Renewable ambition outpaces delivery especially after the Paris Agreement

The Paris Agreement requires countries to set increasingly ambitious targets. Whether that actually leads us closer to the ultimate temperature goals (1.5–2 °C), however, is heavily contested. Scholars disagree whether more ambitious targets remain credible and translate into faster delivery or instead widen implementation gaps. We develop a framework to address this debate by empirically analysing how ambition relates to credibility and delivery, how these relationships changed after Paris, and which national predictors shape ambition and outcomes. We focus on renewable electricity — a central pillar of decarbonisation with observable outcomes — in the G20 and EU, which together account for over 80% of energy-related CO2 emissions and 90% of installed renewable capacity. Drawing on our newly developed database of over 1,100 renewable electricity targets set since 1995, we compare ambition and delivery over time and within and across countries, measuring both as the targeted versus actual acceleration of renewables’ share of electricity generation (percentage points per year, pp/year). We show that while ambition has increased over time, more ambitious targets are less credible and yield only moderate delivery, leaving substantial implementation gaps. This trend has worsened after Paris: before Paris, 1 pp/year higher ambition was associated with 60% lower odds of target attainment and 0.51 pp/year of delivery; after Paris, these changed to 86% lower odds and 0.22 pp/year, a shift evident across every country we analyse. National predictors shaping ambition rarely align with expected outcomes: greater renewable resource potential is associated with higher ambition but wider implementation gaps, while higher GDP/capita and greater institutional capacity reduce, but do not eliminate the credibility penalty of ambition. More effective ratcheting thus requires rising ambition to be matched by supportive conditions and greater implementation capacity. Whether and how quickly these enablers can be strengthened needs urgent scrutiny.