World leaders reaffirm commitment to fighting climate change

In 2015, it released 5.1 million kilotons of carbon dioxide, more than all 28 European Union countries combined, and makes up nearly a sixth of all global emissions.

A frustrated German Chancellor Angela Merkel later warned that Europe "must take its fate into its own hands", citing the differences with Washington on climate change as evidence of their divergent paths.

In March, he signed an executive order to roll back Obama-era policies regulating carbon emissions.

From the campaign trail a year ago, Trump pledged to pull the United States out of the agreement, but waffled on his stance early in 2017.

If the U.S. backs out of the Paris Agreement, what would that look like?

The Paris Agreement was in part brokered by Obama and was seen as a major breakthrough after the previous accord, the Kyoto protocol, failed to include the USA and China, the world's two biggest polluters.

In 2018, and every five years thereafter, countries will take stock of the overall impact of their efforts to rein in global warming.

Could Trump just ignore the agreement?

It has been ratified by 147 parties or countries already, including all the world's largest carbon emitters. The intended result is to limit global warming to less than two degrees.

Some reports in the U.S. suggest he will withdraw. For example, there are no sanctions if the United States breaks its promise of reducing greenhouse gas emissions 26% to 28% below 2005 levels by 2025.

She says in a statement that the landmark accord "honors our collective moral responsibility to leave future generations with a planet that is clean, healthy and sustainable".

The vast majority of scientists agree that higher temperatures will cause rising seas, flooded coastal cities, mass extinction, drought, migration crises, deadlier heatwaves, crop failures, and stronger storms.

Trump could decide as early as this week whether the United States will remain in the historic Paris Agreement, which reflects a voluntary commitment by the world's governments to reduce their carbon emissions.

China will honour its commitments on climate change, its premier has said, as the United States appears poised to pull out of a key deal.

Many economists have big doubts. "It will also be a major geopolitical and reputational blow for the US", Li Shuo, climate analyst for Greenpeace China told CNN. If anything, we hope to see China and India stepping up the pace.

"Trump really isn't as relevant as he wants to be". But the official says there may be "caveats in the language" that Trump uses to announce the withdrawal - and that could leave open the possibility that the decision isn't final.

The Trump administration could withdraw from the entire United Nations Framework Convention on Climate Change, an global treaty ratified by the US Senate and signed by President George H.W. Bush in the 1990s.

  • David Armstrong