The global temperature for 2020 was 0.88C equaling that in 2016 based on GHCN-V4C (homogenised) and HadSST3. The V4U (uncorrected) result is 0.82C for 2020 making it slightly cooler than 2016. These are based on the Spherical Triangulation technique described here.
Global temperature anomalies relative to a baseline 1961-1990, calculated using spherical triangulation.
December saw a large drop in global temperatures relative to November mainly due to a strong La Nina developing in the South Pacific.
December 2020 shows a strong La Nina
The monthly time series looks as follows.
Monthly temperature time series showing significant differences between raw and homogenised data since November 2018. 0.61C is the long term average since 2003.
Nick Stokes (TempLS) uses a similar algorithm but with a loess interpolation. It is interesting to compare his results to mine. I think he is using only the uncorrected V4U data combined with ERSST sea surface temperatures.
TempLS
| Nov 2020 | 0.891 | Ave 2016 | 0.857 |
| Dec 2020 | 0.628 | Ave 2020 | 0.852 |
| Diff | 0.263 | Diff | 0.005 |
My Uncorrected V4U/HadSST3
| Nov 2020 | 0.941 | Ave 2016 | 0.838 |
| Dec 2020 | 0.645 | Ave 2020 | 0.818 |
| Diff | 0.246 | Diff | 0.02 |
My Corrected V4C/HadSST3
| Nov 2020 | 0.960 | Ave 2016 | 0.880 |
| Dec 2020 | 0.655 | Ave 2020 | 0.887 |
| Diff | 0.305 | Diff | -0.003 |
There are some small systematic differences between the results, but we can draw the following conclusions.
- 2020 reached the same temperature as 2016.
- There was a significant drop in temperature in December due to a strong La Nina.
- Consequently 2021 should start cooler
Look what happens if the attention shifts to Corona panic. Global warming disappears.
Thanks for the report and excellent data presentation!
But I have to ask you about your comment on the drop in temperatures in Decemeber, you write: “December saw a large drop in global temperatures relative to November mainly due to a strong La Nina developing in the South Pacific.”
1) Is the current Nina a strong one? Judged by the the ONI index or the MEI2 values it corresponds more to a weak to moderate episode? The MEI 2 values the last 3 months are -1,2, -1,1 and -1.2
https://psl.noaa.gov/enso/mei/ , the most recentt ONI values are -0.9,-1.2,-1.3
2) The drop in temperature from November is most marked in the northern hemisphere and on land, especially in Russia/Kasakstahn/China (as commented by Nick Stokes (“The main very cool region was over Kazakhstan and parts of Russia nearby, with an extension over Mongolia and into China.” and similar by Roy Spencer: ” Cooling in December was largest over land, with 1-month drop of 0.60 deg. C, which is the 6th largest drop out of 504 months.”).
So is it likely or typical that a La Nina in an early phase predominantly will result in cooling of the land, and of the northern hemisphere? I would think that this effect would appear further out in time, and that the effect in december would be more pronounced in sea surface values and in the tropics and southern hemisphere?
Best regards T. Klemsdal, Oslo, Norway.
Thanks for the comments. Certainly Asia was very cold. We can probably judge best where December cooling occurred by looking at the full surface area.
Thanks again – nice illustration!
T. K.