Carbon Budgets For 1.5 & 2°C

Current carbon budgets for 1.5°C and 2°C warming dangerously underestimate risks, relying on uncertain technologies and ignore critical climate feedbacks, leaving no real margin to avoid severe, irreversible climate impacts.

This briefing note on carbon budgets for 1.5°C and 2°C warming highlights serious flaws in current climate targets and budgets. It explains that the IPCC’s carbon budgets underestimate actual and future warming by ignoring critical climate feedbacks and relying on overly optimistic risk assumptions. The note stresses that 1.5°C warming is likely to be reached by 2030 or earlier due to past emissions, and that there is effectively no real carbon budget left to limit warming to 1.5°C without relying on speculative, large-scale carbon removal technologies that remain unproven.

Moreover, the briefing warns that current greenhouse gas levels already commit the planet to around 2°C warming or more, a threshold far from safe and potentially triggering irreversible “Hothouse Earth” conditions. It asserts that no credible carbon budget exists for 2°C if a sensible risk-management approach is applied. Even under IPCC assumptions, developed countries with high emissions must achieve zero emissions before 2030 to stand any chance of limiting warming. The overall message is that the carbon budget concept, while politically attractive, is scientifically uncertain and misleading, emphasising the urgent need for immediate, deep emission cuts.