Inland waterway transport has mostly avoided the kind of emissions oversight that ocean-going vessels face. Yet fresh findings indicate its environmental toll is considerably greater than previously assumed.

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According to a new analysis published in Nature Climate Change, barges and other craft plying rivers and canals released roughly 164 million metric tons of CO2 in 2022, representing 24.7% of all shipping-related carbon output that year. This is notable because such waterways constitute under 1% of the globe’s navigable routes.

While ocean shipping has benefited from extensive tracking via AIS signals, fuel-use records, and emission inventories, no comparable worldwide dataset existed for inland fleets. To address this, researchers in China examined close to 20 billion vessel-position records spanning 2019 to 2022, pinpointing consistent traffic along 12,289 rivers and canals.

Estimating emissions proved challenging. Inland AIS coverage is often incomplete, and standard tracking methods tend to connect position points with straight lines, which can cut across landmasses when vessels follow winding courses. The team therefore devised a route-reconstruction algorithm that respects actual river paths, then paired vessel movements with ship characteristics to calculate fuel burn and resulting emissions.

The data reveal a heavily skewed distribution. Twenty major rivers—among them the Yangtze, Rhine, Mississippi, and Danube—accounted for roughly 69% of inland shipping emissions, with cargo carriers contributing about two-thirds of the total. More troubling is the trend: emissions from inland vessels nearly doubled over the 2019–2022 period, driven largely by heightened traffic and economic expansion, especially across Asia.

The analysis also shows significant fluctuations tied to seasons, hydrological conditions, and weather, underscoring how cargo demand interacts with a river’s capacity to support navigation. Inland shipping is often touted as a greener substitute for trucking, particularly in Europe and China. While this study does not challenge that comparison on a per-tonne-kilometer basis, it does highlight a sizable slice of maritime emissions that has long received limited attention. Economies of scale favor ocean carriers, which are typically much larger and thus move more cargo per unit of pollution. Ironically, though, many of the most innovative low-emission shipping projects over the past decade have emerged on inland waterways.

Source: IndexBox Market Intelligence Platform