Understanding the ocean’s role in climate regulation
The ocean is an important factor in mitigating climate change: it absorbs 25-30% of all the CO₂ which is brought in the atmosphere by humans. Louise Delaigue has focused her PhD research project on how this works, and how the increase of CO₂ changes the natural cycle of carbon in the ocean. On 20 January, she will defend her PhD thesis at Utrecht University.
Since the Industrial Revolution, atmospheric CO₂ levels have surged from 278 ppm to over 420 ppm, disrupting the natural carbon cycle and altering the ocean’s role as a carbon sink. Absorbing 25–30% of anthropogenic CO₂ annually, the ocean mitigates climate impacts but experiences acidification and long-term chemical changes. This dynamic, critical to climate regulation, remains poorly understood, particularly the biological carbon pump (BCP), which sequesters CO₂ through organic matter sinking to the deep ocean.
This thesis investigates how increasing anthropogenic CO₂ and global change influence ocean carbon processes, focusing on spatial and temporal blind spots. Using integrated methods—combining ship-based observations, autonomous sensors, and machine learning—it identifies regional BCP responses and uncovers the dominant role of anthropogenic CO₂ in driving global dissolved inorganic carbon (DIC) increases. High-resolution modeling reveals how the BCP redistributes natural carbon, with notable variability across regions like the Southern Ocean and North Pacific.
By integrating diverse datasets and methodologies, this work enhances predictions of the ocean’s carbon cycle under future climate scenarios. It underscores the need for tailored approaches to improve understanding of the BCP and oceanic carbon dynamics, advancing efforts to monitor and mitigate the impacts of global change.