2016 was the hottest year ever recorded, smashing records set in 2014 and 2015. This marks the third consecutive year of record-breaking heat, a first in the modern era. 2016 is the hottest year on record by a wide margin, 1.69 F (0.94 C) warmer than the 20th century average.

Deke Arndt, chief of global climate monitoring at the National Oceanic and Atmospheric Administration (NOAA), said of the announcement, "The fact that we're punching at the ceiling every year now, that is the real indicator that we're undergoing big changes."

Including last year, 15 of the hottest 16 years on record have occurred since 2001, according to NOAA. The only year from the 20th century to break into the top 16 is 1998 and that year ranks 7th.

"For the first time in recorded history, we have now had three consecutive record-warm years for both the globe and the Northern Hemisphere," Dr. Michael Mann, director of the Earth Science Center at Pennsylvania State University, said.

"The likelihood of this having happened in the absence of human-caused global warming is minimal. As we have shown in previously published work the spate of record-warm years that we have seen in the 21st century can only be explained by human-caused climate change. The effect of human activity on our climate is no longer subtle. It's plain as day, as are the impacts—in the form of record floods, droughts, superstorms and wildfires—that it is having on us and our planet."

This announcement coincides with Scott Pruitt's U.S. Environmental Protection Agency confirmation hearing and comes just two days before Donald Trump takes office. Trump has called climate change a "hoax" and pledged to dismantle U.S. climate regulations.

"No part of the world can now avoid the fact that climate change is striking harder and faster than many scientists predicted, and that its impacts are taking a higher toll on the most vulnerable communities," 350.org climate impacts program coordinator Aaron Packard said. "As important as marking that the record is yet again broken, we need to loudly mark what needs to be done to hold back such destruction: we need to keep fossil fuels in the ground.

"Decades of progress from scientists and engineers has made renewable energy the cheapest and cleanest source of energy in the world, creating the technological momentum that is matched by the millions of people in all parts of the world demanding climate action."