The ocean in a high CO2 world

The anthropogenic CO₂ emissions into the atmosphere have been increasing since the industrial revolution and accelerating during the last decades. This process alters the climate system and the ocean uptake of anthropogenic CO₂, resulting in a shift in the marine carbonate chemistry. Moreover, the extra heat accumulated in the atmosphere due to the greenhouse effect of CO₂ is largely transferred to the ocean, enhancing water column stratification (i.e. a process that hampers the supply of nutrients to the upper ocean layers), and increasing the frequency, intensity, extent and duration of marine heatwaves (periods of extremely high ocean temperatures).

The group intends to unravel the impacts of the rapid human-induced atmospheric CO₂ accumulation on the ocean chemistry (ocean acidification), physics (ocean warming, mixing and circulation) and on the marine ecosystems. The strategy is to target endemic ecosystems, model organisms and keystone species. This implies the combination of biological, micropaleontological and geochemical techniques to quantify and understand the planet Earth functioning under elevated CO₂ conditions. The group is working on the present and past carbonate systems of main marine calcifiers, and their response/interaction to climate variability.

CO₂ vents off the island of Ischia (Italy) (Photo: R. Metalpa)

Major research lines within this MERS topic are:

• Elucidating the role of the ocean as a source or sink of CO₂ via the study of biologically mediated particle formation from mesoscale eddies, nitrogen fixation blooms, the role of sea-ice melting and the capacity of coastal ecosystems (i.e. saltmarshes, seagrass and mangroves in storing carbon over millennia)
• Constraining the carbon cycling and export in the Southern Ocean
• Understanding how ocean acidification, warming and stratification impact marine calcifiers (coccolithophores, foraminifers, pteropods and corals) which play a crucial role in global biogeochemical cycles through field studies and laboratory experiments
• Using paleo-reconstructions in comparison to modern times to better understand how marine organisms coped to periods of natural atmospheric CO₂ increase

Mediterranean coralligenous assemblage (Photo: A. Ferruci)