Initially signed in 1974 by seven parties, today the 10 Contracting Parties include Denmark, Estonia, Sweden, Finland, Germany, Latvia, Lithuania, Poland, Russia and the EU.

The Convention commits parties to preventing pollution from ships and pleasure craft, pollution from land-based sources, pollution from exploitation of the seabed, and from the introduction of harmful substances, as well as to prohibit incineration. Wherever an environmental impact assessment finds that adverse impacts are likely to arise in the Baltic Sea Area, the parties likely to be impacted must be notified and consulted.

In addition to the above restrictions, parties must prevent dumping in the Baltic Sea Area. Dumping is defined as the deliberate disposal of wastes at sea, as well as of other materials from ships or other man-made structures. The definition explicitly excludes material generated from “normal operations” as well as material placed for purposes other than disposal.

Currently, the Convention is interpreted as prohibiting offshore CO₂ storage in the Baltic Sea, based on the definition of dumping above. While exemptions to the definition of dumping are detailed in Article 11, the article does not explicitly exempt CO₂ storage activities, meaning CO₂ storage is implicitly prohibited under the Convention. This restriction is compounded by national-level bans on subsurface storage in the national law of many parties to the Convention.

While Denmark and Sweden are pressing ahead with CO₂ storage plans in regions outside the Convention area, there is currently limited momentum to amend the Convention itself. Key avenues to do so could include arguing that CO₂ storage constitutes a purpose other than disposal, that human life is threatened, or that countervailing agreements exist which take precedence – all of which could exempt CO₂ storage from being considered dumping.

The Convention applies to pollution from land, air and sea. Such substances are defined under Annex I by their intrinsic properties including persistency, toxicity, and bio-accumulation tendency, as well as “characteristics liable to cause pollution”, including transboundary significance, risk of undesirable and irreversible changes in the marine ecosystem and distribution pattern. Annex I also defines priority groups of harmful substances, including heavy metals, radioactive substances, oils and hydrocarbons of petroleum origin, and other organic compounds especially harmful to the marine environment.

 

Relevance for carbon removal

The Helsinki Convention has clear relevance for governing the storage of CO₂ in geological formations offshore. A key question concerns whether CO₂ storage should be considered within the scope of dumping or pollution and thus subject to the same restrictions. Article 2 of the Convention defines pollution from land-based sources as including “deliberate disposal under the seabed”. While certain exemptions are defined under Article 11 (outlined above), the Convention has not been amended to explicitly exempt CO₂ storage, as has been seen with the amendment to the London Protocol (though this amendment has been ratified by less than two-thirds of parties to the Protocol).

On the other hand, if increasing CO₂ concentrations in the Baltic Sea were argued to constitute pollution, carbon dioxide removal (CDR) and the geological storage of CO₂ could perhaps be understood as BEP or BAT, potentially rendering such activities allowable under the Convention.

 

Challenges at national level

Many of the parties to the Convention currently explicitly ban geological CO₂ storage in their national law. Currently, Lithuanian law prohibits the injection of CO₂ into the subsurface other than in quantities under 10,000 tonnes; Finland allows storage only for research purposes, Estonia and Latvia ban storage outright, while until 2024 Poland had a similar ban in place. A draft to amend Germany’s Carbon Dioxide Storage Act is currently under review and would allow offshore storage outside marine protected areas, while maintaining the prohibition of onshore storage. On the other hand, Denmark explicitly allows offshore storage within a limited area, and Sweden is mobilising financial support for storage projects. Denmark recently revised its Marine Environment Act to exempt CO₂ storage from the definition of dumping, potentially providing a path forward for other parties and for the Convention itself.

Nonetheless, the Helsinki Convention still presents a challenge for the development of CO₂ storage in Denmark and Sweden. In an FAQ published in 2024 relating to its second CO₂ storage licensing round, the Danish Energy Agency acknowledged that the Helsinki Convention restricts potential CO₂ storage projects but also recognised its importance for nature preservation. Both countries currently circumvent the restrictions of the Convention by developing CO₂ storage in their exclusive economic zones, waters other than the Baltic Sea, and potentially onshore. However, given the Convention’s catchment-based approach, even storage in such areas may be restricted. For example, the Danish Energy Agency indicated it is not able to issue permits for onshore geologic storage unless the risk of CO₂ migration into the Convention region is shown to be zero.

 

Regulatory framework for CCS in the Nordic countries – Nordic Council of Ministers