natural gas.”