Climate Scientists Lower Worst-Case Global Warming Forecast as Renewable Energy Reshapes Emissions Outlook

For years, the nightmare climate scenario floated around scientific reports like an unavoidable apocalypse: a world warming by 4.5°C by the end of the century, with collapsing ecosystems, disappearing coastlines and weather disasters becoming part of everyday life. That scenario has not vanished entirely — climate scientists are rarely in the business of optimism — but it is now looking considerably less likely.

A new generation of climate projections suggests the planet may avoid the very worst outcomes once considered plausible, largely because renewable energy has become cheaper and more widespread far faster than many experts predicted a decade ago.

According to updated modelling by the international Scenario Model Intercomparison Project (ScenarioMIP), the upper boundary for the most extreme warming pathway has now been revised downward from roughly 4.5°C to around 3.5°C above pre-industrial levels by 2100.

That may sound like good news — and in climate science, where victories are often measured in fractions of a degree, it partly is. But researchers stress that a world warming by 3.5°C would still be profoundly destabilising for economies, ecosystems and human societies. In other words, the catastrophe has become slightly smaller, not cancelled.

The revised scenarios will feed into future assessments by the UN’s Intergovernmental Panel on Climate Change (IPCC), whose reports heavily influence global climate policy.

The reason for the adjustment is relatively straightforward: the world has not continued down the fossil-fuel-heavy path many earlier models assumed. Solar and wind energy prices have collapsed over the past decade, making renewables economically competitive in regions where coal once seemed untouchable. Even governments not especially enthusiastic about climate activism have discovered they quite enjoy cheaper electricity.

As a result, emissions growth has started tracking below some of the more extreme assumptions used in earlier climate models.

The updated projections incorporate real-world data through 2023, rather than stopping at 2015 as previous models did. Scientists also improved simulations of how forests, oceans and other natural systems absorb carbon dioxide as temperatures rise.

Still, the researchers behind the report are careful not to oversell progress.

Even the revised “less terrible” worst-case outcome would still exceed the goals agreed under the 2015 Paris climate accord, where countries committed to limiting warming to well below 2°C and ideally to 1.5°C.

Current policy trajectories point toward roughly 2.5°C of warming by the end of the century if governments maintain existing climate measures without major additional action. Delayed mitigation followed by eventual net-zero emissions could still leave the planet around 2°C warmer.

And even lower-emissions pathways come with serious long-term consequences.

Scientists warn that certain tipping points in the Earth’s climate system may become irreversible even if warming is later reduced. Rising sea levels, shrinking ice sheets and damage to ecosystems such as coral reefs and rainforests could persist for centuries — or longer — once triggered.

The report outlines several possible futures, ranging from aggressive global cooperation on clean energy and emissions cuts to scenarios dominated by geopolitical rivalry, nationalism and renewed dependence on fossil fuels.

The darker pathways envision governments abandoning climate cooperation altogether while increasing investment in energy-intensive industries and technologies. Under such conditions, countries could prioritise economic competitiveness and energy security over environmental targets, leading to renewed expansion of oil, gas and coal production.

Some scenarios even assume that future technologies would allow the extraction of currently inaccessible fossil fuel reserves, effectively prolonging the carbon era far beyond today’s expectations.

Another concern raised in the models is that geopolitical tensions or shortages of critical minerals could slow renewable deployment. Trade disputes involving materials used in batteries, wind turbines and solar panels could potentially disrupt the energy transition.

In other words, climate progress is no longer determined solely by science or environmental policy. It is increasingly tied to industrial supply chains, global trade and political stability — topics that governments often manage with all the grace of a shopping trolley on ice.

The researchers emphasise that while the probability of the most catastrophic warming scenarios has declined, they have not disappeared entirely. Further modelling later this year will also examine carbon-cycle feedback effects, including how warming itself could reduce the planet’s ability to absorb greenhouse gases.

Those results could still shift projections again.

For now, however, the findings offer a rare moment of cautious relief in climate research: humanity appears to have stepped back from at least one edge of the cliff. The problem is that the remaining drop is still very large.

Written by Freya Stensrud