Chapter 01 · Climate & transitionClimate & Greenhouse Gas Emissions
Ambition gap
Definition
The difference between collective climate ambition — as expressed in nationally determined contributions (NDCs) — and the emissions pathway required for the Paris goals. UNEP's Emissions Gap Report 2025 estimates that full implementation of current NDCs implies 2.3–2.5°C of warming this century, versus 2.8°C under current policies; aligning with 1.5°C requires emissions 55% below 2019 levels by 2035.
References
2.3–2.5°C under full NDC implementation vs 2.8°C current policies; 35%/55% cuts needed by 2035 for 2°C/1.5°C.
Implementation gap; 60 Parties covering 63% of emissions had new NDCs by 30 Sep 2025; 2024 emissions 57.7 GtCO₂e.
Net-zero pledges now covering ~70% of emissions; interpretation of trends.
Overview
What it means
The ambition gap is usually presented alongside an "implementation gap" — the difference between pledges and the policies actually in place. Both are quantified annually by UNEP's Emissions Gap Report series. The 2025 report noted that methodological updates and the announced US withdrawal from the Paris Agreement accounted for much of the apparent improvement, meaning new pledges "barely moved the needle".
How it is used
The gap frames the ratchet cycle of the Paris Agreement: each five-year NDC round is assessed against it, and it anchors calls for stronger 2035 targets. Governments, negotiators and media use UNEP's figures to judge whether the world is "on track".
Why it matters
The ambition gap converts abstract temperature goals into a concrete annual shortfall, showing how much faster and deeper cuts must be. It also exposes the credibility problem of climate diplomacy when pledges, policies and required trajectories diverge.
Definitions and controversy
Terminology varies — "ambition gap", "emissions gap" and "implementation gap" overlap; UNEP's annual report is titled *Emissions Gap Report*. Figures are model-dependent and revised yearly.