US officially withdraws from Paris Agreement that aims to combat climate change

The U.S. officially has left the Paris Agreement, three years after President Donald Trump announced he would leave the international climate change forum.

The accord is a collective agreement among nearly 200 countries that aims to prevent the earth's temperatures from rising 2 degrees Celsius above pre-industrial revolution temperatures, the value that climate scientists have determined will have disastrous consequences if exceeded.

The rise could result in rising sea levels and more extreme weather events, such as hurricanes, drought and wildfires. This, in turn, could lead to mass migration and shortages in food production, according to the experts.

In 2017, Trump announced his intention to withdraw from the agreement, claiming it could be economically detrimental and cost 2.5 million Americans their jobs by 2025.

Trump described the pledge that the U.S. entered, which was to reduce greenhouse gases 26% to 28% by 2025, as a "massive redistribution of United States wealth" that would "undermine our economy, hamstring our workers, weaken our sovereignty [and] impose unacceptable legal risk."

Experts have said that as the second-highest emitter of greenhouse gases in the world, the U.S. participating in the accord is crucial to inspiring other countries to take responsibility for their roles in global warming.

Whether the U.S. rejoins the agreement could depend on the winner of the 2020 presidential election.

Former Vice President Joe Biden, who has proposed a $5 trillion plan to combat climate change, has vowed to reenter the U.S. into the agreement should he be elected president, a move that could take less than six months, Varun Sivaram, a senior research scholar at Columbia University's SIPA Center on Global Energy Policy, told ABC News.

Trump, who has walked back dozens of environmental protections since he took office in 2017, has said that he would be open to rejoining the accord after renegotiating a "deal that's fair."