The US is set to become isolated in its stance on the Paris climate agreement, after Syria said it was preparing to join the deal.
The Paris deal unites the world's nations in tackling climate change.
Syria and Nicaragua were the only nations outside the deal when it was agreed in 2015. Nicaragua signed in October.
In June the US said it would withdraw, but the rules of the agreement state that this cannot be done until 2020.
Scientists point out that work to implement the Paris accord must be stepped up if it is to have any chance of success.
Historically, the US, Europe and China account for almost half of the world's carbon emissions.
Scientists point out that work to implement the Paris accord must be stepped up if it is to have any chance of success.
Historically, the US, Europe and China account for almost half of the world's carbon emissions.