Climate pact an 'act of defiance' after Paris attacks: Barack Obama

Pushing for a powerful climate deal, President Barack Obama called the global talks opening today outside Paris an "act of defiance" against terrorism that proves the world stands undeterred by Islamic State-linked attacks in Europe and beyond.

Obama used his speech to more than 150 world leaders to salute Paris and its people for "insisting this crucial conference go on" just two weeks after attacks that killed 130 in the French capital.

He said leaders had converged to show resolve to fight terrorism and uphold their values at the same time.

"What greater rejection of those who would tear down our world than martialing our best efforts to save it," Obama said.

Obama's remarks came at the start of two weeks of make-or-break negotiations to finalise a sweeping global agreement to cut carbon emissions and hopefully stave off the worst effects of climate change.

Obama exhorted leaders here to fight the enemy of cynicism, "the notion we can't do anything" about the warming of the planet.

After sketching dire threats of submerged nations, abandoned cities and ever-worsening flooding and natural disasters, Obama insisted that grim future "is one that we have the power to change."

He urged leaders to "rise to this moment," invoking the late Martin Luther King Jr's observation that there's such a thing as being too late to a cause.

"That hour is almost upon us," Obama said.

Efforts to secure a climate deal have been hampered by a long-running dispute about whether developing nations share the same burden as industrialised nations that have historically polluted much more. The US and other nations have insisted that all countries chip in under the new agreement.

"No nation, either wealthy or poor, is immune to what this means," Obama said as he described spiraling effects of climate change if left unchecked.

Aiming to put a finer point on that argument, Obama met today with President Xi Jinping of China, which has started taking aggressive action to curb emissions, and planned a similar meeting later in the day with India's Prime Minister Narendra Modi.

In his sit-down with Xi, Obama touted close cooperation on climate change as vital to world efforts on global warming, and said nowhere had coordination with Beijing been more critical or fruitful than on climate change.

He credited US and Chinese leadership with leading 180 nations to make their own pledges to curb emissions in the run-up to the Paris talks.

"Our leadership on this issue has been absolutely vital," Obama said. China emits about 30 per cent of the world's greenhouse gases and the US about 16 per cent.