Sandy and Climate Change – An Arctic Connection?

“Superstorm” Sandy is just the latest in a wave of extremely unusual weather events to hit the US and the rest of the world in recent years, leading many to wonder about the possible link to climate change. Host Lisa Mullins raises the question with The World’s environment editor Peter Thomson.

Power failures and transportation gridlock continue to plague much of the northeastern United States Tuesday as what’s now being called “post-tropical cyclone Sandy” moves inland.

The swath of destruction being left by Sandy comes as just the latest in a wave of extreme weather events around the world in the last couple of years.

That’s led many people to wonder whether it’s more than just a string of bad luck.

The World’s environment editor Peter Thomson is here in the studio with me now…

Peter, are scientists seeing the fingerprints of climate change on Sandy?

Thomson: Well, Lisa just about every climate scientist you’ll talk to will say “no,” but many would add “no–but.”

Climate change almost certainly did not cause hurricane Sandy to form. We know that climate change is starting to affect the way storms behave, but most climate models are pretty clear in telling us that it won’t affect the frequency of tropical storms.

So no, no fingerprints, no smoking gun. But to stick with that analogy for a minute, Lisa, a good prosecutor might well make a solid case for charging climate with aiding and abetting in the case of Sandy.

Mullins: Meaning circumstantial evidence?

Thomson: Yeah, I mean to begin with, what many climate scientists are saying is that the entire context in which weather takes place is changing as the atmosphere warms up. James Hansen of NASA compares it to loading the dice. A warmer atmosphere, he says, is increasing the likelihood of extreme events, and perhaps increasing the severity of those events when they do happen.

Now, in this particular case, its likely that warmer ocean temperatures in the Atlantic contributed at least in part to the strength of Sandy. I mean, temperatures in the North Atlantic this fall are several degrees Fahrenheit above normal. And that almost certainly added strength to a storm that of course might well have happened any way.

It’s important to add that again, no one can say for sure that this year’s higher temperatures in the Atlantic are a result of climate change, but the level of scientific certainty that that’s what’s causing oceans to warm up is pretty high.

Mullins: So Peter, there was, as you well know, more to this storm than there might have been to conventional hurricanes. We heard an awful lot about those big weather systems that blocked way north and forced it toward the coastline. Forecasters are saying this is extremely unusual. So what are we to make of that?

Thomson: Well yeah, this is where the emerging climate science gets really interesting… Those weather maps we’ve all been seeing have this big blocking high to the east and this huge dip in the jet stream to the west and it turns out that pattern looks an awful lot like what was predicted by a really interesting paper published earlier this year in the journal Geophysical research letters… It showed that warming in the Arctic, like what we saw this summer, is resulting in big disruptions in weather much farther south, including often pushing waves of the jet stream way down into the temperate zones, like where this storm is happening. It also found a close correlation between a warming arctic and an increase in the kind of “blocking” systems that forced Sandy toward land.

And it turns out that that same kind of big blocking system has been associated with several extreme weather events over the last couple of years… including the massive 2010 drought in Russia and even the bizarre heat wave we had here in the US last March.

I do need to say of course that these kinds of blocks aren’t new, but this report showed some pretty compelling evidence that the warming arctic is formation of these kinds of blocks and these kinds of big dips in the jet stream that are starting to play havoc with our weather all the way down here.

Mullins: The World’s Environment editor Peter Thomson…. Thanks very much.

You can find a link to that study on arctic warming at the world dot org. Peter, thanks again.