Three Peaks

Most climate action is about promises. The United Nations Framework Convention on Climate Change (UNFCCC) states that if global warming is to be limited to 1.5C, greenhouse gas emissions should have peaked by the end of 2024. They didn’t. But on a global level—the only level that matters to the atmosphere—that peak does now appear to be in sight. The “Stated Policies Scenario” in the International Energy Agency’s (IEA) 2025 World Energy Outlook report, which “reflects the prevailing direction of travel” for the energy system,[1] states that CO2 emissions will peak “in the next few years”. The folks at BP—the fossil-fuel firm once known as Beyond Petroleum, newly refocused on gas, oil and value for shareholders—agree: their 2024 Energy Outlook expects peak carbon emissions in the mid-2020s.

If that peak is close, there is still some bad news: even after three decades of climate diplomacy, globally humans haven’t even begun to reduce annual CO2 emissions. What, then, is the fate of the 1.5C temperature target? Should its death be officially declared?

If it is dead, this is not primarily because that peak is coming too late. Rather, it is because beyond the summit looms a giant plateau. To keep within the 1.5C, target emissions must not only peak before 2025—they must then decline by 43 per cent by 2030. By contrast, in that same time period, the IEA expects CO2 emissions to decline by 35 per cent, even in the unlikely scenario that global governments exceed their current policies and stick to their “announced pledges”.

The most important of those pledges is China’s: in 2020 President Xi announced that the country would aim to have emissions peak before 2030, en route to "carbon neutrality before 2060". China may already have achieved this. Its emissions fell by 1 per cent between the starts of 2024 and 2025,[2] and may be entering structural decline thanks to the massive expansion of renewable power and electric transport. Other major emitters are less specific. In 2021 India’s environment secretary Rameshwar Prasad Gupta elaborated on Prime Minister Modi’s pledge to reach net-zero carbon by 2070, adding that he foresaw an emissions peak sometime between 2040 and 2045.

Each of these promised peaks contains within it hidden assumptions. Emissions can peak later, for instance, so long as they then fall faster; however, a faster fall entails quicker and greater capital destruction: a 2022 study in Nature calculated that climate policy could plausibly prevent the realization of $1 trillion in profits from upstream oil and gas assets, a figure that didn’t include potential losses in the coal sector or among manufacturers of fossil-fueled machines. It might be possible to protect more of those assets—to burn more of the carbon that already appears on balance sheets—if humans removed an equivalent amount of carbon from the atmosphere.

But humans have already played that card, at least mentally if not in practice. Most scenarios for keeping warming below 2 degrees demand that at least 4 billion tonnes of CO2 per year is removed from the atmosphere each year by 2050, while 1.5 would require more like 7-9 billion tonnes per year. To put this figure in context, current annual emissions sit around 41 billion tonnes. 4 billion is about twice as much as current removals, virtually all of which comes from conventional methods like planting trees where there is limited room for growth. To achieve this extra removal, climate modellers are counting on novel methods of carbon dioxide removal (CDR), such as the deployment of machines to grab carbon out of the air, to grow astronomically from the current level of 1.3 million tonnes a year, of which only half is stored effectively permanently. This sort of growth would be easier to envision if, as is the case for manufacturing solar panels or batteries, carbon removal made any profits for anyone—if markets naturally assigned it exchange value.

Since so many promised peaks come too late, they tend to rely on “overshoot” to hit the mark: the idea that emissions will temporarily exceed the level required for a given level of warming before negative emissions technologies drag levels back down. The “ideology” of overshoot[3] was laid bare in October 2025 during IPCC chair Jim Skea’s keynote at an overshoot conference in Laxenburg, Austria, which he opened with a spin on the prayer of St. Augustine: “Lord, limit warming to 1.5C over pre-industrial levels,” he said. “But not yet”.

Overshoot ideology faces both a risk related to politics and a problem related to physics. The risk is that carbon removal does not grow as hoped and these scenarios instead provide cover for the continued expansion of fossil fuels. The problem is that carbon removal does not function as a time machine. Once a tipping point is crossed—say, a polar ice sheet begins to melt, or the Amazon rainforest starts becoming a Savannah, or the Atlantic meridional overturning circulation current, that keeps Europe mild and the Western tropics somewhat below boiling, begins to fade away—removing carbon from the atmosphere does not return the system in question to its previous state. Instead, it settles into a new equilibrium. The damage is irreversible.