(WLTX) - Don't let the recent cold snaps and snowstorms that have chilled large parts of the country fool you: winters in most places have been getting milder over the past century - and especially over the past 40 years. In fact, most of the warming the U.S. has experienced over the past century - largely the result of heat-trapping greenhouse gases - has come in winter.
The average winter temperature in South Carolina has actually cooled by -0.07°F per decade since 1912, but has risen 0.46°F per decade since 1970. That's considerably faster than the overall 1.3°F total warming for the U.S. as a whole over all four seasons since 1912.
Some states are heating up more than others, though, and South Carolina turns out to be number 35 on the list of fastest-warming states since 1970.
A recent report by Climate Central, entitled Warming Winters, found that while the U.S. as a whole has seen a warming trend that has raised annual average temperatures by 1.3°F over the past 100 years, warming varies seasonally, and it's winter that has seen the fastest warming. To better understand winter warming patterns we analyzed average-daily temperatures and overnight-low temperatures for December through February for the continental 48 states from 1912-2012 and 1970-2012.
Among other finding was that states with the coldest winters have warmed the fastest. Minnesota's winters have warmed by more than 5 degrees F over the past 40 years. This has resulted to less ice forming on the Great Lakes in the wintertime thus, more potential for heavy snow in the region's snow belts.
- Winter warming accelerated almost everywhere since 1970, and all states have warmed since that time. Nationwide since 1970, winters warmed more than four-and-a-half times faster per decade than over the past 100 years.
- In contrast, over the past century, winters in 13 states - 10 in the South - bucked the warming trend and either cooled significantly or exhibited a non-significant slight cooling trend.
- Winter nights have warmed in all but one of the lower 48 states since 1970. Across the continent, winter nighttime temperatures have warmed about 30 percent faster than nighttime temperatures over the entire year. Since 1970, overnight winter temperatures in Wisconsin, Minnesota and Vermont have warmed faster than 1.29°F per decade, or more than 5°F in just 43 years.
- Since 1912, states with average winter temperatures below 32°F warmed three times faster than states with average temperatures above 32°F. Since 1970, winter warming has accelerated almost everywhere and states that previously cooled began to warm in winter. Yet, the coldest states (below 32°F) have still warmed nearly twice as fast as the rest of the country on average. And during that time, winter nights in the coldest states warmed up to five times faster than those in warm states.
- The pattern of winter warming is different than the pattern of warming throughout the whole year, which was illustrated in Climate Central's June 2012 analysis of annual temperatures, The Heat is On. Some of the fastest-warming states overall, such as Arizona, New Mexico and Colorado have had some of the slowest-warming winters, both since 1970 and over the past 100 years.
In South Carolina the warming winters may be a plus, but it also has some negative effects. The cold winters help keep insects in check. Furthermore, peaches need a certain numbers of hours below 45 degrees each winter in order to bear fruit. If the trend continues, this could put the cash crop in jeopardy.