We appreciate the recent Greenpeace report, ‘In Deep Water: The emerging threat of deep sea mining,’ issued July 3, 2019, as a well-intentioned effort to protect the deep sea.
We agree with its recommendations to (1) establish a comprehensive network of marine reserves covering at least 30% of the ocean by 2030; and (2) establish a strong Global Ocean Treaty in 2020 that promotes sanctuaries across the global ocean, protects marine life from multiple extraction activities and delivers rules and high standards for potentially damaging industries.
The report regrettably contains several factual mistakes, material misrepresentations and partial truths. We are compelled to correct and offer context for several of the report’s claims, specifically with regard to the impacts of collecting polymetallic nodules from the abyssal seabed of the Clarion-Clipperton Zone (CCZ). Given the severity of the multiple climate and wildlife crises facing the planet and the urgent need for action, we believe it’s important for the global community to make decisions based on the best available data.
In the CCZ, carbon is primarily stored in an organic form in ocean sediments and in the form of inorganic carbon dissolved in the water. There are no known methane clathrates (methane ice) or CO2 clathrates in the CCZ.
— Total carbon stored in CCZ sediments is very small. Despite the oceans occupying a vast area of 354 million km2, seabed surface sediments store 15 times less carbon than all the vegetation and soil on land (150 gigatonnes vs. 2,300 gigatonnes - WOR1 2010a). CCZ occupies an area of 4.56 million km2, out of which 1.44 million km2 have been set aside as Areas of Particular Environmental Interest (APEIs) that will never be mined. The area occupied by the CCZ sediments outside of APEIs accounts for 0.88% of the global seabed and the total maximum amount of carbon that could be stored in these sediments is 1.3 gigatonnes. In reality, this amount is likely to be even smaller because overlying waters are among the most oligotrophic (nutrient-poor) of the Pacific Ocean (Lutz et al. 2007). Most of the organic carbon is metabolized during the long 4-6 km descent from the surface to the seabed. As a result, CCZ seabed surface sediments contain only 0.2-0.6 wt% of organic carbon—300 times less than the median value for terrestrial soil in North America (Volz et al. 2018, Lutz et al. 2007).
— There is no pathway for releasing carbon from CCZ sediments. Nodule collection machines on the seabed will disturb and temporarily suspend these sediments (‘plumes’). Plumes will have negative impacts, but release of stored carbon into the atmosphere is not one of them. While definitive direct measurements of how high the plumes will rise above the CCZ seabed will only be available once pilot collection tests are conducted in the next 12-24 months, modelling by GSR and BGR indicate that most sediment particles will deposit as density flow; a secondary dilute plume could rise as high as 200 meters. Nearly all carbon-bearing sediment particles will resettle back to the bottom—large or flocculated particles within days, finer ones more slowly (see section on plumes, below). There is no known natural mechanism for seabed sediments to rise 4-6 km up to the surface other than the global oceanic thermohaline circulation that operates on a time scale of centuries. All currently planned nodule collection systems we are aware of aim to separate sediment from nodules at the seabed. We therefore expect little to no carbon-bearing sediments will reach the surface as a result of nodule collection in the CCZ.
— No inorganic carbon in solution with deep seawater will be released as nodules are collected from the surface of the seabed. These molecules will remain in solution with seawater owing to cold temperature and intense hydrostatic pressure at 4-6 km depths.
— Miniscule amounts of carbon could be released through momentary exposure of deep seawater to the atmosphere during nodule transport to the surface. Nodules collected on the seabed will be pumped to a surface vessel through a riser pipe using deep seawater. Due to low temperature and very high pressure at the seabed, deep seawater contains more dissolved CO2 than surface water or air. As this water moves through the riser, the hydrostatic pressure will decrease, and the temperature will increase. On the surface, deep seawater will be exposed to the atmosphere in the vessel’s hold for up to five minutes before it is reinjected back into the ocean at 1.2 km depth. Calculations indicate that in the worst-case scenario, the upper theoretical limit for associated CO2 release is extremely small, 27 grams of CO2 per wet tonne of collected nodules.
— Comprehensive life cycle sustainability analysis (LCSA) of full climate change impact should be a requirement for all proposed mining projects. Given the severity of climate change and wildlife crises, it is imperative we understand the climate change and biodiversity impact of different sources of metals required for the green transition. The LCSA analysis we performed together with independent consultants for two sources of nickel, copper, cobalt and manganese—land ores and CCZ polymetallic nodules—shows that if we source the metals needed to build 1 billion electric vehicles (EVs) with 75KWh batteries from CCZ polymetallic nodules, we will reduce CO2e emissions by 75% compared to producing these metals from conventional land ores. This represents a saving of 1.5 gigatonnes of emissions – a material contribution to addressing climate change.
The nine areas, each 400 km x 400 km (including the 200 x 200 km core area surrounded by a 100 km buffer zone), along with their locations, closely resemble set-aside recommendations from marine scientists along attributes including area size, species variety, and topographical heterogeneity (Wedding et al. 2013). Dunn et al. (2017) reported one exception: the ISA re-positioned two of the APEIs from recommended subregions within the core of the CCZ to the periphery to avoid overlap with existing exploration claim areas. The current 9 APEIs represent more than 30% of the total CCZ management area. There have been calls to establish even more APEIs, positioned nearer to one another in order to enhance population connectivity. In 2016 the ISA considered creation of two additional APEIs in the CCZ region, which would further increase the total APEI coverage but the final decisions have not been made yet. As Cuyvers et al. (2018) state, the APEIs form a system that seeks to maintain healthy marine populations, account for regional ecological gradients, protect a full range of habitats, and create sufficiently large buffer zones against external anthropogenic impacts like sediment plumes. Unlike the contract zones, the APEIs have straight-line boundaries to facilitate rapid recognition and compliance.
In addition to the regional APEIs, at the local level, contractors are expected to allocate 10-30% of their mining areas as ‘no-take’ zones – offering further habitat protection.
Sediment plumes are a major concern for nodule collection on the CCZ abyssal seabed. Modifications to the harvesting vehicles may reduce the loading and size of plumes, but they will still bury or smother some organisms, clog feeding structures of filter feeders or suspension feeders, reduce visibility for visual feeders and potentially interfere with other processes. The actual extent of plumes will depend on harvester configuration, depth of sediment disturbed, speed of operation, speed of water discharge and local current speed, among other factors.
Noting previous studies indicating that >50% of suspended particles would settle within several kilometers of the source region within 10 days, with the remaining particles transported outside the model boundaries, Gillard et al. (2019) modeled plumes created at faster discharge rates and current flow conditions. Greater turbulence increased particle aggregation and settling rate, so that plumes spread between 4 kilometers under normal flow conditions and 9 kilometers during the passage of an eddy. The very finest sediment particles have longer suspension times, but 99% of the mass of a near-bottom sediment plume is expected to settle within one or two months and within 100 kilometers of the collection machine (Wedding, et al., 2013).
The maximal depth of a sediment blanket precipitating from plumes seems to be about 30 millimeters (Jones, Kaiser, Sweetman et al. 2017). Initial modeling by GSR for the Environmental Impact Statement of their 2019 small-scale testing of nodule collector components indicated a 1 millimeter isopach at 500-750 meters from the collector vehicle. While we expect a full-scale production system to have a stronger impact given greater flux and duration, this initial modeling offers an indication of the likely impact. Results cited by Gillard et al. (2019) indicate that near-field sedimentation of >20 millimeters drastically impacts the deep-sea ecosystem to varying extents; 3 millimeters burial monthly for 6 months has variable effects; but instantaneous burial of 1 millimeter does not affect microfaunal species richness or abundance.
Based on a precautionary approach, they suggested maintaining 1 millimeter as an ecological blanketing threshold value, with the understanding that such threshold levels can only be reached if massive blanketing effects are accepted in smaller fallout areas of a few square kilometers. Given the above cited indications, we believe this could be achievable, but further testing and modeling under existing Exploration Contracts is required to offer definitive environmental impact statements for nodule collection systems.
Deep-sea organisms will be harmed directly by nodule collection, particularly sessile organisms living obligately on nodules, and directly or indirectly by plumes. Population sizes and species distributions will be affected, some for long periods. In that sense, we agree with Niner et al. (2018) that deep-sea mining likely cannot be carried out with ‘no net loss of biodiversity.’ The system of APEIs as well as local contractor ‘no-take’ zones are designed to prevent species extinctions. However, the harsh reality is that such an outcome cannot be guaranteed, since an unknown number of species remain to be discovered and the ranges of known species are still poorly understood, partly due to the very low numerical density of the megafauna in the CCZ (Simon-Lledó et al. 2019). By the same token, we cannot absolutely assert that the loss to marine biodiversity will be irrevocable. If the CCZ seabed remains undisturbed after nodule collection ends, and if APEIs and other set-asides perform as intended, biodiversity will have an unlimited timescale for gradual recovery toward its pre-mining state. But there are no guarantees here either.
This predicament is not unique to deep-sea mining – the Niner’s (2018) conclusion is equally true of mining on land. Despite water accounting for 71% of this planet’s surface, there are six times more species on land than in the ocean, and only about two-thirds of them have been described, with significant gaps remaining especially at meio- and microfauna levels (Costello & Chaudhary, 2017); (Zhang, 2017). Changes in base metal demand and supply are currently shifting biodiversity threats towards more biodiverse regions on land (Sonter et al. 2018).
When a new nickel laterite mine is developed in Sulawesi, Indonesia—one of the most unique and biodiverse island ecosystems on the planet—there is no way to guarantee that these operations will not lead to species extinction, as no exhaustive biodiversity mapping is undertaken. Mining on land harms terrestrial wildlife in many direct and indirect ways: cutting down rainforests and removing topsoil to access ore bodies causes habitat loss at the mine site; breaking and processing ores releases toxic chemicals into water, soil and air causing habitat degradation at much wider regional scales; operations often deplete local freshwater reserves; toxic tailings dam failures extend the harm to hundreds of kilometers beyond the mine site. Development of mines in increasingly remote locations means infrastructure buildout and more human settlements—with associated over-exploitation (e.g., hunting, fishing), invasive species and habitat loss for other land uses. How many species have already gone extinct as a result of mining on land? How many more will disappear over the coming decades? The estimates are devastating but we don’t know for sure.
Unlike terrestrial wildlife, deep-sea wildlife in the CCZ at the very least benefits from the strong application of the precautionary approach: several years of much more in-depth environmental baseline studies (including micro- and meiofauna rarely assessed on land) and environmental impact assessments are being undertaken – under the scrutiny of the international regulator and civil society—before a single kilogram of nodules is collected for commercial purposes from the seabed. On land, the regulation of mineral extraction and processing relies on national laws for biodiversity protection that tend to vary greatly both in terms of their rigor and enforcement.
We cannot afford to simplify complex and controversial issues. To make good decisions, we need to think through different pathways across different spatial and temporal time scales. As a global community, we urgently need to stop the climate crisis and the wildlife crisis, that itself is exacerbated by climate change. Renewables, electric transport and industry all require a massive new injection of base metals. But mining the metals—whether on land or on the seabed—is fundamentally a destructive and energy intensive process. More metal production will generate more CO2 emissions and will cause more habitat loss and degradation. Yet, over the next 30-50 years, a world without mining is not an option. The questions we need to be asking are: how do we produce the metals we need with the least amount of climate change impact and the least amount of biodiversity loss? How do we best mitigate the impacts we will inadvertently cause?
We need both, mining and biodiversity conservation—ideally, working together to define the best pathway forward.
The Sustainable Development Goals are a blueprint to achieve a better and more sustainable future for all by meeting existing global challenges related to poverty, inequality, climate change, environmental degradation, prosperity, peace and justice. Our analysis to-date indicates that sourcing metals from CCZ polymetallic nodules produces less carbon emissions, less impact on carbon sequestration, less impact on water and air, as well as less mortality, injury and illness to people. Producing metals from nodules and land ores both harm biodiversity but in ways that are difficult to compare. Collecting nodules will harm a variety of invertebrate animals, mainly small, many new to science, over a broad area, probably with knock-on effects to some deep-sea fish. Obtaining metals from land harms a much broader variety of organisms, including plants, fish, amphibians, reptiles, birds, mammals and humans.
The transition to a renewable, emission-free economy requires a massive net new injection of metals. Given current stocks, our transitional metal needs for the next 30-50 years cannot be met by recycling alone (Arrobas et al. 2017). Even under the most aggressive scenarios of 90-100% recycling rates, the share of secondary production (recycled metals) is projected to take several decades to catch up with primary production (van der Voet, et al. 2018). The situation is even worse in developing countries where early stages of industrialization mean absence of recyclable stocks. Decisions about where to source the needed primary metals must be made in a comprehensive manner that minimizes overall damage to the biosphere, ecosystems and people.
This article was submitted for publication by Dr. Greg Stone, Chief Ocean Scientist, DeepGreen Metals Inc. DeepGreen is solely responsible for its content. To read the full Greenpeace report click here: In Deep Water: The emerging threat of deep sea mining.
Arrobas, Daniele La Porta; Hund, Kirsten Lori; Mccormick, Michael Stephen; Ningthoujam, Jagabanta; Drexhage, John Richard. 2017. The Growing Role of Minerals and Metals for a Low Carbon Future (English). Washington, D.C. : World Bank Group. http://documents.worldbank.org/curated/en/207371500386458722/The-Growing-Role-of-Minerals-and-Metals-for-a-Low-Carbon-Future
Costello, M. And C. Chaudhary. 2017. Marine biodiversity, biogeography, deep-sea gradients, and conservation. Current Biology 27(11):R511-R527. doi: 10.1016/j.cub.2017.04.060.
Cuyvers, L., Berry, W., Gjerde, K., Thiele, T. and Wilhem, C. (2018). Deep seabed mining: a rising environmental challenge. IUCN and Gallifrey Foundation. https://portals.iucn.org/library/sites/library/files/documents/2018-029-En.pdf.
Dunn, D.C., C.L Van Dover, R.J. Etter, C.R. Smith et al. 2018. A strategy for the conservation of biodiversity on mid-ocean ridges from deep-sea mining. Science Advances 4(7). DOI: 10.1126/sciadv.aar4313.
Gillard, B., K. Purkiani, D. Chatzievangelou et al. 2019. Physical and hydrodynamic properties of deep sea mining-generated, abyssal sediment plumes in the Clarion Clipperton Fracture Zone (eastern-central Pacific). Elem Sci Anth, 7(1), p.5. DOI: http://doi.org/10.1525/elementa.343
Jones,D.O.B, S. Kaiser, A.K. Sweetman, C.R. Smith et al. 2017. Biological responses to disturbance from simulated deep-sea polymetallic nodule mining. Plos One Online at: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0171750
Lutz, M.J., K. Caldeira, R.B. Dunbar and M.J. Behrenfeld. 2007. Seasonal rhythms of net primary production and particulate organic carbon flux to depth describe the efficiency of biological pump in the global ocean. J. Geophys. Res. 112, C10011. doi:10.1029/2006JC003706. 26 pp.
Niner, H.J, J.A. Ardron, E.G. Escobar, M. Gianni, A. Jaeckel, D.O.B. Jones, L.A. Levin, C.R. Smith, T. Thiele, P.J. Turner, C.L. Van Dover, L. Watling and K.M. Gjerde. 2018. Deep-Sea Mining With No Net Loss of Biodiversity—An Impossible Aim. Front. Mar. Sci. 5:53. doi: 10.3389/fmars.2018.00053
Simon-Lledó, E., B.J. Betta, A.I. Veerle et al. 2019. Megafaunal variation in the abyssal landscape of the Clarion Clipperton Zone. Progress in Oceanography 170:119-133. https://doi.org/10.1016/j.pocean.2018.11.003
Sonter LJ, Ali SH, Watson JEM. 2018 Mining and biodiversity: key issues and research needs in conservation science. Proc. R. Soc. B 285: 20181926. http://dx.doi.org/10.1098/rspb.2018.1926
van der Voet, Ester, Lauran van Oers, Miranda Verboon, and Koen Kuipers. 2018. "Environmental Implications of Future Demand Scenarios for Metals." Journal of Industrial Ecology. https://doi.org/10.1111/jiec.12722
Volz, J.B., J. Mogollon, W. Geibert et al. 2018. Natural spatial variability of depositional conditions, biochemical processes, and element fluxes in sediments of the eastern Clarion-Clipperton Zone, Pacific Ocean. Deep Sea Res. Part 1. Oceanographic Research Papers 140:157-172. http://doi.org/10.1016/j.dsr.2018.08.006
Wedding L.M., A.M. Friedlander, J.N. Kittinger, L. Watling, S.D. Gaines, M. Bennett, S.M. Hardy and C.R. Smith. 2013 From principles to practice: a spatial approach to systematic conservation planning in the deep sea. Proc R Soc B 280: 20131684. http://dx.doi.org/10.1098/rspb.2013.1684.
WOR 1. 2010a. The oceans – the largest CO2-reservoir. Living with the oceans. A report on the state of the world’s oceans. World Ocean Review 1. Online at: https://worldoceanreview.com/en/wor-1/ocean-chemistry/co2-reservoir/
Zhang, S. 2017. Why are there so many more species on land when the sea Is bigger? The Atlantic. https://www.theatlantic.com/science/archive/2017/07/why-are-there-so-many-more-species-on-land-than-in-the-sea/533247/ 12 July 2017.