DUBAI, United Arab Emirates — World leaders have assembled for the start of COP28, this year’s pivotal United Nations climate conference aimed at forging renewed global cooperation against an escalating environmental crisis.

The high-stakes gathering will seek to make progress where previous efforts have fallen short. Negotiators hope to keep warming below 1.5°C while managing mounting harm — but face divisions over emissions cuts, deadlines, finance and accountability.

“This may be our last best chance to get on track before it is too late,” warned UN Secretary General António Guterres in opening remarks. He said humanity sits at a “highway to climate hell with our foot on the accelerator” unless urgent breakthroughs emerge from Dubai beginning this week.

Contention however surrounds an agenda to radically speed decarbonization worldwide versus arguments that developing nations require continued fossil fuels during transitions. A emotively-debated loss and damage fund proposed to support climate-vulnerable nations already suffering extremes also factors prominently.

COP28 President Sultan Al Jaber called for pragmatism and technological innovation. “The world is looking to the UAE and our partners to continue pioneering real world solutions,” he said, touting prolific Middle Eastern solar energy investments as models.

Critics counter that finding agreement remains a towering challenge between reluctant mega-emitters and smaller affected countries lacking leverage or resources to act. Demonstrators today chanted “no more greenwashing” at regional fossil fuel producers. Previous COPs have sometimes exposed rifts rather than cooperation between blocs.

Hence focus remains centered on potential unexpected breakthroughs in the 12-day marathon negotiations ahead. Participants emphasize that science shows the stakes have never been higher with each passing year. Hard deadlocks must be dissolved to make tangible progress.

“Whatever it takes, we must seize the chance to stop this suicidal inertia,” implored the Prime Minister of Barbados. “The eyes of the world are truly upon us like never before.”