LIMA, Peru — A typhoon that forced at least 900,000 people to evacuate their homes in the Philippines highlighted the stakes for envoys at United Nations climate talks as a rift opened over how to fight global warming.

The storm named Hagupit was the third of its kind to strike the island nation in as many years during the annual round of UN talks aimed at limiting greenhouse gas emissions. Last year’s Typhoon Haiyan killed 6,300 people.

Developing countries fear storms like Hagupit will become more intense as the planet warms, and that rising sea levels compound the danger. That’s adding to tensions at the UN talks in Lima this year, where poorer countries are being asked to join in costly emissions limits for the first time, even as they argue industrialized nations are delaying action. Envoys are developing building blocks for a deal that will be weighed next December in Paris, including the form the pledges will take for the deal.

“The images of Hagupit should reverberate throughout the halls of the Lima climate conference,” said Shubert Ciencia, of the Philippine Rural Reconstruction Movement and a member of Oxfam’s team at the UN gathering. “Nobody should have to live under the threat of destruction year after year.”

Industrial nations led by the United States, European Union and Japan want contributions from countries represented at Lima to focus on pollution. China and India led developing nations seeking more details from their richer counterparts on how they’d meet a pledge to provide $100 billion a year in climate-related aid by 2020.

The pledges on aid and emissions are at the heart of the deal that would curb fossil-fuel pollution in all nations for the first time. While the debate at Lima is technical, it’s turned highly political because of the nature of the information each country will have to put forward.

“We’ll see the major tensions playing out,” Liz Gallagher, senior adviser to the policy analyst E3G, said in an interview. “Finance will be the sticking point because it crosses some large red lines of what the U.S. and EU can do.”

After a week of discussions in Peru’s capital, envoys from some 190 nations are ready to hand over discussion about how to reach a deal to senior ministers arriving Monday. At least five heads of state and UN Secretary General Ban Ki-Moon will join the meeting in Lima from Tuesday.

Leaders set to attend include presidents Ollanta Humala of Peru, Evo Morales of Bolivia, Michelle Bachelet of Chile, Juan Manuel Santos Calderon of Colombia and Baron Divavesi Waqa of Nauru.

Scientists say the warmer temperatures that the world already is seeing will wreak devastation by generating more frequent droughts and more violent storms.

Given current policies, the world is on track to warm 3.6 degrees Celsius by the end of this century, more than the target of 2 degrees agreed on years ago at these talks. While those levels would be unnoticeable in the course of a single day, when applied to the entire planet that would be quicker than the shift at the last ice age 10,000 years ago.

Divisions this year seem easier to bridge than previously partly because the two biggest polluters – the U.S. and China – came to this meeting with a pact to reduce emissions. Last week, Brazil said it was working on a similar target, the latest developing nation to indicate it would do so.

“We arrived here with a lot of wind in our sails and with people very, very optimistic,” Christiana Figueres, the UN’s top climate diplomat, said in an interview in Lima. “The global mood on climate change has definitely changed.”

The debate in Lima is about what information to require from countries that submit pledges under the Paris deal, which are known in the UN jargon as “Intended Nationally-Determined Contributions,” or INDCs.

The U.S., Europe and Japan want INDCs to focus on how and when each nation will reduce greenhouse gas emissions – mitigation in the UN lexicon.

Developing countries led by India and China think those goals are too narrow. They want specifics included on how the richer nations will pay the aid that they’ve promised to help the poorer nations fight global warming. They say the fight against global warming won’t be credible if focused on emissions alone.

“It’s clear that the Paris agreement is not an agreement centered or exclusively dealing with mitigation,” Raphael Azeredo, a negotiator representing Brazil, said in an interview. “We cannot fathom thinking about mitigation without thinking about adaptation and, of course, means of implementation.”

Richer countries are concerned the UN may adopt too many targets. “We are quite hesitant about that approach because we do think it will distract from the focus on getting mitigation targets as good as they can be and as well fleshed out as they can be,” Todd Stern, the lead State Department envoy on climate, said in Washington before traveling to Lima.

Japanese envoy Hideaki Mizukoshi said “adaptation or finance should be dealt with elsewhere,” and European Union negotiator Elina Bardram, said the notion of INDCs was created “specifically with mitigation in mind.”

There also are other technical issues up for debate. Those include whether the countries make five-year or 10-year commitments, what assumptions they’re making on future emissions growth in the absence of reductions, and whether the Paris agreement should incorporate a long-term goal on aggregate emissions reductions.

“We really need to agree on a couple of very basic things such as base year, what accounting methods are being used, what is the CO2 equivalent,” Bardram said.

For developing countries, those are all sensitive issues because they’re being asked to make pledges on greenhouse gases for the first time in the Paris deal. Since the UN started its global warming talks in 1992, it’s only been the industrial nations that have been required to make reductions.

Other questions might include “When do China’s emissions peak?” said Jake Schmidt, who follows the talks for the New York-based research group Natural Resources Defense Council. “What’s their 2025 target? What does Brazil’s deforestation baseline look like?”

The U.S. and its allies also want to be able to query and comment on the pledges of other nations, and expose them to what Stern calls the “sunlight” of publicity. That notion was rejected last week by China, which is reluctant to have outsiders getting access online to such detailed information about its energy industry.

“We really don’t see that process as being a punitive or normative process, but rather a facilitative exchange of views,” said Bardram from the EU.

For developing countries, finance is the key issue, and Chinese lead envoy Su Wei said last week that efforts by rich nations aren’t “adequate,” even after almost $10 billion in pledges have been counted for the UN’s Green Climate Fund.

Su said industrialized countries must chart how they’ll boost assistance through direct aid, funds and development banks to the $100 billion a year target by 2020. That promise also includes money from private companies.

The problem for the U.S. and EU when it comes to finance is their national budgetary processes mean they can’t apportion specific sums now to be spent on climate aid in 2020 and beyond.

The nature and content of the national contributions for the Paris deal will he be one of the most important elements of the talks in the coming days after “heated” debates in the past week, according do Dirk Forrister, president of the International Emissions Trading Association. The issues envoys talk about range from whether the commitments should be economy- wide, absolute or intensity-based to whether they should address just emissions cuts or also measures to adapt to climate change, finance and technology.

“Given how the contributions discussions have gone down and the importance of having this decision reached in Lima, that’ll be the one to watch,” said Forrister, who was a climate adviser to former president Bill Clinton. “Remember, national contributions are due in the next 100 days – so the guidance about how they’re structured is critical now.”

Two other issues up for discussion include deciding on a set of draft elements to be included in next year’s agreement and the need to increase the ambition of emissions cuts to be made before 2020, when the Paris deal would come into effect. The U.S., EU, Australia, Canada and New Zealand last week rejected a review of those goals, according to non-governmental organizations that are official observers to the talks.

“Negotiators here are fixing the fire alarms while the building burns,” said Tasneem Essop, head of delegation for the environmental group WWF. “Efforts to cut emissions before 2020 have completely fallen off the political radar.”

With assistance from Ewa Krukowska in Lima, Alex Nussbaum in New York and Cecilia Yap and Clarissa Batino in Manila.