|Graph 1: Ascending: The global temperatures of my life. (data source: GISS)|
In a few days, GISS will publish the final data for 2015. Once again, it'll be a new record. This time, by a wide margin. The data will be at http://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts+dSST.txt.
In October, the Global Land-Ocean Temperature Index crossed 1 full degree celsius above normal, for the first time ever. November became the 2nd month in a row above that mark, and December may well make it 3 consecutive. 2015 will also mark the 4th consecutive year of rising global temperatures; the last time that happened was 100 years ago. So far as I can determine, 5 in a row has never happened during the 135 years of record keeping.
As I noted last year, global warming has been consistent over the half century of my life. But warming is measured in increments we might consider "small." The GISS numbers are presented in hundredths of degrees celsius; the average yearly increment over the course of my life is barely one one hundredth of a degree. 2015 was fully a tenth of a degree warmer than 2014, which was already a year of record warmth. That's not really small.
Last year, I wrote: "2014's record warmth -- with no El Niño this time -- was as predictable as the sun rising in the East, and even cherry picked data points won't flatten the trend line anymore (note: with small data sets -- and 17 points is a relatively small set, one anomaly can throw the trend; just as having the start point in 1998 flattens things, so too would a single new "cold" year)."
That all changed, of course. El Niño returned in 2015, and the temperature records were shattered. Of course, once El Niño ends, we'll likely see a drop in global temperatures for a year or two -- just long enough for the deniers to come out of their foxholes again. In the meantime, even with 1998 picked as a startpoint, the trendline is no longer flat, nor even close to flat:
|Graph 2: Even starting with the El Niño of 1998, it's still getting warmer. (data source: GISS)|
|Graph 3: That local trend line is still down! (data source: Weather Underground)|
|Graph 4: Detroit temperatures, compared to normal, in 2015. The historically warm December helped locals forget about February. (data source: Weather Underground)|