Driven by record warmth in the oceans and a sequence of toasty months, the estimated global surface temperature for 2016 was the warmest on record, the National Centers for Environmental Information said Wednesday.
For the year, the average temperature was 1.69 degrees Fahrenheit above the 20th Century average in the federal database, which goes back to 1880.
NASA, which keeps a separate temperature set, also reported that last year was its warmest by a similar margin.
In the NCEI report, 2016 nosed out the new No. 2, 2015, by a mere 0.07 degrees Fahrenheit, with a margin of error of plus or minus 0.27 degrees.
The announcement was hardly a surprise, despite a slight cool-down at the end. For the year, seven of the first eight months set records, NCEI said.
The intense El Nino warming in the tropical Pacific, in which surface temperatures across a continent-size patch of the ocean were abnormally high, was a major contributor.
El Nino faded in the spring, ultimately yielding to a weak version of its opposite, a La Nina cooling.
No land masses were cooler than average, NCEI said.
We remind our readers that taking the planet’s temperature is an immense undertaking; thus the margins of error.
Earth’s surface is a splendidly diverse place with mountain ranges alternating with valleys and grand plains; jungled rain forests and ice sheets; great lakes and deserts, and, of course, the oceans, which are hardly placid.
Over 180 countries contribute to the monthly databases, not all of them reporting in a diligent and timely fashion, and that’s why the reports contain a margin of error, usually in the vicinity of 0.25 degrees Fahrenheit.
From 2,000 to 2,500 land stations file reports, says Deke Arndt, chief of the monitoring branch at NCEI, and "many more" come from ships and buoys. but they aren’t evenly distributed.
The Earth is imprecisely observed, and that’s a big reason why computer models have so much trouble precisely predicting short-term weather.
However, he notes that the major global databases all agree on the fundamental point: the Earth is getting warmer.
"It's not 2016's relationship with 2015 that matters," Arndt said Wednesday night, "2015 was a really warm year too."
"It's 2016's relationship with the longer time series that matters, and it was more than 1.5F warmer than the 20th century.
"Over land areas, where people live, it was more than 2.5F warmer than the 20th century average.
"That's significant. As a thought experiment, think about turning your thermostat up 2-3 degrees, permanently."