Stay informed with free updates
Simply sign up to the Climate change myFT Digest — delivered directly to your inbox.
If you thought the politics of climate change was hard, I am afraid you have seen nothing yet.
As things stand, the world will soon enter the age of climate overshoot for the first time. We are on track to blow through the 2015 Paris Agreement’s goal of trying to stop the long-term average global temperature rising any more than 1.5C from what it was before fossil-fuel burning took off in the late 1800s.
Keeping “1.5C alive” will then require action at such a scale that today’s debates about the costs of net zero or adapting to climate extremes will be transformed by a slew of new and troubling stand-offs.
This thought may jar in a season of hope and joy. But knowing what lies ahead is the best way to avoid the worst of it and, today, understanding is slight.
This is largely because overshoot is so politically fraught.
Researchers have reported for some time that the 20-year average global temperature — a scientific convention for measuring the Paris goals — may reach and then exceed 1.5C in the early 2030s.
In plain English, this alone is an overshoot. But in climate science, the word has come to mean surpassing and then trying to return to a target such as 1.5C this century.
Political leaders have been reluctant to address the problem openly. António Guterres, the UN secretary-general, raised eyebrows in October when he said it would not be possible to contain global warming below 1.5C “in the next few years” and “overshooting is now inevitable”.
November’s COP30 climate conference was the first to formally acknowledge the probability of overshooting, and the need to limit its magnitude and duration.
The reluctance is understandable, considering what is likely to happen once 1.5C is exceeded. For a start, climate action sceptics will almost certainly pounce on the categoric failure of the Paris Agreement. Some will argue such targets are pointless.
But because warming above 1.5C is likely to bring the world closer to irreversible tipping points and other climate risks, some governments may push for targets even more burdensome than the already heroic goal of reaching net zero by mid-century. Net zero means bringing emissions down as much as possible, then balancing any leftovers by removing an equal amount of carbon from the atmosphere.
Temperatures should stop rising once net zero is reached. But the world has been so slow to cut emissions that by then, the average global temperature is set to be higher than 1.5C. So returning to a 1.5C rise would require not just huge emission cuts but the removal of vast amounts of carbon. In other words, we would be leaving the world of net zero and entering an age of net negative emissions goals.
The technical challenges alone would be large. At the moment, about 2bn tonnes of CO₂ is removed each year, roughly 5 per cent of the annual total produced by burning fossil fuels. This is mostly done by restoring or establishing forests. Only a tiny fraction is achieved with more efficient but far more costly measures such as machines that capture CO₂ from the air and store it deep underground.
Lowering the global average temperature by just 0.1C could require a cumulative 220bn tonnes of net negative CO₂ emissions by 2100, according to scientific reports from the UN’s Intergovernmental Panel on Climate Change.
As two contributors to those reports, Oliver Geden and Andy Reisinger, wrote recently, this will require sweeping policy rethinks, especially in richer countries. Even in the green-minded EU, rows would be likely between the poorer nations demanding the right to stay net positive while the richer ones go net negative. Plus, if the whole bloc went net-negative, it would sap revenues from its carbon-pricing system, since there would be less carbon to price.
More broadly, today’s debates on which countries should bear the financial burden of climate action, and how much emerging economies like China should cough up, would go on steroids.
It would therefore be tempting to ditch 1.5C and focus on the Paris Agreement’s other goal, to keep warming “well below” 2C. But how far below? And why would poorer countries already struggling to manage climate damage agree to a higher temperature target without far more financial support?
One way or another, overshoot is set to upend climate politics. Ignoring this is convenient, but ultimately helps no one. As ever, the overwhelming lesson is clear: the sooner we cut emissions today, the less trouble we face tomorrow.