Warsaw - The devastation caused by Typhoon Haiyan cast a gloom over UN climate talks on Monday as the envoy from the Philippines broke down in tears and announced he would fast until a "meaningful outcome is in sight".Naderev "Yeb" Sano's emotional appeal was met with a standing ovation at the start of two-week talks in Warsaw where more than 190 countries will try to lay the groundwork for a new pact to fight global warming.UN climate chief Christiana Figueres also made reference to the "devastating impact" of the typhoon in her opening speech, and urged delegates to "go that extra mile" in their negotiations.Scientists say single weather events cannot conclusively be linked to global warming. Also, the link between man-made warming and hurricane activity is unclear, though rising sea levels are expected to make low-lying nations more vulnerable to storm surges.Nevertheless, extreme weather such as hurricanes often prompt calls for urgency at the UN talks.Voluntary fastingLast year, Hurricane Sandy's assault on the US East Coast and Typhoon Bopha's impact on the Philippines were mentioned as examples of disasters the world could see more of unless it reins in the greenhouse gas emissions that scientists say are warming the planet."We can fix this. We can stop this madness. Right now, right here," Sano told delegates in Warsaw.Choking on his words, he said he was waiting in agony for news from relatives caught in the massive storm's path, though he was relieved to hear his brother had survived."In the last two days he has been gathering bodies of the dead with his own two hands," Sano said."In solidarity with my countrymen who are struggling to find food back home ... I will now commence a voluntary fasting for the climate," he added. "This means I will voluntarily refrain from eating food during this [conference] until a meaningful outcome is in sight."On the sidelines of the conference, climate activists called on developed countries to step up their emissions cuts and their pledges of financing to help poor countries adapt to rising seas and other impacts of climate change.Tense discussions also are expected on a proposed "loss and damage" mechanism that would allow vulnerable countries to get compensation for climate impacts that it's already too late to adapt to.Asked whether the US had any plans to increase its emissions target in the international talks, US negotiator Trigg Talley said the "focus for us now" is to meet the existing target, of cutting emissions by 17% between 2005 and 2020."I think that we are on the right track to achieve it," he said, noting President Barack Obama's plans to cut emissions from power plants, boost renewable energy and other measures.Though no major decisions are expected at the conference in Warsaw's National Stadium, the level of progress could be an indicator of the world's chances of reaching a deal in 2015. That's the new watershed year in the UN-led process after a 2009 summit in Copenhagen ended in discord.