Predictions for 2017 - RSS 4 August Update

The Temperature in August

This post is part of my ongoing global temperature analysis and prediction series for 2017. RSS have now released the figures for August and it was another warm month. At 0.71°C, it was the warmest August in the RSS 4 record, and the warmest monthly anomaly since September 2016. (Incidentally, the old RSS 3.3 version of the data has August at 0.55°C, making it the second warmest August in that data set, only beaten by August 1998 at 0.57°C.)

Here's the entire RSS 4 series, with 12 month rolling average.

RSS 4 TLT Anomalies in °C compared with 1981 - 2010 base period.
Blue - linear trend.
Red - 12 month moving average.

The trend since the start in 1979 is currently 1.85 °C / Century.

Updated Forecast for 2017

The average anomaly for the year 2017 up to August is 0.60°C, compared to 0.58°C for July. My forecast for 2017 is 0.58 ± 0.07°C, compared to last month's forecast of 0.57 ± 0.08°C.

Annual temperatures for RSS 4, and forecast for 2017 based on data up to August 2017.

This slight increase edges the forecast ahead of 1998. This means that there is now a better than 50% chance of 2017 being the second warmest year in the RSS 4 data set.

This table lists the probability of 2017 finishing in each position:

Rank	Year	Anomaly	Probability	Change
1st	2016	0.74 °C	0.0%	+0.0%
2nd	1998	0.58 °C	55.2%	+13.6%
3rd	2010	0.56 °C	20.6%	+0.8%
4th	2015	0.54 °C	15.4%	-4.2%
5th	2005	0.42 °C	8.8%	-10.2%
6th	2014	0.41 °C	0.0%	+0.0%

2017 is most likely to finish in 2nd place, but there is a reasonable chance that it could finish as low as 5th.

Citations

Analysis for this blog post used R.

R Core Team (2015). R: A language and environment for statistical computing.
R Foundation for Statistical Computing, Vienna, Austria. URL
https://www.R-project.org/.

Graphics produced with the GGPlot package

H. Wickham. ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag New York, 2009.