The Met Office Hadley Centre have released their HadCRUT4 data for December 2017. Here is my monthly update describing what that means for the year, and looking at how well my forecast models performed over the year.
Temperatures
The HadCRUT anomaly for December 2017 was 0.585°C compared with the 1961 - 1990 base period. This was the 6th warmest December in its record. Five of the warmest seven Decembers have occurred in the last five years. The other two where in 2003 and 2006, with the 2nd warmest being in 2006.
The mean anomaly for 2017 was 0.68°C, making 2017 the 3rd warmest year in the HadCRUT record. The last four years have been the four warmest on record.
Forecast analysis
My prediction for 2017 based on data up to November would have been 0.680 ± 0.026°C. The actual average for 2017 to 3 decimal places is 0.676°C.
This graph illustrates the changing predictions for each month, along with the 95% prediction interval.
This was not as good as for GISTEMP. For much of the year the forecast was around 0.05°C too warm. For HadCRUT the old model was better than the new, though the better confidence still suggests the newer model is better.
Final Thoughts
Both NOAA and BEST have also released their year end reports, with 2017 coming in respectively 3rd and 2nd warmest.
This means all of the main global temperature data sets, both surface and satellite, put 2017 as one of the three warmest years on record, with 2016 being the warmest. What makes 2017 unusual is that it was not an El Niño year.
But although the last few years have been extraordinary in terms of the global temperatures, they should not come as a surprise. They are not that unusual in relation to the trend seen since the 1970s. A few years ago there was a run of years below the trend, now we have had a run of years above the trend line. This is to be expected. But they should be a shock to anyone who used a few cooler years to claim global warming had stopped at the start of the century.
No comments:
Post a Comment