Part 3 of our series on the new Clintel Report on the new IPCC Report looks at Andy May’s chapter on surface temperature data. He poses the question of whether the data are precise enough or accurate enough to identify changes on the small scale the IPCC is talking about. Answer: no, especially once you understand how the big graphs get put together.
May begins by pointing out that the Northern Hemisphere warms by 13 degrees C every year from winter to summer, while the Southern Hemisphere warms by 6 degrees C from winter to summer, and since these cycles are out of phase the globe as a whole warms by about 3 degrees C over the year. Someone living in either hemisphere experiences an average temperature swing much larger than the 1 degree C change supposedly experienced since the mid-1800s. But that warming estimate comes from the surface temperature network which has many problems especially when it comes to coverage of the oceans.
There is a lot of guesswork involved in filling the gaps, and as we have noted here at CDN, somehow all the adjustments warm the present and cool the past so the trends come out higher. May points out that the big warming period in the record starts after 1980 when the data should be the best quality, yet from one edition of the famous Hadley Centre series to another, it’s the post-1980 part of the record that gets the biggest trend boost.
He then discusses the IPCC’s desire to move away from using sea surface temperature records (i.e. water temperature) and instead switch to air temperatures from above the sea surface, which would make more sense since the land record is an air temperature measure. But there isn’t enough data so the IPCC has to resort to sparse samples and computer simulations.
There were earlier studies using marine buoys that found water temperature and air temperatures above the water tend not to be correlated so it is anyone’s guess whether the sea surface trend and the marine air temperature trends line up. At a certain point, May explains, the IPCC gave up trying to work out the details and just declared the trends to be the same, and on they went.
Finally May points out that there is a basic check on the validity of the surface thermometer data provided by the satellite record. Climate models say that the troposphere above the surface should be warming faster than the air at the surface. But the IPCC surface data is warming faster than the satellite record. This is a strong hint that the recent trends at the surface, after all the kludges and tweaks, have too much warming in them. It’s man-made climate change, just not the kind the experts keep telling us to worry about.