Believe it or not, winters have been warming rapidly in the majority of the continental 48 states since 1970. And, take note Chicago and other Midwest readers: The coldest states are warming the fastest. So says a 2013 report by Climate Central.
In fact, says science writer Andrew Zimmerman, if the climate had not warmed so much during the past few decades, it's possible that the current freezer-like weather would be even colder in those areas. Yikes!
Meanwhile, there have been above-average temperatures across parts of the Arctic, Scandinavia, Europe and Asia this past week, Zimmerman reports. Last month, the northern Alaska coastline, above the Arctic Circle, had the warmest temperatures on record in at least 70 years. It's part of an overall trend of warming in the Arctic area.
But yes, brrrrr, every state in the continental U.S. has had sub-freezing temperatures this week. It's attributed to the behavior of the "polar vortex." The polar vortex (also known as a polar cyclone) is a large swirl of very cold air that sits over the polar regions year round. It intensifies in the winter and weakens in the summer. The jet stream from the Arctic polar vortex sometimes brings extremely cold weather southward into Europe, Asia and the U.S.
According AccuWeather.com, cold outbreaks like the one this week occur "on average once every 10 years. The last far-reaching, bitterly cold blasts occurred in the mid-1990s, during February of 1996 and January of 1994." AccuWeather Senior Meteorologist Brett Anderson said, "We were overdue for a large Arctic outbreak of this intensity."
This time the polar vortex has spread unusually far south into the U.S., giving us the record frigid conditions we've been experiencing.
Is global climate change a factor in this unusual intrusion of the polar vortex? Some scientists say yes; others say the jury is still out. Scientific studies have tied abnormally cold temperatures in the U.S. and Europe to warmer than usual conditions in the Arctic - they dub this the "Warm Arctic/Cold Continents Pattern." This could be driven by the loss of polar sea ice which has been documented over the past few decades. That in turn is spurred by human-caused global warming. Research is ongoing.
"The research linking climate change impacts in the Arctic to more extreme jet stream patterns is still very new, and we need several more years of data and additional research before we can be confident that this is occurring," writes Weather Underground scientist Jeff Masters. "But if the new research is correct, the crazy winter weather we've been seeing since 2009 may be the new normal in a world with rapid warming occurring in the Arctic."
But one thing is sure, scientist agree: cold weather does not contradict the well-established fact that the Earth has been warming overall due to human activity, in particular the massive use of oil, coal and other fossil fuels. The consequences of this, scientists say, include more extreme weather of all kinds.
For a break from the cold, you might want to consider a trip Down Under. Australia has experienced record-breaking scorching hot weather this past year. It's been so hot that mapmakers have had to add a new color to temperature maps to signify the blistering heat there. Australia's winter, which is during our summer months, was "only" the third hottest on record. But its spring temperatures, starting in September, were the hottest ever. January 2014 is starting off with similar heat extremes. Walgett, in New South Wales, recorded 120 degrees Fahrenheit, the second hottest temperature ever measured in the state.
One of the reasons for Australia's record heat in 2013 was very high ocean surface temperatures, the third warmest on record according to preliminary data.
If you are not up for a trip to Australia, not to worry. The record cold in the U.S. will be ending this week, weather forecasters say. Temperatures are predicted to be up to 50 in places like New York and St. Louis.
Photo: A Chicago street scene this week. John Bachtell/PW