It’s been really cold recently, especially in the Northeast, and you know what that means: Liberals, the media and even a fair number of scientists feel compelled to reassert that the excessive cold is “the result of global warming,” not a refutation of it.
That may seem a little counterintuitive, but global warming proponents offer what could be a reasonable explanation.
Now, if only they could get that darn data to agree with them.
Let’s start with a definition from Cornell University’s Climate Change research: “A polar vortex is a system of upper-level winds that circle around one of the poles. Such circumpolar wind systems exist most of the time at both the North and South Poles, but they can change in strength depending on season and also special atmospheric conditions.”
When a strong polar vortex is circling the Arctic, it generally keeps the Arctic air contained at the North Pole. But the vortex can weaken, and when that happens, frigid air can descend to the mid-latitudes, just as it did recently.
Some scientists suggest that global warming has reduced Arctic sea ice, and that reduction can weaken the polar vortex, thereby creating more opportunities for Arctic air to head south. Hence, they say, global warming may be the real cause of the recent sub-zero temperatures.
Even though scientists have known of the polar vortex for well over a hundred years, the term only became popularized during the winter of 2014. Unfortunately, as Live Science points out, the term is increasingly applied to almost any cold snap. Today, the polar vortex has become one more pawn in the climate change debate.
If human-caused global warming is behind the dipping polar vortex, then you would expect to find an increase in the number and perhaps intensity of them in recent decades as Arctic sea ice has declined. But it’s not clear that’s what the data show.
In a 2006 paper for the Journal of Geophysical Research, rated the intensity of the 30 strongest polar vortex dips into the mid-latitudes over a 54-year period, between 1948 and 2002.
While the three coldest on the list occurred after 1980 — the approximate date when some climate alarmists stopped predicting a global ice age and started predicting a global sauna — the next six preceded 1980.
Looking at the second 10 on the list, four came after 1980 and six before. Six of the final 10, the least severe on the list, occurred after 1980.
The authors explain in their article how they measured their data and calculated their findings, which makes it difficult to compare with polar vortex dips that occurred after their paper was published. But their work at least highlights some important points.
- Polar vortex intrusions have a long history; they are not recent phenomena. The three coldest years in the study occurred after 1980 — i.e., 1983, 1989 and 1996 — but the fourth coldest occurred in 1958 and the eighth in 1948.
- Of the last 10 years included in the study, only three (1994, 1996 and 2000) made the list, which seems something less than a trend.
Cornell correctly summarizes the current state of the debate: “Many climate scientists believe that natural variations in the climate system are sufficient to explain the frequency of cold spells in recent years. Others suggest these weather phenomena could be influenced by climate change due to the ongoing decreases in Arctic sea ice and the faster rate of temperature increase in the arctic compared to lower latitudes.”
It should be remembered that the Earth has been on a gradual warming trend since the end of the last ice age thousands of years ago. So while warming may be having an impact on the Arctic’s polar vortex, allowing that frigid air to shift south, many factors affect the climate, not just humans.
Merrill Matthews is a resident scholar with the Institute for Policy Innovation in Dallas, Texas. Follow him on Twitter @MerrillMatthews.