Environmental Impact of Shipping Explained - Desteia

Environmental Impact of Shipping Explained

The maritime shipping industry accounts for 3% of all emissions of CO2. We looked closely at these emissions and their impact.

Pollution in shipping might just be one of the largest problems in global logistics infrastructure—not to mention the planet as a whole. It is currently estimated that maritime shipping—which accounts for 90% of all cargo transported in the world—represents some 3% of all CO2 emissions in the world. That is the equivalent to the carbon footprint of well over 217 million homes or burning 387 bn liters of gasoline. For reference, the U.S. has an estimated 131.43 million households.

In great part, this is due to the great growth in our ability to do maritime trade in recent years. Although humans have engaged in some form of commerce for thousands of years, it wasn’t until fairly recently, with the creation of multimodal shipping containers, that we’ve been able to transport meaningful amounts of cargo with ease. In fact, since containers were invented in the 1950s, total trade in the world has grown 29-fold, and the carrying capacity of container ships has grown from an average of 11 deadweight tons (dwt) in the 1980s to close to 300 dwt in 2022. Simply put, after the shipping container came into the picture, we began a steady race to increase the capacity of our vessels and, through such investments, increase our ability to do trade.

The problem, however, is that, in our container ship building spree, we’ve come to prioritize heavy pollutants. As of 2021—the last year for which the International Maritime Organization released official statistics—, it was estimated that 81.8% of all fuel consumed by the maritime shipping industry was either Heavy Fuel Oil or Light Fuel Oil, both of which are heavy pollutants. More environmentally friendly fuels like Ethanol and Liquified Natural Gas (LNG) account just for just 5.9% of consumption, although there are some early signs that LNG demand might soon be on the rise.

Fuel Composition by the Maritime Industry (2021)

Fuel Consumption by the Maritime Industry (2021)

Fuel Consumption by the Maritime Industry (2021)

(in tons of fuel)

A pie chart showing fuel consumption by time in the Maritime Industry in 2021

Source: IMO Get the data Created with Datawrapper

But it’s not just that our global shipping infrastructure runs on fuels—our consumption is also steadily rising. On average, as of June, 2024, it was estimated that the global shipping industry produces some 910 million tons of CO2 per year. Not to mention that, in 2024 alone, the magnitude of emissions has grown by an additional 23 million tons of CO2 due to routes being altered because of Houthi attacks in the Red Sea. This pushes carriers to divert shipments through the Cape of Good Hope, adding multiple days to their journeys and causing increased congestion in Mediterranean ports.

In 2014, the figure was 694.4 million tons. Thus, in the span of a decade, shipping pollution has grown by 31%. The IMO has a goal of reaching net zero emissions by 2050, which seems challenging given the current trajectory of emissions.

CO2 Emissions from the Maritime Shipping Industry (2021-2024)

CO2 Emissions from the Maritime Shipping Industry (2021-2024)

CO2 Emissions from the Maritime Shipping Industry (2021-2024)

(in annualized tons of CO2)

A line graph showing CO2 emissions from 2021 to 2024.

Source: Bloomberg Get the data Created with Datawrapper

At Desteia, we wanted to delve even further into the impact of the shipping industry to the environment. The global merchant fleet consisted of 108,787 vessels as of 2024, with General Cargo Vessels (19.06% of all ships) accounting for the largest individual group, followed by Bulk Carriers (12.48%) and Oil Tankers (11.46%).

Between 2014 and 2024, the number of ships at sea grew from 87,950 to 108,787 vessels, showing a growth rate of 23.6% during the same time pollution from shipping grew by 31%.

Vessels in the Global Maritime Fleet by Type (2011-2024)

Vessels in the Global Maritime Fleet (2011-2024) by Type

Vessels in the Global Maritime Fleet (2011-2024) by Type

(in number of vessels)

A line graph showing the number of vessels in the global maritime fleet by type:

Source: UN Trade and Development Get the data Created with Datawrapper

The general “other type” of vessels category was the fastest growing in total number of ships. These vessels, in general, tend to be far smaller and thus have a smaller impact in total emissions, which could overestimate the contribution of smaller vessels in emissions.

To address this, we looked at the total capacity of vessels as measured by tonnage. The total cargo weight capacity reveals that bulk carriers (42.7% of all dwt), oil tankers (28.3%), and container ships (14%) account for the vast majority of cargo being transported in comparison to other vessels.

Total Tonnage in the Global Maritime Fleet by Type of Vessel (2024)

Total Tonnage in the Global Maritime Fleet by Type of Vessel (2024)

Total Tonnage in the Global Maritime Fleet by Type of Vessel (2024)

(in dead weight tons)

A pie chart showing the total tonnage in the global Maritime fleet in 2024 by type of vessel:

Source: UN Trade and Development Get the data Created with Datawrapper

Assuming that total emissions from the maritime industry are equally distributed by the share of cargo handled, we estimated emissions per vessel type according to their share of tonnage. We divided the total emissions accordingly.

The average bulk carrier is, by far, the largest source of emissions, resulting in over 28,500 tons of CO2 emitted per year, followed by oil tankers (over 20,600 annual tons of CO2) and containerships (20,782 annual tons of CO2).

Estimated Yearly CO2 Emissions by Vessel Type

Estimated Yearly CO2 Emissions by Vessel Type

Estimated Yearly CO2 Emissions by Vessel Type

(in tons of CO2 per year)

A bar graph showing the estimated yearly CO2 emissions by vessel type:

Get the data Created with Datawrapper

Examining the impact of containerized trade, the annual emissions of the entire container trade industry totals 127,378,404.90 tons and involves 30,273,523 TEUs currently in circulation. Each TEU is responsible for roughly 4.2 tons of CO2 per year.

The 10 largest maritime carriers account for over 84% of all emissions, equating to 107.3M tons of CO2. Future orders for the world's 30 largest carriers equal about 6.09M TEUs, projected to add another 25.6M tons of CO2.

In summary, our research indicates that the shipping industry, heavily reliant on fossil fuels, continues to invest in high-polluting energy sources. Over 910 million tons are emitted annually, suggesting that without significant action, emissions may rise further.