For the third straight year, the Earth was hotter than any other year in recorded history. It’s the second time that the Earth broke temperature records for three consecutive years. To put a finer point on the trend, 16 of 17 hottest years on record happened after 2000.

“A single warm year is something of a curiosity,” said Deke Arndt, chief of global climate monitoring for the National Oceanic and Atmospheric Administration, told The New York Times. “It’s really the trend, and the fact that we’re punching at the ceiling every year now, that is the real indicator that we’re undergoing big changes.”  

Global temperatures in 2015 and 2016 were intensified by a particularly strong El Niño storm, but long-term changes in atmospheric and environmental factors were the main forces behind the steady rise.  

"One could argue that about 75 percent of the warmth was due to human impact," Michael E. Mann, a climate scientist at Pennsylvania State University, told The Times. 

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Tens of billions of tons of greenhouse gases from human activities are emitted into the atmosphere each year, where they trap heat from the sun. While global emissions levels are slowing, they have been rising ever since the modern era of global warming began in the 1970s. A lot of these emissions, especially carbon, and the ensuing heat is absorbed by the world’s oceans, which then warm up, causing the world’s ice to melt.   

2016 culminated a remarkable 3-year streak of record warm years for the globe says @NOAANCEIclimatehttps://t.co/5sDkZyODpI#StateOfClimatepic.twitter.com/7O54sWd3Dz

— NOAA (@NOAA) January 18, 2017

As the world’s ice melts, less cold air is spread throughout the atmosphere, causing more ice to melt, and so on in a runaway feedback loop.
The starkest temperature change is happening in the Arctic, where ice is vanishing at a staggering rate. For stretches in 2016, temperatures in the region were more than 30 degrees hotter than normal.

Read More: Arctic Continues to Break Records — For All the Wrong Reasons

In the years ahead, scientists expect these increases to continue. After all, emissions are continuing to rise, and fossil fuels are still dominant.

But for the Paris climate agreement’s stated goal to be achieved — keeping global temperatures from going above 2 degrees Celsius from pre-industrial levels — then governments around the world have to substantially up their climate commitments.

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However, since climate change takes place on a delayed scale — today’s emissions will be felt in the coming decades — it’s hard to tell if this goal is still possible.