There may be conservation and biodiversity issues in relation to marine species which need to be considered in cases of under sea storage of CO_2^. Additional conservation and biodiversity issues may arise in relation to overground storage and transmission system. An example of a relevant multilateral environmental agreement is the 1992 UN Convention on Biological Diversity.

Energy resource use required to capture and compress CO₂ gives rise to regulatory issues in terms of energy efficiency and additional climate change law considerations. An example of a relevant multilateral environmental agreement is the 1992 UN Convention on Climate Change.

Environmental impact assessment law and policy issues are relevant in relation to CCS. Injection into aquifer and transmission of CO₂ along oil pipelines, for example, are projects that may require local, regional or transboundary assessment of potential significant environmental impacts on the natural areas. An example of a relevant multilateral environmental agreement is the 1991 Espoo Convention on Environmental Impact Assessment in a Transboundary Context.

The potential risks and hazards associated with CCS are, as of yet, relatively unknown, as many of the techniques and technologies have not been tested. Following on from above, acidification of the oceans may be a problem, resulting in the devastion of flora and fauna. The liability issues associated with such situations would have to be explored at national, regional and international levels, and perhaps we might even need a distinct legal regime

Under sea bed storage gives rise to law of the sea issues in terms of rights of access to the sea bed, environmental impacts and potential acidification/pollution of the sea. An example of a relevant multilateral environmental agreement is the 1982 UN Convention on the Law of the Sea. Another pertinent international agreement is the London Convention (1972) and Protocol (1996) that is designed to prevent dumping of waste at sea, this needed amending in 2006 to allow CO₂ storage below the seabed and in 2009 for transboundary movement of CO₂ for storage. You can access the latest information through the United Nation's International Maritime Organisation - IMO. 

There have been a number of recent external scientific studies that are worth highlighting:

Sub-seabed CO₂ storage: Impact on Marine Ecosystems - ECO₂

Quantifying and Monitoring Potential Ecosystem Impacts of Geological Carbon Storage - QICS

Strategies for Environmental Monitoring of Marine Carbon Capture and Storage - STEMM-CCS

The precautionary principle is an accepted principle of environmental law. Referring to the issues above, there are arguments that in the light of scientific uncertainty associated with CCS, we should apply the precautionary principle