Unpopular Opinion 1: 1.5C is dead

In the Paris Agreement the nations of the world agreed to hold “the increase in the global average temperature to well below 2°C above pre-industrial levels” and pursue efforts “to limit the temperature increase to 1.5°C above pre-industrial levels.” It was always an ambitious target and we’ve missed it.

The global annual temperature increase first exceeded 1.5C last year. Climate scientists were surprised at the speed at which it rose and have stressed the impact of a strong El Nino event. This allows them to say that the long-term trend has not taken the temperature over the second Paris Agreement target. Probably true. But so what?

The temperature has exceeded the target and – to coin a phrase – the climate doesn’t care about special factors. Up is up. 2025 will probably be a little cooler but it will be the second or third warmest year on record. Then the increase will resume.

We can be a bit more formal. The admirable Global Carbon Project (GCP) has calculated the remaining carbon budget for an annual temperature of 1.5C at 170 GtonnesCO2. That’s almost exactly four times the likely 2025 emissions. Last year emissions rose by 0.8%; similar to the previous four years. The UN Shared Socioeconomic Pathway that best fits the data (SSP2-4.5) shows annual emissions rising until about 2040. That would exhaust the 1.5C budget within a little less than four years so we'll exceed the target unless we reach Net Zero in 2029.

Surely I’m joking? Yes. Short of a nuclear winter that won’t happen.

So we cannot keep the temperature increase below 1.5C. The target is dead. And I’m not alone in saying so. Michael Le Page said the same in New Scientist last month (19/10/25) as did Hannah Ritchie of Sustainability By Numbers this month.

That matters a lot.

The clear evidence won't stop people arguing to "keep 1.5 alive!" but it can't be done. We can, perhaps, accept that we'll exceed the target but hope to bring the temperature increase back down to 1.5. That's really not the same and any plan to do so will face the same problems that have beset the COP process.