Worldwide, 2016 was the hottest year on record according to reports released today by NASA and the National Oceanographic and Atmospheric Administration (NOAA). The 2016 temps best a record previously set during that comparatively balmy epoch known as 2015, which itself trounced a record set in 2014. If we were talking music charts instead of climate, there'd be little dispute that this constitutes a trend.
“This is the third year in a row in our analysis to set a new [heat] record,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies. “This has only happened once before in 1939-1941.” Those years no longer rank amongst the Earth’s top 30 warmest years.
Eleven out of the 12 warmest years on record occurred after 2000. If you were born after 1979, you've never actually experienced a year of "normal" temperatures.
According to NOAA, the average temperature across global land and ocean surfaces in 2016 was 58.69 degrees Fahrenheit—1.69 degrees warmer than the 20th century average. NASA's analysis found that the Arctic was warming two to three times faster than the rest of the world, which is of little surprise to those who noted that during this year's annual Iditarod dogsled competition in Alaska organizers had to haul in snow by train. In 2015, warm weather moved the Iditarod's start north from Willow, Alaska to Nome. That's just the second time the race has been moved in its 44-year history. The other relocation incident—also due to warm weather—occurred in 2003.
Further south, the Northeastern United States baked through summer heatwaves. But it was southern cities like Montgomery, Alabama, Shreveport, Louisiana and Atlanta, Georgia that racked up the most record highs. Scientists predict that the southeast will just keep getting hotter and drier as climate change continues.
Last year’s temperature increase was exacerbated by the fact that it was an El Nino year; El Nino years tend to be warmer while La Nina years tend to be cooler. But, warns Schmidt, El Nino is just boosting the underlying warming signal—like attaching a mic to a screaming baby—not creating the warming pattern.
“You can statistically try and remove the impact of El Nino on the annual mean temperatures,” said Schmidt. And in 2015—another El Nino year—NASA did just that, uncovering an El Nino-induced temperature boost of about .12 degrees Celsius. “For 2016, the modern trend [of global warming] is contributing 90% of the signal and El Nino about 10% of the signal," Schmidt said. "We’re only seeing the records because of the effect of the greenhouse gas.”
“I think for those in the climate community this is not a big surprise,” said John Reilly, the co-director of the Massachusetts Institute of Technology (MIT) Joint Program on the Science and Policy of Global Change. “We’ve been watching the temperature average month by month and it was pretty clear even three or four months ago that we were in line to have another record or close-to-record year.”
There may be a silver lining to this troubling superlative: it could help kill the idea of a so-called "warming hiatus"—put forth by those who think that climate change is a hoax—for good. The use of El Nino data as a baseline has helped climate deniers gain traction with the idea. By comparing record-breaking years to other El Nino years instead of truly "average" years, the anti-science crowd can make the warming records seem less profound than they actually are.
But NOAA noted that despite the influence of a weak La Nina towards the end of the year—which should have cooled things down—2016 ended with the third warmest December on global record. And things are warming up even when you just compare El Nino years to one another.
“We can see that the El Nino periods are getting warmer, the La Nina periods are getting warmer and the neutral periods are getting warmer as well,” said Derek Arndt Chief, Monitoring Branch, NOAA’s National Centers for Environmental Information.
What about discrepancies within the models themselves? For example, NASA's data shows 2016 as being slightly warmer than NOAA's. The discrepancy exists because NOAA relies mainly on instrument data from the Arctic, which is relatively scarce due to its isolated location, while NASA extrapolates data over the region to estimate arctic warming. But both data sets show the same overall trend—the earth is warming—and both indicate that 2016 is the hottest year on record.
“If you're in a movie theater and one person says they smell smoke on the left and the other person says they smell smoke on the right, do you say you don't believe there's a fire,” said Reilly.