What the U.S. is committing to as it rejoins the Paris climate accords — and why it matters

On Friday, the United States will reenter the Paris Agreement, a climate treaty dedicated to lowering greenhouse gas emissions in more than 180 countries around the world. It was originally signed and negotiated during the final years of the Obama administration, withdrawn from by President Trump in 2020, and reentered by President Biden on his first day in office.

The drafting of the agreement took place at the 21st Conference of the Parties of the United Nations Framework Convention on Climate Change, also known as COP21. The treaty was originally...