In his plenary talk at the American Chemical Society last week, Nobel winner Mari Molina painted a picture of our atmosphere as wafer thin – like the skin of an apple. So it shouldn’t be too surprising, he said, that our activities have changed its composition. Molina shared the Nobel Prize for his work connecting refrigerants, spray can propellants and other pollutants to the depletion of atmospheric ozone and the ozone hole.
Now he’s turned his attention to climate change. Molina pointed out that CO2 is a trace gas, but it has a profound effect. Its absence would turn our planet into an iceball, with global average temperatures falling from about 60 degrees F to less than 0 F.
Now, fossil fuel burning and deforestation have nearly doubled Earth’s atmospheric CO2 from before the industrial revolution. Earth has seen high levels like this in earlier eras during periods of extreme heat.
“We’re not breaking any paradigms here,” he told the audience. “We’re using very basic science.” But the atmosphere is a complex system and we can’t predict exactly what’s going to happen. To illustrate the point, he showed a drawing of two roulette wheels, each one showing a different range of temperature increases. One represented a future with business and usual and showed a higher range of possibilities. The other wheel represented a future in which we curtail global fossil fuel burning and it displayed a more moderate range of possibilities. Either way we have to play roulette, he said, but which wheel would you rather spin?
He also made the point that scientists and journalists may be misleading the public by claiming that individual hurricanes or fires or disease outbreaks are caused by global warming. Such statements are answers to the wrong question. “It’s not whether any given event was caused by climate change but whether such events are increasing in intensity,” he said. There were always floods and fires and heat spells and outbreaks of disease. To see what’s changing you have to take a big picture view.