1. Introduction
Shipping has long presented a conundrum for economists and environmentalists. Relegated to the category of a derived demand (something that happens logically subsequent to the key economic activities of production and consumption) in a space that is external to the fundamental regulatory world of state territories, shipping and the ocean within which it occurs has all too often been an afterthought when it has been considered at all (Campling & Colás, Reference Campling and Colás2021; Steinberg, Reference Steinberg2001). More recently, inspired by the crucial role of global trade in the world economy (‘globalisation’), including, especially, ocean-going trade, as well as by the role of oceanic processes in generating and exhibiting the impacts of climate change, the ocean and the shipping that occurs therein has become a focus for environmental intervention (e.g. Bows-Larkin et al., Reference Bows-Larkin, Anderson, Mander, Traut and Walsh2015).
In short, shipping, once thought of as ‘small’ and ancillary, is now seen as ‘big’ and foundational, and this has elevated the position of the shipping sector, and the ocean more broadly, as a potential focal point for environmental intervention. Similarly, maritime transport (and notably container ships) often serves as a shorthand for trade (e.g. “West coast ports brace for China tariffs to dent import volume within days,” 2025). As we discuss in this intelligence briefing, however, this ‘bigging up’ of the ocean is itself problematic, partly for empirical reasons (depending on one's measure, shipping, and the ocean, can actually be seen as quite small) and partly for programmatic reasons (the policy implications of ‘bigness’ are not straightforward). Therefore, we conclude by suggesting that if one is to consider shipping as a pressure point for climate policy, rather than thinking of shipping (and the ocean) as either ‘big’ or ‘small’ it would be more effective to rethink the nature of shipping as an economic activity that is one of the many interrelated processes that influences the planet's thin ‘critical zone’ on which all life depends (Latour, Reference Latour2017; Lovelock, Reference Lovelock2016).
2. The politics of big numbers
The title of Rose George's book Ninety Percent of Everything (Reference George2014), alludes to a common claim: cargo ships transport 90% of everything (Economist Impact, 2023; OECD, 2023). Some put the number closer to 80% (UNCTAD, 2022; see also, Liquid Time, Reference Liquid2024), but the exact percentage matters little for our argument. The key message is clear: Shipping is big; shipping is important.
Environmentalists have picked up on this figure, arguing that if maritime transport plays such an out-sized role in the world economy then it would be a logical site for climate intervention, particularly if a reduction in shipping would be paired with a reduction in global consumption. Consuming less, this argument goes, would reduce wasteful use of planetary resources and bring down shipping demand, leading to a reduction in global emissions (De Beukelaer, Reference De Beukelaer2022, Reference De Beukelaer2023, Reference De Beukelaer2024).
This narrative is particularly appealing when viewed within the context of how the shipping industry has evolved over the past 100 years. Over the course of the 20th century, shipping transformed from a risky and often deadly business into a well-oiled machine that promises frictionless supply chains (see Sekula & Burch, Reference Sekula and Burch2010), inspired by military logistics developed during successive wars (Cowen, Reference Cowen2014; Khalili, Reference Khalili2020). Technological innovations and major investments increased ship sizes (Leivestad & Schober, Reference Leivestad and Schober2021), facilitated inter-modal transfer of containerised cargo (Klose, Reference Klose2015; Levinson, Reference Levinson2016), and connected bodies of water through canals (Fletcher, Reference Fletcher1958; Lasso, Reference Lasso2019), while expanding ports to accommodate ever-growing ships and cargoes (Sharpsteen, Reference Sharpsteen2011; van Veelen, Reference van Veelen2022). Increased maritime transport thus has enabled spiralling energy and material demands while relying on fragile natural and geopolitical environments as conduits of trade. Meanwhile, the Anthropocene confronts us with planetary boundaries (Richardson et al., Reference Richardson, Steffen, Bendtsen, Cornell, Donges, Drüke, Fetzer, Bala, Von Bloh, Feulner, Fiedler, Gerten, Gleeson, Hofmann, Huiskamp, Kummu, Mohan, Nogués-Bravo and Rockström2023). However, the transgression of these planetary boundaries remains mostly unseen to the rich thanks to the ceaseless import of resources and the export of invisible social and environmental ‘externalities,’ even though it is the rich who have contributed disproportionately to their exhaustion (Biermann & Kim, Reference Biermann and Kim2020; Malm & Hornborg, Reference Malm and Hornborg2014).
This narrative about maritime transport focuses on the highly unequal levels of consumption around the world, enabled by maritime transport. While some live lavish lifestyles, others don't manage to attain even the most basic ‘decent living standards’ because of inequitable resource distribution (Vélez-Henao & Pauliuk, Reference Vélez-Henao and Pauliuk2023). The excess consumption is generated by the top 10% (including us, authors), who consume far more than our fair share of planetary resources. To reprise, the commonly repeated argument is that consuming fewer things and consuming locally-sourced and manufactured goods would not only curb the wasteful consumption that is practiced disproportionately by the wealthy (Akenji et al., Reference Akenji, Bengtsson, Toivio, Lettenmeier, Fawcett, Parag, Coote, Spangenberg, Capstick, Gore, Coscieme, Wackernagel and Kenner2021), but it would also reduce demand for maritime transport. If 90% of what we consume is transported by sea, then bringing down consumption would foster equality and reduce carbon emissions of the shipping industry.
Environmentalists have paired the ‘90% of everything’ statistic that appeals to the apparent significance of maritime transport with a parallel statistic that appeals to the apparent significance of the space in which that transport occurs: the ocean covers 71% of Earth's surface. Thus, the High Level Panel for a Sustainable Ocean Economy heralds the ocean as a ‘climate solution’ (Hoegh-Guldberg, Reference Hoegh-Guldberg2019) because of its out-sized role absorbing both heat and carbon. Up to 20 Gt of CO2 are absorbed by oceans every year (Wang et al., Reference Wang, Fu, Le Moigne, Letscher, Liu, Tang and Primeau2023), which is up to 20% more than previously thought (Landurant & Le Moigne, Reference Landurant and Le Moigne2023). Considering that the ocean makes up just 0.12% of the planet's volume (a point we return to below) and that it has absorbed nearly 90% of global warming (Von Schuckmann et al., Reference Von Schuckmann, Minière, Gues, Cuesta-Valero, Kirchengast, Adusumilli, Straneo, Ablain, Allan, Barker, Beltrami, Blazquez, Boyer, Cheng, Church, Desbruyeres, Dolman, Domingues, García-García and Zemp2023), it seems clear that the ocean is an essential climate regulator. The implication of these appeals to the ocean's significance is that we need to take action if, as some assert, the ocean's capacity to continue playing that role is under immense pressure (Armstrong Mckay et al., Reference Armstrong Mckay, Staal, Abrams, Winkelmann, Sakschewski, Loriani, Fetzer, Cornell, Rockström and Lenton2022; Lenton et al., Reference Lenton, Armstrong Mckay, Loriani, Abrams, Lade, Donges, Buxton, Milkoreit, Powell, Smith, Zimm, Bailey, Dyke, Ghadiali and Laybourn2023).
As rhetorical framings, these two figures – that 90% of everything is shipped by sea and that 71% of Earth's surface is ocean – serve similar purposes. They highlight the simultaneous enormity and fragility of the ocean as well as its importance for regulating both economic and geophysical systems. Yet the implications of these ‘big’ numbers are not so straightforward. Although the ‘bigness’ of shipping and the ocean has been seized on by some to argue that it is an essential area for climate intervention, the shipping industry has long used its size and implied importance to argue against taking climate action. As Koji Sekimizu, then Secretary General of the International Maritime Organisation (IMO), noted in 2015:
… world leaders might be tempted to consider specific measures aimed at reducing shipping's overall contribution of CO2 emissions, such as global overall cap. Such measures would artificially limit the ability of shipping to meet the demand created by the world economy, or would un-level the level playing field that the shipping industry needs for efficient operation, and therefore must be avoided. If such measures are enforced, it will seriously distort the shipping industry and have a serious impact on the economy of almost all nations. (Sekimizu, Reference Sekimizu2015)
Sekimizu was, in effect, arguing that the industry is too big to fail. If the industry's freedom to pollute is restricted, it could collapse and bring the entire world economy down with it, a vision that is dramatized in Shipping Moves the World (Union of Greek Shipowners, 2024), an eight-minute video produced by the Union of Greek Shipowners that presents a dystopian scenario where maritime transport comes to a halt, outlining the impacts over days, weeks, and months. This argument about the essential nature of shipping is further bolstered by others who have noted that ships are the least polluting means of transport (expressed in GHG emissions per tonne-mile of goods transported) (ITF, 2023; Sims et al., Reference Sims, Schaeffer, Creutzig, Cruz-Núñez, D'Agosto, Dimitriu, Figueroa Meza, Fulton, Kobayashi, Lah, McKinnon, Newman, Ouyang, Schauer, Sperling, Tiwari, Edenhofer, Pichs-Madruga, Sokona, Farahani, Kadner, Seyboth, Adler, Baum, Brunner, Eickemeier, Kriemann, Savolainen, Schlömer, von Stechow, Zwickel and Minx2014).
The contrast between a big useful industry and its comparatively small environmental impact is meant to sketch a favourable image of the shipping sector. This juxtaposition further supports Sekimizu's admonition that one should be cautious in adopting regulations that may hinder the efficiency or profitability of this gentle giant that is crucial to the world economy. While the IMO has significantly increased its ambition to tackle climate change in the last decade (De Beukelaer & Smith, Reference De Beukelaer and Smith2023; Bilgili & Ölçer, Reference Bilgili and Ölçer2024; Bullock et al., Reference Bullock, Mason and Larkin2023), the industry continues to frame itself as both fundamental and relatively benign. For instance, the 2025 Report of the 18th Intersessional Working Group on GHG Emissions states: ‘…several other delegations…recalled that the shipping sector was responsible for less than 3% of global GHG emissions while around 80% of the world's goods are transported by sea, emphasizing the responsibility of the shipping sector with its crucial role in the global trade supply chain, in particular for the supply of agricultural goods’ (ISWG-GHG 18/WP.1/Rev.1).
3. Recalibrating shipping in a sea of numbers
As the previous section has demonstrated, even when the significance of the maritime transport sector and the fragility and importance of the ocean environment are recognised, the policy implications are not straightforward. Additionally, these numbers that celebrate the industry's importance are contestable. As we have noted, Rose George (and countless others) have written that ‘90% of everything’ is transported by sea. By contrast, the NGO Circle Economy, using statistics gathered by the International Resource Panel, calculates that the metabolism of the global economy in 2021 was 101.4 billion tonnes of ‘raw’ materials (2022) and UNCTAD reports that 11.0 billion tonnes of goods were transported that year by ship (UNCTAD, 2022). If we accept both Circle Economy's 101.4 billion tonne material footprint and UNCTAD's 11.0 billion tonne maritime trade flow, then cargo ships transport only about 10.8% of ‘everything’ (see Figure 1).
Figure 1. Material footprint versus trade in 2021.
In fact, these two figures (material footprint and trade) are not comparable because the two data sets measure different things. Circle Economy focuses on the metabolism of the globalised economy. This means they calculate all resources, including ores and energy, that are ‘consumed’ by the production processes that leave us with manufactured goods, edible food, and electricity. The processes that create a flow of consumer goods and services rely on resources totalling ten times the mass of the final, traded commodity. For instance, the material footprint of steel plates includes not just the plates that are traded but also the iron ore and energy (currently mostly coal) used in manufacturing the steel.
Additionally, the two sources of data differ because UNCTAD measures only what is traded internationally. Since UNCTAD uses data based on customs declarations, ‘trade’ refers only to goods that are transported across nation-state borders. This means that goods transported between Kinshasa and Brazzaville across the Congo River are counted in these statistics, but freight hauled by sea between Saint Petersburg and Vladivostok in the Russian Federation (some 6500 km as the crow flies) or between the islands of Kiritimati and Tarawa in Kiribati (some 3200 km) is not.
In sum, restricting ‘everything’ to goods that are traded internationally is problematic; it excludes both goods that are traded domestically and material inputs that are embedded in a commodity but not traded after the point of production. When the objective is Earth System governance (see e.g. Gupta et al., Reference Gupta, Bai, Liverman, Rockström, Qin, Stewart-Koster, Rocha, Jacobson, Abrams, Andersen, Armstrong Mckay, Bala, Bunn, Ciobanu, DeClerck, Ebi, Gifford, Gordon, Hasan and Gentile2024), trade, let alone international trade, cannot simply be used as a proxy for the materiality of production and for the environmental impacts that result from the transformation of matter and its movement from location to location.
Just as the ‘90% of everything’ figure can be questioned, so too can the figure that the ocean covers 71% of Earth's surface. This is an areal delimitation for a space that, arguably, should more appropriately be measured volumetrically, especially when one's concerns are environmental processes and impacts. A range of other, volumetric, calculations are possible. The ocean's share of the planet's total volume is just 0.12% (Steinberg, Reference Steinberg, Anderson and Peters2014); its share of the planet's ‘critical zone’ would be higher than 0.12% but still much smaller than 71%; its share of atmospheric space would be even smaller than 0.12%. Regardless, our point is not to establish a definitive number but to note that, as with the ‘90% of everything’ statistic, a big number like ‘71% of the planet,’ in addition to having ambiguous policy implications, is itself contestable. Appeals to size and scale are problematic as starting points for policy arguments.
4. Rethinking numbers in shipping policy
In 1609, the Dutch jurist Hugo Grotius claimed that ocean life is inexhaustible and maritime transport is harmless (Feenstra & Vervliet, Reference Feenstra and Vervliet2009). We now know both these claims to be wrong. Overfishing has decimated marine life (Standing, Reference Standing2022) and anthropogenic greenhouse gas (GHG) emissions significantly impact the oceans, through warming the water, raising sea levels, increasing acidification, and disrupting currents and conveyor systems (Merrie et al., Reference Merrie, Dunn, Metian, Boustany, Takei, Elferink, Ota, Christensen, Halpin and Österblom2014). While a single ship may do little harm, the tens of thousands of them that burn fossil fuels can do much harm, directly from shipborne GHG emissions, but also indirectly by enabling globalised consumer capitalism. This point was made abundantly clear in the 2024 International Tribunal of the Law of the Sea Advisory Opinion that explicitly frames GHG emissions from ships (and from all other sources) as pollution of the marine environment (ITLOS, 2024).
To illustrate, global warming leads to both a warmer atmosphere and warmer oceans. Warmer oceans evaporate more water into a warmer atmosphere that can hold more humidity. This results in more unpredictable weather patterns and more intense storms, which has implications for maritime transport (Hanson & Nicholls, Reference Hanson and Nicholls2020; Walsh et al., Reference Walsh, Lazarou, Traut, Price, Raucci, Sharmina, Agnolucci, Mander, Gilbert, Anderson, Larkin and Smith2019). Changes in rainfall can lead to floods and droughts, which can disrupt inland waterways and the waterborne traffic they allow. This has repeatedly affected cargo flows along the Rhine, with significant implications for German and Swiss industry as well as overseas shipping (“Droughts Leave Cargo Riverboats High and Dry,” 2023). The Panama Canal has faced capacity reductions owing to reduced rainfall and concomitant water levels of the lakes feeding its many locks (“Severe drought is constraining the Panama Canal, 2023). Rising sea levels also affect ports and port operations (Goodell, Reference Goodell2018).
What is at stake is not just the transition away from fossil fuels towards zero GHG propulsion of ships or toward producing and consuming locally. What is at stake is the need to transition to a global economy that can exist within a safe operating space for humanity (Gupta et al., Reference Gupta, Bai, Liverman, Rockström, Qin, Stewart-Koster, Rocha, Jacobson, Abrams, Andersen, Armstrong Mckay, Bala, Bunn, Ciobanu, DeClerck, Ebi, Gifford, Gordon, Hasan and Gentile2024; Rockström et al., Reference Rockström, Gupta, Qin, Lade, Abrams, Andersen, Armstrong Mckay, Bai, Bala, Bunn, Ciobanu, DeClerck, Ebi, Gifford, Gordon, Hasan, Kanie, Lenton, Loriani and Zhang2023, Reference Rockström, Steffen, Noone, Persson, Chapin, Lambin, Lenton, Scheffer, Folke, Schellnhuber, Nykvist, de Wit, Hughes, van der Leeuw, Rodhe, Sörlin, Snyder, Costanza, Svedin and Foley2009). As part of this transition, oceans and waterways will need to be safe and reliable conduits for global trade, whether we think of shipping as representing 90% or 10.8% of ‘everything,’ and whether we think of the planet as being 71% or 0.12% ocean.
5. Conclusions
The modern world is infatuated with scale and size (Smil, Reference Smil2023). Carbon emissions need to be measured, aggregated into sector-wide numbers, and ultimately eliminated. Maritime transport's sizable contribution to global emissions (nearly 3%) has underpinned calls for reducing the industry's impact on climate change (Bows-Larkin et al., Reference Bows-Larkin, Mander, Gilbert, Traut, Walsh and Anderson2014; Bullock et al., Reference Bullock, Mason and Larkin2022), either by reducing emissions per tonne-mile (i.e. more efficient ships) or by shipping less (i.e. reducing demand) (Balcombe et al., Reference Balcombe, Brierley, Lewis, Skatvedt, Speirs, Hawkes and Staffell2019; De Beukelaer, Reference De Beukelaer2022; Bows-Larkin et al., Reference Bows-Larkin, Anderson, Mander, Traut and Walsh2015).
To this end, the uncritical quantification of shipping and the ocean – ‘90% of everything’, ‘71% of the planet’ – have played a prominent role in the campaign for maritime awareness. These numbers give further weight to the observation that the ocean contains more carbon than either land or atmosphere and that it plays a hugely disproportionate role in absorbing excess heat due to climate change (Czerski, Reference Czerski2023).
However, any approach grounded on an uncritical appraisal of the 90% and 71% figures might lead to simplistic ‘solutionism’ such as restricting climate action to what is acceptable within narrow economic constraints or calling for ‘local’ production and consumption. ‘Local’ production and consumption is, perhaps counter-intuitively, not necessarily the best way to curb shipping emissions. Most of what is consumed is not transported internationally. Most resources used are already local; or at least domestic (see Figure 1). Additionally, as our discussion of material footprint has revealed, we need to focus on the total environmental impact of trade, not just transport. In this context, it might be more important to address the quantity of emissions and other environmental impacts embedded in goods (i.e. from the extraction and manufacturing of inputs) than how far the good has travelled. Potentially, the clustering of efficient production could reduce environmental pressures more than producing things closer to home, even if it would lead to a less significant reduction in the amount of goods transported by sea (McKinnon, Reference McKinnon, Secchi and Gili2024; Le Moigne & Ossa, Reference Le Moigne and Ossa2021).
Planetary boundaries don't care about national borders (e.g. Rockström et al., Reference Rockström, Kotzé, Milutinović, Biermann, Brovkin, Donges, Ebbesson, French, Gupta, Kim, Lenton, Lenzi, Nakicenovic, Neumann, Schuppert, Winkelmann, Bosselmann, Folke, Lucht and Steffen2024). Nor do finite resources care where or by whom they are used up. The challenges of climate justice through emissions reductions, meeting social thresholds within environmental boundaries, and ensuring a just and equitable transition are not easily confined to these frameworks for governance (Biermann, Reference Biermann2014; Freestone, Reference Freestone, Vidas and Schei2011; Rockström et al., Reference Rockström, Kotzé, Milutinović, Biermann, Brovkin, Donges, Ebbesson, French, Gupta, Kim, Lenton, Lenzi, Nakicenovic, Neumann, Schuppert, Winkelmann, Bosselmann, Folke, Lucht and Steffen2024). A narrow corridor exists for all people to live well within earth system boundaries (Gupta et al., Reference Gupta, Bai, Liverman, Rockström, Qin, Stewart-Koster, Rocha, Jacobson, Abrams, Andersen, Armstrong Mckay, Bala, Bunn, Ciobanu, DeClerck, Ebi, Gifford, Gordon, Hasan and Gentile2024; Hickel, Reference Hickel2019; O'Neill et al., Reference O'Neill, Fanning, Lamb and Steinberger2018), though not without simultaneously correcting inequalities upwards and downwards. This requires a high degree of imagination when approaching both the economy and the environment.
An exclusive focus on maritime international trade provides an incomplete picture. Notwithstanding the significance of maritime transport and the role of reducing its GHG emissions in a global emissions reduction strategy, other efforts, including demand-side climate action (Creutzig et al., Reference Creutzig, Fernandez, Haberl, Khosla, Mulugetta and Seto2016, Reference Creutzig, Niamir, Bai, Callaghan, Cullen, Díaz-José, Figueroa, Grubler, Lamb, Leip, Masanet, Mata, Mattauch, Minx, Mirasgedis, Mulugetta, Nugroho, Pathak, Perkins and Ürge-Vorsatz2022; Grubler et al., Reference Grubler, Wilson, Bento, Boza-Kiss, Krey, McCollum, Rao, Riahi, Rogelj, De Stercke, Cullen, Frank, Fricko, Guo, Gidden, Havlík, Huppmann, Kiesewetter, Rafaj and Valin2018) and socio-cultural shifts to sufficiency (Herlitz, Reference Herlitz2019; Robeyns, Reference Robeyns2024; Wiedmann et al., Reference Wiedmann, Lenzen, Keyßer and Steinberger2020) remain necessary, even if challenging. Even if shipping did facilitate the transport of 90% of ‘everything,’ a reduction in the tonne-miles transported by ship or an improvement in shipping's fuel efficiency would be just one of many efforts needed to make an impact on how global political economy affects the marine environment, let alone the global climate.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/sus.2025.10027.
Acknowledgements
The authors wish to thank the participants of the One Planet Shipping workshop aboard the Clipper Isis in May 2024 (which De Beukelaer co-organised with Elisabeth Schober, Hege Høyer Leivestad, and Lucy Gilliam), as well as participants in De Beukelaer's Durham University IAS seminar talk and Steinberg's PORTS Speaker Series seminar at the University of Oslo for their constructive and critical comments.
Author contributions
De Beukelaer: conceptualization (lead); formal analysis (equal); funding acquisition (lead); investigation (equal); methodology (supporting); validation (equal); writing – original draft (lead); writing – review & editing (equal). Steinberg: conceptualization (supporting); formal analysis (supporting); investigation (equal); methodology (supporting); validation (equal); writing – review & editing (equal).
Funding statement
De Beukelaer received funding from the Durham University Institute of Advanced Study, the ClimateWorks Foundation, the Marie Sklodowska-Curie Actions (FIAS COFUND/945408), and the Riksbankens Jubileumsfund, through the Swedish Collegium for Advanced Study. Steinberg supported the acquisition of the above Durham University Institute of Advanced Study funding.
Competing interests
The authors have no conflict of interest to report.
Data availability
Datasets used for this study are publicly available – see references.
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