Environmental Impact

It is important to minimize environmental impact independent of the source of minerals. We must understand the risk and mitigate the potential negative impact related to both exploration and exploitation of marine minerals.

Marine mineral resources represent new environmental challenges that must be carefully managed. A key challenge for the exploitation of marine minerals are environmental concerns, including the potential for damage to unique ecosystems.

Seabed massive sulphides (SMS) deposits is expected to come with about 5-10 times higher ore grade than land-based sites, while nodules and crusts come with very limited waste and tailings. High ore grad and limited amount of light and nutrients suggests the potential for a lower environmental impact for deep sea minerals than current land-based mining.

It has been suggested to blended high ore grade SMS with declining copper ore from land, to extend the lifetime and utilising more of the land-based resources, providing a win-win by combining land and ocean minerals resources.  

Life cycle analysis performed by The Benchmark Minerals Intelligence shows that polymetallic nodules outperform land-based mining in almost all categories. Life cycle assessment by Alvarenga et al., shows 38% reduction in carbon footprint.

Different types of resources and environment could make it challenging to compare different projects, however a framework for comparing environmental impact of deep seabed and land-based mining has been proposed. 

The basis for being awarded Green Platform funding of the EMINENT project is the belief that deep sea mining can be performed with a significant lower environmental and climate impact compared to current land-based mining.

Biodiversity 

Loss of biodiversity is a main concern with possible future deep sea mining.   

It is predicted about 8.7 million species on the earth, of which 2.2 million are marine species. Animalia species is the large majority with about 7.8 million in total and 2.15 million marine species. It is estimated that 86% of existing species on Earth and 91% of species in the ocean still await description. 

As the ocean covers about 70% of the earth, it is about 7 times as likely to find an undescribed species on the same size area on land as in the ocean.   

Number of species varies widely between different areas/regions. If we look at the deep sea, the Clarion-Clipperton Zone (CCZ) in the Pacific is the area being most explored with the highest interest for deep sea mining. The estimated total number of species in the entire CCZ is estimated to be approximately 8000. 5142 of these species are recorded and have received informal names, but are by June 2023 yet to be detailed described and given scientific name as species.  

There are set aside 13 protected areas in the CCZ to help minimise risk of species extinction.  

It looks to be widely recognised that the rainforest is the most biodiverse place on the planet, with over 3 million species.  

Coral reefs are considered to be the most biodiverse of all marine ecosystems. The Coral Triangle region around Indonesia with an area similar to the CCZ is recognised to matches the species richness and diversity of the Amazon rainforest. 

As comparison, there were 46 891 known species in Norway by August 2023, with an expected total of 72 190. About 18 % of the known species are living in the ocean, 9% in fresh water and 73% on land.  

Carbon sequestration 

Resuspension and release of carbon store in sediments at the seabed is a concern raised related to deep sea mining.  

Deep sea sediments have an overall low organic carbon content due to low productivity and input of organic matter.  

Researchers estimates that deep sea mining will have a trivial impact on the ecosystem service of carbon sequestration. Most of the disturbed organic carbon will be redeposited on the seafloor and sequestered.  

The European Academies Science Advisory Council states that “At the current state of knowledge, deep-sea sediment disturbance seems unlikely to lead to significant additional release of carbon dioxide, although uncertainties remain”. 

For more detailed information please see: ISA Fact-check 2024/1 – The carbon cycle in the Area. This note is addressing nodules, while crust is fixed to seamounts and are not associated with sediments. Sulphides deposits can be buried under sediments, but these deposits are located at very small and localised area compared to nodules.