Paris (AFP) - Rising seas from global warming could submerge swathes of New York and Shanghai, and drive millions of people into poverty worldwide, researchers warned Monday as climate-altering carbon levels broke new records.

The slew of fresh planetary warnings came as ministers met in Paris searching common ground of a crunch climate summit.

If the planet warms by four degrees Celsius (7.2 degrees Fahrenheit) -- double the targeted UN ceiling -- oceans will swallow land inhabited by more than 600 million people, said a survey by Climate Central, a US-based research group.

At the same time, the World Meteorological Organization said concentrations of climate-altering greenhouse gases in the atmosphere broke new records last year.

"Concentrations of greenhouse gases in the atmosphere are now reaching levels not seen on Earth for more than 800,000, maybe even one million years," WMO chief Michel Jarraud told reporters.

"This means we are now really in uncharted territory for the human race," he warned.

The new warnings came as environment and energy ministers met in Paris seeking convergence on issues still dividing nations negotiating for a climate rescue pact to be inked at a November 30-December 11 UN summit in the French capital.

Climate Central said that even if the agreement succeeds in limiting average global warming to 2C over pre-Industrial Revolution levels, areas today home to 280 million people would slip under the waves.

A separate World Bank study late Sunday said there could be "more than 100 million additional people in poverty by 2030" unless action is taken to stem climate change.

"The poor are more vulnerable to climate-related shocks than wealthier people," said the report, urging "strong action" from the Paris summit.

French Foreign Minister Laurent Fabius, hosting ministers and climate envoys from 70 countries in Paris to prepare for the summit over which he will preside, issued his own dire warning.

"It is life on our planet itself which is at stake," he said at the start of talks Sunday.

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"There is absolute urgency" to achieve the 2 C goal, said Fabius. Anything higher would have "catastrophic consequences" -- including wars over dwindling water and other resources.

Fabius also announced that Russia's President Vladimir Putin would be among world leaders to attend the November 30 summit opening.

- High stakes -

The summit will be opened by some 100 heads of state and government, also including US President Barack Obama, China's Xi Jinping, and Narendra Modi of India.

It is meant to produce the first truly universal pact to rein in climate change by curbing emissions from burning fossil fuel.

Ministers are the ones who will ink the deal at the end.

They gathered in Paris for pre-summit talks, hoping to identify areas of possible consensus -- working off a blueprint for the deal compiled by rank-and-file diplomats over years of tough negotiations in the UN climate forum.

For now, the draft remains little more than a laundry list of often directly opposing national options for dealing with the challenge at hand.

Countries remain divided on issues of fairness and finance -- basically who must be doing what.

Developing countries insist rich ones should lead the way in slashing emissions as they have polluted for longer.

They also want assurances of finance to make the shift from cheap and abundant fossil fuel to greener energy sources, and to shore up defences against climate change-induced superstorms, drought, flood and sea-level rise.

But industrialised countries point the finger at emerging giants such as China and India spewing carbon dioxide as they burn coal to power expanding populations and economies.

As the bickering continues, the UN last week issued a fresh warning that national carbon-curbing pledges submitted to date set the stage for warming of about 3 C, or more.

Last month, scientists said the first nine months of 2015 had been the hottest on record worldwide.