How much must emissions fall each year to reverse the 1.5C overshoot, according to the UN Emissions Gap Report?

Global emissions must be reduced by nearly 6% a year for the world to have a good chance of bringing warming back down to the Paris Agreement limit of 1.5C, according to the UN Emissions Gap Report published on 21 October. The report frames this as the path needed to reverse an overshoot of 1.5C by the end of the century, rather than to avoid crossing the threshold in the first place.

A second set of figures from the United Nations Environment Programme puts the near term picture in starker terms. Global greenhouse gas emissions would need to fall by nearly a fifth in five years, an 18% cut, for just a 50% chance of keeping the temperature rise at a peak of 1.8C this century. In other words, even the more modest outcome now requires a steep drop within a single reporting cycle for most companies.

For sustainability teams, these numbers matter because they set the external yardstick against which corporate targets will be judged. A transition plan built on a gentle linear decline will look thin next to a benchmark of roughly 6% a year. Teams drafting or refreshing targets under the CSRD and ESRS E1 will face harder questions from auditors, investors and NGOs about whether their pace of reduction bears any relation to what the science now demands.

The practical consequence is a higher premium on credible, measured baselines. Annual cuts of that size cannot be demonstrated without reliable GHG Protocol Scope 1, 2 and 3 data collected consistently year on year. Companies with patchy supplier data or estimated Scope 3 figures will struggle to show whether they are on or off the trajectory, let alone defend it in a limited assurance review.

What to watch next is how these UN figures filter into voluntary frameworks and investor stewardship. Expect asset owners and lenders to cite the 6% annual figure when they challenge portfolio companies on target ambition. The report adds weight to a message that has been building across recent editions: targets are no longer enough, and delivery against a steep, measurable curve is where scrutiny is heading.