1 July 2005: Drop in ocean pH confirmed

The average pH of the oceans will fall by up to 0.5 units by 2100 if global emissions of CO₂ continue to rise at present rates, report leading researchers. Surface oceans currently have an average pH of 8.2. 

’Basic chemistry leaves us in little doubt that our burning of fossil fuels is changing the acidity of our oceans,’ said John Raven, professor of biology at the University of Dundee, UK. ’The rate of change we are seeing to the ocean’s chemistry is a hundred times faster than has happened for millions of years. We just do not know whether marine life which is already under threat from climate change can adapt to these changes.’ 

The Royal Society has just released results of a study of rising acidity in the oceans produced by a team led by Raven. It took experts a surprisingly long time to recognise the possibility of a link between increasing CO₂ emissions and decreasing pH in the oceans, Raven conceded. 

’It should have occurred to me, but it didn’t,’ he told Chemistry World when the investigation was launched in August 2004 (Chemistry World, October 2004, p11). 

The report, released to coincide with the upcoming G8 summit (6-8 July), insists that anthropogenic CO₂ emissions must be considerably less than 900 Giga tonnes of carbon by 2100 to cut the risk of irreversible damage, particularly in the southern ocean.

’Our world leaders meeting at next week’s G8 summit must commit to taking decisive and significant action to cut CO₂ emissions,’ said Raven. ’Failure to do so may mean that there is no place in the oceans of the future for many of the species and ecosystems that we know today.’ 

Uncertainty remains around the ecological impacts of ocean acidification and the report calls for a major international effort to be launched into this relatively new research area. Bea Perks