The project

The research project addresses two interrelated environmental problems caused by the increase in carbon dioxide (CO2) concentration in the atmosphere: global warming and ocean acidification.

The entire scientific community now agrees that human activities, the use of fossil fuels and deforestation have led to an increase in CO2 levels in the atmosphere with consequent global warming. This causes many impacts on human activities and in particular on ecosystems, as reported in the report of the Intergovernmental Panel on Climate Change (IPCC).

Among the 17 Sustainable Development Goals of the 2030 United Nations Agenda, Goal 14 is to conserve and sustainably use the oceans, seas and marine resources for sustainable development. The most important and indispensable strategy to reduce the impact of the ongoing climate change is reducing our CO2 emissions, however, it has been calculated that our present efforts should be supported by active strategies of CO2 reduction (Carbon Dioxide Removal = CDR). The ocean is a key player in the climate dynamics and in all strategies aimed at subtracting the excess CO2 from the atmosphere (Negative Emissions Technologies = NETs).

Among the proposed NETs, Ocean Liming (OL) is one of the possible techniques to increase the Ocean Alkalinity by enhanced absorption of CO2 (Ocean Alkalinity Enhancement = OAE), which allows the active removal of CO2 from the atmosphere. The increased alkalinity contrasts ocean acidification by favoring bio-calcifiers.

Ocean based methods of CO2 removal from the atmosphere

OACIS (Ocean Acidification and other ocean Changes – Impacts and Solutions) is a Monegasque association created in 2013 at the initiative of the Prince Albert II of Monaco Foundation to study the impact of climate change on the ocean, such as acidification, as well as potential solutions to mitigate its impacts. It is supported by the Prince Albert II of Monaco Foundation. In this context, the project "Ocean liming in European seawater: a mesocosm scale approach" with Prof. Basso as PI, was supported (February 2023-February 2025).

Slaked Lime (SL) can be massively discharged in the surface ocean waters within the wake of ships as a side-activity on normal maritime traffic. The feasibility of this technique depends on the trade-off between an economically sustainable transport and the needed caution in using the lowest effective concentration of SL.

Nevertheless, the effect on marine organisms is still little known and more studies both on plankton and pelagic ecosystems are needed; the influence of OL on biological calcification needs to be clarified. Moreover, ocean liming may induce CaCO3 precipitation during slaked lime dissolution, reducing the efficiency of CO2 uptake. Further research are fundamental also to determine the concentrations that could be added for CO2 removal without affecting marine life. The project will assess:

the chemical kinetics of OL in different types of seawater;
the response of plankton abundance, photosynthetic efficiency and diversity to repeated pH peaks in natural seawater, by small-scale, short-term experiments in microcosms;
the response of plankton and benthic calcareous red algae forming maerl/rgodoliths to repeated pH peaks in natural oligotrophic seawater (HCMR), and eutrophic seawater (UVigo), by mid-term mesocosm experiments.

Project results will clarify the ecosystem-scale response of marine organisms to simulated OL over medium-term experiments, and will inform OAE technology developers with criteria and guidelines to minimize impacts.

Why it matters?

It is important to conserve the world's ocean, seas and marine resources as there is only one ocean that support and regulate the global climate system. Oceans are the largest ecosystem and provide support to the global population needs. Moreover, everyday, the ocean absorbs more than a quarter of CO2 emitted by human activities, reducing the amount of it in the atmosphere; therefore without the ocean global warming would be an even bigger problem.

Despite the importance of preserve the ocean, decades of irresponsible exploitation have led to an alarming degradation.