The acidity of the ocean has increased by 30% since pre-industrial times and is predicted to double by 2100 because of increased uptake of CO2 according to expatriate Australian Australia’s leading oceanographer, Dr Tony Haymet, former Chief of Marine and Atmospheric Science at CSIRO, now director of the prestigious Scripps Institution of Oceanography and Vice Chancellor of Marine Sciences at the University of California.
Increasing the amount of CO2 in the oceans causes an increase in hydrogen carbonate ions, HCO3-, but a decrease in carbonate CO22- which organisms need to make calcium carbonate shells and other structures.
The predicted acidity increase will have unknown consequences for marine life and ecosystems such as coral reefs, tiny marine organisms called pteropods, and fish larvae to name but three. Each of these organisms plays a fundamental role in local ecosystems and the food web, therefore amplifying the effects of their forced changes.
“Unknown consequences” means we know it’s going to be bad, but not exactly how bad.
The pteropods are a critical species near the bottom of the food chain. If they are depleted weâll have less fish to eat.
Acidity will inhibit the growth of corals, an adverse impact additional to coral bleaching.
55 million years ago when ocean acidity was much higher than today, shell-forming organisms vanished together with those higher in the food chain. But change is occurring faster now.
It is believed that the speed at which we are altering the current acidity of the ocean has not been seen before, and therefore we may not be able to anticipate the changes based on historical data.
Haymet believes that:
Ocean acidity, rather than temperature warming, may determine the upper limit of atmospheric CO2 that Earth can safely tolerate.
But even if emissions stopped today the acidification effect would continue for a century or more.
Roby Williams had an interesting chat with Joellen Russell of the University of Arizona recently about the increased uptake of CO2 in the Southern Ocean. It seems that the temperate storms, the low pressure systems, âthe largest, strongest mean surface winds in the worldâ? have moved south and intensified. This is causing direct mixing of sea and atmospheric gases to a depth of three kilometers with two effects.
Firstly, there is the same adverse impact on shell-forming organisms identified by Haymet.
Secondly, the additional uptake from the southerly movement of the winds is extraordinarily large, amounting to 20% of the ânormalâ global uptake of CO2. Thatâs a lot of acid, but the good news is that global warming may be slowed by 20 to 40 years. Well, itâs not all that good, if, as Haymet suggests, the critical danger point may come from acidification of the oceans rather than temperature rise as such.
A final thought: When Haymet was out here for Ruddâs Climate Change Summit he told Kerry OâBrien that we were only 2% of the worldâs innovation system and we should concentrate on things that we are good at. Although claiming he was misquoted by the SMH he was, I think, implying that âclean coalâ technology was not one of them.