COP28 President Sultan Al Jaber urged countries on Friday to get out of their comfort zones and work together to reach an agreement before the two-week summit ends.
"Let's please get this job done," he said, opening a plenary session as the summit entered its toughest phase of negotiations.
"I need you to step up and I need you to come out of your comfort zones," he said.
With five days left before the conference's scheduled end on December 12, country ministers are joining the deliberations on Friday.
Still unresolved is how the nearly 200 countries at COP28 will handle the thorny issue of fossil fuels, the main source of climate-warming emissions, with at least 80 countries demanding a COP28 agreement that calls for an eventual end to their use.
Such a position would be unprecedented, after three decades of UN climate summits that have never addressed the future role of fossil fuels head on.
Meanwhile, eastern European countries are working to resolve an impasse over where to hold next year's COP29 summit after Russia said it would block any EU member as COP president.
As of Friday, the candidates included Azerbaijan, which offered to host the event. Both Moldova and Serbia have also offered to take on the rotating presidency.
“COP28 is already sending a clear signal that all of us, small and large, can make a difference.”— COP28 UAE (@COP28_UAE) December 8, 2023
Dr. Sultan Al Jaber calls on parties to deliver the most ambitious decision possible at COP28. #COP28 pic.twitter.com/a2NO9Vol7i