There have been a number of interesting recent posts elsewhere about satellite temperature. Most of this has been motivated by claims that the satellite data is the best data that we have and that it should play some kind of pivotal role on our assessment of anthropogenic global warming (AGW). Even if the satellite data was excellent, this would be an odd thing to suggest given that it’s only measuring one part of the system; the troposphere. We really should be considering all the evidence, not simply one dataset associated with a small part of the climate system.
However, even those who work with satellite data regard it as less reliable that the surface temperature datasets. As Carl Mears says:
A similar, but stronger case can be made using surface temperature datasets, which I consider to be more reliable than satellite datasets (they certainly agree with each other better than the various satellite datasets do!).
This doesn’t mean that it should be dismissed, but does suggest that claims that it’s the best data we have are unjusitified.
Kevin Cowtan also has a very nice article that compares satellite datasets and surface temperature datasets. It essentially shows that the uncertainty in the satellite data is quite a bit greater than that in the surface data, and concludes that
on the basis of the best understanding of the record providers themselves, the surface temperature record appears to be the better source of trend information. The satellite record is valuable for its uniform geographical coverage and ability to measure different levels in the atmosphere, but it is not our best source of data concerning temperature change at the surface.
The latter seems pretty obvious, given that the satellite measurement are used to estimate temperatures in the atmosphere, not the surface.
Peter Sinclair has also produced a very nice video about the satellite data. I’ve included it below, but it discusses how actually determining temperatures from the measurements requires a model, points out that there have been a number of well-documented errors that have had to be corrected (typically changing the trend), and that really we should consider all the data when trying to assess AGW. It also points out, quite rightly, that it’s odd that those who regularly criticise adjustments to surface datasets, ignore not only that satellite data requires a great deal of model-based analysis, but has a history of corrections that make substantial changes to the trend.
Some people are not very happy with the video. John Christy is accusing those involved of smearing him. As far as I can tell, everything in the video is true, even if it does reflect poorly on some. On the other hand, he appears to have said this to James Delingpole, someone who has made a career out of smearing climate scientists. It’s hard to take John Christy’s concerns all the seriously, given that it’s being reported by someone with James Delingpole’s history.
At the end of the day, we should consider all the evidence, satellite too. However, we should also be aware of the complexities involved in analysing these datasets. No single dataset will be perfect, and no single dataset will be completely useless.