The US may violate its own standards on water quality by refusing to limit emissions of carbon dioxide, suggests a new study modelling ocean acidification.
鈥淎bout one-third of the CO2 from fossil-fuel burning is absorbed by the world鈥檚 oceans,鈥� explains Ken Caldeira at in California, US, who led the study.
The CO2 lowers the pH of the ocean鈥檚 surface, a phenomenon known as ocean acidification. This is predicted to have dramatic consequences on marine life by dissolving the shells of tiny organisms and corals.
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If governments do nothing to limit greenhouse-gas emissions, CO2 levels in the oceans will rise to a point where, by 2050, ocean acidification will reach a level considered to be industrial waste by the US鈥檚 own standards, found the study to be published on 25 September.
Industrial waste
鈥溾�漌e need to start thinking about carbon dioxide as an ocean pollutant,鈥� urges Caldeira. 鈥淲hen we release carbon dioxide to the atmosphere, we are dumping industrial waste in the ocean.鈥�
The US Environmental Protection Agency (EPA) , states that the pH of ocean waters beyond 200 metres deep should not be changed more than 0.2 units outside natural levels. Estimates put natural levels at a range from 8 to 8.25 pH. Anything beyond this is considered industrial waste. However, these standards are not enshrined in US law.
Caldeira鈥檚 team calculated how CO2 emissions from fossil-fuel burning impact on ocean acidification.
聭Dangerous interference鈥�
鈥淚f atmospheric CO2 goes above 500 parts per million, the surface of the entire ocean will be out of compliance with EPA pH guidelines,鈥� says Caldeira. Currently, concentrations are at 380 ppm. However, computer models suggest that if governments do nothing to limit greenhouse-gas emissions, concentrations could climb to at least 760 ppm by 2100 and could reach 500ppm by 2050.
The Kyoto protocol seeks to curb the growth of greenhouse gas emissions. The US government has repeatedly refused to ratify it. Yet, Caldeira points out that the US government has unwittingly already set itself emissions targets, in the form of the EPA鈥檚 water quality standards.
鈥淭he UN talks about avoiding 鈥榙angerous anthropogenic interference with the climate system鈥� but leaves vague what constitutes 鈥榙angerous interference鈥�. The US already published a number 鈥� 0.2 pH units 鈥� with the implication that greater changes constitute dangerous interference in the marine system,鈥� he told New 杏吧原创.
Journal reference: (DOI: 10.1029/2006GL027288)
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