RealClimate did a brief post about the latest global temperature data, just released. A reader comment says, “I think it would be a good idea to publish graphs with the influence of El Nino, etc, removed, if this is possible.”
Happy to oblige.
Here’s the original graph comparing many data sets, from the RealClimate post:
They’ve set all data sets to a common baseline: 1979 through 1988. It’s an uncommon choice, but makes sense for two reasons. First, satellite data sets don’t even start until 1979; second, by aligning them to the first 10 years of the satellite era we get a clearer picture of how the various data sets have diverged since then.
In response to the reader comment, Gavin posted an adjusted set for NASA GISS data:
It accounts for el Niño, but doesn’t remove the influence of volcanic eruptions or solar variations. Also, I think my method of accounting for el Niño is better (but I certainly haven’t proved that). In any case, I applied my adjustment method (an improved version of Foster & Rahmstorf). I also included two additional data sets: those from NOAA (National Oceanic and Atmospheric Administration) and HadCRU (Hadley Centre/Climate Research Unit in the U.K.). I don’t have December 2017 data for all of the data sets yet, so those are only based on 11 months out of last year, but I reckon that’ll be enough to inform but not mislead. Here are the adjusted data (annual averages, 1979 through 2017):
Two interesting facts become clear. First, the hottest year on record after removing the influence of fluctuation factors was 2017, in all seven data sets. Second, the “odd man out” is clearly the data from UAH.
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