Brazil on Sunday promised ambitious cuts in greenhouse gas emissions, boosting efforts for a global climate accord as leaders warned more work was needed.

In one of the last big meetings before a high-stakes climate summit in Paris later this year, French President Francois Hollande pressed for hard commitments during consultations at the United Nations.

Brazilian President Dilma Rousseff used the occasion to announce the rainforest-rich nation's plans to reduce emissions blamed for the planet's rising temperatures.

Rousseff said that Brazil will cut emissions by 37 percent over the next decade and 43 percent by 2030 from 2005 levels.

Rousseff, who has faced domestic pressure over a wobbly economy, noted that Brazil was one of the few developing countries to promise not just to slow down but to cut emissions in absolute terms.

"In spite of having one the world's largest populations and GDPs, our goals are just as ambitious, if not more so, than those set by developed countries," she said in an address to the world body.

Her plan would also include restoring 12 million hectares (30 million acres) of forest and recovering another 15 million hectares (37 million acres) of degraded pasture.

Brazil's announcement came two days after President Xi Jinping of China -- the world's largest emitter -- pledged on a US state visit to step up action including by setting up a "cap-and-trade" system to restrict emissions.

Indonesia and South Africa also recently released action plans, with an announcement expected in coming days by India.

- Still far from ideal cuts -

Kumi Naidoo, international executive director of Greenpeace, agreed that momentum was building for the Paris talks but said that far more action was needed as the world had long "dragged its feet."

"On the one hand, there is movement in a positive direction, but it's still fundamentally out of synch with what the science is telling us to do," Naidoo told AFP.

He praised Brazil's plan as ambitious, although he questioned why the plan takes until 2030 to end illegal deforestation, let alone authorized logging.

Rainforests in Brazil, Indonesia and other tropical countries mitigate climate change by essentially sucking up carbon emissions.

The UN climate body warned last week that the planet was still on course for warming of three degrees Celsius (5.4 Fahrenheit) above pre-industrial levels, well above the two-degree threshold considered the limit to prevent the worst damage from climate change, or the 1.5 degrees advocated by low-lying islands.

Hollande discussed the state of negotiations with leaders over a lunch -- which was cooked from food that would have otherwise gone to the trash, in an effort to highlight the vast contribution of food waste to climate change.

"The intentions are there and there are plenty of pledges, but there is still lots of work to do between this willingness and the conditions for a credible agreement," Hollande told reporters.

"I have only one message -- speed up," he said, calling on countries both to submit more plans on emission cuts and to commit more money to help hardest-hit poor countries.

"The entire world is convinced that there will be an agreement in Paris, but the question is, what kind of agreement?" he said.

- Fears in small islands -

US President Barack Obama in a UN address called for efforts towards a  "strong" agreement in Paris, citing Pope Francis in calling climate action "a moral calling."

"All our countries will be affected by a changing climate, but the world's poorest people will bear the heaviest burden -- rising seas, more intense droughts," Obama said.

The Marshall Islands, the Pacific archipelago that fears for its very existence, agreed there were "good signs" but said it was crucial to solidify a deal.

"We can't very well go back to our constituents and say we tried 1.5 (degrees) and then two and that won't happen," Foreign Minister Tony De Brum said.

"That won't be very comforting for those who see and feel the threat now."