Gravity
Just stumbled on what may be "at the core" of this fuss about small surface temperature fluctuations on Planet E.
See the homepage of the Grace gravity satellites. It has a map showing deviation in the geoid, in August 2002, just after Tom and Jerry, their two satellites, went up, as compared to the data from the previous year from other sources.
See the second image at www.csr.utexas.edu/grace/publications/fact_sheet/3.html. Here it is:
, sorry. (Image credit: Paul Thompson / UT-CSR)
Compare that one with the one below. Again, unfortunately, the projections don't match, so you have to make some adjustments in your head, sorry.
(Image credit: Goddard Institute of Space Science)
There may be errors and I may have misunderstood the import, but the two maps show remarkable similarities in their respective biggest hotspots, for gravity and surface temperature changes. Keep in mind there is a huge data hole in the temperature map, west of the Antarctic Peninsula. Otherwise, the northern hemisphere anomaly highs have much the same shape even. If you run few more years, some bits fit better and some worse. Google http://data.giss.nasa.gov/gistemp/ then click on the global maps image and do your own maps, for whatever years you choose. I picked the five years before 2001. If you run the temperature map for the five years after the gravity measurements, there is not much similarity. I am assuming that, if this cycle is driven by mantle pluming, the heat moves ahead of the mass movement in time. Perhaps that is reasonable.
If the GRACE map was in fact generated from GPS data, and not from gravity data as the website says, surface heating may merely have caused the geoid to expand slightly, and this interesting but not highly significant. But if the change in the geoid was calculated directly from gravity measurements, then real lithic material has moved, I think it says, and that movement is directly linked, in its geographic expression, with where the surface of this planet is heating most.
If that gravity trend is ongoing, and their instruments are not somehow merely recording temperature because of some oversight, then we have the geoid thereafter bulging a few millimetres at the main temperature hotspots, but not from expansion of the surface lithology - it must be the result of the movement of real mass and probably, given the matching geomagnetic shifts, of very deep-seated changes.
My first guess is mantle pluming, but as the geomagnetic bulls eyes pretty much match the gravity and surface temp ones, and the mag changes, (if Jeremy Bloxham knows his stuff, and I think he does), originate at the core-mantle boundary, the source may well be there, down deep. It is perhaps being driven by heat released by crystallisation from the core, with the solidifying material raining "up," onto the bottom of the mantle. As that precipitation is perhaps in some way controlled by orbital irregularities, this may help explain the partial link to solar activity. The Milankovitch cycles are only at times in step with the glaciations, if our data is accurate. I have plotted the two, and some mesh, but some complete glaciations are totally out of synch. So we need another driver as well.
I think maybe this is it. Gravity changes say that mass is moving, and it's dense material, at that.
Take out the temperature hotspots around the Antarctic Peninsula and the big diffuse one that runs from Siberia into North America, and there is not much variation left for AGW to account for. Take out the urban and tractorland heating, and the lost forests, and there is even less.
If this turns out to be correct and a new observation, this may be where you read it first. I will see what the GRACE folk have to say. If they will reply.
PR, Closeburn, 20 October, 2008.