Ocean acidification 'may increase by 170 per cent' by end of 21st century

Press release issued: 14 November 2013

The acidity of the world’s ocean may increase by around 170 per cent by the end of the century bringing significant economic losses, according to a major new international report. People who rely on the ocean’s ecosystem services – often in developing countries – are especially vulnerable.

An international team of experts, which included Dr Daniela Schmidt from the School of Earth Sciences at the University of Bristol, has summarised the state of knowledge and assessed ‘levels of confidence’ in relation to ocean acidification statements.

This summary for policy makers results from the Third Symposium on the Ocean in a High CO2 World, the world’s largest gathering of experts on ocean acidification, which was held in Monterey, California in September 2012. Dr Schmidt was one of the keynote speakers at this conference.

The summary will be launched at the UN Framework Convention for Climate Change Conference of the Parties (COP 19) in Warsaw on Monday 18 November.

The researchers also found that the world's oceans are acidifying at an 'unprecedented rate', which may be faster than at any time in the past 300 million years.

They conclude that marine ecosystems and biodiversity are likely to change as a result of ocean acidification, with far-reaching consequences for society. Economic losses from declines in shellfish aquaculture and the degradation of tropical coral reefs may be substantial owing to the sensitivity of molluscs and corals to ocean acidification.

The chair of the symposium, Ulf Riebesell of GEOMAR Helmholtz Centre for Ocean Research Kiel said: "What we can now say with high levels of confidence about ocean acidification sends a clear message. Globally we have to be prepared for significant economic and ecosystem service losses. But we also know that reducing the rate of carbon dioxide emissions will slow acidification. That has to be the major message for the COP19 meeting."

The summary for policymakers makes 21 statements about ocean acidification with a range of confidence levels from 'very high' to 'low' which include:

Very high confidence

• Ocean acidification is caused by carbon dioxide emissions from human activity to the atmosphere that end up in the ocean

• Reducing carbon dioxide emissions will slow the progress of ocean acidification

• Anthropogenic ocean acidification is currently in progress and is measurable

• The legacy of historical fossil fuel emissions on ocean acidification will be felt for centuries.

High confidence

• If carbon dioxide emissions continue on the current trajectory, coral reef erosion is likely to outpace reef building some time this century.

• Cold-water coral communities are at risk and may be unsustainable.

• Mussels, oysters and pteropods are one of the groups most sensitive to ocean acidification.

• The varied responses of species to ocean acidification and other stressors are likely to lead to changes in marine ecosystems, but the extent of the impact is difficult to predict.

The Cabot Institute

The Cabot Institute at the University of Bristol carries out fundamental and responsive research on risks and uncertainties in a changing environment. Its interests include natural hazards, food and energy security, resilience and governance, and human impacts on the environment. Its research fuses rigorous statistical and numerical modelling with a deep understanding of interconnected social, environmental and engineered systems – past, present and future. It seeks to engage wider society – listening to, exploring with, and challenging our stakeholders to develop a shared response to twenty-first century challenges.