The US on Wednesday officially exited the Paris Agreement, making the country the only major polluter in the world leaving the historic pact reached to combat climate change.
The US' withdrawal was formally set in motion by President Donald Trump with a letter exactly one year ago, although he had announced the decision in June 2017.
Trump had argued that the accord provided disadvantages for the US for the benefit of other countries, and it had a negative impact on American workers, jobs, wages, and overall economy.
Around 195 countries drafted the Paris Climate Agreement in 2015 with the aim of limiting the global warming increase at 1.5 degrees Celsius (2.7 degrees Fahrenheit) and keep the rise in global temperature below 2 C (3.6 F) compared to to pre-industrial levels.
The president's move was harshly criticized by environmentalists, but rejoiced by American oil, natural gas and coal industries since the US has become the world's largest oil and gas producer since the shale revolution that started in 2008.
Although Washington have stopped implementation of the non-binding accord and its financial and economic requirements on June 1, 2017, the UN regulations require withdrawal decisions to become official four years after the deal came into effect on Nov. 4, 2016 -- coincidentally a day after the 2020 US elections.
The UN rule was also influenced by former President Barack Obama, who joined the US into the agreement and wanted to ensure that it would take time for any future US president to withdraw the country from the deal.
The world's second largest polluter of fossil fuels and carbon emissions after China, and representing 15% of global greenhouse gas emissions, the US still has the option to rejoin the accord if a future president chooses.
Democratic presidential candidate and former Vice President Joe Biden vowed during his campaign to have the US rejoin the deal on his first day of the office if he was elected.
"I will put us back in the business of leading the world on climate change. And I will challenge everyone to up the ante on their climate commitments," Biden said in a speech in September.
By Ovunc Kutlu