There are two main reasons why Earth may be due for a short-term cooling trend in the next few years, says Larry Cosgrove, WeatherAmerica meteorologist. Both reasons are measurable and verifiable, he points out.
“From 1970 to 2007, the trend has been for warmer years, but in the past 6-12 months our climate has been cooler than previous years,” Cosgrove says. “We’re still globally warm, but the heat has been down in the past year, which may indicate the start of a cooling trend.
“The second reason we may see a cool cycle ahead is due to less solar activity.”
A reduction in sun spots and solar flares can apparently have a huge influence on Earth’s temperature, says Elwynn Taylor, Iowa State University Extension climatologist.
“In the 1640s, sun spots disappeared and didn’t come back for 100 years,” he points out. “As a result, the 1700s were called ‘the little Ice Age.’ During that time, the Northeast was bitterly cold.”
The earth’s atmosphere has been warming since the last major Ice Age, but there are periods when it naturally cools off following reduced solar activity, agrees Drew Lerner, World Weather Inc., owner and meteorologist.
“The amount of energy coming off the sun has decreased in general since the early 1980s, based on sunspots,” he says. “Since there is a lag time of 25-30 years between a change in sunspots and the earth’s temperatures, we will likely see a cooling trend in global temperatures in the next 15-20 years.”
The biggest decline in Earth’s temperatures will probably occur between 2013 and 2019, with a considerable amount of year-to-year and region-to-region variability in temperatures from 2009 to 2012, Lerner predicts.
He adds that a third reason to anticipate colder weather ahead results from tracking weather cycles in the Arctic and North Atlantic oceans.
“The Arctic and North Atlantic oscillation indexes tend to cycle in 10- to 20-year cycles,” he explains. “Right now we are finishing up a long period of warmer winters, and the trends in both indexes show that we are moving toward a new phase where colder winters will predominate.
“These are very dependable winter weather indexes,” Lerner emphasizes. “Summer weather may be cool, as well, but I don’t have summer indexes like I do for winter that are as trustworthy as those two. So, I can’t make a statement as sweeping about summer weather.”
Taylor agrees the Midwest goes through 10- to 20-year cycles of cooling and warming winters.
“We probably just ended a 20-year cycle of milder winters, and we will now have a 20-year cycle of colder winters,” he says. “But just because we have colder winters doesn’t mean that this will affect the corn crop. We had very good crops back in the 1940s and 1950s, and those were really awful winters.”
Although it’s difficult to predict how colder winters will impact crop production in the Midwest, Lerner anticipates that the northwestern Corn Belt near the Canadian border may see reduced corn and soybean production within the next 5-10 years.
“I don’t think that the Corn Belt will be shifting southward, but we may see farmers using shorter-maturity hybrids than they use now,” Lerner predicts. “I also don’t expect a dramatic change in overall yields with the cooler weather. We might even have better yields, for all I know. The biggest issue will probably be increased demand for home heating fuel.”
-- John Pocock