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Health, Science, Environment

National Academy of Sciences president: people are contributing to climate change

President of the National Academy of Sciences Ralph Cicerone says rising sea levels—and the loss of ice from polar regions—are at least partially caused by human activities. (Karen de Seve)

There is strong evidence that human-produced greenhouse gases—like carbon dioxide and methane—are changing the Earth’s climate.

So says the President of the National Academy of Sciences, Ralph Cicerone.

He spoke about the science of climate change at the Saint Louis Science Center this week.

And Cicerone told St. Louis Public Radio’s Véronique LaCapra that although the climate has changed in the past, this time is different.


Cicerone said part of the difference is that temperatures are rising everywhere. During previous periods of climate change in human history, like the so-called Medieval Warm Period in Europe, or the Little Ice Age, temperature changes were regional, occurring in one location, but not in another. “This change is everywhere,” said Cicerone. “It’s the whole planet, as if the planetary energy balance is involved. ”

Cicerone said we’re already seeing more record high temperatures than we are record low temperatures. According to him, in the past 30 years—with a couple of exceptions—we’ve had mostly mild winters, and we’re seeing more intense rainfall events. “Those patterns are not completely clear yet,” Cicerone said, “but we think we’re seeing them. ”

He said it’s not yet possible to predict what will happen at a regional level, like in the Midwest. “We know that some vegetation zones are moving northward, towards what were previously colder areas, but our ability to predict like down at the state level is not here yet,” Cicerone said. Scientists are predicting that wet areas of the world are probably going to get wetter, and dry areas are probably going to get drier. “But that’s not very satisfying if you want to know what’s going to happen in Kansas, in Missouri, Illinois—we’re not there yet,” Cicerone said.

The global average temperature has gone up about a degree Fahrenheit in the last 30 years, “and we’re already locked into about another degree, no matter what we do, but it’s probably going to go well beyond that,” Cicerone said. He said that typical predictions range from four to eight degrees of warming, this century.

Cicerone said our first action should be to limit the amount of these greenhouse gases—mostly carbon dioxide and methane—that we’re putting in the air every year. “We have to do everything we can. ”  Cicerone said it will take a combination of increasing energy efficiency, and using more renewable energy and nuclear power to substitute for coal and gas. “But economically that’s not easy because nuclear power happens to be very expensive,” said Cicerone.

Cicerone said that if we want to stabilize the amount of carbon dioxide in the atmosphere instead of allowing it to continue to increase, we will have to cut back on fossil fuel usage as much as 50 to 75 percent. He said a combination of more efficiency, renewable power, nuclear power, and possibly carbon capture and sequestration will be needed.

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