We now have all the data for 2017 from all surface data sets, but I'll stick to the schedule of a single post for each set I'm tracking. So this post will look at GISTEMP and there will be another looking at HadCRUT. (And at some point I might get back to writing proper debunking posts.)
2017 from NASA
NASA's GISTEMP for December 2017 has been announced with a press release. This shows to little surprise that 2017 was the second warmest year in their data set, and also mentions that NOAA has it as 3rd warmest. They also remind us that individual rankings of years are not that important, and the main message is that the long term trend is continuing.
December
The GISTEMP anomaly for December was 0.89°C, compared to the 1951-1980 base period. This makes it the 2nd warmest December on record, with the last 4 years having the 4 warmest Decembers.
The mean anomaly for the year was 0.9°C, making 2017 the second warmest year in the GISTEMP record. The last 4 years have been the 4 warmest on record.
Forecasts
Note - as always references to previous forecasts are based on recalculations using the latest data. They may differ slightly to the published forecasts.
Based on data up to November I predicted that 2017 would be 0.892 ± 0.025°C. The actual result was 0.897°C. A difference of 0.005°C.
Here's how the forecast would have changed each month, compared to the actual annual value.
I'd say the GISTEMP forecasts were pretty successful. They were always within 0.03°C of the actual annual figure. For comparison, in March the average of the first three months was 1.067°C, my forecast would have been 0.915°C.
This graph compares the new and old models.
For most of the year the old model was better than the new. After August there was little to choose between the two. More importantly the confidence was much higher throughout.
As with the satellite data this should not be taken as too much evidence that the newer model is better. As we will see the results are quite different for HadCRUT.
No comments:
Post a Comment