River shipping packs a larger climate punch than previously thought, study reveals
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A study published this week in Nature Climate Change finds that greenhouse gas emissions from inland waterway shipping have been significantly underestimated. The research, led by D. Lu and colleagues, shows that river cargo vessels emit up to 30% more CO2 per tonne-kilometer than previous models suggested. The findings challenge the assumption that river transport is a low-carbon alternative to road freight, even as governments promote inland waterways to cut road congestion.
The Findings
The study analyzed emissions from over 2,000 cargo ships operating on rivers in China, the European Union, and the United States between 2019 and 2024. Using on-board sensors and satellite data, the researchers found that methane and nitrous oxide emissions were particularly underestimated, in some cases by a factor of two. The total climate impact of river shipping, when converted to CO2-equivalent, rivals that of some small nations. The authors attribute the discrepancy to outdated engine emission factors and a lack of real-world testing.
Policy Implications
The International Maritime Organization currently focuses its decarbonization efforts on ocean-going vessels, while inland shipping falls under national jurisdiction. This regulatory gap means that many governments do not monitor or report river ship emissions systematically. The study’s authors call for an update of emission inventories and the inclusion of inland waterways in the Paris Agreement’s national reporting requirements. Without such measures, they warn, global climate targets may be undermined by a hidden source of pollution.
What's Next
The IMO’s Marine Environment Protection Committee is scheduled to review inland shipping emissions at its meeting in October 2026. It remains unclear whether member states will back binding targets for river vessels, given the potential economic impact on freight-dependent industries.
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River shipping packs a larger climate punch than previously thought, study reveals
