French President Emmanuel Macron is due to address a UN climate summit in New York, where world leaders have gathered to try to inject fresh momentum into efforts to curb carbon emissions.
Monday's "climate emergency" summit is aimed at reinvigorating the 2015 Paris Agreement against global warming, at a time when mankind is releasing more greenhouse gases into the atmosphere than at any time in history.
UN Secretary-General Antonio Guterres has warned governments that they would have to offer action plans to qualify to speak at the summit.
"Millions around the world saying clearly, not only that they want change, not only that decision-makers must change – but they want them to be accountable," Guterres said at a separate youth climate summit he hosted on Saturday.
Other world leaders due to address the one-day gathering include German Chancellor Angela Merkel and Indian Prime Minister Narendra Modi. US President Donald Trump and Brazilian President Jair Bolsonaro are not attending.
