Wednesday, February 24, 2010

It's COLD! It's SNOWING! So is climate change a hoax??

Guest post by Rebecca Anderson, ACE Team Scientist

We are getting slammed with winter this year... it’s been snowing all over the country, all the time! It’s cold!

So doesn't this mean this whole climate change thing is a hoax??

Reasonable question but... umm, no.

Although that’s what a lot of skeptics would like people to think, as Jon Stewart said last week on The Daily Show: “These snow storms still do bring joy to two types of people: Children… and global warming deniers.”

We all understand that the change in seasons every year doesn't mean climate change is a hoax. The onset of winter every year and the cold weather (and snow) that come with it are expected. That’s the difference between weather and climate afterall!

And yet, climate deniers are having a party shouting down climate change using our "intense winter" this year. Jon Stewart and Rachel Maddow made some really great analogies to help shine some light on these arguments (See their vids here and here.).

Saying one snowstorm disproves climate change is like:

- the fact that it's been steadily getting colder since last summer disproves climate change

Picture 3

- saying it's hot right now in Australia proves global warming

Picture 4

- (My personal favorite) when it rains in the desert means it's not the desert!

These are all excellent examples of weather that doesn't go along with a long-term trend. The long-term trends (like a desert being a desert) make complete sense to all of us and none of the above events change our beliefs! So why would it be any different with snowstorms in winter?? It's not.

Climate change could mean more intense snowstorms:

I can take it one step further: there's a good chance that these big snowstorms not only don't disprove climate change, but they could actually be explained and caused by climate change!

You need 2 things to get a big snowstorm:

1. Temperatures below freezing
2. Lots of moisture to make the snow

In a warming world, it's still going to get below freezing in much of the U.S. during the winter. But the closer you get to freezing, the warmer the air is and the more moisture it can hold. So warmer temperatures (as long as they're still below 32ºF) can actually mean a greater chance of getting a really big snowstorm.

One recent study found that 60-80% of snowstorms in the U.S. occur during warmer-than-normal years. (details) The study predicts that "a future with wetter and warmer winters... will bring more snowstorms than in 1901–2000." (read more here.)

Whether the "Snowmageddon" and "Snowpocalypse" storms were actually part of this trend is something we won't know for sure until we get a few more years into the future and can see if they were part a bigger trend or not. But, like Hurricane Katrina, they do fit the predicted pattern of more intense storms in a warmer world.

To read more about this, check out two posts on Joe Romm’s Climate Progress blog here and here.

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