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Elkhorn coral, once the dominant reef-forming coral of the Caribbean, has nearly disappeared © Alex Rogers, Department of Zoology
Elkhorn coral, once the dominant reef-forming coral of the Caribbean, has nearly disappeared

If we fail to cap global warming the effect on the world’s oceans will be catastrophic, with far reaching consequences for mankind.

A paper published in Science warns that an immediate and substantial reduction of CO2 emissions is required to prevent massive and irreversible impacts on ocean ecosystems and their ability to capture CO2 and absorb heat. As CO2 increases, the protection, adaptation and repair options for the ocean become fewer and less effective.

Impacts on key marine and coastal organisms and ecosystems from CO2 emissions are already detectable across various latitudes, and several will face high risk of impacts well before 2100 even with stringent cuts in CO2 emissions.

The findings demonstrate the importance of the outcomes of negotiations at the Paris Climate Conference also known as COP21, which is being organised by the United Nations Framework Convention on Climate Change later this year.

The globally agreed ‘Copenhagen Accord’ goal of a global atmospheric temperature increase of less than 2°C by 2100 already carries high risks of impacts for warm-water corals and mid-latitude bivalves, but other risks for the ocean will remain moderate as long as we do not exceed this goal.

Research leader Jean Pierre Gattuso, Senior Scientist at the French National Centre for Scientific Research said, ‘The oceans have been minimally considered at previous climate negotiations; our study provides compelling arguments for a radical change at COP21’.

Professor Alex Rogers from Oxford’s Department of Zoology made a significant contribution to the research.

Alex said, ‘Marine ecosystems such as coral reefs and vital ecosystem services such as fisheries are already impacted by the climate change we have seen so far. Continuing on a business as usual pathway of CO2 emissions will be catastrophic for many marine ecosystems with far reaching social and economic consequences for humankind.’

Alexandre Magnan, scientist at the Institute for Sustainable Development and International Relations and co-author of the paper, said, ‘Given the extent of the expected changes no country is in a safe position, making this issue a worldwide problem that challenges the traditional North/South divide’.

Atmospheric CO2 has increased by more than 40 per cent over the industrial period. The world’s oceans have absorbed 93 per cent of the earth’s additional heat since the 1970s, keeping the atmosphere cooler but simultaneously increasing ocean temperature and raising the sea level. Oceans have captured 28 per cent of human-caused CO2 emissions since 1750, but this has acidified the ocean. Melting ice has also increased sea levels.

Professor Rogers leads the Ocean Research and Conservation Group in the Department of Zoology. The group is currently researching the consequences of climate change and other human impacts on coral reefs and deep-sea ecosystems.

The paper Contrasting Futures for Ocean and Society from Different Anthropogenic CO Emissions Scenarios can be read in full on the Science website.

This research is part of the Oceans 2015 Initiative, launched to provide COP21 negotiators with key information on how the future ocean will look. It is led by CNRS-UPMC and IDDRI and is supported by the Prince Albert II of Monaco Foundation, the Ocean Acidification International Coordination Centre of the International Atomic Energy Agency, the BNP Paribas Foundation and the Monégasque Association for Ocean Acidification.

Please see coverage of this story on the BBC news website and on The Guardian website