It happens every year and it seems to be getting worse.  We get a big snowstorm on a major metropolitan area and all the sudden people start pointing their finger at Al Gore.  "It's snowing, so surely global warming must be a farce designed to make Al Gore rich, poison your kids, bankrupt our governments and turn America into a haven for socialistic gay-sex-and-abortions-for-all loving hippies."

The wrong wing loves to gloat when we get a lot of snow.  To be fair, for the average layperson (emphasis added) there is a very slightly counter-intuitive notion about having a warming climate yet seeing more snow.  So here's a basic lesson that I am sad to have to explain again this year:  weather is what happens next weekend in Chicago, climate is what happens over a long period of time covering a large area.  Saying that global warming doesn't exist because we get a lot of snow, or even many many bad snow storms, is like saying that diet and exercise doesn't work because I ran for an hour and I still have a fat ass.

But don't take my word for it, listen to what scientists are getting tired of repeating year after year (from Discovery):

I'm not saying anything new here, but the whole idea behind climate change is that it's happening to the entire planet. It takes years, even decades to move the needle on Earth's climate. Meanwhile, heat waves, cold snaps, droughts, and snowstorms come and go. As this piece in Time points out "Weather is what will happen next weekend; climate is what will happen over the next decades and centuries." Again, old news.

And yet, we routinely conflate current and near-term weather conditions with what's happening to the global climate. It's exactly the wrong thing to do, and yet we do it every day. Why? Because, let's be honest, everyone enjoys complaining about the weather.

That's completely fine: getting frustrated about something that is utterly out of your control and can ruin your day makes sense -- like a mysterious charge on your credit card bill, say.

But statements about fickle weather have little place in the discussion about large-scale climate change. Studies do suggest more stormy weather is possible as the atmosphere becomes supercharged with moisture due to global warming. And if parsed just right, good arguments can be made that explain short-term weather in context of long-term climate records.

So if you want to have a rational fact based conversation about why we're having all this wacky weather, here  are a few key points that scientists keep saying again and again:

• The past decade was the warmest on record and that the Earth has been growing warmer over the last 50 years (source: More than 300 scientists from 160 research groups in 48 countries contributed to this NOAA report)
• Analysis of global surface temperatures by NASA scientists finds 2009 was tied for the second warmest since 1880. In the Southern Hemisphere, 2009 was the warmest year on record. (source: NASA, and this is despite the crazy weather from El Nino)
• Global precipitation in 2010 was well above the 1961–1990 average, ranking as the wettest on record since 1900. (source)
• Rising Arctic temperatures have reduced floating ice cover by 20 percent over the last three decades.
• December 2010 had the lowest ice extent for the month since the beginning of satellite records. The linear rate of decline for the month is –3.5% per decade. (source NSIDC)
• This past year the arctic had the warmest waters they've had in the past 2000 years, and the scientists who wrote the study add: "On a scale of 2,000 years, it stands out dramatically as something that does not look natural."
• See more facts and figures

Beginning to see the big picture?  So now back to the wacky weather, most scientists agree that an increase in the amount and severity of storms, snow storms and other bad weather is completely consistent with their climate models and studies...and it's only going to get worse as the earth warms.  We're feeling the effects of a 1 degree warming so far, and scientists say that we're looking at 4-5 degrees even if we do nothing because of the greenhouse gases we've already released.

To break it down even further, when we stop complaining about the weather we can begin to explain the wacky weather using science.  A warmer global temperature means more water exists on Earth as water vapor, which means more and more severe precipitation.  Not that complicated is it?  Here's another interesting part which explains why all these wacky effects are compounded even further:

The recent rapid melting of sea ice in the arctic (see facts above) is creating unusually high pressures that are changing the jet streams.  Similarly Britain saw one of its worst winters ever, which scientists say is not only consistent with the climate models, it's further proof of global climate change.

Counterintuitive but true, say scientists: a string of freezing European winters scattered over the last decade has been driven in large part by global warming.
The culprit, according to a new study, is the Arctic's receding surface ice, which at current rates of decline could disappear entirely during summer months by century's end.
The mechanism uncovered triples the chances that future winters in Europe and north Asia will be similarly inclement, the study reports.

The only thing finger we should be pointing at Al Gore is that he should not have called it global warming (even though that's what's happening), it should be called climate change.  Because so many people don't know that there's a difference between weather and climate.


Some good links:

http://www.youtube.com/watch?v=QXbI8vnfncc
http://news.discovery.com/earth/what-strange-snowstorms-say-about-global-warming.html
http://www.epa.gov/climatechange/science/futurepsc.html
http://www.dailykos.com/story/2011/1/13/936031/-2010-wettest-year-on-record,-tied-for-hottest