Heh, Nate is quick to jump on the well managed news release that 2010 according to massaged NCDC temperature series, is the 'hottest on record' *so far*. This pop-up myth rlies on the fact that we just came out of a long El Nino which lifted temperatures globally *temporarily*. Conditions are now rushing headlong in La Nina conditions and South america is already hard hit.
Not only are hundreds of people dying of extreme cold in Bolivia at the moment (the Govt has declared a state of emergency in response to the -24C temperatures experienced in the last few days) but snow is coming early in the northern hemisphere too. The Arctic is below seasonal averages, and I predict another savage winter ahead.
But it's not all extreme weather news at the moment.
John Christy (yes *that* John Christy) has just had a paper published in Energy and Environment showing a pretty much zero trend in snowpack for the southern Sierras over the last 100 years. Here's a free copy for BPL climateers:
Now returning to Nate's observation that the high recent global temperature coincides with a period of solar quiet, he may be interested to know that most big El Nino's occur near solar minimum, and during low solar cycles, and that many more occur on the downslope of solar cycles rather than the upramp. Why is that?
My hypothesis is that the worlds oceans gain net heat-energy when the sun is more active than average. This is confirmed by records of th ocean heat content anomaly, which has been rising since the sixties. At the same time, the sun was very active, with well above average sunspot numbers and lots of big solar flares and coronal mass ejections.
But the proponents of the co2 caused global warming hypothesis say the sun can't be responsible for the modern period of global warming because the solar cycles have been getting lower since the end of the fifties, while temperature has risen.
The thing is, it doesn't work like that. While it's true solar cycle peak amplitudes have fallen, the cycles have been short, a lot higher than average and with brief minima between. This means the sun has been kicking out more energy for more of the time than usual. Sami Solanki, head solar physicist of the Max Planck institute in Switzerland says the sun has ben at it's most active for 8000 years.
The result is, the oceans have absorbed and retained a lot of heat from the sun over the last fifty years. The heat being forced down into the deeps by tidal action, subducting currents of different relative saltiness, and meridional overturning caused by the changing declination of the Moon.
Now the sun has gone quiet since 2003, that heat is able to escape again, which it is doing, in El nino events. There was a similar situation in the late 1800's when the solar cycles got low for 30 years following an active period. Here comes the first graph, showing the sea surface temperatures then (red) and now (green), with the solar cycles than and now below:
So, big el nino's soon after solar minimum causing spikes in temp a decade apart as solar activity dropped. Big el nino's reduce ocean heat content, and se surface temperature falls afterwards. The air temperature follows a couple of months later. This is because the ocean drives the atmosphere, not the other way round.
You can see this clearly in the next graph (sorry Arapiles) of sea surface temp (green) against air temp (red). I've scaled the sst's by a factor of 1.7 so you can see the relationship clearly. Small changes in sea surface temp have a big effect on air temp because the specific heat capacity of water is so much bigger than that of air. There is as much energy in the top 2 meters of ocean as ther is in the entire atmosphere above it. This fact should give all thoughful climateers a clue as to the relative importance of trace gases in the atmosphere compared to the sun warmed ocean bulk.
I made a prediction last year that following the coming El Nino, temperatures would plummet to below the dec-jan 2008 anomaly. I still stand by that. If I turn out to be right, you'll know I'm onto something, and the clue will be that you'll spot Dean fingering his wallet nervously, Assuming he hasn't backed out of our $1000 dollar bet.
Finally (hurrah!), here's a plot I did last year to think about. It features a cumulative count of solar activity levels either side of the long term average whch matches the ocean equilibrium value. This mimics sea surface temperature and ocean heat content well. And so it should, since it is the cause of both of them.
You see that huge drop in sea surface temperature around 1940? That's what is coming up next.