It’s near certain that in the GISS global temperature data set, 2010 will end up the hottest year on record. In fact some of those who deny the reality of global warming have already begun to “spin” the event, downplaying its significance by suggesting that observing the “hottest year” is no big deal. This, from the same people who believe in the mythical “levelling off” or “cooling” of temperatures over the last decade or so.



As I’ve tried to emphasize often, it’s the trend that’s the big deal. Not the moment-to-moment noise, or month-to-month or year-to-year noise, not some false trend you think you see (or don’t see) because you so desperately want to believe in Santa Claus.

Let’s look back at the decade of the 2000s (up to the end of 2009), to discover whether or not it behaved as was expected according to global warming. Then we’ll add the year 2010 to the mix, and ponder whether this single year has any real implication for global warming. To set the stage, here’s the global annual average data from GISS, from 1975 through the end of 1999:

I’ve also plotted the trend line (in blue), which illustrates the global warming trend observed during this time period.

Did that trend continue in the 2000s? In other words, did we observe something reasonably close to the red line in this graph?

The answer is: YES.

Yes, global temperature during the 2000s behaved just as expected, according to the “global warming will continue” theory. In fact the decadal average from 2000.0 to 2010.0 is a wee bit warmer than the projected average using the 1975.0-2000.0 trend.

Let’s add the year 2010 as the final red dot on the graph:

What’s the significance of the 2010 result? Simply that it too is in accord with the “continued global warming” theory. In fact, it looks like the decade of the 2010s is off to an even warmer start than expected.