Temperature Updates - October 2017, GISS

Here is my analysis of NASA's GISTEMP global temperature data for October 2017. All figures are for the Anomaly compared to the 1951 - 1980 base period.

One important note - all comparisons to previous months data and predictions are based on the current data. There are often minor changes to the data in the months following the first publication as more data is added or corrected. I always recalculate my predictions using the current published data, so it is possible the changes to my predictions will not reflect the exact predictions I made the previous month.

Data

The anomaly in October was 0.90°C, compared to 0.80°C in September. This is the second warmest October, although almost identical to last October's figure of 0.89°C. The last four Octobers have been the four warmest on record.

The rolling 12 month average rose by an insignificant amount, less than 0.001°C.

The average for the year is now 0.911°C, almost unchanged from the average up to September of 0.912°C.

Predictions

The prediction for 2017 is now for a final average of 0.904 ± 0.039°C. This is unchanged apart from greater confidence, from the prediction from September of 0.904 ± 0.054°C.

The probability of GISTEMP having it's second warmest year has increased to over 95%.

Probability of GISTEMP Rankings for 2017 - From Data to October.

Rank	Year	Anomaly	Probability	Change
1	2016	0.99	0.00%	-0.10%
2	2015	0.87	95.55%	+5.94%
3	2014	0.73	4.44%	-5.84%

Temperature Update - October 2017, RSS

The October data for RSS 4 has been released. As with UAH it's a record October.

Temperatures

October was 0.80 °C above the base period of 1979 - 1998. This is the warmest October on record, 0.08 °C warmer than the previous record set in 2015. As with UAH the three most recent Octobers have been the three warmest.

The anomaly for October was slightly down on that for September, but the cumulative year-to-date average continues to increase. It is now 0.643 °C, up from 0.625 °C in September.

Predictions

The projection for 2017 is now 0.621 ± 0.043 °C, compared with the forecast based on data up to September of 0.605 ± 0.060 °C.

RSS is looking quite likely to finish as the 2nd warmest year, with only about 3% chance of failing to beat current 2nd place of 1998.

Ranking Probabilities for RSS 4.0 - Based on Data to October

Rank	Year	Anomaly	Probability	Change
1	2016	0.74	0.00%	-0.00%
2	1998	0.58	96.91%	+17.31%
3	2010	0.56	2.55%	-9.01%
4	2015	0.54	0.52%	-6.58%
5	2005	0.42	0.03%	-1.72%

Temperature Update - October 2017, UAH 6

As always the first of the month's temperature updates is from the UAH Satellite data, reported by Dr Roy Spencer here. As with last month it's a surprisingly warm month.

The anomaly for October is reported as 0.63°C compared with the 1981 - 2010 base period. This makes it the warmest October in the UAH record, beating the previous record set in 2015 by 0.20°C. The three most recent Octobers have been the three warmest.

This means we are now seeing an unexpected uptick in the rolling 12 month average.

The year-to-date average is now 0.371°C, up from 0.342°C in September.

Predictions

My statistical prediction for 2017, with only two months to go, is 0.357 ± 0.043°C, compared with the prediction from September of 0.333 &pm& 0.058°C.

This rise in the predicted value for 2017 has had a dramatic effect on the ranking probabilities. Two months ago the prediction was below 2010, and it seemed most likely UAH would be the 4th warmest. Last month this had changed to a roughly even chance that 2017 would beat 2010 to finish 3rd. Now the odds on 2017 finishing 3rd have shot up, to over 86%. Intuitively this seems to high to me, as the last two months have been so anomalously warm, and one suspects some sort of correction is due, but for what it's worth here is the table showing the probability for each ranking.

Ranking Probabilities for UAH 6.0, Based on Data to October

Rank	Year	Anomaly	Probability	Change
1	2016	0.51	0.00%	-0.00%
2	1998	0.48	0.00%	-0.00%
3	2010	0.33	86.62%	+37.44%
4	2015	0.27	13.38%	-36.16%
5	2002	0.22	0.01%	-1.26%
6	2005	0.2	0.00%	-0.01%

Footnote

The fact that satellite data has been increasing whilst surface data has been decreasing, over the last couple of months, has been noted by Dr Spencer and Anthony Watts. Only a day before the latest UAH results were released Watt's Up With That were insisting global temperatures were cooling, based entirely on surface data from HadCRUT.

I've no idea why there is this apparent divergence. It maybe that the lower troposphere is gaining more heat than the surface, or it might be some error. If it is an error I suspect it will more likely be a problem with the satellite data than the surface data. But it is interesting seeing the so called skeptics, suddenly showing some much needed skepticism to the satellite data, and even emphasizing that satellites are not measuring the same thing as the surface data sets.