Technological and sectoral pathways to decarbonisation: evidence from CO2 emissions interlinkages in major economies

Purpose Global decarbonisation efforts are increasingly challenged by rising CO2 emissions across major economies, underscoring the need to understand not only emission drivers but also the systemic interactions among emitting sectors. This study examines the interconnectedness and shock transmission of sectoral CO2 emissions across the world's three largest emitters – the USA, the European Union (including the United Kingdom) and China – thereby addressing a critical gap in the emissions literature. Design/methodology/approach The analysis employs high-frequency sectoral CO2 emissions data (MtCO2/day) spanning 1 January 2019 to 31 May 2025 (2,342 observations). A Quantile-on-Quantile (Q–Q) connectedness framework is adopted to capture nonlinear, asymmetric and regime-dependent spillovers among six sectors: Domestic Aviation, Ground Transport, Industry, International Aviation, Power and Residential. Robustness is ensured through a rolling time-varying Q–Q connectedness approach that tracks the dynamic evolution of inter-sectoral linkages across economic and environmental regimes. Findings Results reveal pronounced regional heterogeneity. In China, emissions spillovers are strongly dominated by the Power and Industrial sectors at higher quantiles. The EU exhibits heightened vulnerability within the Residential and Transport sectors, while the USA demonstrates more balanced spillover dynamics, with Power and Industry acting as both net transmitters and receivers. Overall, emission interdependencies are highly quantile-sensitive and region-specific. Originality/value This study advances the literature by shifting focus from emission determinants to sectoral emission interconnectedness using a novel quantile-based connectedness framework, offering system-wide and policy-relevant insights for resilient decarbonisation strategies.