Sir, The latest findings from the Intergovernmental Panel on Climate Change (IPCC) provide more detailed evidence than ever before of two things: first, that the ocean has been our buffer from the worst effects of man-made climate change until now; and second, that this role as buffer is seriously compromised, meaning a huge risk for every one of us.

Any businessperson or policy maker who still does not see the linkages between climate change,the ocean, our economies, health and security, needs to have a closer look at the facts. The ocean is the driving force of our planetary system, providing us with 50 per cent of our oxygen. It produces 80m tonnes of food each year and underpins energy, medicine, transport and job creation.

The IPCC report confirms that the current rate of ocean acidification is unprecedented in the last 65 or even 300 million years. Experts are calling climate change the “death knell” for vital coral reef ecosystems.

Added to this, warming ocean temperatures are projected to cause large-scale shifts in the geographic distribution of fish stocks, representing a serious threat to food security, in particular for poorer communities in tropical coastal regions dependent on fish for nutrition.

These facts emphasise that we should act now on the other non-climate threats currently undermining ocean health. Almost 90 per cent of all marine fisheries are either over-exploited or fully exploited, and many important commercial fish stocks are close to collapse. With the global population moving towards 9bn, we should be actively protecting and nurturing all sources of food. The lawless nature of overfishing on the high seas means we are squandering one of the most precious of these. Overfishing is a highly solvable problem. Stricter quotas, more stringent monitoring and compliance measures, and more marine protected areas, are all proven effective methods that we should be scaling up in order to end the appalling “tragedy of the commons” free-for-all, and to build resilience in a system under pressure.

The new IPCC report should not have us wringing our hands. Climate change is transforming the ocean ecosystem and the decline in ocean health is costing us dearly. Action to protect and reinvigorate this highly threatened system is required immediately.

Trevor Manuel, Global Ocean Commission Co­Chair; former Finance Minister of South Africa; Minister in the  Presidency of South Africa

José María Figueres, Global Ocean Commission Co­Chair; former President of Costa Rica

Carol Browner, Global Ocean Commissioner; former administrator, U.S. Environmental Protection Agency

The Global Ocean Commission will release proposals for the reform of ocean governance in June 2014

Read the letter at Financial Times