A drop in the ocean

With all that extra atmospheric CO2 being soaked up by the sea, the Royal Society has embarked on a study to find out what is currently known about the possible effects of a consequent drop in pH on marine biosystems.

There is laboratory evidence to suggest such a drop would endanger organisms dependent on CaCO3, such as corals or animals with shells, but ’it’s difficult to tell what’s happening in the natural world,’ says John Raven, professor of biology at the University of Dundee, UK. Raven is chairing the working group conducting the study, whose members include Ken Caldeira of the Climate and Carbon-cycling Modelling Group at the Lawrence Livermore National Laboratory, California, US.

Caldeira first raised the issue of falling pH levels last year in the journal Nature. His model suggests that if CO2 levels continue to rise at the present rate, we can expect changes in ocean pH greater than any experienced in the past 300 million years. ’Owing to a paucity of relevant observations, we have a limited understanding of the effects of pH reduction on marine biota,’ wrote Caldeira at the time. Researchers do not appear to have addressed the issue.

’It should have occurred to me,’ says Raven, who’s been studying carbon cycling for almost 40 years, ’but it didn’t’. This latest study was commissioned by David Read, biological secretary and vice president of the Royal Society (RS). An international group of experts in geochemistry, climate modelling and marine biology will review what is currently known in the area. Anyone with information that could be included is asked to contact the RS.

It appears that the group has its work cut out, as it hopes to publish a full report on the study - along with possible recommendations for future research - by early 2005. Raven says he is surprised at just how many people have asked him what the group expects to find during the study. ’If we knew that,’ he sighed, ’we wouldn’t have to go through all this palaver’.

Bea Perks