2014 was a record warm year for the global temperature datasets maintained by the Americans: NOAA, GISS and BEST, as well as for the Japanese dataset. For HadCRUT from the UK it seems not to be clear which year will be highest.*
[UPDATE: data is now in: HadCRUT4 global temperature anomalies:
2014 0.56°C (Value from press release. The dataset itself states: 0.557°C, but this may still be a preliminary value.)
That is too close to call, the value to of 2014 could still change with new data coming in.]
The method of Cowtan and Way (C&W) is expected to see 2014 as the second warmest year.
(The method of C&W is currently seen as the most accurate method, at least for short-term trends; it makes recent temperature estimates more accurate using satellite tropospheric temperatures to fill the gaps between the temperature stations.)
Up to now I had always thought that you set a record when you get the largest or lowest value, whichever is hardest. The world record in marathon is the fastest time in an official race. The worlds best football player is the one getting most votes from sports journalists. And so on.
Climate change, however, has a special place in the heart of some Americans. These people do not see the question whether 2014 was a record in the datasets as an interesting question; the normal definition. Rather they claim, you are only allowed to call a year a record if you are sure that it was the highest value for the unknown actual global mean temperature. That is not the same.
Last September a new marathon world record was set in Berlin. Dennis Kimetto set the world record with a time of 2:02:57, while the number two of the same race, Emmanuel Mutai, set the world second best time with 2:03:13. Two records in one race! Clearly the conditions were ideal (the temperature, the wind, the flat track profile). Had other good runners participated in this race, they may well have been faster.
Should we call it a record? According to the traditional definition, Kimetto run fastest and has a record.
According to the new definition, we cannot be sure that Kimetto is really the fastest marathon runner on the world and we do not know what the world record is. Still newspapers around the world simply wrote about the record as if it were a fact.
When Cristiano Ronaldo was voted world footballer of the year 2014 with 37.66% of the votes, the BBC simply headlined: Cristiano Ronaldo wins Ballon d’Or over Lionel Messi & Manuel Neuer.
According to the traditional definition, Ronaldo is fairly seen as the best football player. According to the new definition, we cannot tell who the best football player is. He had such a small percentage of the votes, journalists clearly are error prone and they have a bias for forwards and against keepers.
In the sports cases it is clear that the probabilities are low, but hard to quantify them. In case of the global mean temperature we can and statistics is fun. All American groups were very active in communicating the probability that the global mean temperature itself was the highest in 2014. An interesting information quantum for the science nerd that may have put some people on the wrong foot.
@windbarb yes. Individual years are statistically close, but 2014 btw 1.5 and ~3 times likeliest to be warmest yr.— Gavin Schmidt (@ClimateOfGavin) January 18, 2015
And just for the funsies.
* Interesting, that Germany, France and China do not have their own global temperature datasets. Okay, Germany makes an effort not to look like a world power, but one would have expected France to have one. China is making a considerable effort in homogenization lately and has a large network already. I would not be surprised if they had their own global dataset soon, maybe using the raw data collection of the International Surface Temperature Initiative.
[UPDATE. I swear, I did not know, but Ronan Connolly pointed me to a new article on a Chinese global dataset. :) It integrates the long series of four other global datasets: CRUTEM3, GHCN-V3, GISSTMP and Berkeley.]
More informationA Deeper Look: 2014′s Warming Record and the Continued Trend Upwards
An informative article by Zeke Hausfather puts the 2014 record into perspective. The trend is important.
How ‘Warmest Ever’ Headlines and Debates Can Obscure What Matters About Climate Change
Andrew C. Revkin with a long piece with a similar opinion.
Thoughts on 2014 and ongoing temperature trends
The article by Gavin Schmidt at RealClimate is very informative, but more technical. For someone liking stats. He begins with some media critique: for the media a record is clearly an important hook. (They want news.)