After a three-year delay, the United States has become the first country to officially withdraw from the Paris agreement.
Whoever occupies the White House for the next 4 years could play a major role in the fight against climate change.
Scientists studying climate change say that the re-election of Donald Trump could make it difficult to keep global temperatures in check. Researchers are also worried that another four years of Donald Trump would favour the use of fossil fuels for decades to come rather than pushing for green energy.
President Trump's strong support for fossil fuels has been a success from an economic perspective. Thanks to fracking, the United States briefly became the world's biggest oil exporter late last year.
Joe Biden's climate plan, the scientists argue, would give the US a better fighting chance.
Biden wants the US energy sector go carbon-free by 2035. This would allow the US to become a net zero emitter by 2050.
Achieving net zero means that any carbon emitted source is balanced out by removing an equivalent amount from the atmosphere through planting forests.
Joe Biden has revolutionary plans to upgrade US transport by investing in electric vehicles and trains. He also plans to build 1.5 million sustainable housing units. His ambitious plan would help keep global temperatures down.
Donald Trump announced withdrawing from the Paris Agreement in June 2017, but UN regulations meant that his crucial decision only takes effect 3 years later, the day after the US election.
President Trump spoke of negotiating a new agreement, but nothing has come of that idea.
Withdrawing from the Paris agreement was a strong message to the rest of the world that the United States no longer shared the international consensus on climate change.
If a new president is elected, The US could re-join it in the near future.
Joe Biden promised to resign the climate agreement if he is the new President of the United States.
In some parts of the United States, the lack of action from the Trump government on climate change has served as a call to action.
Several residents in South Carolina are worried about climate change and rising sea level.
Indeed, water levels in the region used to rise about 2.5cm every decade - now they're going up by that amount every 2 years.
With a pressing need for new sea defences, the local authority has sued twenty-four fossil fuel companies for their role in producing the carbon that is linked to the rising waters.