The rise of the EU climate leadership occurred primarily between 1997 and 2005. During this period, the EU emerged as a prominent actor in international climate negotiations, with its leadership steadily strengthening. The EU played a pivotal role in the formulation of the Kyoto Protocol, not only as a key driver of agenda-setting but also by actively seeking compromise and cooperation between developed and developing countries to facilitate the Protocol’s ratification (Sbragia and Damro, 1999).

By implementing stringent emission reduction policies, the EU demonstrated its commitment to addressing climate change. Under the Kyoto Protocol framework, the EU’s member states shared responsibilities and adopted measures such as emissions trading and fiscal instruments, achieving significant emission reductions. These efforts not only earned the EU’s international recognition but also established its leadership in global climate governance.

Subsequent milestones included the launch of the European Climate Change Programme in 2000, the adoption of the Emissions Trading Directive in 2003, the inclusion of climate clauses in accession conditions for new member states in 2004, and the launch of the world’s first carbon market in 2005 (Eldredge and Gould, 1972).

During this era, the EU made substantial contributions to global climate governance through its strong leadership and action. It pioneered market-based governance innovations, such as carbon trading, and reinforced climate policy consistency during its eastward expansion. These measures solidified the EU’s position as the undisputed leader in climate governance (Ellerman and Buchner, 2007).

Entering the 21st century, the EU actively advanced climate policies to consolidate and strengthen its leadership. In 2005, the EU succeeded in including the “2 °C temperature control target” in the G8 Summit communiqué and launched the EU-China Partnership on Climate Change. In 2007, it adopted the binding “20-20-20” targets, aiming to reduce greenhouse gas emissions by 20% below 1990 levels by 2020 (Climate and Energy package 2009, 2008). At COP13 in Bali, the EU pushed for a “two-track negotiation” approach, creating a standoff with the U.S. position. During the 2008 economic crisis, the EU insisted on integrating climate action into recovery plans. It also legislated to include aviation in the EU Emissions Trading System (EU ETS), a move that inadvertently sowed the seeds for the subsequent decline of its climate leadership (Oberthür and Kelly, 2008).

On the policy front, the EU continuously refined its climate policy framework. In 2009, it adopted the Climate and Energy Package, providing clear guidelines for member states to coordinate emission reduction efforts.

In international cooperation, the EU played a critical role in the adoption of the Paris Agreement. It actively mediated between parties to facilitate negotiations and inject momentum into global climate governance.

In technological innovation, the EU increased investments in clean energy R&D (Paramati et al., 2021). The rapid growth in renewable energy sectors like wind and solar power reduced reliance on traditional energy sources and enhanced the EU’s technological edge. Through policy leadership, international cooperation, and technological innovation, the EU consolidated and strengthened its leadership in global climate governance, becoming a key driver of global climate action (Oberthür, 2007).

The systematic application of the PET framework in policy studies can be traced back to the seminal work Agendas and Instability in American Politics. As a foundational text of PET theory, this book analyzed policy changes in areas such as civil nuclear power, smoking regulation, and automotive safety, indirectly revealing the underlying logic of environmental governance in the United States. The theoretical framework aligns closely with the actual trajectory of U.S. air pollution governance. According to PET theory, the evolution of U.S. air pollution governance policies can be divided into “periods of equilibrium” and “point of punctuation,” a process fully consistent with the PET logic of long-term stability interspersed with short-term radical change (Table 1).

Germany, as a global benchmark in energy transition, has long anchored its renewable energy policy on a “radical decarbonization” approach. However, the dual shocks of the 2022 energy crisis—triggered by the Russia-Ukraine conflict—and concurrent breakthroughs in green technologies fundamentally disrupted the conventional energy policy equilibrium. This disruption has driven a shift in policy orientation from idealism toward pragmatic balance (see Table 2).

Refers to how the public and political elites perceive and understand policy issues. Different policy images guide policy participants to take different actions. If the EU’s climate policy is perceived by the public as promoting green job growth, implementing such policies will proceed more smoothly. Conversely, if climate policies are seen as detrimental to employment—particularly in regions where polluting industries account for a large share of jobs—policy implementation becomes more difficult (Vona, 2019). Changes in policy image often trigger policy punctuation.

This refers to the environment in which policies are formulated and implemented, encompassing government agencies, interest groups, experts, and other actors. In the EU’s climate policy venue, the interactions among these actors and their power dynamics influence policy direction. In recent years, many scholars have begun to criticize the limitations of a “rules-first” approach in climate governance. The cross-scale and cross-sector nature of climate issues requires rule-makers to reconcile cultural differences among diverse stakeholders (Bremer et al., 2021).

These are specific events or moments that trigger dramatic policy changes (Baumgartner and Jones, 2010). For example, major climate disasters or the signing of international climate agreements can serve as turning points, shifting the EU’s climate policy from equilibrium to punctuation (Dupont et al., 2020).

Incremental change refers to slow, gradual policy adjustments over long periods, while punctuated change involves significant, short-term policy shifts. The decline in the EU’s climate leadership may stem from mismanagement during the transition from incremental to punctuated change.

Policy images and policy venues interact through mutual construction, jointly amplifying or mitigating the impact of external shocks on leadership. When the direction of the policy image aligns with that of the policy venue, adjustments to EU climate policy instruments tend to be more disruptive. However, this alignment also significantly increases the cost of internal interest coordination, accelerating both internal fragmentation of leadership and the loss of external authority—as exemplified by the response to the Russia-Ukraine war (see Figure 4).

Conversely, when the policy image and the policy venue diverge—such as during the dual shocks of the 2015 refugee crisis and the Paris Agreement—the policy image shifted from coercive dominance toward negotiated coordination. Yet the policy venue became fragmented, marked by the rise of the Visegrád Group in Eastern Europe and its resistance to emission-reduction targets. This led to a transition in venue power from core-member-state dominance to multipolar contestation (Zapletalová and Komínková, 2020). The result was a complex outcome: while international discursive influence recovered somewhat, internal leadership became significantly polarized, thereby offsetting part of the leadership decline that might otherwise have followed such shocks (see Figure 5).

The compatibility between different external shocks and the policy image and policy venue varies, leading to differences in the intensity of causal transmission. In a global public crisis such as the COVID-19 pandemic, the demand for economic recovery resonated with the consensus on green transition, enabling the policy image of “green recovery” to rapidly gain social and political acceptance (Wang, 2023). During this period, the European Commission took the lead in allocating recovery funds, resulting in a shift in the power structure of the policy venue that aligned closely with the policy image. This synergy temporarily strengthened leadership in the short term. Conversely, in the case of geopolitical conflicts such as the outbreak of the Russia-Ukraine war, the immediate disruption to energy supply chains led to a sudden increase in the influence of energy and foreign affairs departments. While the resulting policy adjustments exhibited emergency-driven characteristics and alleviated the energy crisis in the short term, they contradicted the EU’s long-term climate objectives, thereby severely undermining the legitimacy of the EU’s leadership in climate governance (see Figure 6).

A linear causal chain focuses only on the unidirectional transmission of “external shocks leading to leadership decline.” In practice, however, governance exhibits significant reverse causality: the decline of leadership itself weakens the EU’s capacity to respond to external shocks, which in turn triggers more frequent and more intense policy punctuations, ultimately forming a cyclical pattern of decline. This process can be broken down into three components:

One core manifestation of the EU climate leadership is “agenda-setting and risk anticipation”—during the Kyoto Protocol phase, the EU could mitigate the impact of external shocks by proactively designing rules and consolidating internal consensus. As leadership has eroded, however, internal interest fragmentation and loss of international discursive power have reduced its ability to anticipate potential shocks, while effective advance coordination mechanisms have been lacking. After the 2009 COP15 setback, the EU failed to repair internal consensus and international cooperation networks in a timely manner. Consequently, when the European debt crisis erupted in 2010–2014, there was no contingency plan for “coordinating economic crisis response with climate policy,” forcing a passive cutback in emission-reduction investments that further weakened leadership. Similarly, after the 2020 pandemic, despite launching a green recovery plan, the EU—already experiencing phased weakening of leadership—could not drive member states toward unified implementation standards. This resulted in uneven efficiency in the use of funds, sowing the seeds for policy reversals after the 2022 Russia-Ukraine war.

Weakened leadership makes it difficult for the EU to formulate a unified and effective policy response to external shocks, leaving it to rely on compromise-based adjustments or emergency-driven changes. This, in turn, provokes more radical policy punctuations. Under the twin shocks of Brexit and the U.S. withdrawal from the Paris Agreement (2016–2019), the EU—facing an internal leadership vacuum (diminished weight after Brexit, diverging member-state interests)—neither filled the global climate leadership gap nor advanced substantive policy reforms. The revision of the Energy Taxation Directive was stalled for 28 months. Such ineffective responses broke the institutional inertia of the policy equilibrium period. When the pandemic struck in 2020, the EU could only drive policy punctuation through extraordinary fiscal measures. This model of punctuations reliant on a single instrument lacked sustainability; once subsequent shocks occurred, policy had to shift again—as seen in the turn toward energy-security priorities after the Russia-Ukraine war. A vicious cycle thus emerged: ineffective shock response leads to policy vacillation, which in turn intensifies punctuations.

Internally, repeated policy adjustments, compromises on emission-reduction targets, and contradictions among instruments exacerbate distrust among industries and the public: traditional industries struggle to form long-term investment expectations, while public skepticism grows regarding the rationality of policies—as illustrated by the 2023 farmer protests. Consequently, social and industrial support for policy implementation continues to decline, and internal leadership becomes further fragmented (Brewer et al., 2004). Externally, policy instability reduces the credibility of the EU as a rule-setter: the EU Carbon Border Adjustment Mechanism (CBAM) underwent multiple revisions to its exemption clauses from proposal to implementation¹, and even after its 2023 launch a transition period until 2026 was retained. The Office of the United States Trade Representative (USTR) stated in its 2024 National Trade Estimate Report on Foreign Trade Barriers that the CBAM rules lack long-term stability, as the emission accounting methodology was revised twice in 2024 alone. This has forced U.S. steel companies to invest an additional $20 million to adapt their compliance systems. The USTR accuses the EU of using climate goals as a pretext to set up trade barriers, undermining businesses’ trust in regulatory consistency (United States Trade Representative (USTR), 2024). This compromise-based rollout has raised doubts among other countries about the stability of the EU’s climate rules, reducing their endorsement of the EU-led regulations and leading to a continuous erosion of international discursive power.

In summary, The causal relationship behind the decline of the EU climate leadership exhibits a cyclical and cumulative pattern: external shocks trigger → mediating variables interact and transmit → leadership declines → capacity to respond to shocks is weakened → more intense policy punctuations occur → leadership declines further. In the initial phase (2009–2015), external shocks were the dominant driver, with linear causality prevailing; leadership decline was directly caused by shock-induced policy adjustments. In the middle phase (2016–2020), reverse causality began to emerge: leadership decline led to ineffective shock response, the frequency of policy punctuations increased, and the pace of decline accelerated. In the later phase (2021–2023), cyclical cumulative effects became prominent: external shocks and internal decline reinforced each other, while the interaction between policy image and policy venue further amplified the erosion of leadership, shifting the process from “gradual weakening” to “accelerated loss.”

The decline of internal leadership is primarily manifested in the significantly reduced coordination and implementation efficiency of climate policy-making. At the legislative level, the advancement of key bills has been hindered. The revision of the Energy Taxation Directive was stalled for 28 months, and the process from the adoption of separate Emissions Trading System (ETS) proposals for the transport and building sectors to the final clarification of carbon prices spanned over 2 years, highlighting how severe bargaining among member states over their interests has obstructed legislative progress, breaking the EU’s previous rhythm of efficient climate legislation. At the policy goal-setting level, contrasting sharply with the earlier style of setting clear deadlines and pushing aggressively, frequent compromises are now made to balance the economic interests of some member states. This leads to a lack of coherence and foresight, undermining the authority and enforceability of climate policies.

The weakening of external leadership is reflected in the continuous erosion of the EU’s rule-making dominance and cooperative influence in global climate governance. In terms of rule construction, the European Union once led the negotiation process of the Kyoto Protocol, but in recent years, it has faced challenges in multi-party coordination when promoting global climate rules. For example, the global carbon price linkage scheme proposed by the EU was not widely adopted in the follow-up negotiations of the Paris Agreement, and during COP28 in 2023, the EU primarily played a coordinating role. Meanwhile, as major carbon emitters, China and the United States demonstrated stronger agenda-setting influence in pre-conference consensus-building, agenda-setting, and negotiation coordination, particularly on core issues such as fossil fuel phase-out, climate finance, and energy transition. The EU’s proposal for linking its carbon border adjustment mechanism was not included as a core outcome of the conference, as it was perceived by some countries as unilateral (Akhtar et al., 2024).

In terms of financial cooperation, in 2023, the EU and its member states collectively provided 28.6 billion euros in public climate funds and mobilized an additional 7.2 billion euros in private funding. However, its detailed proposal for the allocation of the 100 billion U.S. dollar climate finance pledge failed to gain widespread support due to insufficient responsiveness to the concerns of emerging economies. In contrast, differentiated climate assistance proposals put forward by China and the United States received greater recognition from developing countries.

In terms of project cooperation, in Southeast Asian renewable energy collaborations, the regional grid decarbonization projects promoted by the EU have been adjusted or shelved by some host countries due to their relatively stringent rule design and numerous attached conditions. In comparison, the project-oriented and flexibly adapted cooperation models adopted by China and the United States have garnered more attention in certain regions (Trang, 2025). These developments reflect the existing diversity in strategies, pathways, and levels of acceptance among current international climate cooperation participants, and they also provide indirect evidence for the argument regarding the weakening of the EU’s external leadership (Zartman, 1994).

The insufficiency of instrumental capacity is evident in the dual weaknesses of the effectiveness of climate policy tools and resource guarantee capabilities. Regarding policy tools, core instruments like the EU Emissions Trading System (EU ETS) have failed to fully deliver, with long-term low carbon prices proving inadequate to effectively drive industrial emission reductions. Policy tools for specific sectors have been slow to materialize, failing to form a synergistic portfolio. In terms of resource guarantees, the coverage capacity of EU-level climate funds is declining. For instance, in 2025, the Innovation Fund allocated €520 million for net-zero technology R&D, yet required an additional €176.5 million in national funds from member states to fill the funding gap. Industrial support tools lack flexibility. Transformation costs for traditional energy-intensive industries remain high. The green hydrogen-based steelmaking transition for the steel industry requires a total investment of €130 billion, with a single large enterprise bearing over €5 billion. In the chemical industry, only 12% of decarbonization funding is covered by the EU, leaving the remaining costs to be borne by the companies themselves. This renders the policy tools insufficient to gain industry support and, instead, triggers collective resistance.

The erosion of normative authority stems from the continuous weakening of the social legitimacy and international credibility of the EU’s climate policies (Parry, 1976). Domestically, public support for climate policies is divided. A 2025 the EU poll showed that 85% of citizens acknowledge the seriousness of climate change, but 38% have already felt the negative impacts of climate policies. In eight countries, including Southern Europe and Poland, over half the population believes the policies are increasing the cost of living. Between 2022 and 2024, there were over 30 protests against climate policies triggered by rising energy prices. Collective actions, such as a 100,000-person demonstration in France and strikes by chemical workers in Germany, have severely shaken the social foundation of the policies. Internationally, the instability of its policies has diminished the EU’s credibility as a rule-maker.

The decline in the EU climate leadership has significantly affected the global climate governance agenda. As a long-standing leader, the EU played a crucial role in advancing global climate policy formulation and fostering international cooperation. However, as its leadership weakens, the momentum of global climate governance has slowed, and international collaboration faces increasing challenges. The erosion of the EU leadership has contributed to a lack of dynamic impetus in global climate governance, making coordination and cooperation among countries on climate policies more difficult. Moreover, the EU’s diminished role in climate governance has left some countries without clear guidance or benchmarks in addressing climate issues, which in turn has undermined the direction and effectiveness of global climate governance. On the other hand, the decline in the EU climate leadership has prompted other countries, such as China and the United States, to assume more proactive roles in global climate governance. While this has partially filled the leadership gap, it has also introduced new power dynamics and governance challenges, rendering the process of global climate governance more complex and fluid.

The decline in the EU’s climate leadership has significantly affected its international standing. Historically, the EU has served as a leader in international climate governance, but in recent years its leadership position has increasingly been challenged. The erosion of climate leadership has weakened the EU’s discursive power in global environmental governance, diminishing its influence and credibility in international affairs. Furthermore, the EU’s failure to fulfill its climate policy commitments as pledged has tarnished its international image. This has not only reduced other countries’ trust in the EU but also undermined its bargaining power and negotiation position in international cooperation (Zartman, 1994). More critically, amid the rise of emerging market economies, the EU’s position in the global economic landscape has also been challenged. The decline in climate leadership has further exacerbated the EU’s isolation in addressing global climate change, hindering its ability to play a leading role on the international stage. This not only damages the EU’s international reputation but may also adversely affect its long-term economic and social development. Therefore, the EU must engage in deep reflection and take effective measures to restore its leadership image in international climate governance.

The decline in the European Union’s climate leadership provides crucial insights for climate policy formulation in other countries globally. First, the stability and continuity of climate policy leadership are fundamental prerequisites. Policymakers need to establish mechanisms resistant to interference, ensuring policy implementation is not disrupted by internal political changes or external pressures. Second, international cooperation is the core pathway for addressing climate change. Countries should strengthen multilateral communication and collaboration, jointly advancing the process of global climate governance. Third, it is necessary to learn from the EU’s experience in constructing a robust climate policy system, which involves clarifying emission reduction targets, improving implementation mechanisms, and strengthening oversight effectiveness. Fourth, focus should be placed on the dual drivers of technological innovation and financial investment to accelerate the research, development, and application of clean energy and low-carbon technologies. Countries must draw lessons from the EU’s practice, maintain a firm stance on climate governance, actively fulfill international responsibilities, and, through sustained and coordinated efforts, collectively build a green, low-carbon, and sustainable global development landscape.