Alright, you caught me. That headline is a bit misleading. 2015 was just the warmest year in the 136-year period since we started keeping temperature records. In the interest of total honesty, the headline should have been, “2015 the Hottest Year Since the First Boer War,” or “2015 the Hottest Year Since the Hayes Administration,” or “2015 the Hottest Year Since Commercial Electricity Was a Thing.”
I apologize if that wasn’t clear.
Scientists Called This One Early
The National Oceanic and Atmospheric Administration (NOAA) made the official announcement on Tuesday, but NOAA scientists were predicting as early as September that 2015 would break the record set just last year for global average temperature. After calculating 10,000 different August-December values, they estimated it was 97 percent certain that 2015 would be a warm one. And they were right.
Of course, unofficial predictions date back even earlier. In March, meteorologist Eric Holthaus wrote that the one-two punch of El Niño and the Pacific Decadal Oscillation would significantly “increase the odds that 2015 will rank as the warmest year on record globally.” And he was right.
But 2015 didn’t just break previous years’ temperature records, it set those figures on fire and pissed all over the ashes. I’ll try not to get too technical as I explain why.
First off, average temperature across global land and ocean surfaces in 2015 was 1.62°F (0.90°C) above the 20th century average. In all the years between 1880 and 2015, that was the highest it’s ever been recorded (higher than last year by 0.29°F, or 0.16°C), and the largest margin by which an annual global temperature record has been broken. Furthermore, 10––count ‘em––10 months had record high temperatures for their respective months last year. Five of those months had the highest departures from average for any month, ever.
February, March, May, June, July, August, September, October, November and December all reached record warm in 2015. January and April only missed out because they were the second and third warmest for their months respectively.
Yeah, but It’s All El Niño’s Fault, Right?
El Niño has definitely had an impact on this year’s temperatures. According to NOAA, the warmth in 2015 was due to the “near-record strong El Niño” in the Northern Hemisphere that developed in spring and to the “large regions of record warm and much warmer-than-average sea surface temperatures in parts of every major ocean basin.”
So yes, “The Boy” did a lot of the heavy lifting this year, but so did record warmth in the global oceans (ocean warming is now proceeding at such a rate that it is “breaking scientists’ charts”). And if we step back a bit, we see that 2015 serves as just one more proof that planetary warming is trending ever upward. Take a gander at this graph from the Japan Meteorological Agency:
What does this mean in layman’s terms? It means there have been 39 consecutive years since 1977 that annual temperature has been above the 20th century average. It means that 15 of the 16 warmest years on record have all occurred in the 21st century (and it hasn’t been a long century). It means it’s time for another graph, because I’m tired of writing the same thing over and over again. This one’s from NOAA’s annual Global Analysis:
That’s pretty cut and dry, but I’ll toss you one more fact to chew on before I go: The Earth has not experienced a record cold year since 1909. That was 107 years ago.