The United States officially rejoined the landmark international accord to limit global warming known as the Paris Agreement on Friday.
Hours after he was sworn-in on January 20, President Joe Biden signed an executive order beginning the 30-day process for the US to reenter the global pact.
The US had officially exited the agreement late last year on former President Donald Trump's orders, becoming the first and only country to formally pull out of the deal since it was adopted in 2015.
Rejoining the Paris Agreement is a significant step by the Biden administration to reverse the climate policies of the last four years, during which Trump rolled back or loosened many of the country's bedrock environmental policies and regulations.
On Twitter Friday, Secretary of State Tony Blinken called it "a good day in our fight against the climate crisis" and promised that the US would "waste no time in engaging our partners around the world to build our global resilience."
"Now, as momentous as our joining the Agreement was in 2016 -- and as momentous as our rejoining is today -- what we do in the coming weeks, months, and years is even more important," Blinken added in a statement.
Under the agreement, countries are expected to enhance their commitments to curb greenhouse gas emissions every five years. The goals of the global pact are to limit global warming to well below 2°C and pursue efforts to limit it to 1.5°C.
Under the Obama administration, the US had pledged to slash carbon emissions by 26%-28% below 2005 levels by 2025.
2020 was supposed to be the next mile marker for nations to increase their greenhouse gas emission pledges, but the Covid-19 pandemic postponed the climate negotiations to November in Glasgow, Scotland.
Biden plans to host a climate summit of world leaders on Earth Day, April 22, where he will roll out the US' goal for reductions of carbon emissions by 2030 -- known as the nationally determined contribution under the Paris accord.
Alok Sharma, the President of 26th United Nations Climate Change Conference, welcomed the US' return to the Paris accord on Friday, writing in a CNN op-ed that he looks "forward to working as a matter of urgency with President Biden's administration and governments around the world, to deliver decisive climate action."
This story has been updated.