“You can’t tell much about the climate or where it’s headed by focusing on a particularly frigid day, or season, or year, even,” writes Eoin O’Carroll of the Christian Science Monitor. “It’s all in the long-term trends,” concurs Dr. Gavin Schmidt, a climatologist at NASA’s Goddard Institute for Space Studies.
Most scientists agree that we need to differentiate between weather and climate. The NOAA defines climate as the average of weather over at least a 30-year period. So periodic aberrations—like the harsh winter storms ravaging the Southeast and other parts of the country this winter—do not call the science of human-induced global warming into question.
The flip side of the question, of course, is whether global warming is at least partly to blame for especially harsh winter weather. As we pointed out in a recent EarthTalk column, warmer temperatures in the winter of 2006 caused Lake Erie to not freeze for the first time in its history. This actually led to increased snowfalls because more evaporating water from the lake was available for precipitation.
But while more extreme weather events of all kinds—from snowstorms to hurricanes to droughts—are likely side effects of a climate in transition, most scientists maintain that any year-to-year variation in weather cannot be linked directly to either a warming or cooling climate.
Even most global warming skeptics agree that a specific cold snap or freak storm doesn’t have any bearing on whether or not the climate problem is real. One such skeptic, Jimmy Hogan of the Rational Environmentalist website writes, “If we are throwing out anecdotal evidence that refutes global warming we must at the same time throw out anecdotal evidence that supports it.”