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  • Writer's pictureKristina Barclay

Scientist Spotlight: Benjamin Richaud, Ph.D. Candidate, Dalhousie University

Benjamin Richaud is a Ph.D. candidate at Dalhousie University studying the variability of biogeochemistry in the Arctic Ocean using a numerical modelling approach. His research examines the impacts of biogeochemistry and sea-ice on carbon dioxide exchange between the ocean and the atmosphere. Benjamin shares with us his background and interests in marine carbonate chemistry, chemical oceanography, and perspectives on Canada’s role in marine carbon research.

A person wearing sailing gear looks at the camera. Water is visible in the background
Benjamin Richaud, Ph.D. Candidate at Dalhousie University.

“I have always had an interest in the ocean,” Benjamin says.

Benjamin grew up in France, spending holidays in Brittany, the western tip of France that dives into the Atlantic, and Provence, a region in the southeast of France that borders the Mediterranean Sea. Spending time near the sea fostered his interest in marine science and sailing early on, but also made him aware of climate change. Benjamin says as a teenager he started to think about the consequences of climate change for both his generation and future generations. These experiences drove him to pursue his interests in oceanography and he earned an Engineering Diploma from ENSTA Paris (specializing in mechanical and naval engineering, and physical oceanography) and completed, in parallel, an M.Sc. in physical oceanography and renewable energies from Polytechnique Graduate School in France. He also took a gap year before his M.Sc. at Woods Hole Oceanographic Institute (USA), where he conducted climatology and observation-based research, and then started working at OpenHydro in Ireland doing resource assessments for tidal turbines.

Benjamin then applied for a Ph.D. program at Dalhousie University with Drs. Katja Fennel and Eric Oliver. The project he works on examines biogeochemical variability and extreme events in the Arctic using numerical models. Benjamin said he was intrigued at the prospect of using modeling studies which he describes as an “amazing complementary tool to observations” to study carbonate chemistry and the role of sea ice in controlling air-sea carbon dioxide fluxes.

“Ice is a full ecosystem on its own,” Benjamin continues.

The life inside and surrounding ice adds a layer of complexity that is usually discounted in models, he explains. But the density of bacteria and phytoplankton can be very high, especially in brine channels and directly below sea ice. For example, long strings or chains of diatoms are commonly found attached to the bottom of the ice.

“It’s fascinating to think that organisms can thrive in such cold and salty environments,” Benjamin adds.

Benjamin’s research seeks to account for the life and chemistry that occurs in and around sea-ice in models of carbon dioxide fluxes between the ocean and the atmosphere (air-sea carbon dioxide fluxes). These models are important to both national and global carbon budgets, and help us predict how and where atmospheric carbon will be taken up by the oceans. His research thus far indicates that this biogeochemistry and sea ice life enhances carbon dioxide uptake, at least on regional and seasonal scales.

A person kneeling on ice holding a piece of ice in their hands
Benjamin examining sea ice along the shores of the Gulf of St. Lawrence, in March 2021.

Some of the tools, equations, and theoretical framework that Benjamin has developed can also be applied to a relatively new field of study on ocean alkalinization. Alkalinization seeks to increase the buffering capacity of seawater and increase its carbon sink without increasing seawater acidity. This is usually done through a geoengineering process, but it is also naturally occurring in polar seas, Benjamin explains. When sea-ice forms, it naturally decreases the ratio of total alkalinity (TA) to dissolved inorganic carbon (DIC) in the underlying waters. This reduces the ability of the oceans to store carbon dioxide and could even lead to outgassing of carbon dioxide into the atmosphere during winter. Then, in spring, as the sea-ice melts, it releases the TA back into the water, leading to stronger uptakes of carbon dioxide while buffering the co-occurring acidification.

“Ocean alkalinization is the same idea,” Benjamin explains.

By increasing seawater alkalinity (TA), the oceans can take up more carbon dioxide, but retain their buffering capacity, meaning that acidification (a by-product of added carbon dioxide in seawater) is avoided. The concept of ocean alkalinization has therefore drawn the interest of researchers wanting to explore ways of increasing seawater alkalinity as a possible means of mitigating ocean acidification.

The sea-ice systems that Benjamin studies might allow him to better understand these processes on a larger scale, as well as how sea-ice life might impact these cycles. For example, Benjamin points out that despite seasonal effects and variability, there is still increasing sea-ice melt occurring, which will impact carbon sinks, especially in the Arctic.

Benjamin says that one of the take-homes of his research is that it demonstrates the strong impact the ocean has on our lives.

“People in Canada, even those not close to the oceans, will still be impacted [by changes to the carbon cycle and by climate change].”

His work will help us understand carbon sinks in the Arctic, which has a direct impact on Canada’s carbon budget. There are also many social impacts of air-sea carbon dioxide fluxes to consider, Benjamin points out. Everything from our lifestyles, such as how much carbon we can use, to policy and social outcomes, will be impacted by ocean acidification and climate change. Even policy impacts and efforts towards Truth and Reconciliation will become harder, as Indigenous communities are put under even more strain due to the impacts of climate change. And delaying action will only make these social impacts harder to address, he concludes.

But while the future might be full of challenges, Benjamin adds that there is a lot to be excited about in Canadian climate change research. He is part of Canada’s Marine Carbon Cohort, a group of students and early career researchers that work together to better assess the role of Canada’s oceans on carbon sinks and sources. Some of his favourite aspects of the group are the opportunities to interact, build skills, work together, and learn from other students, postdocs, and PIs (Principle Investigators). He says they build their knowledge by pushing each other forward. The group is part of a larger community at the forefront of climate change research. Benjamin is excited to be part of this research field right now, as he says there is an expected boom in our knowledge of [carbonate] chemistry. New technologies, such as improved biogeochemical sensors and oceanographic equipment (like the northwest North Atlantic BGC [biogeochemical] Argo array overseen by Dr. Katja Fennel and colleagues), will improve our understanding of biogeochemistry and help constrain models. Alkalinization is based on new technology, and could lead to new solutions and knowledge that could mitigate the effects of ocean acidification and climate change.

“It’s really motivating to know that this work is at the forefront of the biggest challenge of the 21st Century,” Benjamin says.


To learn more about Benjamin and his research, visit his website.

To learn more about the Canadian BGC Argo initiative, visit their website.


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