I’m not keen on short term trends at all, they have a habit of flicking in and out of statistical significance with each month’s new data, or even switching from cooling to warming. But for what it’s worth, and only time will tell, perhaps the world entered the downswing of the PDO cycle in temperatures circa 2005.
If the world was entering a gently cooling phase, this is what it would look like
Syun Akasofu pointed out that there was a simple 60 year oscillation of global temperatures (about 30 years of warming, about 30 years of mild cooling) on top of a long slow rise that started more than 200 years ago. He predicted that we were at the top of one of the cycles, and were about to see the beginning of a cooler cycle. This early data suggests he may be right.
The cooling for the last eight years is statistically significant in 4 of the 5 major air temperature datasets. One, UAH, shows a small (statistically insignificant) rise since 2005.
And here’s the political point: how many of the policy makers, the media, or the public are even aware of the current trend? Approximately no one. I’ll bet even most skeptics didn’t know it.
Cue critics who’ll tell me I’m cherry-picking data…
Note I’m not suggesting that this shows CO2 doesn’t cause warming, I’m not suggesting this is evidence (yet) that the models are wrong (they’re wrong, but for other reasons), I’m not even saying that the world is definitely cooling. I’m pointing out that if we were entering a cooler phase, this is what it would look like.
Perhaps the most important thing about these graphs is to juxtapose that claim the world is “still warming” in recent years. If statistical significance is where you hang your hat, the warming trend is not statistically significant, and yet (at the moment anyway) it is statistically significant to say the opposite about the last 8 years in 4 out of 5 datasets.
Btw, all five of the datasets have uncertainties of about 0.05 degrees C, so any change less than that is statistically insignificant.
UPDATE: Graph title corrected in the RSS graph.