Reposted from my comment at: ...and Then There's Physics about "the Pause".
Oh people are putting up graphs (thinks..."now's my chance"). Here's my theory for "the pause" (aka non-statistically significant rise). I don't think we need to invoke pirates. (Incidentally, why are Pirates, Pirates? Because they Aaaaargh.)
It's caused by the AMO. What causes the AMO? Cloud variations. What causes the cloud variations? Magnetic shifts (mostly terrestrial but also solar) that alter the angle of the aurora open to glactic cosmic rays.
[..imagines the look on our hosts' face.. but continues anyway...]
We can see that the AMO pattern results in a strong SST signal (and, yes, before people mention it the AMO is derived from detrended SST's). That signal is cyclical and matches the SST trends (both northern and, surprisingly, southern hemispheres):
* the rise to 1870
* the fall 1870 to 1910
* the rise 1910 to 1940
* the fall 1940 to 1970
* the rise 1970 to 2010
These are SST's, not land temps, but as we know land temperatures are very much influenced by sea temperatures.
Notice how we are at a rough peak of the AMO? The peak may continue for a while, it may go down a bit, who knows we may be in for a bit of "global cooling"(TM) to the likely bottom of the cycle in 2030-2040. So, the pause is looking likely to last for a while yet.
An interesting aside is that we currently have a very low Arctic ice extent. Did we also have a low Arctic ice extent in the last rise/peak of the AMO in the 20's to 40's? Obviously before the satelite era, but it seems likely that we did. See (e.g.) here for a discussion on it.
What about those cloud variations I mentioned? Well here's the graph that a certain commentator here loves to attack (hiya):
And here is the AMO for that period.
..and here are the two compared in a very rough mashup - just for demonstration (note the AMO is INVERTED):
The dates fit. It's a highly plausible mechanism. Clouds --> SST's --> AMO.
What about the magnetic part I mentioned...? Well, we have the largest movement of the N-pole ever recorded, and the lowest ice extent. Gravitation shift from losing glacial ice? Possibly, but there's something else. The last N-pole shift co-incided with the last low arctic extent (1920s-40's). Why is it important where the N-pole is? Because it, (along with declination changes) changes the oval where galactic rays can enter the troposphere! Read all about it at my place.
Oh, forgot to mention *why* the AMO also seems to effect Southern Hemisphere SST's:
Three points in my proposed mechanism
1) The declination of the planet means that the auroral oval in high northern latitudes allow the Galactic rays to enter, seeding clouds, whose quantity varies with the "open-ness, or closed-ness" of the oval.
2) The major ocean in the NH is the Atlantic, hence the direct effect there
3) It's known that many of these galactic cosmic rays are so energetic that they can pass right through the planet. This may seed clouds "down-under" [Edit: speculative, but possible..]. And/Or global changes in cloudiness are transmitted by weather patterns, and/or ocean currents move the Atlantic changes to the southern hemisphere.