Pilot study first to estimate the greenhouse gas emissions of all large industrial vessels operating in the ocean
As part of our ongoing work to shine a light on all industrial activity at sea, we have, for the first time ever, mapped and estimated the emissions of all industrial vessels operating in the ocean.
Our analysis, working with our partners at University of California, Santa Barbara’s Environmental Markets Lab (emLab) and Climate TRACE, covered more than half a million ocean-going vessels that broadcast their GPS positions using the automatic identification system (AIS). Additionally, we used satellite radar to detect vessels not tracked by AIS. These vessels that are absent from public monitoring systems, or “dark fleet” vessels, provide a more comprehensive picture of human activity at sea, as they have typically remained undetected through traditional tracking systems until now.
Our pilot study focused on large industrial vessels, specifically those over 15 meters in length, and their activity from 2016 to 2023. Future research will extend to smaller vessels, which could increase our estimates of total marine emissions. Previous estimates only accounted for vessels that broadcast their locations via AIS. These new data will improve our understanding of how much greenhouse gas emissions are produced as a result of ocean-based activities and provide actionable information to willing actors seeking to reduce emissions. More accurate emissions data will allow us to unlock and inform various types of policy and market-based solutions that could help reduce at-sea greenhouse gas emissions.
Key Findings
Industrial vessels emitted approximately 1.3 billion tons of carbon dioxide in 2023, accounting for about 3 percent of global fossil fuel emissions.
Mapping emissions of maritime vessels – both those using AIS and “dark” vessels – allows us to produce detailed spatial maps of their maritime carbon dioxide emissions. In this map of estimated emissions from maritime traffic in 2023, greater emission concentrations can be seen in the shipping lanes of the world, with the highest levels in East and Southeast Asia.
Maritime emissions are likely growing more than twice the rate of global carbon dioxide emissions. Between 2016 and 2023, global fossil fuel emissions increased by 7 percent, while emissions from maritime vessels grew by about 20 percent.
As seen in this graph covering 2016 through 2024, emissions dropped every year coinciding with northern hemisphere holidays and peaked during summer in the northern hemisphere. Overall, emissions increased every year except 2020, when it declined due to the COVID-19 pandemic.
While 85 percent of maritime emissions in 2023 came from vessels broadcasting their positions via AIS, understanding dark fleet activity is crucial for estimating total emissions and tracking changes over time. Emissions from dark vessels decreased by 17 percent, whereas emissions from AIS-tracked vessels rose by 33 percent. This shift is largely due to increased AIS adoption and advancements in AIS technology.
From 2016 to 2023, increases in emissions from AIS-tracked vessels were primarily concentrated in the Pacific waters of East and Southeast Asia, which accounted for nearly half of the overall increase. Similarly, decreases in dark fleet emissions were also concentrated in this region, contributing to about half of the total reduction.
Our analysis also revealed seasonal and event-driven variations in emissions. Emissions consistently dipped during major holidays, including Christmas, New Year’s Day, and Chinese New Year, and also fell during the COVID-19 pandemic. Furthermore, our analysis also shows changes in the geographical distribution of emissions that are likely driven by new policies and infrastructure development.
Expanding This Work
Including smaller vessels: We will expand our research to include the activities of smaller vessels through the use of higher-resolution satellite optical imagery. This will provide a more complete picture of global maritime emissions, as the scale of emissions from smaller vessels is not yet fully understood.
Refining emissions estimates: We estimate that emissions have increased by about 20 percent since 2016, which is more than twice as fast as global fossil fuel emissions. We aim to refine these estimates and improve confidence in our numbers.
Emissions of vessels that could be tracked with AIS transponders rose quickly, partially offset by a decrease in emissions from dark vessels. Overall emissions grew every year except for a slight decrease during the pandemic.
Identifying trends, drivers and policies: We will continue to analyze where and why emissions are rising or falling across the global oceans. Our goal is to better understand the factors driving these changes, identify policies that can promote reductions in maritime emissions and quantify the potential impact of these new policies, such as the global carbon price proposed by the International Maritime Organization.
Quantifying emissions in the seafood sector: We would also like to investigate fishing vessel emissions in order to better understand emissions associated with catch of specific fisheries, the relationship between emissions and overfishing, and the potential co-benefits between sustainable fisheries management and emissions reductions.
Our approach is still under active development, which means that these preliminary results could change. We will continue to refine the model over the coming months and aim to publish the work in a peer-reviewed journal. This data can currently be accessed through the Climate TRACE website for download and global visualization and we aim to have it available on our platform later this year.