The world’s oceans are warming, rising, and acidifing due to human action. The German Advisory Council on Global Change (WBGU) on May 31 2006 released a new report on climate change and the world’s oceans, The Future Oceans: Warming Up, Rising High, Turning Sour, that synthesizes current knowledge on climate change and oceans. They state that climate change in combination with over-fishing is threatening already depleted fish stocks. Sea-level rise is exposing coastal regions to mounting flood and hurricane risks. They argue that to keep the impacts on human wellbeing within manageable limits it is necessary to both increase coastal and ocean resilience and reduce the amount of future global warming and ocean acidification. The WBGU recommends that societies act to:

Limit acidification and temperature rise
Adaptation measures can only succeed if sea-level rise, ocean warming and ocean acidification are limited to tolerable levels. The only way to do this is through aggressive climate protection policies. WBGU has already recommended previously that the rise in global mean temperature be limited to a maximum of 2 degrees Celsius above the pre-industrial level. Ocean conservation is a further reason for imposing this limit. Furthermore, in order to restrain acidification it is essential to reduce not only emissions of the overall basket of greenhouse gases, but also to ensure that carbon dioxide emissions in particular are sufficiently abated. It follows in WBGU’s view that global anthropogenic greenhouse gas emissions will need to be approximately halved by 2050 from 1990 levels.

Strengthen the resilience of marine ecosystems
To strengthen the resilience of marine ecosystems to elevated seawater temperatures and acidification, it is essential to manage marine resources sustainably. In particular, over-fishing must be stopped. In addition, WBGU recommends designating at least 20–30 per cent of the global marine area as conservation zones. The international community has already adopted goals in this regard, for instance at the World Summit on Sustainable Development in Johannesburg. These must now be implemented, and the regulatory gap for the high seas closed by adopting an appropriate international agreement.

Develop new strategies for coastal protection
About every fifth person lives within 30 kilometres of the sea. Many of these people are put at immediate risk by sea-level rise and hurricanes. Coastal protection is thus becoming a key challenge for society, not least in financial terms. National and international strategies for mitigation and adaptation need to be further developed and harmonized. This includes plans for a managed retreat from endangered areas. In developing countries, financing needs to be secured by means of both existing and innovative financing instruments such as micro-insurance.

Give legal certainty to refugees from sea-level rise
At present, international law neither establishes a commitment to receive people who are forced to leave coastal areas or islands because of climate change, nor is the cost question resolved. Over the long term, a quota system is conceivable, under which states would have to adopt responsibility for refugees in line with their greenhouse gas emissions. This will require formal international agreements and the establishment of dedicated funds for international compensation payments.

Use carbon dioxide storage only as a transitional solution
To mitigate emissions, carbon dioxide can be captured in energy-generating facilities and then stored in geological formations on land or under the sea floor. Direct injection into the deep sea is a further option under debate, but this lacks permanence and harbours a risk of ecological damage in the deep sea. WBGU therefore recommends prohibiting the injection of carbon dioxide into seawater in general. In contrast, storing carbon dioxide in geological formations under the sea floor can present a transitional solution for climate protection, complementing more sustainable approaches such as enhancing energy efficiency and expanding renewable energies. Permits should only be granted, however, if such storage is environmentally sound and is secure for at least 10,000 years.