At Midway Point, 2017 Is 2nd-Hottest Year on Record
At the halfway point of the year, 2017 remains the second-hottest year to date — a surprise given the demise of the El Niño that helped boost temperatures to record levels last year.
The continued near-record warmth is a marker of just how much global temperatures have risen thanks to the greenhouse gases accumulating in the atmosphere from fossil fuel use.
“Personally, I wasn't expecting it to be as warm as it has been,” Ahira Sanchez-Lugo, a National Oceanic and Atmospheric Administration climate scientist, said in an email. “After the decline of the strong El Niño I was expecting the values to drop a bit and rank among the top five warmest years. This year has been extremely remarkable.”
The odds are good that 2017 will stay in second place through the end of the year, and it is even more likely that it will remain in at least the top three hottest years.
Wherever its final rank ends up, 2017 will almost certainly be hot enough to knock 1998 — the only remaining 20th century year among the top 10 warmest — down another spot, to No. 9 in NOAA’s rankings.
At the time, 1998’s heat was exceptional, and was fueled in part by a major El Niño, which tends to raise global temperatures. But as Earth’s temperature has steadily risen because of heat-trapping greenhouse gases, an El Niño isn’t necessary to reach those heights anymore.
In fact, years with La Niñas (which tend to cool global temperatures) are today warmer than El Niño years several decades ago. 2017 actually started out with a La Niña, albeit a weak one, but it is 0.38°F (0.21°C) ahead of 1998, Sanchez-Lugo, said.
If the streak of very warm years continues, “I wouldn't be surprised if the next two to three years we would see '98 drop out of the top 10 warmest years on record,” she said.