CO2 storage plans threaten harbour porpoises in the North Sea: Five NGOs submit statement opposing ExxonMobil’s plans

The organisations reject the application due to significant legal, technical and environmental-law deficiencies and criticise that CO2 storage would entail immense environmental risks for the North Sea. Essential information — in particular geological data, risk assessments, evidence of site integrity, and current ecological baseline data — remains incomplete or is improperly deferred to later stages of the procedure.

In March of this year, the US oil major applied to assess the suitability of a large area of seabed in the Exclusive Economic Zone (EEZ) as a CO2 storage site. Specifically, exploratory drilling and three months of seismic surveys using airguns are planned in the central North Sea behind the island of Heligoland. In the view of the environmental organisations, not only is the legal basis for approval lacking; the project is also incompatible with marine conservation, in particular the protection of harbour porpoises and the climate protection function of the oceans.

Airguns produce some of the loudest man-made noises in the ocean. Their sound can reach harbour porpoises many kilometres away and trigger behavioural responses. Studies show that harbour porpoises avoid seismic noise at distances of up to ten to twelve kilometres. Flight responses or reduced feeding can have population-level effects. The distance to the protected areas provided for in the application — Sylt Outer Reef and Borkum Reef Ground — is only around 8.8 kilometres, too close to rule out harm to the animals that raise their calves in these areas.

Underwater noise threatens the entire ecosystem

Underwater noise affects not only marine mammals but also fish and marine invertebrates, down to zooplankton, and thus the food base of the entire marine ecosystem. Nevertheless, the application lacks an assessment under the European Habitats Directive (FFH). The fact that ExxonMobil has failed to address this important aspect is a warning sign.

The organisations criticise the planned use of airguns: “The North Sea is already one of the most heavily burdened seas in the world. Marine mammals such as the harbour porpoise are already having to flee from shipping noise and construction noise, for example from offshore wind farms. If airguns are added on top of that, the central North Sea will become too loud for them to survive.”

Denise Risch, bioacoustics researcher, who studies underwater noise: “The use of airguns in the search for oil and gas reserves — or, as in the current application, for potential CO2 storage sites — can have devastating consequences for marine species. The intense underwater noise, which spreads rapidly and over great distances, can drive harbour porpoises out of their habitats or cause them physical harm. These planned activities can hardly be considered a climate protection measure; rather, they represent an additional threat to a North Sea that is already under pressure.”

A single shot from a seismic airgun alone can kill zooplankton. Here, however, shots are to be fired around the clock for three months — directly next to areas where harbour porpoises raise their calves. Underwater noise is life-threatening for harbour porpoises, as it disrupts their navigation, hunting and communication with other members of their species.

Organisations call for real climate action instead of carbon dioxide storage

Carbon Capture and Storage (CCS), the capture and underground storage of CO2, is often presented as a contribution to climate protection. In fact, a climate benefit from the technology has not yet been demonstrated. Its widespread use in energy and industrial policy risks delaying the phase-out of fossil fuels and crowding out urgently needed investment in renewable energy, energy efficiency and emission-free production processes. At the same time, CCS involves high costs, considerable energy expenditure, and unresolved long-term risks associated with CO2 storage sites.

Effective and sustainable climate protection must therefore focus primarily on avoiding emissions, as well as on the preservation and strengthening of natural carbon sinks, which are themselves endangered by CCS. Healthy oceans play a key role: they absorb large amounts of CO2, store carbon over the long term, and stabilise the global climate system.

Given the already poor condition of the North Sea, a risky venture such as CCS must not be implemented. The organisations call on the federal government and the state government of Lower Saxony to implement real solutions to the climate crisis: a consistent phase-out of fossil energy, and emission reductions through less waste, a shift in construction practices, greater nature conservation, and the strengthening of natural carbon sinks.

The organisations: “While oil and gas companies extract hydrocarbons from the North Sea at nature’s expense in one place, they want to press carbon dioxide back into the seabed elsewhere using equally destructive methods. Protecting the planet’s largest carbon sink and reducing emissions must take absolute priority over risky pseudo-solutions. Instead of placing further strain on a North Sea already under pressure from fishing, shipping and industry, we urgently need an energy and climate policy that lives up to its name and ends the fossil fuel era.”

Background

In CCS technology (Carbon Capture and Storage), carbon dioxide (CO2) from industrial exhaust gases is extracted using a chemical process that requires high energy input (carbon capture), transported by pipeline or ship, and pumped under high pressure into the seabed or underground on land (storage). This is intended to isolate climate-damaging gases from the atmosphere for millennia in CO2 storage sites. This technology is already in use in the North Sea off Norway and the United Kingdom, though with considerable technical difficulties.

The majority of the few realised CCS projects worldwide have failed so far. Nevertheless, with the amendment of the Carbon Dioxide Storage Act (KSpG) in January 2026, the German Bundestag paved the way for the export and storage of CO2 in the German North Sea. Environmental and water associations criticise the high risks to land and marine ecosystems as well as the questionable climate benefit of CCS. The planned expansion of CCS infrastructure would divert enormous public and private funds that would then be unavailable for genuine climate solutions.

Moreover, the promise of subsidised CCS is paralysing the expansion of renewable energy and efficiency measures. Instead of reducing climate-damaging emissions, power plants, the chemical industry and waste incineration plants could pipe these emissions under the North Sea and store them in the seabed. Gas-fired power plants could also be built and receive subsidies under the law by being labelled “CCS ready.” Once built, gas-fired power plants are operated for decades to amortise investment costs. This cements dependence on gas in the power sector and slows the integration of renewables.

More information:

• OceanCare report on the impact of underwater noise on fish and invertebrates
• Effects of underwater noise on marine life
• CMS Family Guidelines on Environmental Impact Assessments for Marine Noise-generating Activities
• Best Available Technology (BAT) and Best Environmental Practice (BEP) for Mitigating Three Noise Sources: Shipping, Seismic Airgun Surveys, and Pile Driving

Media contact

Nicolas Entrup, Director International Relations, OceanCare, +43 660 2119963, nentrup@oceancare.org