“The climate has shifted to a new state capable of delivering rare & unprecedented weather events,” explained Weather Underground director of meteorology and former hurricane hunter, Dr. Jeff Masters.
Increasingly, scientists and meteorologists are asking whether global warming is driving a quantum jump — a non-linear shift — in our extreme weather.
We now have enough observations and analyses that a scientific literature on this subject has begun to emerge:
- Arctic Warming Favors Extreme, Prolonged Weather Events ‘Such As Drought, Flooding, Cold Spells And Heat Waves’
- Is Climate Change Bringing the Arctic to Europe?
- Hansen et al: “Extreme Heat Waves … in Texas and Oklahoma in 2011 and Moscow in 2010 Were ‘Caused’ by Global Warming”
This is not your father’s climate, as Stu Ostro, senior director of weather communications at the Weather Channel has documented at great length (see this big PDF)
Peter Sinclair has put together an excellent video for the Yale Forum on why even the modest 1°C warming we’ve seen over the past century can cause a disproportionally large shift in our weather systems:
RealClimate ran an excellent, semi-technical explanation by Stefan Rahmstorf and Dim Coumou of Germany’s Potsdam Institute for Climate Impact Research. They explained how global warming sharply increases the likelihood of ‘outlandish’ heat waves (see charts below) and concluded:
So in summary: even in the most simple, linear case of a shift in the normal distribution, the probability for “outlandish” heat records increases greatly due to global warming. But the more outlandish a record is, the more would we suspect that non-linear feedbacks are at play – which could increase their likelihood even more.
Since this is an emerging field, it’s no surprise that not every climate scientist agrees. Martin Hoerling, who heads the “Climate Scene Investigators” at the National Oceanic and Atmospheric Administration, emailed blogger Andy Revkin a statement that included this truly remarkable sentence:
After all, the irony of extreme events is that the larger the magnitude the smaller the fractional contribution by human climate change.
This is the linear view of things: The modest amount of warming that we have had to date can have no more than a modest impact on any extreme event, large or small.
The emerging literature says otherwise. I asked for a comment by two leading climatologists, Michael Mann and Kevin Trenberth. Here is Mann, director of the Earth System Science Center at Penn State: