Out of sight, out of mind – the dangers of Deep Sea Mining

The deep sea describes the water column of the worlds’s oceans and seas below 200m depth. We know it to be dark, cold, hostile and unchartered. While only 0,001% of the deep has actually been seen, what we have seen so far has highlighted what an important and diverse habitat is is. Beyond its diversity, the deep sea is also a place of exchange where nutrients are cycled and returned by currents to the surface. It also has a regulatory function, sequestering carbon and methane and absorbing atmospheric heat.

Amidst all these characteristics, the deep sea has only gained popularity and value in the last years for one specific reason; the fact that it is also a place where important minerals and metals can be found. This has grasped the attention of mining companies around the globe, who now have all expressed their intentions of extracting these minerals from the seafloor. The biggest arguments are rooted in support of a “green transition”. The ever-growing low carbon economy has lead to an increased demand in specific metals, particularly of cobalt, nickel, lithium and copper, with estimates predicting the demand for nickel (Ni) and cobalt (Co) to be 4x greater than today. The narrative presented by the mining companies to support their intentions, is that it is an unavoidable consequence of an ever-growing demand, or “the lesser of two evils” in comparison to land-based mining, which has a significant environmental and social impact. 

So before we argue why deep-sea mining is a big problem, let’s get a picture of what happens exactly during a simple mining process. An operation vessel at the surface launches a collector vehicle, that is tethered to the vessel via pipes, to collect metals such as poly metallic nodules (potato shaped rocks on the seabed) from the site. As metals are collected, a plume is created which is pumped up through a riser pipe to the surface. In the operation vessel, metals are separated from other unwanted debris/marine life and the latter is then released as a discharge plume into the mid-water column.

Of course mining such a complex and unchartered environment is not a good idea and can have extremely detrimental effects on the marine life. Mining impacts include light and noise pollution, sediment plumes and biodiversity loss resulting from widespread habitat fragmentation. Collector and discharge plumes pose a significant risk to midwater ecosystems, which represent more than 90% of the biosphere, contain a large part of the fish biomass which supports our fishing industry, connects the shallow and deep ecosystems and play a key role in carbon export and nutrient regeneration. Both deep and midwater ecosystem services can be negatively affected by return sediment plume, projected to be discharged at around 1200m that may persist for hundreds of km and, amongst other things, clog respiratory and olfactory surfaces. These affects will likely lead to an increased loss in biodiversity and ecosystem function; in the deep sea this means that we will lose species, ecosystems and their services before we even knew they existed.

Generally speaking, 3 types of metal-rich deposits of interest in the deep ocean have been identified; Abyssal plains, Sulfide deposits at hydrothermal vents and seamount crusts rich in Co. All these deep-sea metal deposits also represent important habitats that host a diversity of deep-sea life. At limit of Madeira EEZ, crusts rich in cobalt (iron-manganese) have been detected in the seamounts. Also, the southern part of the Madeira-Tore submarine plateau (Madeira constitutes extreme southwest) is Portuguese subregion with high average values of Co, Ni, Cu and Zn, making Madeira a potential candidate for the interest of mining companies.

Apart from direct effects mentioned above, socio-economic implications of deep-sea mining will also have a huge impact, destroying eco-tourism, causing the collapse of fish stocks thereby affecting the fishing industry as well as reversing and halting deep sea research in Madeira.

The global authority responsible for granting mining licenses for the deep sea is the International Seabed Authority (ISA). Several NGOs and government officials, including from France, Germany and Portugal, have expressed their concern over mining an environment that hasn’t even been researched properly yet. In late July, the ISA announced it will not issue any extraction permits for deep-sea mining until it finalizes its mining regulations, and it indicated they might not be completed until 2025. This may sound like good news but the pressure from mining companies on the ISA is increasing. Global networks such as the SOA (sustainable ocean alliance) network are calling for a moratorium to at least delay deep sea mining until its potential effects are properly studied, which can be signed and supported by anyone.

If this article convinced you of the dangers of Deep Sea Mining, then we encourage you to sign one of the petitions for a moratorium, for example that of SOA. This is a severe environmental  problem which we can still prevent!

By Paula Thake