What major international climate agreement did the US formally leave for the second time in January 2026?

The major international climate agreement that the United States formally left for the second time in January 2026 is the Paris Agreement. This significant event took place on January 27, 2026, when the US officially exited the accord. The withdrawal process was initiated by President Donald Trump shortly after he began his second term in office in January 2025, signaling a renewed shift in the nation's approach to global climate policy.

The Paris Agreement is a landmark international treaty adopted in 2015, uniting nearly every nation in a common framework to address climate change. Its central aim is to substantially reduce global greenhouse gas emissions to limit the global temperature increase in this century to well below 2 degrees Celsius above pre-industrial levels, while pursuing efforts to limit the increase to 1.5 degrees Celsius. Countries commit to setting their own national emissions reduction targets and regularly reporting on their progress.

The United States has experienced a complex history with the Paris Agreement. It initially became a signatory and accepted the agreement under President Barack Obama. However, President Trump announced his intent to withdraw in 2017, and the US formally left the pact in November 2020. President Joe Biden then rejoined the agreement on his first day in office in January 2021, with the US formally becoming a party again in February 2021. The latest withdrawal in January 2026 marks the second time the United States has departed from this critical climate accord, making it the only country to do so.

This repeated withdrawal highlights a fluctuating commitment to international climate action, often driven by domestic policy priorities. The administration has cited concerns that the agreement could hinder the US economy and has pursued an "America First" policy approach to energy and environmental regulations.