This week, IoM Friends of the Earth’s Tony Brown looks at the impact of rising ocean acidification on our planet, and our diets
In 2010, a report by the US National Research Council found that pH levels – the level of acidity or alkalinity – at the oceans’ surface had fallen from a measure of 8.2 in pre-industrial times, to 8.1 in modern times.
This has taken place as something between a quarter and a third of man-made CO2 emissions have been added to the natural absorption rates of those oceans.
Since pH is measured on a logarithmic scale, this means that there has been a 10-fold decrease in alkalinity – or to put it another way, an increase in acidity.
The rate of change is 100 times faster than anything the world’s oceans have experienced for the last few million years.
By 2100, pH levels could, it’s estimated, drop to between 7.7 and 7.8, if we continue to emit CO2 at present rates. A pH of 7.0 is ‘neutral’, so this is significant – it would be the lowest level for 55 million years, when during the Paleocene-Eocene thermal maximum (PETM), a sudden die-off of shell-based ocean life forms took place in the space of around 1,000 years. If projections are correct, our extra CO2 emissions will cause a similar demise in a few centuries, with no time for species to evolve or adapt.