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Climate change and the ocean

The ocean regulates the global climate by mediating temperature and determining rainfall, droughts and floods. The ocean has already absorbed over 90% of the excess heat trapped by the rising concentration of greenhouse gases. While the ocean’s ability to store heat has slowed global warming, this in turn is changing the ocean’s chemistry. The complex interactions between continued emissions of greenhouse gases and changes in the ability of the ocean to store excess heat will be a major determinant of the speed and magnitude of long-term climate change impacts, with global economic implications.

The ocean and coastal communities are being disproportionately impacted by increasing greenhouse gas emissions. Warming is leading to the melting of inland glaciers and ice, causing rising sea levels with significant impacts on coastal areas such as coastal flooding and erosion, saltwater intrusion, and habitat destruction. Communities and infrastructure are already under pressure from coastal flooding and erosion.

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Building resilience

The OECD is working to support governments to adapt to the risks from sea-level rise. The consequences of which are far reaching, with flood damage under high-end sea-level rise (1.3 metres) estimated to reach approximately 4% of world GDP annually. Marine ecosystems are similarly being severely impacted. The Special Report on Global Warming of 1.5°C estimates that coral reefs are likely to decline between 70% and 90% with a 1.5°C increase. If global warming reaches 2°C, more than 99% of coral reefs are projected to decline.

 Infrastructure networks will be affected by the physical impacts of climate variability and change, such as increased coastal flooding. They will also play an essential role in building resilience to those impacts. New infrastructure assets should be prioritised, planned, designed, built and operated to account for the climate changes that may occur over their lifetimes. Existing infrastructure may need to be retrofitted, or managed differently, because of climate change. 

In addition to making infrastructure resilient to change, additional infrastructure, such as sea walls, will need to be constructed to address the physical impacts of climate change. Coastal protection can reduce the future costs of sea-level rise by 2-3 orders of magnitude. However, in the context of rising risks, there is a need to move to a flexible, forward-looking approach to resilience. This includes integrating hard infrastructure with nature-based solutions (e.g. protection or restoration of coastal ecosystems), new technologies for accommodating flood risk (e.g. permeable pavement), and potential managed retreat in some areas.

Key publications

Responding to Rising Seas: OECD Country Approaches to Tackling Coastal Risks reviews how OECD countries can use their national adaptation planning processes to ensure that coastal communities are adapting to the impacts of rising seas. Specifically, the report examines how countries approach shared costs and responsibilities for coastal risk management and how this encourages or hinders risk-reduction behaviour by households, businesses and different levels of government. The report outlines policy tools that national governments can use to encourage an efficient, effective and equitable response to ongoing coastal change, such as land-use regulation that includes sea-level rise considerations. It is informed by new analysis on the future costs of sea-level rise, and the main findings from four case studies (Canada, Germany, New Zealand and the United Kingdom).

The policy paper “Climate Resilient Infrastructure” outlines the co-ordinated response needed to ensure that new and existing infrastructure networks are resilient to climate change impacts.