In a new position paper, Seas At Risk cautions against the high risks of marine geo-engineering (mGE) and calls on the EU to prohibit it in its seas, champion an international moratorium and restore the ocean to health by 2030. Instead of investing in speculative techno-fixes, Europe should address the root causes of the climate crisis by phasing-out fossil fuels, halving energy demand, and transitioning to 100% renewables by 2040. 

Climate change is here: floods, hurricanes and droughts are ravaging vast areas on all continents, and biodiversity is collapsing. Yet, efforts to cut greenhouse gas emissions to zero remain sub-standard and nature – including the ocean – is being depleted at an alarming rate.  

Meanwhile, speculative geo-engineering practices like carbon dioxide removal and solar radiation modification are gaining traction. While at surface level the intention sounds positive, in reality these high-risk “false friend” methods could cause vast and irreversible harm to marine biodiversity, disrupt livelihoods in coastal communities and delay the deep emission cuts that are necessary right now. mGE methods can lead to creating vast areas of algal blooms by adding nutrients (e.g. iron) to the ocean, dumping huge quantities of minerals such as ground limestone, and large-scale seaweed farming with sinking of the biomass into the deep sea.  

To result in a meaningful reduction of atmospheric CO2, these methods must be deployed on a massive scale (some up to 10% of the ocean), continuously for decades or indefinitely and at high energy costs. This would cause vast and irreversible harm to marine biodiversity and food webs, alter ocean chemistry and regional weather patterns, and exacerbate inequalities.

Internationally, a de-facto moratorium on geo-engineering exists under the Convention on Biological Diversity (CBD). The London Protocol and Convention prohibit ocean fertilisation (which causes algal blooms), with discussions underway to include additional mGE methods. Despite these frameworks, various technologies are being tested, with millions invested in mGE research. 

The EU takes a precautionary stance on mGE, prioritising the restoration of ecosystems with a high CO2 absorbing capacity (e.g. mangroves, tidal marshes, seagrass and kelp). However, some EU climate policies and regulations, such as the Carbon Removals and Carbon Farming Certification Regulation, risk paving the way for mGE. The Marine Strategy Framework Directive, which aims to achieve good environmental status for European seas, could help prevent mGE practices if better aligned with EU climate policies. 

MGE is not a solution—it’s a threat, a dangerous distraction from real climate action. To address these threats, Europe should: 

  • Reduce GHG emissions to zero, halve energy demand (compared to 2020), phase out fossil fuels, and transition to 100% renewable energy by 2040. 
  • Enforce the international moratorium on geo-engineering under the CBD, support efforts to regulate additional mGE technologies under the London Convention and Protocol, and ratify and implement the BBNJ Treaty. 
  • Prohibit mGE in European seas and exclude mGE technologies and practices from the CRCF Regulation and 2040 EU Climate Target. This ban should encompass research, testing and deployment of geo-engineering techniques.  
  • Redirect existing and future funds intended for research into mGE towards efforts to restore the ocean to health and make it climate resilient by 2030. 
  • Prohibit ocean carbon storage in the water column and on the seabed and halt storage in sub-seabed geological formations until there is proof of no environmental harm. 

Read our full position paper here.