Joe Biden believes the changing climate is an urgent threat.

Unlike Donald Trump, who withdrew from the only international agreement to tackle it. "The United States will withdraw from the Paris Climate Accord." Now there'll be a huge push for renewable energy on an epic scale, says Mr Biden, for the US to be carbon neutral by 2050 a difficult challenge.

But climate experts say it's needed.

Biden understands time is short and intends toe act vigorously and with the greatest ambition of any US president ever internationally, where he is huge authority and that means huge incentives for other countries to reduce their emissions even as he tries to regulate US emissions ourselves.

Oh my God, fires, droughts and all kinds of extreme weather are set to intensify as global temperatures rise.

So Mr Biden promises action on his very first day in office.

His pledge to rejoin the Paris agreement negotiated five years ago amid great celebrations.

It was then abandoned by Mr Trump.

The agreement is about cutting the gas.

Is that air heating up the atmosphere?

And many hope that it will make ALS the difference toe Have America, the world's largest economy, taking part once again?

Unless we all address climate change, we will all be vulnerable to climate change.

So it is very refreshing to a know that we are going back into a collaborative frame of mind that helps everyone but coal mining and many heavy industries air at stake.

Joe Biden is offering green jobs instead, but he's bound to face opposition in the Senate and maybe the courts as well.

This comes as more than 100 countries are now talking of going carbon neutral around the middle of the century on America's new leader will be working to make that happen.