Recent analysis by scientists at the NASA Goddard Institute for Space Studies (GISS), shows 2009 to be tied for the 2nd warmest year in the instrumental record. The warmest year on record was 2005, and (statistically) tied for second place are the years 1998, 2002, 2003, 2006, 2007, and 2009.

Source: Hansen et al. (2010)

This is according to a draft article by James E. Hansen and colleagues, If It’s That Warm, How Come It’s So Damned Cold?, providing early analysis of temperature for 2009 as well as providing some commentary on some of the disinformation talking points used by global warming skeptics.

As you may have noticed, much of the US was caught in a cold snap the past few weeks. Some in the media immediately made the connection that because it’s cold outside, global warming must not exist. In fact, the recent cold weather can be blamed on the Arctic Oscillation, which is currently in a strong negative phase, leading to colder temperatures in the northern hemisphere mid-latitudes (North America and Eurasia).

Another talking point is that there has not been any global warming for the past decade (see the end of George Will’s column). This does not hold if one looks at longer term trends (to smooth out any interannual climate variability), which clearly shows a warming trend. As Hansen says at the end of the article:

“The bottom line is this: there is no global cooling trend. For the time being, until humanity brings its greenhouse gas emissions under control, we can expect each decade to be warmer than the preceding one. Weather fluctuations certainly exceed local temperature changes over the past half century. But the perceptive person should be able to see that climate is warming on decadal time scales.”

The 2000s just went down as the warmest since thermometers were invented, and if you believe in rigorous scientific analysis of glacier ice cores and tree rings, then the warmest in 125,000 years.

Sources:
Hansen, J. et al. (2010) “If It’s That Warm, How Come It’s So Damned Cold?”
Hansen, J. et al. (2008) “Target atmospheric CO₂: Where should humanity aim?“