2. Methods
As a group of interdisciplinary scientists, with expertise in marine pollution, we participated in the Future Seas project (www.FutureSeas2030.org) and followed the method outlined in Nash et al. (2020). The project involved a structured three-step discussion process, (Step 1: problem identification, trust and awareness building, step 2: future discovery and development, step 3: learning) to explore the direction of marine social-ecological systems over the course of the UN Decade of Ocean Science. The three-step process resulted in developing two alternate future scenarios of marine pollution, a ‘business-as-usual’ future that is the current trajectory based on published evidence, and a ‘more sustainable’ future that is technically achievable using existing and emerging knowledge and is consistent with the UN’s Sustainable Development Goals. To ensure a wide range of world views were present in the future scenarios, Indigenous Leaders and Traditional Knowledge Holders from around the world came together and presented their views, experiences and identified their priorities to remove and reduce marine pollution (Nash et al. 2020; Fischer et al. 2020).
We defined the scope of our paper by identifying key pollutant sources, types and drivers of marine pollution (Table 1 for pollutant sources and types; section 3.2 for drivers).We then developed a list of feasible actions that could drive the current state of the Ocean towards a cleaner, more sustainable future (supplementary Table 1). From these actions we deliberated as a group and identified ten that have high potential to be implemented within the next decade and significantly reduce marine pollution (Figure 1). The linkages between our ten priority actions and the SDGs are outlined in supplementary Table 2.
Future Narratives
We identified three broad sources of marine pollution: land-based industry, sea-based industry and municipal-based sources (Table 1). We framed our two contrasting future scenarios (business-as-usual and a technically feasible sustainable future), around these pollutants and their sources (Box 1). In addition to these future narratives, we (the initial participants) reflect on the present impacts that pollution is currently having on the livelihoods and cultures of First Nations peoples and traditional knowledge holders. We include the narratives of the palawa pakana people, from lutruwita/Tasmania (Box 2), and the Greenlandic Inuit people (Box 3).
Drivers
We identified three key drivers that will substantially contribute to an increasingly polluted ocean if no actions are taken to intervene; societal behaviours, equity and access to technologies, and governance and policy. Alternatively, these pollution drivers can be viewed as opportunities to implement strategic measures that shift the dial from a polluted marine environment to a healthier marine environment. Below we highlight how current societal behaviours, lack of implementation of technological advancements, and ocean governance and policy making contribute to an increasingly polluted ocean and drive society towards a BAU future (Box 1). Importantly, we discuss how changes in these behaviours, and improvements in technologies and governance can lead to reduced marine pollution, ultimately driving a cleaner, more sustainable Ocean for the future.
Societal behaviour
Societal behaviours that drive increasing pollution in the world’s Ocean
A consumer culture that prioritizes linear production and consumption of cheap, single-use materials and products over circular product design and use, ultimately drives the increased creation of materials. Current production culture is often aligned with little consideration for the socioeconomic and environmental externalities associated with the pollution that is generated from a product’s creation to its disposal (Foltete et al. 2011; Schnurr et al. 2018). Without a dedicated management strategy for the fate of products after they have met their varying, often single-use objectives, these materials will enter and accumulate in the surrounding environment as pollution (Krushelnytska 2018; Sun et al. 2012). Three examples of unsustainable social behaviours that lead to products and materials ending up as marine pollution are: i) the design and creation of products that are inherently polluting. For example, agricultural chemicals or microplastics and chemicals in personal care and cosmetic products. ii) social behaviours that normalize and encourage consumption of single-use products and materials. For example, individually wrapped vegetables or take-away food containers. iii) low awareness of the impacts and consequences and therefore the normalization of polluting behaviours. For example, noise generation by ships at sea (Hildebrand 2009) or the large application of fertilizers to agricultural products (Sun et al. 2012).
Shifting societal behaviours towards sustainable production and consumption
A cleaner Ocean with reduced pollution will require a shift in production practices across a wide array of industries, as well as a shift in consumer behaviour. Presently, consumers and industry alike are seeking science-based information to inform decision making (Englehardt 1994; Vergragt et al. 2016). Consumers have the power to demand change from industries through purchasing power and social license to operate (Saeed et al. 2019). Policymakers have the power to enforce change from industries through regulations and reporting. Aligning the values between producers, consumers and policymakers will ensure best practices of sustainable consumption and production are adopted (Huntington 2017; Moktadir et al. 2018; Mont and Plepys 2008). Improved understanding of the full life cycle of costs, consequences (including internalised externalities, such as the polluter-pays-principle (Schwartz 2018)), materials used, and pollution potential of products could substantially shift the dial in both production and consumerism towards cleaner, more sustainable seas (Grappi et al. 2017; Liu et al. 2016; Lorek and Spangenberg 2014; Sun et al. 2012). For example, economic policy instruments (Abbott and Sumaila 2019), production transparency (Joakim Larsson and Fick 2009), recirculation of materials (Michael 1998; Sharma and Henriques 2005), changes in supply-chains (Ouardighi et al. 2016).
Equity and access to technologies
Inequitable access to available technologies
Despite major advancements in technology and innovation for waste management, much of the current waste infrastructure employed around the world is outdated, underutilised, or abandoned. This is particularly the case for rapidly developing countries with large populations who have not had access to waste reduction and mitigation technologies and systems employed in upper income countries (Velis 2014; Wilson et al. 2015). The informal recycling sector (IRS) performs the critical waste management role in many of the world’s most populous countries.
Harnessing technologies for today and the future
Arguably, in today’s world we see an unprecedented number and types of technological advances stemming from but not limited to seismic exploration (Malehmir et al. 2012), resource mining (Jennings and Revill 2007; Kampmann et al. 2018; Parker et al. 2016), product movement (Goodchild and Toy 2018; Tournadre 2014) and product manufacturing (Bennett 2013; Mahalik and Nambiar 2010). Applying long term vision rather than short term economic gain could include supporting technologies and innovations that provide substantial improvements over business-as-usual. For example, supporting businesses or industries that improve recyclability of products (Umeda et al. 2013; Yang et al. 2014), utilize waste (Korhonen et al. 2018; Pan et al. 2015), reduce noise (Simmonds et al. 2014), and increase overall production efficiency will substantially increase the health of the global ocean. Efforts should be made wherever possible to maintain current waste management infrastructure where proven and effective, in addition to ensuring reliance and durability of new technologies and innovations for improved lifespan and end of life product management. Consumer demand, taxation and subsidies will play a necessary roll to ensure the appropriate technologies are adopted (Ando and Freitas 2011; Krass et al. 2013).
Governance and Policy
Lack of Ocean Governance and Policy Making
The governance arrangements that address marine pollution on global, regional and national levels are complex and multifaceted. Success requires hard-to-achieve integrated responses. In addition to the challenges discussed in Alexander et al. (2020 ), which largley focuses on the marine environment, we highlight that land-based waste is the largest contributor to marine pollution and therefore requires governance and policies that focus on pollution at the source. Current regulations, laws and policies do not always reflect or address this grand challenge. The Ocean has traditionally been governed through sectoral approaches such as fisheries, tourism, offshore oil and mining. Unfortunately, this sector approach has caused policy overlap, conflict, inefficiencies and inconsistencies regarding marine pollution governance (Haward 2018; Vince and Hardesty 2016). Although production, manufacturing, and polluting may largely take place under geo-political boundaries, pollution in the high seas is often hard to assign to a country of origin. This makes identifying and convicting polluters very difficult (Urbina 2019). For example, the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78) has been criticised as ineffective in reducing marine pollution, largely due to the lack of easily monitoring, identifying and convicting offenders (Henderson 2001; Mattson 2006).
Harnessing ocean governance and policy
Binding domestic policies and international agreements are regulatory levers that can drive change at local, community, state, federal and international scales (Vince and Hardesty 2018). The UN Law of the Sea Convention Part XII (articles 192-237) is dedicated to the protection and preservation of the marine environment and marine pollution is addressed in article 194. It also sets out the responsibilities of states and necessary measures they need to undertake to minimise pollution their own and other states’ jurisdictions. While the Law of the Sea recognises the differences between sea-based and land-based pollution, it does not address the type of pollutants and technical rules in detail. Voluntary measures including MARPOL 73/78 (IMO 1978), United Nations Environment Assembly resolutions (UNEA 2019) and the FAO voluntary guidelines for the marking of fishing gear (FAO 2019), already exist in an attempt to reduce specific components of marine pollution. However, the health of marine ecosystems would benefit from multilateral international or regional agreements that minimise the production of items or the use of processes that result in high levels of marine ecosystem harm. For example, international regulation for underwater sound (McCarthy 2004), policies to reduce waste emissions (Nie 2012) and the polluter pays principle (Gaines 1991). Global and regional governance can create a favourable context for national policy action. Policies that adapt to shifts in climate and are guided by science and indigenous knowledge could be more likely to succeed (Ban et al. 2020).
Actions to achieve a more sustainable future
The grand challenge of reducing ocean pollution can seem overwhelming. However, there are myriad actions, interventions and activities which are highly feasible to implement within the next decade to rapidly reduce the flow of pollution. Implementing these actions requires collaboration among policymakers, industry and consumers alike. To reduce pollution from sea-based industries, land-based industries including land-based sources (Table 1), we encourage the global community to consider three ‘zones’ of action or areas to implement change: at the source(s), along the way/along the supply chain, and at sinks (Figure 1). It is important to highlight that we cannot act at any one zone only. For example, repeated clean ups at the sink may reduce pollution in an area for a time, but will not stem the flow of pollutants.
Actions at the source(s)
Reducing pollution at its multitude of sources is the most effective way to reduce and prevent marine pollution. This is true for land-based industry pollutants, sea-based industry pollutants and municipal-based pollutants. An example for each includes; reduction in fertilizer leading to less agricultural runoff in coastal waters (Bennett et al. 2001), changes in packaging materials may see reductions in production on a per item basis, and a lowered frequency and timing of seismic blasting would result in a decrease in underwater noise pollution at the source. The benefits of acting at the source are powerful: if a pollutant is not developed or used initially, it cannot enter the marine environment. We can act at the source using various approaches such as; prevention of contaminants, outreach campaigns, introduce bans and incentives and the replacement of technologies and products for less impactful alternatives (Figure 1). However, achieving public support for step changes can be difficult and time consuming. Such changes may meet resistance (e.g. stopping or changing seismic testing) and there are other factors beyond marine pollution that must be considered (e.g. health and safety of coastal lighting in communities may be considered more important than impacts of light pollution on nearby marine ecosystems). Actions such as outreach and education campaigns (Supplementary Table 2) will be an important pathway to achieve public support.
Actions along the way
Reducing marine pollution along the way requires implementation of approaches aimed at reducing pollution once it has been released from the source and is in transit to the marine environment (Figure 1). Acting along the way does provide the opportunity to target particular pollutants (point-source pollution) which can be particularly effective in reducing those pollutants. While municipal-based pollutants can be reduced ‘along the way’ using infrastructure such as gross pollutant traps (GPTs) and wastewater treatment plants (WWTPs), some pollution such as light or sound may be more difficult to minimize or reduce in such a manner. WWTPs can successfully capture excess nutrients, pharmaceuticals and litter that are transported through sewerage and wastewater systems. However, pollution management ‘en route ’ means there is both more production and more likelihood of leakage to the environment. In addition, infrastructure that captures pollution is often expensive, requires ongoing maintenance (and hence funding support), and if not managed properly, can become physically blocked, or result in increased risk to human health and the broader environment (e.g. flooding during heavy rainfall events). When considering management opportunities and risks for both land and sea-based pollution, the approaches required may be quite different, yielding unique challenges and opportunities for resolution in each (Alexander et al. 2020 ).
Actions at the sinks
Acting at sinks essentially requires pollution removal (Figure 1). This approach is the most challenging, most expensive, and least likely to yield positive outcomes. The Ocean encompasses more than 70% of the earth’s surface and extends to depths beyond ten kilometres. Hence it is a vast area for pollutants to disperse and economically and logistically prohibitive to completely clean. However, in some situations collecting pollutants and cleaning the marine environment is most viable option and there are examples of success. For example, some positive steps to remediate excess nutrients include integrated-multitrophic-aquaculture. ‘Net Your Problem’ is a recycling program for fishers to dispose of derelict fishing gear (netyourproblem.com). Municipal-based and sea-based industry pollutants are often reduced through clean-up events. For example, large oils spills often require community volunteers to remove and clean oil from coastal environments and wildlife. Such activities provide increased awareness of marine pollution issues, and if data are recorded, can provide a baseline or benchmark against which to compare change. However, addressing pollution at sinks means identifying those accumulating areas. Repeated removal or cleaning is unlikely to yield long term results, without managing the pollution upstream –whether along the route or at the source.
Conclusion
To achieve the More Sustainable Future, and significantly reduce pollution (thereby achieving the SGD targets in Supplementary Table 2), we must take ongoing action now and continue this movement beyond 2030. Prioritising the prevention of pollutants from their sources, using bans and incentives, outreach and education, and replacement technologies, is one of the most important steps we can take to shift towards a more sustainable future. Without addressing pollution from the source, we will continue to remediate rather than mitigate the damage pollution causes to the Ocean and organisms within. For pollutants that are not currently feasible to reduce at the source, collection of pollutants before they reach the Ocean should be prioritised. For example, wastewater treatment plants and gross pollutant traps located at point-source locations such as stormwater and wastewater drains. Actions at the sink should target areas where the maximum effort per quantity of pollution can be recovered from the Ocean. For example, prompt clean-up responses to large pollution events such as oil spills or flooding events and targeting clean-ups at beaches and coastal waters with large accumulations of plastic pollution.
These priority actions are not the perfect solution, but they are great examples of what can be and is feasibly done to manage marine pollution. Each action is at risk of failing to shift to a cleaner ocean without the support from governments, industries and individuals across the whole system (from the source to the sink). Governments and individuals need to push for legislation that is binding and support sustainable practices and products. Effective methods for policing also need to be established in partnership with the binding legislation. Regardless of which zone we address, our actions on sea and coastal country must be guided by Indigenous knowledge and science (Fischer et al., 2020).
We recognise the major global disruptions which have occurred in 2020, particularly the COVID-19 pandemic. The futures presented here were developed prior to this outbreak and therefore do not consider the effects of this situation on global pollution trends. In many ways, this situation allows us to consider a ‘reset’ in global trajectory as discussed by Pecl et al. (2020). Our sustainable future scenario may be considered a very real goal to achieve in the coming decade.
Author Contributions P.S. Puskic and K. Willis share equal lead authorship on this paper. All authors wrote sections of this manuscript and contributed to concept design and paper discussions. N.F and H.P. wrote the narratives for box 3. D.G. wrote Box 2. All authors provided edits and feedback to earlier drafts.