In a previous post I mentioned the work of the indomitable Bärbel Hönisch. I refered to the fact that she could write the textbook on past events of ocean acidification. As it turned out she had just published a paper (in Science no less) titled, ‘The Geological Record of Ocean Acidification‘. I wasn’t far off. I’ve just spent my evening pouring over the article and I must say it is compulsory reading for both those interested in the fate of our oceans as well as the expert already in the field. The interplay between the carbon cycle, calcification and the chemical state of the ocean are described and illustrated in detail set against the backdrop of some of the most environmentally catastrophic events in geological time. While the article is elegantly written, it is nothing short of alarming.The 20 strong authors synthesise existing evidence and report that the oceans are currently acidifying at a rate possibly not seen in at least 300 million years.
Bärbel and co. systematically review the evidence of past ocean acidification events in the hope of finding comparable situations, or analogues, from which to model scenarios for our own future. They invoke evidence from the fossil record of cataclysmic volcanic eruptions, mass extinction events caused by asteroid impacts and geological formations that could all result in dramatic CO2 rise. These occurrences could all have resulted in significant ocean acidification events in their time. There is a common thread however that makes each of the events incongruous with our present situation, and that is the rate of change.
One of the papers most alarming messages is that while the earth may have seen atmospheric CO2 even higher than present day, the rate with which these concentrations are presently accelerating is unprecedented. When CO2 increase occurs over longer timescales feed back mechanisms, such as rock weathering, increase the ocean’s ability to buffer the acidity caused by CO2 rise. While current CO2 rise may seem slow relative to the human life, in terms of geological time it is instantaneous. Our present understanding of how oceanic ecosystems function puts us at distinct disadvantage as to predict what the future may hold.
I have had the distinct pleasure of spending two seasons with Bärbel culturing the foraminifera she uses to inform her research. While the situation may seem overwhelming, to scientists of the ilk of Barbel, it simply means we must go to work and find the answers. So what are you still sitting there for?