Every movement needs a symbol, and for nearly a decade, the 1.5°C global warming limit has been the North Star of international climate action. It has rallied governments, inspired activists, and catalyzed global investment in renewable energy. Yet, in the stark light of COP29 in Baku, the cracks in this once-aspirational goal are glaring. Scientists are virtually unanimous: the 1.5°C target is slipping out of reach if it hasn’t already been surpassed. So why are world leaders and climate advocates clinging to a goal that increasingly feels more like a relic than a roadmap?
To answer this, we need to explore not just the science but the psychology, politics, and economics that have enshrined the 1.5°C target as a totem for the climate movement—even as the world hurtles toward 3°C of warming by the end of the century.
A Goal That Defined a Movement
The 1.5°C threshold didn’t emerge arbitrarily. It resulted from a pivotal moment in 2015 when the Paris Agreement sought to unify the world behind a clear, ambitious climate benchmark. Initially, the agreement focused on limiting warming to “well below 2°C,” but advocacy by small island nations, among the most vulnerable to climate change, helped cement 1.5°C as the aspirational target. The science that followed gave weight to their demands: a special 2018 report from the Intergovernmental Panel on Climate Change (IPCC) revealed that a 2°C world would be exponentially more destructive than a 1.5°C one—higher sea levels, more extreme heat waves, and greater species loss.
This half-degree difference became a rallying cry. It galvanised nations and corporations to set bold decarbonisation goals and pour trillions into renewable energy. As Samantha Gross from the Brookings Institution observed, “It wasn’t that long ago that we were on a 3°C, 4°C trajectory, and now we’re not.” The 1.5°C target became shorthand for survival, hope, and action.
The Inconvenient Truth: 1.5°C Is Already Lost
But reality has caught up. A new study suggests that global temperatures were already 1.49°C above pre-industrial levels at the end of 2023, and 2024 is set to be the hottest year on record. Even if temperatures temporarily stabilize due to cyclical climatic factors like La Niña, the planet is locked into warming. The United Nations projects that we are on course for 3.1°C warming by 2100 without drastic action.
The mood at COP29 reflects this sobering reality. World leaders have failed to show up in force, and domestic political crises—from U.S. disengagement under Donald Trump’s expected second term to Europe’s energy struggles—are sidelining climate priorities. Even Ilham Aliyev, Azerbaijan’s president and the host of this year’s summit, has spent more time defending fossil fuels than advocating ambitious climate policies.
Against this backdrop, the 1.5°C goal feels increasingly untenable. “It’s been deader than a doornail for a while now,” says Zeke Hausfather, a climate scientist at Berkeley Earth. And yet, the number remains ubiquitous in speeches, signage, and declarations. Why?
Why the Climate Community Can’t Let Go
The clinging to 1.5°C isn’t just inertia—it’s strategy. Symbols matter, and for better or worse, the 1.5°C goal has become a potent symbol of what’s at stake. It communicates urgency in a way no other metric has, translating abstract climate science into something tangible and motivating. As Wopke Hoekstra, the EU’s climate commissioner puts it: “No matter how difficult it is, I don’t want to give up on that goal, well knowing what the damage is that lies on the other end of that 1.5.”
Letting go of 1.5°C without a clear replacement could unravel years of progress. It risks signalling defeat, demoralising activists, and providing an excuse for governments and corporations to scale back their commitments. The stakes are particularly high for vulnerable nations, where 1.5°C represents a target and a lifeline. “AOSIS finds it necessary to disabuse critics of this notion that 1.5°C is dead,” said Cedric Schuster, the Samoan minister who leads the Alliance of Small Island States. Maintaining 1.5°C as a benchmark for these nations keeps the pressure on wealthier countries to act—and pay up.
What Comes After 1.5°C?
Even as the climate community doubles down to 1.5°C, there’s a growing recognition that a new framework is needed. But what should it look like? Should the world pivot to 1.6°C or 1.7°C as more “realistic” goals? Or should we abandon temperature thresholds altogether in favour of more actionable targets, such as achieving “real-zero” emissions—a concept championed by Australian billionaire Andrew Forrest—or limiting the cumulative carbon budget?
Some scientists and policymakers have embraced the idea of overshooting 1.5°C and returning to it, which would involve temporarily exceeding the target but removing enough carbon through reforestation and emerging technologies like carbon capture to bring temperatures back down. However, this is far from a panacea. Many climate impacts, such as sea level rise and biodiversity loss, are irreversible even if temperatures eventually cool. Overshoot scenarios also depend on speculative technologies that have yet to be proven at scale.
The Risk of Despair
Perhaps the greatest danger of acknowledging the death of 1.5°C is the psychological toll it could take on the global climate movement. For years, the narrative has been one of hope: that we can avert the worst outcomes through collective action. Admitting failure could lead to fatalism, especially when economic challenges and backlash against decarbonization policies already strain political will.
This tension is evident in the rhetoric of climate leaders. As Gross from Brookings points out, there’s a need to tread carefully. “You don’t want it to look like Trump killed it,” she says. “Because he actually didn’t. It was already dead.”
What COP30 in Brazil Could Reveal
Next year’s COP30 in Brazil will be a pivotal moment. Countries will be expected to set new emissions targets through 2035, and the success—or failure—of those commitments will reveal whether the world can pivot from symbolic goals to meaningful action. The stakes couldn’t be higher. If COP29 has been a sobering wake-up call, COP30 will determine whether the climate movement can reinvent itself for a world where 1.5°C is no longer possible.
Until then, the 1.5°C target remains a bittersweet symbol—a testament to the power of shared ambition and a reminder of how far we’ve fallen short. Whether it’s time to let it go or reimagine it may ultimately depend on what inspires the world to act before it’s too late.