Warmest Year on Record: 2010?

After a relatively cool spring in the Southwest, we’ve switched to some above-normal temperatures in recent weeks, and the National Weather Service is predicting that this warm trend will continue in coming months  (see the June 24, 2010 issue of the Southwest Climate Outlook for details). This got me wondering where things stand on the global temperature front. Early last fall, I considered the global warming trend of the last half century, along with the then on-going El Niño, and I bet a bottle of wine with a geoscientist colleague that 2010 would be the warmest globally since temperature monitoring began in the 19^th century. How’s that bet looking now?

Well, so far so good. Even though some folks made a big deal of cold winter temperatures in the eastern U.S. as we moved into 2010, it turns out (no surprise to climate scientists) that that was just regional weather. In contrast, global temperature has been on a record-setting pace since the start of the year, and through May, both U.S. agencies monitoring global temperature—NOAA and NASA— show record warming for the year.

First, NOAA - the folks that run the National Weather Service and lead the nation in monitoring the state of our climate.  Their most recent report indicates that “The combined global land and ocean average surface temperature for May 2010 was 0.69°C (1.24°F) above the 20^thcentury average of 14.8°C (58.6°F). This is the warmest such value on record since 1880.” What’s more, May 2010 caps off a run of warm months, and “the combined global land and ocean average surface temperature for January–May 2010 was the warmest on record. The year-to-date period was 0.68°C (1.22°F) warmer than the 20^thcentury average.”

Interesting way to start a new decade: record warmth following on the tails of the warmest decade (2000-2009) since the instrumental record began in the 19^th century. There is no doubt the Earth is warming up.

What about NASA? Their global analysis also indicates that January-June, 2010 was the warmest on record – since 1880.  A couple things are worth highlighting. First, it’s important not to be confused over what we’re talking about. We’re talking global temperature, and climate—the trend in temperatures over years to decades and longer. What’s happening in any one place, and during one week or month, is regional weather.  Second, while the globe as a whole has been breaking temperature records, some places have stayed relatively cool. For example, if you look at Figure 1 (from NASA, see caption for more info) you can see that the globally record breaking January to June 2010 has been cool in parts of the southern U.S. And it’s a good time not to be in Central Asia – cold!

Lastly, although it helps to have a clear trend of past change (warming, in this case) to draw on when thinking about the future, we’re on much safer ground if we understand why things are changing as they are. I’ll talk about that in my next post. In the meantime, Paul, I’m looking forward to that nice bottle of Malbec…