By Joleen Murphy
The US President has committed America to halving its greenhouse gas emissions by 2030.
Joe Biden's promise, based on his country’s 2005 output, comes alongside a virtual global summit at the White House.
It is double its previous promise, with the target based on 2005 levels.
The US president's hosting 40 world leaders in a virtual Earth Day summit at the White House and urged all nations to "step up" in the fight against climate change.
"This is the decade we must make decisions that will avoid the worst consequences of the climate crisis.
"We must try to keep the earths temperature to an increase of 1.5 degrees Celsius.
"We have to take action, all of us."
Kate Norgrove, from the World Wildlife Fund, has been following what they've been announcing.
"We have heard statements today from the US, UK, Japan, China and South Africa and it's really encouraging to see world leaders raising their ambition to reduce carbon emissions.
"But we still need those words to be translated into a plan, into urgent action."
