Ecologists at UN climate talks in Warsaw downed forks Tuesday in a solidarity fast with the typhoon-ravaged Philippines' chief negotiator, demanding "ambitious action" to halt global warming.

When the 12-day summit opened in the Polish capital on Monday, Naderev Sano pledged to fast until progress is made towards fighting the climate change he blames for the super typhoon that struck his country.

About 30 environmentalists from countries including Sri Lanka, Ukraine, Poland, India and the United States, announced Tuesday they would also stop eating in support.

"Some are fasting in solidarity with Mr. Sano with no food whatsoever, just water, to the end of the summit, or until real progress is made," Anjali Appadurai, an activist with Friends of the Earth Sri Lanka, told AFP.

Protesting at one of the conference venue's many busy cafeterias, activists wore large red dots on their lapels as a symbol of solidarity with the Philippines envoy and touted signs reading: "It's lunch time but we're not eating", "We stand with you, we stand with the Philippines", and "Climate justice now!"

Lydinyda Nacpil, an activist with the Jubilee South Asia Pacific Movement on Debt and Development, called for "ambitious compensation and finance, reparations, solidarity and ambition and overall equity" for developing nations hardest hit by extreme weather events they blame on climate change.

Sano himself urged a "meaningful outcome" at the Warsaw talks on the creation of a mechanism that would provide compensation for countries that suffer losses and damage due to climate change-induced weather events.

"We will continue fasting until a meaningful outcome is in sight in these negotiations, until the loss and damage mechanism sees light," Sano told reporters.

"It's very obvious that the loss and damage mechanism is something that we care about as a delegation because the Philippines is bearing the brunt of this climate crisis."

The issue of "loss and damage" nearly scuppered last year's round of negotiations in Doha, Qatar, with countries led by the United States fearing an open-ended liability for compensation.

The Doha meeting agreed to put in place "institutional arrangements" for loss and damage in Warsaw.

Sano said his father's family hails from the Tacloban region of the Philippines that bore the brunt of Super Typhoon Haiyan, the strongest storm ever recorded to have made landfall.

"Until this hour it remains uncertain what happened to many of our relatives," he said.

"It gives me great strength and big relief to hear from my very own brother who has survived the ordeal and I stand in solidarity with him."

World nations launched a new round of talks in Warsaw Monday to pave the way for a 2015 deal for cutting climate-altering greenhouse gas emissions.

The 12-day United Nations talks opened amid a slew of warnings about potentially disastrous warming with increasingly extreme weather phenomena unless humankind changes its atmosphere-polluting, fossil-fuel burning ways.