On Monday, the U.S. changed administrations, and with this change, shifts in policy have already occurred.  On the environmental front, the current administration made a notable action in its first few hours of leadership through an Executive Order withdrawing the U.S. from the Paris Agreement. Under the Paris Agreement, countries agree to cut greenhouse gas emissions in an effort to curtail global warming and climate change.  Notably, withdrawal from the Paris Agreement is a repeat endeavor: the U.S. previously sought to withdraw in 2016, and in both cases, the administration focused on the potential for negative impacts of the Paris Agreement on U.S. jobs and the economy.  

The Paris Agreement is not the only climate change related agreement that may be affected during this Administration. One area of concern recently raised relates to the practical implications of U.S. withdrawal from the MARPOL Convention ("MARPOL”). 

Background

MARPOL, which is an international convention covering prevention of pollution of the marine environment by ships, was developed by the International Maritime Organization (IMO) and the U.S. is a signatory. Annex VI of MARPOL, concerning the air pollution from ocean-going ships, was implemented in the U.S. when Congress approved the Act to Prevent Pollution from Ships (APPS, 33 U.S.C. 1901-1915), in 2007. The Environmental Protection Agency (EPA) and U.S. Coast Guard are jointly in charge of enforcing the regulations in the U.S.

Fundamentally, Annex VI sets limits on NOx and SOx emissions, particulate matters, carbon intensity classifications, energy efficiency indices, and Greenhouse Gas standards.  According to the IMO, as a result of Annex VI and other regulations, global shipping emissions have been reduced by 7%, while shipping volume has increased by 34%.

The potential withdrawal of the U.S. from MARPOL Annex VI would represent a significant shift in maritime environmental policy. However, its practical impact on global shipping operations and environmental compliance is uncertain. The analysis below examines the potential consequences through three key perspectives: operational realities, geopolitical implications, and infrastructure momentum.

Operational Realities and Economic Constraints

It is possible that a U.S. withdrawal from MARPOL Annex VI could technically exempt vessels operating in U.S. waters from emission regulations, as the U.S. Coast Guard and Environmental Protection Agency would likely cease enforcement activities. However, several practical factors would likely minimize the real-world impact. 

The global nature of modern shipping means that most vessels do not operate exclusively within U.S. waters. Most ships that call at U.S. ports also service routes to other regions where MARPOL regulations remain in force, particularly the European Union and Asia. The economic inefficiency of maintaining dual compliance systems – different hardware and fuel systems for U.S. waters versus other jurisdictions – would likely discourage shipping companies from taking advantage of relaxed U.S. standards. The cost and complexity of switching between compliance modes for the relatively brief periods spent in U.S. waters would very likely outweigh potential savings.

Geopolitical Implications and Policy Cascade Risk

There is potential for a ripple effect of U.S. withdrawal. When the U.S. shifts course, the world takes notice. A withdrawal could trigger a cascade of similar actions by other nations, particularly those already resistant to stringent environmental regulations. This scenario potentially represents a material risk to global maritime environmental standards. 

If multiple significant maritime jurisdictions follow the U.S. example, it could create regulatory havens large enough to make dual compliance systems economically viable. This could lead to a fragmentation of global maritime environmental standards, and increased complexity in shipbuilding, an already highly technical and costly endeavor.

Infrastructure Inertia and Investment Patterns

The maritime industry's infrastructure investments may provide a counterbalancing force to policy volatility. Several factors contribute to this stabilizing effect, potentially negating any long-term changes by the shipping industry.

For example, substantial investments have already been made in MARPOL-compliant infrastructure, including port facilities, fuel supply chains, and vessel modifications. These represent long-term commitments that cannot be easily reversed. The shipping industry operates on long term horizons, with vessels and infrastructure expected to remain in service for decades. The possibility of policy reversal in subsequent political cycles creates investment uncertainty, perhaps encouraging companies to maintain MARPOL compliance rather than risk stranded assets.

Looking Ahead

While a U.S. withdrawal from MARPOL Annex VI would represent a significant policy shift, the practical impact on global shipping operations may be limited by economic and operational realities. Perhaps the greatest risk lies not in immediate operational changes but in the potential erosion of global consensus on maritime environmental standards. However, the industry's existing infrastructure investments and need for operational consistency across jurisdictions provide significant inertia against rapid changes in environmental compliance practices.

The effect of U.S. withdrawal may not shift the tides, with continued broad adherence to MARPOL standards by the global shipping industry, regardless of U.S. policy changes.  As discussed above, this would be driven by the practical necessities of international commerce and existing infrastructure investments. Nevertheless, careful monitoring of potential policy cascade effects would be prudent, particularly in key maritime nations and regions.