Scientists from the USA, Canada and Mexico took samples along 13 separate survey lines stretching from central Canada to northern Mexico. They identified acidic seawater much closer to the surface than expected.

Ocean acidification is a consequence of atmospheric carbon dioxide being absorbed by seawater. However, the water that the team was testing had welled up from deep in the ocean, having last been at the surface about 50 years ago. The presence of such acidic water so close to the surface wasn’t expected to occur until 2050. ‘When the upwelled water was last at the surface, it was exposed to an atmosphere with much less CO2 than today, and future upwelled waters will probably be more acidic than today’s because of increasing atmospheric CO2,’ said Burke Hales, a co-author of the research, which appears in the
online journal Science Express.

‘While this absorption provides a great service to humans by significantly reducing the amount of greenhouse gases in the atmosphere and decreasing the effects of global warming, the change in the ocean chemistry affects marine life, particularly organisms with calcium carbonate shells, such as corals, mussels, molluscs, and small creatures in the early stages of the food chain,’ said lead author Richard Feely.

August 2008