But in June this year, Obama's successor, Donald Trump, announced that America would pull out of the agreement, which he said imposed "draconian financial and economic burdens" on the United States.
The US can only withdraw four years after the deal officially entered into force in November 2016, which means November 2020 — two months before Trump's term ends.
The hard-fought pact commits countries to limiting average global warming to under two degrees Celsius (3.6 degrees Fahrenheit) over Industrial Revolution levels, and 1.5 C if possible, to avert calamitous climate change-induced storms, drought and sea-level rise.
To bolster the agreement, nations submitted voluntary commitments to curb greenhouse gas emissions from burning coal, oil and natural gas.
But the 1 C mark has already been passed, and scientists say that on current country pledges, the world is headed for a 3 C warmer future, or more.
Many fear that America's exit from the agreement will make the 2 C goal that much harder to reach.
On Monday, a White House delegation hosted a controversial event on the sidelines of the UN climate conference, promoting "cleaner" fossil fuel use to the chagrin of green energy campaigners and fellow negotiators.