What is the Paris Agreement, the United States’ international climate change treaty pulled out of?

CNN
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President Donald Trump signed acts 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 could not be higher for the planet and humanity’s ability to adapt to the changing climate and the rising costs of climate-related disasters.

The planet crossed an impact threshold in 2024 – 1.5 degrees Celsius of global warming – dating back to the day the Paris Agreement was adopted.

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 Paris Climate Agreement, to limit global warming to well below 2 degrees Celsius, but preferably to 1 .5 degrees.

There was agreement between the countries on whether the target should be 1.5 or 2 degrees. The lower threshold was the one called for by climate scientists and was ultimately added to the text as an ideal rather than the agreement’s formal goals.

But since then, climate change has accelerated, and the planet is warming at a pace that even scientists did not predict. Evidence has grown in recent years that nature and humanity’s ability to adapt to global warming will decline significantly if the planet experiences sustained warming above 1.5 degrees.

Although the adoption of the Paris Agreement was a watershed moment and set the world on a path that scientists supported, it did not become specific about how countries should achieve their goals. The agreement is not binding; countries are not required to reduce their climate pollution under international law. Countries set their own pollution targets and methods to meet them.

The Biden administration presented an ambitious new target on behalf of the United States in December 2024, saying the country would reduce climate pollution by up to 66% below 2005 levels by 2035.

Former President Joe Biden knew at the time that Trump intended to withdraw the United States from the Paris Agreement, so the goal was a symbolic statement about the course the country could have taken if Americans had elected a climate-friendly president.

Climate advocates across the board said the goal was ambitious.

“For this new, very ambitious target for 2035, we are not on track – and we are likely to be further away under a Trump administration,” said Kate Larsen, who leads Rhodium’s international energy and climate research.

Representatives from the United States were leaders in the Paris Agreement negotiations. It was adopted by nearly 200 countries under the Obama administration in 2015.

Trump announced his intention to withdraw the United States from the Paris Agreement in 2017, although it was not formalized until November 4, 2020, one day after the presidential election, which Biden ultimately won.

On the first day of his term, Biden announced his intention to rejoin 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 fossil fuel production.

In short, yes. But that may depend on what the Trump administration does next.

A “Project 2025” document from the Heritage Foundation recommends that Trump should completely leave the overarching U.N. treaty that governs the deal — a decision that would shake up international climate negotiations and make it harder for a future administration to re-enter.

Meanwhile, a leading UN climate change official reiterated “the door remains open to the Paris Agreement.”

“We welcome constructive engagement from all countries,” UN Climate Change Executive Secretary Simon Stiell said in a statement.

Still, Stiell emphasized the clean energy boom taking place around the world, worth $2 trillion last year and growing, and warned that countries that don’t embrace it will be left behind.

“Ignoring it only sends all that enormous wealth to competing economies, while climate disasters like droughts, wildfires, and superstorms worsen, destroying property and businesses, hitting nationwide food production, and driving price inflation throughout the economy.”

CNN’s Ella Nilsen and CNN staff contributed to this report.