The role of marine plankton in the Earth's chemistry

The IPCC has stated that "natural global climate change at rates slower than current anthropogenic climate change caused significant ecosystem shifts and species extinctions" amid growing concern about the impact rapid climate change has on marine ecosystems and the services they provide to humans. Marine calcifying plankton have a fossil record of >100 Million years. The composition of marine carbonates evolved from a coccolithophore dominated ooze to a balance between foraminiferal (marine protist) and coccolithophore. Project aims: assess (1) the link between oceanography and evolution in changing this carbonate factory; (2) modern drivers of carbonate production and (3) vulnerability of carbonate production in response to changing climate. The geological record and an Earth system model will be used to determine the environmental and ecological drivers behind this change and whether there is a tipping point beyond which marine plankton cannot deal with the impact of climate change. The hypothesis that environmental change will reduce carbonate production by marine plankton in the future will be tested using a combination of the geological record of biotic response to environmental perturbations and its impact on the carbon cycle with Earth System modelling. The most promising events will be identified and size records will be generated across events. (1) The impact of abiotic versus biotic drivers on the long term composition of marine carbonates will be determined (2) A novel a size structure trait-based plankton model within an Earth system model of these historical time intervals will be used to disentangle different drivers of change (3) The model will be used to quantify how traits might change across the transitions (4) modelled changes in traits will be compared to evidence from geological record. Environmental pressures under different futures will be considered and projections of how carbonate production might change in response will be developed.