12 November 2013
There are claims going around that Typhoon Haiyan was a result of climate change, and this is nothing short of ridiculous. There is some evidence that climate change will change the numbers (and intensity) of tropical cyclones, and some that the storms that do form will be stronger and wetter. That said, there is still a lot of uncertainty in those predictions. An excellent paper on this subject is from Dr. Kerry Emanuel at MIT, and a later paper is IMHO the definitive best science on it.
There is an excellent graphic (below) that shows the correct way to think about how the weather will change as the climate warms and it’s worth looking at carefully.
While this graphic is for temperature, you can use it for extreme weather events of many types. Flood events are expected to increase, and years with unusually low Arctic Sea ice are another. The best way to think about it is this: as years go by (and the planet gets warmer), we will see more extreme heat waves and fewer extreme cold waves. Cold waves will still happen though, and you can see that claiming a big snowstorm disproves climate change is just as silly as claiming a super typhoon is the result of one.
Look at that graph, and you will see that ALL weather events are being affected by climate change, but not any one event. If we see an increase in the most extreme type of tropical cyclones over the next 30-50 years, then perhaps you can say climate change is causing more of them.
We are already seeing this with temperatures by the way. The number of record highs is outpacing the number of record lows, just like the bell curve indicates. As the planet gets warmer, the increase in extremes on the right will become ever more pronounced (compared to the extremes on the left).
In some ways this is a better indication the planet is warming than trying to take the global temperature!