Nine of the 10 warmest years on record have occurred since 1998. But forget individual years. That data is noisy. A single year can see its temperatures rocket for reasons having little to do with climate change.

Look, instead, at decades. There, the data is a little clearer, as the idiosyncrasies of any one year are balanced by its nine compatriots. That's exactly what the World Meteorological Association did in a recent report. Here's the graph:

Each one of those bars aggregates 10 years of data. And the trend, particularly in recent years, is clear: The world is getting warmer. "The period 2000-2010 was the warmest decade on record since modern meteorological records began around 1850," the authors write.

And it's not abating. NASA says 2012 was the ninth warmest year on record.