US President Barack Obama has said the UN climate conference in Paris could be a "turning point" in global efforts to limit future temperature rises. Negotiators from 195 countries will try to reach a deal within two weeks aimed at reducing global carbon emissions and limiting global warming to 2C (3.6F).

Leaders from 147 nations are addressing the meeting, known as COP21.

President Obama urged negotiators to deliver a meaningful deal, because the "next generation is watching".

COP21: Latest updates from Paris

He told delegates: "Climate change could define the contours of this century more than any other (challenge).

"I came here personally to say the United States not only recognises the problem but is committed to do something about it."

He added that recent years had shown that the global economy had grown while emissions had remained flat, breaking the old arguments for inaction "that economic growth and environmental protection were in conflict".

Much of the discussions are expected to centre on an agreement to limit global warming to 2C (3.6F).

Assessments of more than 180 national climate action plans that have been submitted by countries suggest that if they were implemented the world would see a rise of nearer to 3C.

Peruvian Environment Minister Manuel Pulgar Vidal, who declared the Paris meeting open, said strong action on carbon emissions was essential for multiple reasons.

Mr Vidal, who hosted last year's UN climate conference in Lima, said a deal would show the world that countries can work together to fight global warming as well as terrorism.

Christiana Figueres, the head of the UN's climate change negotiations, also addressed delegates, saying never before had a responsibility so great been in the hands of so few.

"The world is looking to you," she said. "The world is counting on you."