2011 was a year of extremes. Extremes like Tim Tebow's winning streak and Kim Kardashian's shortest-ever marriage, but also extremes of the weather variety.
Last year, the U.S. got hit with a record-breaking total of 14 weather disasters of over a billion dollars each, from Hurricane Irene to wildfires in Texas to the series of tornado outbreaks last spring. (2008 is the #2 year with only 9 billion-dollar weather disasters.)
The Mississippi River massively flooded in the spring, prompted by heavy rainfall and lots of melting snow in the Midwest. This flood was considered a 100-year event, even though similar floods along the Mississippi have happened several times in the last few decades. Could climate change be at work? The Army Corps of Engineers says, "Possibly, yes."
At the same time, neighboring Texas endured (and continues to endure) its worst drought in the state's history. Although rain brought minor relief at the end of the year, much of the southern part of the state is still classified as in an "exceptional" drought. In total, wildfires burned almost 4 million acres (approximately double the previous record in Texas) and over 2,800 homes.
Much of the country, especially the east coast, got slammed with a major heat wave this July, shattering thousands of temperature records, buckling roads and railroads. The high humidity and hot nights made this heat wave especially brutal.
Playing roles behind the scenes in these events are a couple key factors: climate change and La Niña. Was climate change involved? Yes. Climate change plays a role in all our weather events these days. To use an increasingly popular phrase, "We are loading the dice" towards more heat extremes and intense storms as we increase both the heat in the atmosphere as well as the moisture. (Read more here on why climate change brings with it crazy weather.)
La Niña, a cooling of the equatorial Pacific Ocean that affects global weather patterns, also played a role. La Niña was in strong effect last winter and continues in 2012 in a more weakened form. (Think of climate change and La Niña like two directors in a performance, each shaping the outcome of events with sometimes coordinated, sometimes competing directions.) La Niña tends to make global temperatures cooler than average and that proved true in 2011 as well. Preliminary calculations for the year's average temperature put 2011 as only the 10th hottest year on record, but still warm enough to make it the warmest La Niña year ever. (This just in -- NASA puts 2011 at #9 and NOAA puts it at #11.)
So now, what's in store for 2012? Being winter in the northern hemisphere, hopefully it'll mean snow in the near term, at least more than the 0" we in northern California have gotten so far this year. For the year as a whole, La Niña is still in the mix, making forecasters predict a slightly warmer year than 2011 but not as hot as the hottest year on record, 2010.
Maybe it's the year when Rebecca Black will record a new hit single, "Turn out the lights -- it's Friday" or the world-famous talking dog will speak up about canines leading the way to a sustainable future. It could happen! Young people will be right there with them.