A second ice age might not be around the corner any time soon.
While many students may be quick to blame New Haven’s seemingly aberrant weather — the heavy rainfall last fall, or the decidedly mild weather experienced after winter break — on global warming, Yale geologists said that the unseasonably mild weather this year has been neither exceptional nor extraordinary. Professors of geology and geophysics Alexey Fedorov and Steven Sherwood and researcher Dorothy Koch said weather patterns this winter are within the normally expected range. Fedorov and Koch suggested that the recent changes in climate may be caused by global warming.
“I don’t think this weather is anything out of the ordinary,” Fedorov said. “From day to day, week to week, and year to year you can expect different weather patterns. And while we may notice when things are just a little bit out of the ordinary, if you compare data over the years, what we are experiencing is not too extreme.”
For New England, in particular, it is not out of the ordinary to have a week of warm weather in the middle of winter, Fedorov said.
Sherwood said he did think that the precipitation last fall was heavier than what people have come to expect, but not necessarily indicative of any major climatic shifts. He explained that different wind currents are the cause of such varied weather patterns.
“The reason we can get such violent swings of weather in Connecticut is that we have the option of getting air from the gulf region, which is warm and moist, or from the Arctic region, or we can get continental air from the west,” Sherwood said. “Having different air can cause rather dramatic changes in the weather.”
The warmer temperatures New Haven has recently experienced, including today’s predicted 50 degrees Fahrenheit, have been a result of airflow from the Gulf area, Sherwood said.
“Flow patterns are governed by waves and the atmosphere, and there isn’t a neat and simple explanation for why we get something one week and something else the next week,” Sherwood said.
Sherwood said he assumes the heavy precipitation last fall and the milder temperatures Yalies are currently enjoying are a result of some unusually warm and humid air that came up from the South. Additionally, he said there have been some relatively intense cyclones — a standard, rotating weather system akin to the hurricane — in the New England region this year that dropped rain, rather than snow, because the air was too warm.
Fedorov also noted the prevalence of storms the Northeast region has been experiencing over the past few years, but offered an explanation that takes into account the effects of global warming.
“If you look over the last years, it looks like the number of snow storms was kind of large,” Fedorov said. “It might just be another irregularity that is to be expected, but in a global warming climate, you expect it to be more humid. And if you get a front of this moist air in cold weather, you will have more snow. But this connection is very speculative.”
Similarly, Koch, who is on sabbatical in Italy this year, said that weather fluctuations are normal, but such fluctuations may be on the rise as a result of rising global temperatures.
Drawing from data released by the NASA Goddard Institute for Space Studies, Koch said that New England temperatures in 2005 were one-half to one degree Celsius warmer, on average, relative to temperatures between 1951 and 1980. She said this anomaly was most evident last winter, when New England temperatures were one to two degrees Celsius warmer than the recorded average.
“This appears to be related to the high temperatures in the Arctic,” Koch said, which were three to four degrees Celsius above average in some regions.
Fedorov also said that in Arctic regions the climate change is much more noticeable, as evidenced by warmer winters and melting ice. In Russia, the winters are becoming discernibly warmer, whereas in this part of the globe there will not be much of a difference from one decade to another, he said.
“There are places where the impact of global warming is very real,” Fedorov said. “Glaciers are retreating in some places, for example. But places like Connecticut, I don’t think are as affected. Florida is maybe a different story, with the question of hurricanes and their possible connection to global warming, but the United States in general, and Connecticut at least, are not really affected.”
As for the warmer weather of the past few weeks, Sherwood advised students not to get their hopes up just yet.
“There have been no strong statements that it’s going to be a mild winter at this point, even though the last few weeks have been pretty mild,” he said.