What are the odds that 2015 will not be the hottest year on record?
Let me be upfront with you: I think it's a foregone conclusion that 2015 will beat out 2014 as the hottest year on record. However, I decided to test that idea, just to be certain. The way I did it was simple: I first calculated the year-to-date average (January - July) and then calculated what the August — December average would have to be to keep the 2015 average temperature at or below that of 2014. I then calculated the August — December average for each year since 1970, fitted a trend, and calculated the standard deviation of the residuals. Last, I calculated the expected August - December average for 2015 given the trend and the difference between the expected August - December average and what that average would have to be to keep 2015 from setting a new record. I then used z-scores to calculate the probability that the remainder of 2015 would fall to that level or below. Annual global temperature according to NASA GISS since 1970 Year to date, 2015 sits at +0.82