Climate change typically takes place gradually. But Jim White, director of the Institute of Arctic and Alpine Research, said the change could occur at a much more dangerous pace. He addressed this issue of abrupt climate change to an audience of about fifty CU graduate students and professors in a colloquium at CU Boulder’s Cooperative Institute for Research in Environmental Sciences on Thursday.
White studies ice cores—historic popsicles from the Greenland ice sheet that give scientists a taste of past climate conditions. Specifically, he looks at past climate patterns as a means of informing future climate predictions.
All it takes is a trigger and the system will shift with a bang, White said.
White explained that global climate is controlled by three basic factors: 1) the amount of solar energy entering the atmosphere, 2) greenhouse gas concentrations, and 3) the albedo effect, a measure of how much of the sun’s energy is reflected back to space. Fluctuations in any one of these controls will cause changes in climate, usually over long periods of time.
What sets abrupt climate change apart is the timescale on which it operates, White explained. What kind of a change would be considered abrupt? It must be “fast enough that people would care” and “large enough that it challenges adaptability,” he said.
White admitted that his definition is vague and illustrated the idea with a historic example. The last time the earth experienced abrupt climate change was at the end of the Younger Dryas, a period of cold, dry conditions, roughly 12,000 years ago. In addition to significant changes in precipitation and greenhouse gas concentrations, the global temperature increased 10 degrees Celsius in about 50 years. The rise came in two 5-year bursts, where temperatures rose one degree per year, with a 30- or 40-year stabilization period in between, he explained. White paralleled this change to Atlanta’s average temperature shifting to that of Minneapolis within a human lifetime.
Prevailing theory says that such an abrupt shift in climatic conditions will the shock the system, thereby scaring people into action. “I don’t know that that’s true,” White said.
If the current abundance of knowledge regarding human-caused climate change hasn’t set people off, the idea of climate change with a little extra oomph probably isn’t going to be a game-changer, he said.
The problem is that people and policy makers require details—details that climate scientists can’t provide. Despite the progress that White and his colleagues have made, their reconstructions of past climatic conditions are still riddled with unknowns. If we still can’t “post-dict climate,” White asked, how are we supposed to predict it?
Despite his confidence that the climate will change significantly in the future, White said he remains unconvinced that such major changes will be enough to impact policy, adaptation measures, or even public opinion.
White’s advice? “Stay healthy,” with the hopes that you’ll live long enough to see what promises to be a dramatic climatic show.
For more on White’s work on climate change and the potential impacts of rising sea levels on low-lying coastal cities like Miami (which White says will disappear under water in future) see Tom Yulsman’s post at CEJournal.