Delegates to a United Nations climate conference on Saturday committed 195 nations to substantially reducing their greenhouse gas emissions in order to stifle rising global temperatures.
The accord, reached after two weeks of talks at the conference in Paris, stipulates that countries set individual emissions targets every five years beginning in 2020.
Developed nations would set stricter limits, while developing nations would be expected to ease emissions growth and adjust their goals as circumstances warrant.
Proponents hope that the targets would be increased in five-year increments as renewable energy becomes more prevalent.
The deal also establishes disclosure requirements and calls for wealthier nations to provide funding to help poorer nations reduce their emissions and cope with the effects of climate change.
Ultimately, the proposal aims to cap the global rise in temperatures at 1.5 degree Celsius and to eventually achieve zero emissions — ensuring that man-made emissions can be absorbed by the planet.
World leaders promptly characterized the conference as a landmark diplomatic achievement that included all nations in discussions about climate change for the first time.
“This is truly a historic moment,” UN Secretary General Ban Ki-moon told The New York Times. “For the first time, we have a truly universal agreement on climate change, one of the most crucial problems on earth.”
Achieving its goals, however, will prove to be extremely difficult.
Global temperatures increased by about 1 degree Celsius since the dawn of the Industrial Revolution, and experts said curbing the overall increase at 1.5 degrees could already be impossible.
The deal also would not impose penalties on nations that fail to meet their emissions standards, and the economic cost of eliminating more than 7 billion tons of carbon production could be staggering.
"The problem is not solved because of this accord," President Obama said following the deal. "But make no mistake, the Paris agreement establishes the enduring framework the world needs to solve the climate crisis."
Republicans on the campaign trail and in Congress, however, largely dismissed it.
“The president is making promises he can’t keep, writing checks he can’t cash and stepping over the middle class to take credit for an agreement that is subject to being shredded in 13 months,” said Senate Majority Leader Mitch McConnell, R-Kentucky.