2016 was the hottest year yet, scientists declare

Last year, global warming reached record high temperatures -- and if that news feels like deja vu, you're not going crazy.

The planet has now had three consecutive years of record-breaking heat.

The National Oceanic and Atmospheric Administration has just released its annual State of the Climate report, which says it hasn't been this hot since scientists started tracking global temperatures in 1880.

A separate analysis, by NASA scientists, came to the same conclusion.

The news comes as a confirmation hearing begins for Oklahoma Attorney General Scott Pruitt, who has been nominated to head the Environmental Protection Agency. Pruitt has ardently defended fossil fuels and fought against federal efforts to regulate greenhouse gases that warm the planet.

President-elect Donald Trump has professed open-mindedness about climate change. Still, he once called it a hoax, and scientists have been worried by his picks for his transition team and administration, as well as by the questions asked about climate scientists at the Department of Energy.

As the politics swirls around them, climate scientists keep churning out data.

"[Last year] was the warmest year on record, beating 2015 by a few hundredths of a degree, and together those two years really blow away the rest of our record," says Deke Arndt, chief of the monitoring group at NOAA's National Centers for Environmental Information in Asheville, N.C.

He says 2016 was about 1.7 degrees Fahrenheit above the global average for the 20th century. "And that doesn't sound like a lot, but when you take that and you average it all the way around the planet, that's a big number," Arndt says.

The warming was truly global. "Some part of every continent, and some part of every major ocean basin was warmest on record," Arndt says, adding that in the United States, only Georgia and Alaska had record-setting warmth but "pretty much the entire country was above normal, and well above normal."

This represents long-term warming along with the short-term effects of the El Nino weather phenomenon, he explains, predicting that the streak of breaking records will probably end this year as those El Nino effects dissipate. But the long-term warming trend should continue to go up and, Arndt says, threatens new records almost every year.

"The long-term warming is driven almost entirely by greenhouse gases," Arndt says. "We've seen a warming trend related to greenhouse gases for four, five, six decades now."