Introduction
The worldwide ocean economy is experiencing rapid growth (Jouffray et al. 2020). It is already valued at around USD 1.5 trillion per year (2010 estimates) and is projected to more than double by 2030 (OECD 2016, 2019). As space on land becomes increasingly crowded and terrestrial resources reach their sustainable limits, the ocean will play a key role in providing goods and services for global populations (OECD 2016; Nyström et al. 2019; United Nations, Department of Economic and Social Affairs, Population Division 2019). Increased economic activity in the ocean will offer benefits, however it will also pose important environmental risks that need to be mitigated (Jouffray et al. 2020), and it will likely be accompanied by social, distributional, legal, political, and technological challenges (OECD 2016, 2019; Kraemer 2017; Cisneros-Montemayor et al. 2019). The ‘Blue Economy’ is a term that has increasingly come to represent the range of economic sectors and related policies that, if coordinated and integrated, could ensure socio-economic and environmentally sustainable ocean resource use (World Bank 2017).
The ocean uses, governance instruments and regulatory frameworks which underpin the Blue Economy are likely to differ between ocean zones and jurisdictions (Garland et al. 2019; Jouffray et al. 2020). The scope of Blue Economy activities can be divided into three broadly recognized ocean zones (Fig. 1):
  1. Coastal waters: usually within 12 nm of shore (UN General Assembly 1982). This is an often crowded zone where national and sub-national legislation regulate different ocean uses, competition over space and resources is already high, and degradation is most evident (Jackson et al. 2001; Pandolfi et al. 2003; Halpern et al. 2019; Bax et al. 2020a).
  2. Offshore waters: adjacent to the coastal zone and stretching from 12 nm of shore to the extent of the Exclusive Economic Zone of 200 nm (UN General Assembly 1982). This zone faces many spill-over effects and economic activities from the coastal waters. Countries around the world are formally resolving and delimiting their maritime boundaries and increasingly turning their attention towards the resources contained within these boundaries (e.g. see Patil et al. 2018). However, legislation is often lacking, fragmented or inadequate for the new uses of this zone (e.g. Stuiver et al. 2016).
  3. Areas beyond national jurisdiction: outside of the 200 nm EEZ, and also often referred to as the high seas (water column) and the Area (seabed) (UN General Assembly 1982). At present, negotiations are underway to develop or adapt existing international laws in these areas in order to regulate resource use, whilst also maintaining the principles of freedom of navigation (Mickelson 2019) and the continued recognition of seabed resources as the common heritage of mankind (Taylor 2014).
Offshore waters are likely to be a particular focus of Blue Economy expansion over the next decade. This is because of the already crowded nature of coastal waters and the logistical and economic challenges of industrial exploitation in areas beyond national jurisdiction. The development of offshore industries is already growing strongly. For example, between 2010 and 2020 there was a 30% expansion of offshore wind energy production. This was mainly driven by anchored installations, but floating platforms for deployment in deeper waters are also becoming more common (following a pattern seen in oil and gas exploration many years previously). In June 2020, the Ocean Renewable Energy Action Coalition (OREAC) announced its goal of providing 10% of the world’s electricity (approximately 1,400 GW) via offshore wind by 2050. Meeting this goal given current zoning and physical constraints means many more developments will occur offshore within the next decade, with offshore applications already occurring in Northern Europe, China, Japan, Turkey, Brazil and Australia. Similarly, the pressure to increase seafood production by aquaculture has seen a small but growing number of offshore installations deployed in the EEZs of Norway and China, with interest also growing in southern hemisphere countries such as Chile and Australia.
The specific appeal of offshore waters is the available space for potential expansion. For instance, aquaculture is expected to provide around 62% of aquatic foods by 2030 (World Bank 2017), but most of the current production is on land and in crowded coastal waters where space for expansion is limited. This has led governments, industry and academia to consider offshore sites as a potential solution to such limitations (High Level Panel for a Sustainable Ocean Economy 2019). Development of infrastructure and service industries, including marine transportation (Pomeroy et al. 2006) and offshore harbours, would be needed to service offshore production sites. A growing marine sector generally, will further drive an increase in demand for energy. With a need to decarbonise the global economy, this growth provides additional incentive for greater uptake of offshore renewable energy technologies (Appiott et al. 2014; Rockström et al. 2017; High Level Panel for a Sustainable Ocean Economy 2019).
Offshore areas also provide access to an attractive range of resources over which coastal states maintain sovereign rights. Extensive deposits of mineral bearing seafloor massive sulphides, cobalt-rich ferromanganese crusts and phosphorites are located within offshore waters (especially in the Indian and Pacific Ocean basins; Hein et al 2013). These deposits contain metals such as copper, zinc, gold, silver, nickel and cobalt, as well as many rare earth elements, and their volume is greater than that of accessible terrestrial deposits (Toro et al. 2020). This is important given the demand for metals in modern economies. For example, growth in renewable energy use will increase demand for essential minerals that are used in storage batteries (Hein et al. 2013; Buchholz and Brandenburg 2018). The European Commission estimates that 10% of world mineral supply may come from the seafloor by 2030 (European Commission 2012), and seafloor mining activities are currently already occurring in some countries’ offshore waters (Miller et al. 2018). These activities may increase as mineral resource demands grow, land mineral resources become scarce, and social, economic, political, and technological thresholds are met (Teske et al. 2016; Miller et al. 2018). Examples of these thresholds are increases in minerals prices and the development of deep sea mining tools to cover the different phases of mineral extraction and processing (Hein et al. 2013; Ribeiro et al. 2020).
Many coastal states have recognised the potential of offshore waters to deliver economic growth, and this has led to increased research and development activity addressing the logistical and technical challenges of working in this area. For example, development of multi-use offshore platforms to integrate offshore activities is a particular focus of current research and testing (Zanuttigh et al. 2016; Dalton et al. 2019; Lagasco et al. 2019) and individual sectors, such as aquaculture, are actively developing offshore options.
The growth in offshore economic activity brings additional environmental risks, including further exacerbating climate change, pollution (e.g. plastics and chemicals) and habitat degradation (Hoegh-Guldberg and Bruno 2010; Halpern et al. 2019; Pörtner et al. 2019; Egger et al. 2020; see also Melbourne-Thomas et al. 2020, Trebilco et al. 2020, Ward et al. 2020, and Willis et al. 2020). Marine ecosystems are inter-connected, and the full cumulative implication of emerging offshore developments is uncertain (Halpern et al. 2019). Nevertheless, the Blue Economy, if governed correctly, can present sustainable and equitable solutions to the current pressures faced in the oceans (High Level Panel for a Sustainable Ocean Economy 2019; Hoegh-Guldberg et al. 2019). Sustainable development of offshore areas has the potential to reduce pressures on coastal and terrestrial systems, reduce climate impacts, and provide ecological restoration opportunities without undermining the state of offshore ecosystems, thereby positively contributing to ocean health (Hoegh-Guldberg et al. 2019; Nash et al. 2020b). This can be achieved through, for example, the use of innovative technologies for carbon drawdown and sequestration and for novel or more efficient resource use (Zanuttigh et al. 2016; Buck et al. 2017; High Level Panel for a Sustainable Ocean Economy 2019; Bax et al. 2020b).
This paper represents the first known dedicated examination of the opportunities and challenges associated with Blue Economy developments within the offshore zone. While quantitative projections for economic and employment growth for the overall Blue Economy abound, at the time of writing, projections specific to the offshore waters are rare. To the best of our effort, we could only find trends inferred from more general discussions of the Blue Economy across all regions and jurisdictions, or descriptions of qualitative and aspirational trends, whose quantification is heavily conditioned on the development of supporting technology and future market trends. With projections hard to come by, planning may develop around assumptions, expectations and concerns, and may tend towards supporting path dependency (the risk of missed opportunities due to sequencing of developments) along a business as usual trajectory.
This paper begins to address this gap by exploring a number of questions. First, we ask to what extent a business as usual development can achieve the Blue Economy promise of significant economic benefits while ensuring environmental protection and social justice. Since our analysis suggests that this is unlikely, next we ask what a realistic future characterized by socially equitable economic and environmental sustainability would look like. Finally, we ask how the future can be steered from the more likely business as usual to the more desirable, sustainable one. Our vision integrates ecological, economic, social, political and technological drivers and is capable of directing offshore activities towards an equitable and sustainable future by accounting for both past lessons of unsustainable coastal and land developments (e.g. Caswell et al. 2020) and future technological possibilities. The more desirable and sustainable offshore Blue Economy vision we propose will help shape the direction of ocean developments over the course of the UN Decade of Ocean Science for Sustainable Development (2021-2030; UNESCO 2019). It is congruent with the UN Sustainable Development Goals (SDGs), which are globally accepted recommendations for future developments in areas as diverse as poverty, education and climate change (Nilsson et al. 2016).