Assessing risks to the implementation of NDCs under the Paris Agreement

The Paris Agreement introduced a system of voluntary commitments based on a framework of pledges and reviews. Central to its success are the Nationally Determined Contributions (NDCs), which outline each party’s mitigation efforts. However, a substantial gap remains between the emissions reductions promised in the NDCs and the levels required to limit global warming to well below 2°C, raising concerns about an ‘implementation gap’. This study investigates potential threats to NDC implementation across 21 countries and the EU. We identify five key risks, NDC ambition, institutional capacity, opposition by interest groups, policy inconsistency, and monitoring and enforcement, and use cluster analysis to group countries by common risk profiles. We identify four distinct clusters, each characterized by different configurations of constraints. While some countries are better positioned to implement their pledges, three of the four clusters face substantial risks that jeopardize full implementation. In addition to showing how the drivers of implementation failure differ across contexts, our findings underscore that short-term threats are related to a lack of political will, and often tied to weakened civil societies or entrenched fossil fuel interests. Moreover, we argue that while institutional capacity represents a structural constraint, other risks – such as policy inconsistency or lack of stakeholder engagement – are more tractable and may be addressed through targeted governance reforms. Finally, our results suggest that uniform global climate support mechanisms are unlikely to be effective; differentiated strategies tailored to countries’ institutional and political risk profiles are essential to closing the implementation gap.Full implementation of NDCs is unlikely as most groups of countries face significant risks to achieving full implementation.Paris Agreement parties can be divided into clear groups based on NDC ambition, institutional capacity, opposition by interest groups, inconsistencies in policy mixes, and a lack of monitoring and enforcement ability.The most common risks to NDC implementation are political in nature (e.g. intentionally weakened policy monitoring and enforcement systems and inconsistent policy design).Not all risks are equally pernicious. While structural risks, such as institutional capacity, are more difficult to overcome, other risks (e.g. inconsistent policy mixes and a lack of stakeholder engagement) can be ameliorated more easily.Gathering data on the domestic factors influencing NDC implementation is a priority for future policy-relevant research.