I’m about half a centimetre long, I live near the top of the ocean in a shell made out of chalky stuff and I’m incredibly important to the oil industry. What am I? I bet you’ll never guess…
I’m a foraminifera! These beautiful little ocean dwelling bugs are not widely known amongst the general population but are famed amongst climate scientists for their pivotal insights into Earths past climate. They also give clues about past ocean environments, which is useful for oil companies looking for likely places to drill. They have lived for millions of years, evolving their shape, size and habitat; each one forming a shell chemically imprinted by the seawater in which they formed. We can use their shells to read past shifts in ocean chemistry, which we can use as an analogue for current climate change.
We know from looking into Earth’s history that the climate and the ocean are inextricably linked so if one is perturbed the other will also be affected, albeit a few hundred or thousand years later. In the case of today’s climate change, we have no such time luxury. This change is happening fast. The excess CO2 in the atmosphere is dissolving into the ocean and reacting with water to form a weak acid, reducing the pH of the ocean. This is commonly called ‘Ocean Acidification’.
In fact, the change in ocean chemistry caused by excess atmospheric CO2 is happening so fast that scientists say they haven’t seen anything like it in the past 300 million years.
Creatures that use calcium carbonate to form skeletons or shells such as corals, marine snails and foraminifera are at the frontline of this change in pH. Oceanographers at the Open University and University of Tromso are interested in what is happening to the foraminifera in particular. They form a major base of the food chain and they also piggyback CO2 to the seafloor when they die and get buried under sediment, trapping CO2 with them and balancing the carbon cycle.
As the ocean becomes less alkaline, foraminifera shells should become thinner and more fragile. Essentially they will be running in order to stand still; they will need to use extra energy to build their shells in order to compensate for the lower pH environment and other climate change related stressors. The scientists can measure this by looking at the change in shell thicknesses of foraminifera over the last 30 years and comparing them to foraminifera collected before the industrial revolution and over a glacial-interglacial cycle. This will help us to understand the magnitude of changes in shell thickness over a natural cycle compared to how modern ocean acidification is now impacting on these bugs. The Polar Regions are particularly susceptible to ocean acidification because more CO2 dissolves in colder waters. There is a drive to study foraminifera from these regions, as they are likely to show the biggest change in shell thickness.
Foraminfera could be the key we need to measure the impact of modern climate change on the microbiology of the ocean. Ironically, they are also the key to unlocking more oil…
Hönisch, B., Ridgwell, A., Schmidt, D.N., Thomas, E., Gibbs, S.J., Sluijs, A., Zeebe, R., Kump, L., Martindale, R.C., Greene, S.E., Kiessling, W., Ries, J., Zachos, J.C., Royer, D.L., Barker, S., Marchitto, T.M., Moyer, R., Pelejero, C., Ziveri, P., Foster, G.L., Williams G., (2012) The Geological Record of Ocean Acidification, Science, Vol. 335 no. 6072 pp. 1058-1063, DOI: 10.1126/science.1208277