Global warming has many good and bad effects, but one that is becoming especially clear is that it makes us all weenies when it comes to colder weather.
You might have noticed that this winter is cold. OK. But it's not nearly as nasty as, say, the late 1970s, which brought the three coldest consecutive U.S. winters in the entire record (which started in 1895). The last winter of any consequence was 2000-01, but that was only the 26th coldest. Where this one will wind up no one can say, but I would be surprised if it even gets to the bottom 20.
Blame global warming
So why all the bellyaching? Well, it turns out you can blame your current discomfort on global warming. Greenhouse gases, like carbon dioxide and methane, warm up winters more than summers. In other words, since the second warming of the 20th century began more than 30 years ago, it's the coldest days of the winter that have warmed up more than any others — and our bodies adapted. So when a truly cold winter shows up, people are physiologically and psychologically shocked.
The coldest temperatures in the Lower 48 are caused by big high pressure systems that form in northwestern North America or (rarely) Siberia. They are blown southward by unusual waves in the jet stream that should become less common in a warmer world. As these are the systems most susceptible to greenhouse warming, extreme cold "outbreaks," like the two we have seen this January, should become more moderate and less frequent.
There are real consequences when certain extreme types of weather become rarer, or when they visit places where they are very uncommon: Besides making people uncomfortable, they tend to kill. But as luck would have it, this effect has been studied more for heat waves than it has for cold.
The U.N.'s Intergovernmental Panel on Climate Change, which purports to be the prime authority on all things climatic, has maintained for years that global warming's more frequent heat waves will kill increasing numbers of city dwellers. If so, we should be seeing more headlines of heat-related deaths in urban areas. Indeed, cities laden with brick and concrete warm up on their own, global warming or not.
In reality, as heat waves become more frequent, fewer people die in them because they adapt. There's hardly any heat-related mortality in Tampa or Phoenix (despite large populations of retirees) because heat waves are common. The only large U.S. city that shows a recent spike in heat-related mortality is Seattle, because heat is rare there.
What about cold spells?
But virtually nowhere is the U.N. on record that the same phenomenon holds true for cold. The great cold wave of Christmas 1983 killed dozens in South Carolina, where cold is rare, but hardly anyone in Chicago, where everyone expects minus-20 wind chills. This winter in northern India, more than 300 deaths have been attributed to "intense cold" — even though the lowest recorded temperature in the state having the most deaths was 39 degrees.
All this underscores the reality that "heat" and "cold," while having real and sometimes dire consequences, are largely a matter of perception. For those of us fortunate enough to have access to adequate clothing and shelter, this winter merely holds the lesson that sometimes, we need to stop complaining about the weather and just deal with it.