Current Projects

Leveraging the Ocean Observatories Initiative (OOI) to constrain the high-latitude ocean carbon cycle

The high-latitude ocean plays an outsized role in the marine carbon cycle, accounting for nearly half the global ocean carbon sink in only 25% of the ocean area. Monitoring the high-latitude ocean carbon cycle requires sustained observations to capture seasonality and interannual variability in biological productivity and deep winter convection, which together influence carbon uptake and sequestration. Despite the importance of monitoring the high-latitude ocean, there are few high-latitude marine biogeochemical time series sites, limiting our understanding of current carbon cycling processes and our capacity to detect long-term perturbations due to anthropogenic climate change. Our research addresses this need by leveraging biogeochemical sensor data collected by the Ocean Observatories Initiative (OOI) from high latitude open ocean arrays of moored and mobile platforms in the subpolar North Atlantic and Northeast Pacific Oceans.

Our current research is funded by a NSF CAREER Award, which will enable our group to create analysis-ready time-series of biogeochemical variables from high latitude open ocean OOI Arrays in the Irminger Sea and at Ocean Station Papa, and use these data to 1) improve mechanistic understanding of the drivers of the biological carbon pump and its contribution to long-term carbon sequestration, and 2) assess the relative and inter-related roles of biological, chemical, and physical processes driving the ocean carbon sink over >10 years at each of these sites. Teams from our research group have previously joined OOI research cruises to the Irminger Sea in 2018, 2019, and 2024, and will join upcoming cruises in 2025 and 2026, enabling collection of supplementary samples that will support calibration and interpretation of the OOI biogeochemical sensor data as well as video footage that will be incorporated into educational videos for use in undergraduate courses.

Our current work builds on efforts Palevsky co-led with colleague Sophie Clayton to develop a community consensus on Best Practices for how to calibrate and validate the biogeochemical data from the OOI Arrays to produce science-ready data products. Together, a 25-member Working Group (including lab member Dr. Kristen Fogaren) and 14 Beta Testers (including lab members Meg Yoder and Jose Cuevas) developed the OOI Biogeochemical Sensor Data Best Practices and User Guide, following a process that prioritized collaboration and community input to enhance the accessibility and utility of the end product (Palevsky et al. 2024). It also builds on prior NSF-funded research in collaboration with Dr. David Nicholson (WHOI) to improve the accuracy and utility of oxygen measurements from the OOI Irminger Sea Array.

Our findings thus far have demonstrated strong seasonality and interannual variability in surface ocean carbon cycling (Yoder, Palevsky & Fogaren, 2024), in the flux to depth of sinking organic carbon particles (Cuevas thesis, 2024), and of re-ventilation of respired carbon during deep winter ventilation (Palevsky and Nicholson, 2018; Wanzer thesis, 2019). Ongoing analysis is being led by PhD student Meg Yoder and Senior Research Associate Dr. Kristen Fogaren. We also are looking for a new PhD student to join our team for this project - learn more about the opportunity here!

Oxygen and carbon uptake by the deep ocean in the subpolar North Atlantic

The Atlantic Meridional Overturning Circulation (AMOC), driven by physical circulation in the subpolar North Atlantic Ocean, plays a key role in both the ocean’s capacity to absorb anthropogenic carbon and in oxygenation of the deep ocean. The international Overturning in the Subpolar North Atlantic Program (OSNAP) has provided critical observational measurements of AMOC physical circulation from moored sensors continuously deployed across the basin since 2014. Beginning in 2020, our research group has been part of a NSF-funded collaborative project (together with Jaime Palter, URI; Isabela Le Bras and David Nicholson, WHOI; Dasha Atamanchuk, Dalhouse University) that has added autonomous oxygen sensors to OSNAP moorings in Labrador and Irminger Seas (Atamanchuk et al. 2022). Our team’s ongoing analysis of the data collected thus far has yielded both new methods for calibration of moored oxygen sensor data and insights into the processes driving oxygen and carbon uptake by the deep ocean.

Biogeochemical cycling in a dynamic, human-influenced salt marsh system

Coastal environments play a disproportionately large role in the global carbon cycle relative to their physical area, yet the rates and processes of coastal carbon cycling remain poorly characterized due to their biogeochemical and physical heterogeneity. Coastal salt marshes are of particular interest due to their high rates of “blue carbon” storage and their rapid ongoing changes in response to sea level rise and human land use change. Our research group is currently studying salt marsh carbon and biogeochemical cycling at the Seven Mile Island Innovation Laboratory (SMIIL) in New Jersey, established by colleagues at The Wetlands Institute and the Philadelphia District of the US Army Corps of Engineers (USACE). This project is part of a funded collaboration between a team of Boston College Earth and Environmental Sciences faculty and the USACE Engineer Research and Development Center (ERDC).

From 2021 to 2024, our research group established and maintained autonomous monitoring sites at three open water platforms and six salt ponds at SMIIL, providing continuous measurements of physical and biogeochemical properties. We have also monitored to assess potential impacts on open water biogeochemistry from USACE efforts piloting beneficial use sediment management projects, in which dredged sediment removed from navigation channels is used to enhance the elevation of the marsh platform. Ongoing analysis of these data is being led by PhD student Jake Supino and Postdoctoral Research Fellow Emily Chua.

Model analyses of future changes to the ocean’s biological carbon pump

Global Earth system models (ESMs) are among the key tools used to project how the Earth’s climate system will respond to accelerating fossil fuel carbon emissions over the coming decades and centuries, and are critical to understanding and predicting future changes to the ocean carbon cycle and its role in global climate. However, many processes that play a significant role in export flux and its feedbacks on global climate are currently missing from most ESMs and therefore add uncertainty to these future projections (Henson et al., 2022).

Our research on the biological carbon pump in ESMs aims to bridge observational and modeling research, applying insights gained from observational analyses and targeting results that can inform future observational studies. Building on our observational work showing the importance of accounting for deep winter ventilation in evaluating export-driven carbon sequestration, our group’s recent research has used ESM simulations of 21st century climate and biogeochemistry under high carbon emissions scenarios to assess the sensitivity of projected future changes in the biological pump to the choice of export depth horizon, or how far particles must sink to be counted as exported (Palevsky and Doney, 2018, 2021). Our current work, led by Stevie Walker, investigates the importance of the choice of export depth horizon for multi-model analyses of how the biological pump will change over the 21st century using depth-resolved output widely archived across multiple ESMs for the first time in the 6th Coupled Model Intercomparison Project (Walker and Palevsky, in review).

Past Projects

The North Pacific biological pump: Rates, efficiency and influence on ocean uptake of carbon dioxide

The North Pacific features a band of strong atmospheric carbon dioxide uptake at the transition between the subarctic and subtropical gyres, making it a region of particular interest to quantify the mechanisms of ocean carbon uptake. Palevsky’s PhD dissertation assessed the rates and efficiency of biological carbon export and evaluated the relative roles of biology, physical circulation, and temperature-driven solubility changes in driving ocean carbon uptake throughout the full annual cycle across the North Pacific basin (35°N – 50°N, 142°E – 125°W).

To do this, we used data collected on sixteen container ship transects between Hong Kong and Long Beach, CA from 2008-2012, on which we measured the the surface concentration of dissolved inorganic carbon (DIC), the partial pressure of carbon dioxide to determine air-sea carbon dioxide flux, and triple oxygen isotopes and oxygen/argon dissolved gas ratios as non-incubation based geochemical tracers of gross primary production and net community production. These results demonstrated that the physical dynamics of winter ventilation are a key mechanism controlling the rate and efficiency of the biological pump in the North Pacific (Palevsky et al. 2016), and that biological carbon export is the dominant process driving ocean carbon uptake in the eastern north Pacific while physical processes drive the strong ocean carbon sink in the western North Pacific (Palevsky and Quay, 2017). Comparison between our geochemical-based primary and export production estimates and estimates from satellite algorithms and global biogeochemical models identified discrepancies that underscore the need to evaluate satellite- and model-based estimates using multiple productivity parameters measured over broad ocean regions and throughout the full annual cycle, including during winter ventilation, in order to accurately estimate the rate and efficiency of carbon sequestration via the ocean’s biological pump (Palevsky, Quay, & Nicholson, 2016).

Inside the Atlantic Cod Fishery: In Search of a Sustainable Future

In 2007-2008, Palevsky traveled to Iceland, Denmark, Scotland, Norway and Newfoundland to study fisheries science, the fishing industry, and management policies as a Thomas J. Watson Fellow. This project included two fisheries research cruises, one with the Marine Research Institute of Iceland's Northern Shrimp Survey and one with the Scottish Fisheries Research Services as part of the International Bottom Trawl Survey, and first-hand research in fishing communities while living in the homes of fishing families in Peterhead, Scotland, the Lofoten Islands of Norway and Fogo Island, Newfoundland. I also contributed to a published book chapter on European fisheries policy in collaboration with researchers in Denmark and Norway. You can read full details of my experience from my fellowship blog.