2014: Hottest Year on Record

We all know by now that 2014 will go down as the hottest year on record globally. It was already clear back in September that the planet was on track to reach the dubious milestone, and by mid-December, it was all but inevitable. Sure enough the Japanese Meteorological Agency, one of the four major global recordkeepers, last week declared 2014 as the hottest on record. NASA and NOAA will officially release their data on Friday and all signs point to the same conclusion.

So 2014 is the hottest yet — but what does that actually mean? It means 13 of the hottest years recorded since 1880 have happened in the past 15 years. Without global warming, you’d expect warm and cold years to happen randomly over that period. But the odds that this would happen without the additional CO2 humans have put into the atmosphere is incredibly low. How low? Try less than 1-in-27 million that they’d line up this way by chance.

So while it’s theoretically possible that we’ve gotten 13 of the warmest years over the past decade and a half just by chance, without global warming, is it likely? You do the math.

NOTE:

• To evaluate how unlikely it is that this many hot years has lined up in the past 15 years, Climate Central conducted a statistical analysis whereby the 135-year global record was reordered randomly to represent the absence of a long-term climate trend (using 2-year blocks). Under these conditions, the probability is 1 in 27 million.

• Since each organization has different data processing and calculation techniques, there could be slight differences in the specific numbers and yearly rankings. However, the overall trend is clear — that 2014 was at least one of the hottest years on record, if not the hottest, with the hottest of years all stacking up from 1998 on.