A Multivariate Statistical Analysis of Environmental Compliance Under IMO Regulations: Integrating Socio-Legal Dynamics in Maritime Engineering

Abstract

Background and Aims: The implementation of the International Maritime Organisation’s (IMO) IMO 2020 sulfur cap and subsequent regulatory amendments to MARPOL Annexe VI have markedly reshaped environmental compliance behaviour across the global shipping industry, directly influencing air quality and operational practices. IMO 2020 reduced the permitted sulfur content in marine fuel from 3.5 % to 0.5 % outside emission control areas, with even stricter limits within designated zones, driving widespread adoption of very low sulfur fuel oil and emission control technologies.
Methodology: This study develops a multivariate statistical model to quantify the determinants of compliance with IMO environmental standards and to evaluate associated socio-legal outcomes across global shipping fleets. Using empirical datasets—such as average fuel sulfur content (falling from ~3.03 % in 2019 to ~0.25 % by 2022) and observed noncompliance rates (5 of 78 ships exceeding the sulfur limit in open ocean measurements)—we apply panel regressions and logistic models to relate compliance levels with operator characteristics (e.g., flag state, vessel age), port state control rigour, and legal enforcement practices.
Findings: Findings reveal statistically significant correlations between robust enforcement regimes and higher compliance rates, alongside notable socio-legal disparities tied to flag-of-convenience registrations, which are associated with higher incidences of non-compliance.
Novelty and Implication: The research‘s novel contribution lies in its integrated socio-legal–mathematical framework that transcends traditional engineering assessments of emissions, offering policy-relevant insights into how regulatory design and enforcement mechanisms interact with maritime socio-economic structures to influence environmental outcomes. Implications include evidence-based recommendations for strengthening port state control practices, harmonising international compliance monitoring, and aligning maritime law with statistical indicators of environmental performance.