By global temperature, this October was the second-hottest October on record, according to a report from NOAA’s National Centers for Environmental Information. And by their Global Annual Temperature Rankings Outlook, 2019 will probably be the second hottest year on record.

2016 is currently the hottest year on record since recording started in 1880, Scientific American reports. That was a strong year for El Niño, which is unusually hot weather over the Pacific that affects global climate. The fact that 2019 is approaching 2016’s global temperatures is worrisome, given that 2019 had a weak El Niño effect that ended in July.

“The near-record warmth of 2019 is thus a testament to how greatly human-caused global warming is impacting the planet,” Jeff Masters, an extreme weather expert, writes for Scientific American. It also means that the last six years, from 2014 to 2019, will be the hottest six years since recording started in 1880.

Solar activity, which has an 11-year high-to-low oscillating cycle, can also affect global temperatures. But this year was at the minimum of the cycle, so solar activity is likely not to blame. Many specific regions, including Southeast Asia, southern Africa, and Australia, are expecting to measure their hottest year on record.

“The last time we had a below-average temperature in October was in October 1976,” Ahira Sánchez-Lugo, a climatologist at NCEI and author of the agency’s newly released climate report, told NBC News. “We’ve been on an upward swing since then.”