Simon Stiell, Executive Secretary of UN Climate Change, has warned that exceeding the 1.5 degrees Celsius global temperature limit is now guaranteed, at least temporarily, even as he insisted the world must accelerate efforts to bring the temperature rise back down.
Stiell specifically urged the tech industry to integrate AI more deeply into climate solutions while urgently curbing its own growing environmental footprint. He noted that if AI can solve complex mathematical problems that stumped researchers for decades in mere days, it holds untapped potential to accelerate progress on critical climate challenges, such as enhancing early-warning systems for extreme weather disasters, optimizing electricity grids for greater efficiency, and supporting adaptation efforts in vulnerable regions.
Stiell made the remarks at the Industrial Transition Accelerator’s Industry Acceleration Summit in New York on Monday, September 21.
He said holding the rise in global temperature to 1.5 degrees Celsius this century is demanded by science, agreed by nations, and essential to protect every person and economy, but a recent report by the UN Environment Programme has reaffirmed that the limit will be exceeded.
“You’re allowed to think about the worst possible scenario. But you’ve got to go out there and do something about it,” Stiell said, quoting New York Knicks basketball star Jalen Brunson.
He said the response must be building resilience and cutting greenhouse gas pollution faster to bring the temperature rise back below 1.5 degrees as quickly as possible, which demands international cooperation focused on implementation.
Stiell noted that “UN-convened cooperation and national efforts have reduced the projected global temperature rise from well over 4 degrees Celsius to 2.6 degrees Celsius, describing it as undeniable progress that is still not enough to avoid catastrophe”.
He cited new data released by the International Renewable Energy Agency showing that renewable capacity additions reached a record high of 693 gigawatts last year, more than half the installed power capacity of the entire United States.
According to Stiell, global renewables helped humanity avoid almost half a trillion US dollars in fossil fuel costs last year, a figure larger than the national GDP of over three-quarters of countries on Earth.
He said clean energy attracted more than $2 trillion in investment last year alone, while driving jobs and growth around the world.
“Narrowing the gap between pledges and action on the ground would be a central focus of COP31 in Türkiye and COP32 in Ethiopia next year, with the second global stocktake in 2028 expected to show substantial progress against commitments made in the first,” he noted.
He disclosed that UN Climate Change is exploring whether countries could designate a representative to coordinate across governments and the private sector to drive the transition in every industry, alongside operational changes such as an Action Agenda closing plenary at COP summits.
The Turkish COP31 Presidency, working with Australia, has set clear Action Agenda targets including for electricity to reach 35 percent of global energy use by 2035, according to Stiell, who urged countries, business leaders and investors to bring solutions to Antalya.
He said the UN carbon market is up and running, providing potential new channels of investment, with this year’s focus on meeting existing finance commitments and mobilising public and private finance, climate funds and Multilateral Development Banks to move the Baku to Belém Roadmap toward its $1.3 trillion target.
Stiell praised the ITA for showing what it takes to drive progress, noting that 19 commercial-scale projects reached final investment decision in the first half of the year, together worth an estimated $43 billion.
He stated that “bringing global temperature rise back down to 1.5 degrees Celsius will require much greater cuts to fossil fuel pollution, alongside carbon dioxide removals as an addition to, not a replacement for, transitioning away from fossil fuels”.
On artificial intelligence, Stiell said the technology could do more on key climate challenges such as improving early warning systems for climate disasters and accelerating grid efficiency, but warned that energy-guzzling AI is driving up pollution from coal, oil and gas while raising energy costs for households and businesses.
“AI leaders are now on thin ice when it comes to license to operate, and sinking deep underwater when it comes to public support,” he said, noting that data centres are being put on hold in parts of the United States and elsewhere.
He called on tech industry leaders and boards to set and deliver credible climate targets, invest in efficiency, disclose their energy and water use, and power data centres with renewable energy.
Stiell warned that the climate crisis is now a national economic and security emergency for all nations, citing disasters in the Himalayas, brutal heatwaves and the supercharged impacts of El Niño.
He said fossil fuel dependence has heaped over $100 billion in extra costs on US consumers alone in higher gas and diesel prices since the Middle East conflict began.
“Countries that choose to resist the clean transition aren’t protecting old industries – they’re sending new innovations, sectors, jobs and pay checks to competitor economies,” Stiell said, noting that renewables overtook coal as the world’s top electricity source last year.
He concluded by calling for a doubling down on climate multilateralism, noting that every nation agreed at COP30 that the Paris Agreement is working and must be made to go further and faster.
