Signatories to the Paris climate accord have been urged to step up their support for global climate change mitigation efforts, in the light of the US' regression in its support for such efforts under President Donald Trump.

Bill McKibben, Co-Founder of 350.org, a grassroots climate campaign based in the US, said on Thursday that the rest of the world now had to choose one of two options in the light of Trump's stance on climate change.

The American administration has been cutting down on its commitments to address climate change, which Trump has openly described as a hoax.

There is currently a potential that Trump would withdraw America from the Paris Climate Accord.

McKibben said most Americans were opposed to Trump's stance and actions on climate change issues, with several marches organised in Washington DC to resist Trump on these issues.

"He may withdraw America from the Paris climate accord. If that happens, the rest of the world has a choice. It has one of two options: It can either say if Americans won't work on this, we don't have to work on this either."

McKibben noted, however, that this choice would mean that climate change would continue to progress, with the poorest countries being the hardest hit by the situation.

"The other option for the rest of the world, is to say 'we're going to step up and we're going to do more because we have no choice' and I hope that that's what happens," he stated.

McKibben urged other world leaders to demonstrate more commitment to addressing climate change.

"It is a real moment for the rest of the world to demonstrate that the US is not the most important country in the world and that the world can figure out how to do things even when the US is going backwards," he said.