NAS president Cicerone talks on climate

In the talk, titled “Climate Change: A Scientist’s Perspective,” Cicerone spoke extensively about the differences in climate change over past years.

The current concentration of carbon dioxide presence is 390 parts per million, up from a previous rate of 313 ppm, he said.

“The rate of increase [of carbon dioxide] itself is increasing as the cost of fuel increases,” he explained. “This increase is not so well understood ... There are multiple things going on.”

Cicerone also discussed the apparent effects of temperature on carbon dioxide emissions and the similar impact of carbon dioxide emissions on temperature.

“It’s important to know what leads and what lags — did temperature follow carbon dioxide?” he asked.

Cicerone explained that temperature leads carbon dioxide in about two-thirds of cases, with carbon dioxide leading temperature in the other third.

“There is all kinds of evidence that the carbon dioxide increase that we are seeing now is from human activity,” Cicerone said.

“In my view, there is no real silver bullet that convinces me that the carbon dioxide rise is from fossil fuels,” he explained. “But there are five, six, seven lines of evidence there.”

Cicerone noted that most of the carbon dioxide emitted is from fossil fuel usage but that roughly 15 percent is from deforestation.

Cicerone also said that there are currently about three to four places around the world where researchers are keeping track of temperature changes very carefully, one of which is in New York City. By studying temperature patterns in 30-year intervals, these scientists can observe trends in temperature changes.

An interesting trend, Cicerone noted, is that the Southern and Northern hemispheres “lag” each other in terms of temperature patterns. “When the Northern Hemisphere was relatively cool, around 2008-09, the Southern Hemisphere set an all-time record high,” he said. “In 2010, when the Northern Hemisphere was back up to something near its highest point, the Southern Hemisphere was down a little bit from 2009.”

Cicerone stressed that current emissions of carbon dioxide from fossil fuel usage weigh in at 8.5 billion tons, a number that is quickly rising, and that 100 years ago we emitted less than 1 percent of this number.

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Cicerone received the Franklin Institute’s 1999 Bower Award and Prize for Achievement in Science for his work regarding atmospheric chemistry, the radiative forcing of climate change due to trace gases and the sources of atmospheric methane, nitrous oxide and methyl halide gases.

He has also been awarded both the 1979 James B. Macelwane award for outstanding contributions to geophysics by a young scientist and the 2002 Roger Revelle Medal for research contributions to the understanding of Earth’s atmospheric processes, biogeochemical cycles and climate system by the American Geophysical Union. The World Cultural Council also presented him its 2004 Albert Einstein World Award in Science.