The EU’s Green Leadership Under Strain: Climate Diplomacy, Green Deal Diplomacy, and External Action in a Turbulent Geopolitical Era

Ten years after the Paris Agreement, the European Union (EU) finds its long-asserted leadership in global climate governance increasingly contested and internally constrained. This paper assesses the evolution and resilience of the EU’s external climate action—encompassing traditional climate diplomacy as well as the broader and more ambitious European Green Deal (EGD) diplomacy—in an era marked by geopolitical turbulence, geo-economic rivalry, and overlapping poly-crises. The paper situates the EU’s external climate engagement in the shifting geopolitical order shaped by the United States’ withdrawal from multilateral climate cooperation, the rise of China as both a systemic rival and indispensable climate actor, and the intensification of South–North debates on equity, development, and climate finance. Against this backdrop, the EU has attempted to recalibrate its diplomatic posture through EGD diplomacy, linking climate ambition to just transition frameworks, renewable energy partnerships, energy democracy, green industrialization, and expanded financial instruments. Yet the EU’s capacity to project stable and credible leadership is increasingly undermined by internal political developments. The roll-back of the EGD, the strategic reorientation toward an “industrial deal” prioritizing competitiveness and security of supply, and the growing influence of authoritarian populism and climate skepticism challenge the coherence and legitimacy of the EU’s external climate ambitions. These dynamics have weakened the Union’s ability to present itself as a normative frontrunner, complicating negotiations with Global South partners who already view EU initiatives such as the Carbon Border Adjustment Mechanism (CBAM) through the lens of distributive justice and green protectionism. Drawing on critical geopolitics, climate governance scholarship, and work on the geo-economics of the green transition, this paper evaluates whether the EU can sustain its leadership role in shaping global climate norms, institutions and practices. The paper examines how internal and external pressures interacted during the lead-up to and outcomes of COP30 in Belém, highlighting the tensions between the EU’s ambition to achieve global decarbonization and its constrained diplomatic maneuverability. It argues that while the EU retains significant regulatory, market, and diplomatic power, its leadership is increasingly conditional, negotiated, and vulnerable to both internal fragmentation and external strategic competition. Ultimately, the paper contributes to debates on the future of climate multilateralism by assessing whether the EU can adapt its climate and EGD diplomatic practices to remain a stabilizing and transformative force in a rapidly changing geopolitical environment.