Trump’s climate pullout won’t halt warming—but it risks fracturing global cooperation

US actions were hardly unexpected. Donald Trump’s renewed assault on climate multilateralism follows a familiar script—withdrawal, obstruction and disregard for scientific consensus.

His decision to pull the United States out of the UN Framework Convention on Climate Change and disengage from the Intergovernmental Panel on Climate Change changes nothing about the physical realities of the climate system. Temperatures will continue to rise. Seas will keep swelling. Extreme weather will intensify. Nor does exiting more than 60 international treaties and multilateral bodies reverse the economic direction of travel, as investment in low-carbon energy continues to outpace fossil fuels.

What it does do is drain funding from non-profit organisations working on climate action and inject uncertainty into a sense of inevitability that had begun to take hold among governments, markets and the public.

More critically, this retreat reshapes the politics of cooperation at precisely the moment when speed and coordination matter most. Climate negotiations are entering a far more complex phase—defined by carbon budgeting under overshoot scenarios, contested debates on geoengineering, and the urgent need to deploy solutions faster than impacts are accumulating. Walking away from global forums erodes trust, narrows diplomatic space and leaves the hardest questions unresolved. It also shifts costs inward. As UN climate chief Simon Stiell has warned, American households and businesses will ultimately pay the price through greater energy volatility, rising climate damage and missed economic opportunities.

Against this backdrop, the message from the UNEP Emissions Gap Report 2025 is stark. The so-called multi-decadal average global temperature is now expected to temporarily breach 1.5°C within the next decade. To remain aligned with the 1.5°C goal, global greenhouse gas emissions would need to fall by roughly 55 per cent by 2035—a target far beyond current national pledges. The World Meteorological Organization reinforces the warning: 2025 ranked among the three warmest years ever recorded, extending a run of unprecedented global heat.

Even in the United States, where emissions fell by about 20 per cent between 2005 and 2024, progress is losing momentum. Last year saw an uptick in both methane and carbon dioxide emissions. That reversal matters because it reflects a broader global problem: mitigation is not happening at the pace required, even as climate impacts accelerate.

For the Global South, this is not an abstract concern. In India, heat has become a direct economic shock. The Lancet Countdown estimates that in 2024 alone, heat exposure cost the country around 247 billion potential labour hours, translating into nearly $194 billion in lost income. As warming intensifies, these losses will compound, widening inequality and undermining development gains.

This context makes the choice of solutions crucial. As pressure mounts, so does the temptation to reach for quick fixes. Geoengineering is increasingly framed as a backstop in an overshoot world. Solar radiation modification—such as stratospheric aerosol injection—aims to cool the planet by reflecting sunlight back into space. But the science remains incomplete and the risks profound: disrupted rainfall patterns, damage to the ozone layer, threats to food systems and serious public health concerns. The geopolitical questions are equally fraught. Who decides when and how such technologies are deployed? What happens when countries blame floods or droughts on deliberate intervention? And how do we manage the risk of “termination shock” if such measures are abruptly halted?

More fundamentally, solar dimming does not address the root cause of climate change. Temporarily lowering temperatures is not the same as reducing or removing greenhouse gases from the atmosphere. A sunscreen is not a cure. Leaning on speculative fixes risks weakening incentives for real mitigation at the very moment when resolve is most needed.

There is, however, a faster and safer lever available. Cutting short-lived climate pollutants, particularly methane, offers the most effective way to slow warming in the near term. Methane—the second-largest contributor to warming after carbon dioxide—accounts for roughly 30 per cent of observed warming and around 0.5°C of current temperature rise. Over a 20-year period, it is more than 80 times as potent as CO₂. Its concentrations have more than doubled since pre-industrial times and continue to climb.

The key difference lies in methane’s short atmospheric lifetime. Rapid reductions can deliver rapid results. A global effort to cut methane emissions by 45 per cent by 2030 could avoid nearly 0.3°C of warming by the 2040s—several times the near-term benefit expected from carbon dioxide reductions alone. This is the closest thing the climate system offers to an emergency brake. Without it, the risk of overshoot grows, along with pressure to gamble on unproven technologies.

December 2025 marked 10 years since the Paris Agreement was signed. The accord did bend the curve, pulling the world back from a pre-Paris trajectory of roughly 3.5°C of warming to around 2.3–2.5°C. That remains dangerously above the agreed 1.5–2°C range, but the progress was real. The anniversary serves as both a reminder of what coordinated action can achieve—and a warning of how much harder the road ahead has become.

Paris was never meant to be an endpoint. It was meant to be a framework for escalation. Ten years on, the test is whether countries choose to accelerate cooperation and mitigation, or retreat just as the costs of delay become impossible to ignore.