The US has pledged to cut carbon emissions by 50-52% below 2005 levels by the end of this decade.
This new target, which was unveiled at a virtual summit of 40 global leaders, essentially doubles their previous promise.
The Americans hope that their ambitious new plan will encourage China, India and others to go further before the crucial COP26 meeting, in Glasgow in November.
President Biden said at the summit’s opening address: “Scientists tell us that this is the decisive decade – this is the decade we must make decisions that will avoid the worst consequences of the climate crisis.
“We must try to keep the Earth’s temperature to an increase of 1.5C. The world beyond 1.5 degrees means more frequent and intense fires, floods, droughts, heatwaves and hurricanes – tearing through communities, ripping away lives and livelihoods.”
Earth Day, celebrated every year on April 22, is designed to drive action on the environment and climate crisis around the world.
According to Earth Day President, Kathleen Rogers, the overarching theme this year is ‘Restore Earth’, supported by three pillars – ‘restoration, mitigation and adaptation’.
Restoration, she says, is a more hopeful way of approaching the climate challenge, and she is adamant the Earth can be restored, despite the alarming problems it faces.
Ms Rogers says in a time-span of between a few years and a decade, 70% of the world’s topsoil will be useless for growing, largely due to the over-use of chemicals. But she insists it can be restored.
The coronavirus pandemic has again affected Earth Day, starting with ten hours of online programming which started at 2pm UK time.
As well as the climate summit, thousands of local events are taking place too, both online and in person.
The first Earth Day was 51 years ago, organised by US Senator Gaylord Nelson from Wisconsin and graduate student, Denis Hayes.
The senator had been appalled by the impact of a massive oil spill in California in 1969 and wanted to channel the energy of the student anti-war movement into action to protect the environment.
The first Earth Day in 1970 event saw 20 million people across the US take to the streets – around 10% of the country’s population at the time.
Within a year, President Richard Nixon had set up the Environmental Protection Agency and a host of new laws, including the Clean Water and Air Acts, and the Endangered Species Act, followed.
Its roots are in the US, but Earth Day became an international campaign in 1990, paving the way for the 1992 UN Earth Summit.
Another milestone, Earth Day 2000, chose to address the growing issue of global warming and the switch to clean energy sources.