Temperature Update - January 2018, the Satellites

This post starts my ongoing monthly summaries of global temperature anomalies from different data sets. In this I'll look at the two main satellite data sets - UAH 6, and RSS 4.

The anomalies (relative to their respective base periods) for January 2018 are

• UAH 6: +0.26°C (Relative to 1981 - 2010)
• RSS 4: +0.546°C (Relative to 1979 - 1998)

Translating RSS to the UAH base period would give RSS an anomaly of +0.401°C. Both are cooler than December 2017 - UAH down 0.15°C, RSS down 0.044°C.

In the UAH set January 2018 is the 10th warmest January. In the RSS set it is the 7th warmest.

These graphs show the monthly data across the satellite era, along with the trend and the 12 month moving average. January 2018 is highlighted in red.

In both cases Janury 2018 is very close to the long term.

Forecasts

Using my simple statistical model, the predictions for 2018 are that UAH will have an annual anomaly of 0.256 ±0.185°C, and that RSS will have an anomaly of 0.551 ± 0.167°C.

Note that in both cases the most likely prediction for 2018 is very close to the values for January. This is to be expected given the the fact that January was very average. But of course the uncertainty is large.

Predicting a specific ranking is probably foolish at this point, but both sets are looking to finish close to the current 5th warmest year of 2015. UAH has around a 55% chance of finishing below 2015 and 45% above, whilst RSS has more or less equal chances of finishing above or below 2015.

If UAH finishes below 5th place, it could end up just about anywhere as there are a lot of years with very similar values. It's unlikly to finish 1st or 2nd but there is around a 1 in 5 chance of UAH finishing 3rd or 4th.

For RSS there's a prety good chance (~40%) that it will finish between 2005 and 2015 for 6th place (owing to the big gap between the two), but only a slim chance (less than 10%) that it will finish below 6th. Though if it does it could finish just about anywhere. It has about a 1 in 7 chance of finishing 2nd.

As always these probabilities are based solely on past statistical inference and do not factor in the probability of a La Niña this year.

One Last Thing

As there will likely be a lot of talk of a returning pause as the next La Niña takes hold, it's worth seeing where we are in comparison to the previous powerful El Niño of 1998. (What am I saying? There have been talk of a return of a pause since 2016.) Anyway, this graph compares the 5 years surrounding 1998, with those surrounding 2016.

UAH 6 shows the least warming since 1998. But even with that data set, whilst the peaks of the two El Niños are similar, the years before and after have been considerably warmer.