President Donald Trump signed actions on the first day of his second term to pull the United States out of the Paris Agreement, an international climate change treaty in which nearly 200 countries agreed to work together to limit global warming.
The stakes couldn’t be higher for the planet and humanity’s ability to adapt to the changing climate and the increasing cost of climate-related disasters.
The planet crossed a consequential threshold in 2024 — 1.5 degrees Celsius of global warming — that dates back to the day the Paris Agreement was adopted.
What is the Paris Agreement?
In 2015, more than 190 countries gathered at a United Nations climate summit in Paris and approved what became known as the Paris Agreement, or the Paris Climate Accord, to limit global warming to well below 2 degrees Celsius, but preferably to 1.5 degrees.
Consensus was split between countries on whether to make the goal 1.5 or 2 degrees. The lower threshold was the one urged by climate scientists, and was ultimately added to the text as an ideal rather than the agreement’s formal goal.
But since then, climate change has accelerated and the planet is warming at a pace even scientists didn’t predict. Evidence has grown in recent years that nature and humanity’s ability to adapt to global warming will drop significantly if the planet experiences sustained warming above 1.5 degrees.
Although the adoption of the Paris Agreement was a landmark moment and set the world on a path that scientists supported, it didn’t get specific about how countries should achieve its goals. The agreement is non-binding; countries aren’t obligated to reduce their climate pollution under international law. Countries set their own pollution goals and methods to meet them.
What is (was) the US climate goal?
The Biden administration submitted a new, ambitious goal on behalf of the US in December 2024 that said the country would cut climate pollution by up to 66% below 2005 levels by 2035.
Former President Joe Biden knew at the time Trump intended to put the US out of the Paris Agreement again, so the goal was a symbolic declaration of the course the country could have set out on had Americans elected a climate-friendly president.
Climate advocates across the board said the goal was ambitious.
“For this new, very ambitious target for 2035, we’re not on track — and we are likely to be further off track under a Trump administration,” said Kate Larsen, who leads Rhodium’s international energy and climate research.
What is America’s history with the Paris Agreement?
Representatives from the US were leaders in the Paris Agreement negotiations. It was adopted by nearly 200 countries during the Obama administration in 2015.
Trump announced his intent to pull the US out of the Paris Agreement in 2017, though it wasn’t formalized until November 4, 2020, a day after the presidential election that Biden ultimately won.
On the first day of his term, Biden announced his intent to reenter the Paris Agreement.
On the first day of Trump’s second term in January 2025, Trump ordered the withdrawal from the Paris Agreement again as he sought to increase US production of fossil fuels.
President Donald Trump holds an executive order announcing the US withdrawal from the Paris Agreement on January 20, 2025. – Jim Watson/AFP/Getty Images
Can the US reenter the Paris Agreement again?
In short, yes. But it could depend on what the Trump administration does next.
A “Project 2025” document from the Heritage Foundation recommends Trump should fully exit the overarching United Nations treaty that governs the agreement — a decision that would rock international climate negotiations and make it harder for a future administration to re-enter.
In the meantime, a leading United Nations climate change official reiterated “the door remains open to the Paris Agreement.”
“We welcome constructive engagement from any and all countries,” UN Climate Change Executive Secretary Simon Stiell said in a statement.
Still, Stiell emphasized the the clean energy boom taking place around the world, valued at $2 trillion last year and rising, and warned that countries that don’t embrace it will be left behind.
“Ignoring it only sends all that vast wealth to competitor economies, while climate disasters like droughts, wildfires and superstorms keep getting worse, destroying property and businesses, hitting nation-wide food production, and driving economy-wide price inflation.”
CNN’s Ella Nilsen and CNN staff contributed to this report.
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