The United States officially left the Paris Agreement on Nov. 6, nearly three years after President Donald Trump initially announced this decision in 2017. The United Nations formally approved the paperwork for withdrawal this past week.

The Paris Agreement is a joint effort by 197 countries to combat climate change. As global warming becomes an increasingly pressing concern each year, the pact calls for “keeping a global temperature rise this century well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius,” according to the United Nations.

The conception of the environmental treaty came in 2015, with the purpose of reducing continuous pollution and helping developing countries remain eco-friendly as they grow. Participating countries agreed that once a country joined, it could not leave for three years. If it chose to leave by that point, it must wait a year and file documentation.

Although President Obama signed the United States into the deal, President Trump decided to exit the agreement. In a 2017 speech, he stated the agreement would severely reduce U.S. industries like steel and coal mining, and hurt manufacturing. The official White House website mirrors this disapproval of the Paris Agreement, stating that the United States has done a better job handling the climate crisis alone than being a part of the pact.

After making the announcement, the U.N. allowed Secretary of State Mike Pompeo to begin the paperwork to leave the agreement on Nov. 4, 2019. A year later, Americans woke up to their nation no longer being in the Paris Agreement.

Considering that the agreement decreased harmful greenhouse gases and carbon emissions worldwide, many countries were upset that a world power was leaving the pact. Britain, Chile and Italy issued a joint statement expressing their disappointment.

“There is no greater responsibility than protecting our planet and people from the threat of climate change,” the statement said. “The science is clear that we must urgently scale up action and work together to reduce the impacts of global warming and to ensure a greener, more resilient future for us all. The Paris Agreement provides the right framework to achieve this,” according to the Associated Press.

In conjunction with this news, President-Elect Joseph Biden announced he would enter the U.S. into the Paris Agreement again once in office. One of the platforms he ran on was climate change and implementing measures to mitigate it.

He intends to implement a policy that would bring net-zero carbon emissions by 2050, according to his official campaign website. It also states that $1.7 trillion will be invested in environmental recovery from the pandemic.

Lastly, under his plan, U.S. carbon dioxide emissions would decrease exponentially. In fact, “Calculations by the Climate Action Tracker show that this reduction would be enough to avoid a temperature rise of about 0.1C by 2100,” The Guardian reported.

Since the Paris Agreement strives to keep the global increase in temperature below 2 degrees Celsius, Biden’s proposed plan would align with the rest of the world’s goals. The United States is second in the world for having the most carbon dioxide emissions, according to the Union of Concerned Scientists. If Biden’s plan comes to fruition as predicted, the United States would adapt practices that prevent global rising temperatures.

Though environmentalists remain hopeful that Biden will take up the climate change helm and work to combat the issue, the Trump administration’s decision to withdraw from the agreement has smeared U.S. reputation in regards to science.

“The United States can’t simply jump back in and pretend it’s all back to 2015,” Michael Oppenheimer, a climate-policy researcher at Princeton University, said. “It will need to work to regain trust.”

As of now, America awaits to see how Biden will battle climate change in both the states and overseas.