Temperature Update - April 2018, RSS

The RSS satellite global temperature for April 2018 shows a slight drop on March. Compared to UAH satellite data, there has been slightly more movement in RSS data, with a range of around 0.1°C compared with UAH's 0.05°C, but overall the picture is very similar so far, with temperatures being slightly below the long term trend, but no sign of the big reversion seen after the 1998 El Niño.

Details

RSS has April 2018 at 0.45°C above the 1979-1998 base period, compared to 0.54°C for March. This makes 2018 the 6th warmest April in the RSS data set.

The trend since 1979 is 1.93°C / century.

In contrast to the UAH satellite data, RSS is the fastest warming of all data sets over the satellite era.

Prediction

The prediction for 2018 shows a slight drop from last month. My simple statistical analysis suggests 2018 will average 0.527 ± 0.118°C, compared with last month's prediction of 0.541 ± 0.136°C.

The average for the first 4 months is 0.506°C, so this will require warmer temperatures to develop later in the year. As with other data sets this prediction is based mainly on the assumption that temperatures will tend towards the trend, not on any specific predictions of weather conditions.

On this basis, there is a good chance (~60%) that 2018 will be the 6th warmest on record. There's a small chance (~7%) that it will finish below 6th, though if it does it could fall someway down the rankings. There's a reasonable chance (~30%) that it could be 5th or better, though almost certainly not 1st.

RSS 4.0 Probabilities of Rankings for 2018

Rank	Year	Anomaly	Probability	Cumulative
1	2016	0.75	0.02%	0.02%
2	2017	0.64	3.11%	3.13%
3	2010	0.58	14.88%	18.01%
4	1998	0.58	0.21%	18.23%
5	2015	0.55	13.61%	31.83%
6	2005	0.43	61.93%	93.77%
7	2014	0.43	1.02%	94.79%
8	2003	0.39	3.95%	98.74%
Below 8th	n/a	n/a	1.26%	100.00%

Closing Thoughts

Both satellite data sets are predicting 2018 will probably be around 6th warmest, whereas surface data sets are tending towards 4th warmest. The difference between the two is mostly to do with the satellite data showing 1998 and 2010 as being much warmer than in the surface sets. In terms of recent history, all data sets are suggesting similar things, that the past 4 years have all been pretty hot, and this is very different to the previous El Niño peaks, that only lasted for a single year.

All this suggests we are not likely to see the return of the old Great Pause any time soon, and probably ever. If warming did stop in 1997 it's certainly going again, and had no effect on the long term trend. It's easy to predict what happens next, and this can be seen in many discussions I've had on WUWT.

1. The claim of a new pause, starting just before the latest El Niño. Last time we had to wait seven years before claims that there had been no warming since 1997, or even that there had been rapid cooling, but now I'm already seeing claims based on the last two years.

2. Some, such as Lord Monckton, will deny they ever thought the pause was important and will insist that the real point is that temperatures may not warm as much as expected, and that warming is a good thing.