The Convention on the Protection of the Marine Environment of the Baltic Sea Area – also known as the Helsinki Convention – was originally signed in 1974 by all Baltic Sea coastal countries, seeking to address the increasing environmental challenges from industrialisation and other human activities and that were having a severe impact on the marine environment. It entered into force on 3 May 1980. The Convention includes the protection of the Baltic Sea from all sources of pollution from land, air and sea. The Helsinki Convention was updated in 1992 to take into account the geopolitical changes and emerging environmental challenges in the region and was extended to ten Contracting Parties, including the European Union. The updated Helsinki Convention of 1992 entered into force on 17 January 2000.
According to the articles in the Helsinki Convention  dumping in the Baltic Sea is generally forbidden. Carbon storage can be seen as dumping when regarding it as “deliberate disposal at sea or into the seabed of wastes or other matter” (article 2.4 a (i)). If there is not an applicable exemption (article 2.4 b – not seen as dumping, or 11.4 – exception from prohibition due to that safety of human life is threatened, or 29 – prohibition not applicable due to the relation to other Conventions) carbon storage then is forbidden (article 11.1), and that prohibition shall be implemented in national law through its national authorities (article 4.2).
There is though a common interest among several countries around the Baltic Sea to be able to store carbon in the Baltic Sea in the future, in order to reduce CO2 emissions and reach the common climate goals. For example, Sweden is right now, through its authority Geological Survey of Sweden, investigating the possibility of storing carbon within Swedish territory in the Baltic Sea.
Therefore, there is also a discussion among the countries who have signed the Helsinki Convention about how to go forward making sure carbon storage is in agreement with the Convention. One way could be to look at how this problem was dealt with in the London Protocol – 1996 Protocol to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, 1972 (see article 4.1, and Annex I 1.8 and 4) , where carbon dioxide was added to the list of matter that may be considered for dumping if certain conditions are being met (disposal into a sub-seabed geological formation, consisting overwhelmingly of carbon dioxide, no wastes or other matter are added for the purpose of disposing of those wastes or other matter).