A critical UN conference aimed at agreeing a new global approach to climate change is set to open in Paris.
The meeting, known as COP21, will see negotiators from 195 countries attempt to finalise a new treaty over the next two weeks.
Political leaders from 147 countries will address the conference throughout Monday.
But the poorest countries say they fear being “left behind” in the push to agree a deal.
The French government will officially take over the running of the talks during the opening ceremony on Monday.
Police have locked down the conference centre in Le Bourget, closing roads in the area amid strict security for the leaders’ visit.
Presidents and prime ministers will address the gathering amid a growing sense of optimism that an agreement can be secured.
“It will be the turning point, which is what the world requires,” said French Foreign Minister Laurent Fabius at a news conference over the weekend. Mr Fabius will chair the conference until it reaches a conclusion.