The COP30 climate summit opened this week with United Nations climate chief Simon Stiell urging countries to cooperate as global efforts to limit warming face strains from a fractured international consensus.

Brazil, the host nation, brokered an agenda agreement for the two-week meeting in Belem, heading off attempts by developing-country blocs to insert divisive issues such as climate finance and carbon taxes. It remained unclear whether nations would seek a final agreement at the close of the event, given heightened geopolitical tensions and U.S. resistance to phasing out fossil fuels.

Stiell told delegates from more than 190 countries that their task was to confront the climate crisis together. A new U.N. analysis estimated global emissions would fall 12% by 2035 compared with 2019 levels, still far short of the 60% cut needed to limit warming to 1.5°C.