How did Mt. Pinatubo Impact Ocean Biogeochemistry?

Mt. Pinatubo impacts on ocean carbon and oxygen

We are excited to share a new paper, led by Amanda Fay, on the impact of Mt. Pinatubo on ocean carbon and oxygen. We used experiments with the Community Earth System Model Large Ensemble, at the National Center for Atmospheric Research to explore the forced response of air-sea fluxes and interior distribution of ocean carbon and oxygen.

We demonstrate that the eruption forced the high latitude northern oceans to take up anomalous pulses of oxygen and carbon, due to surface cooling and deep mixing. At the same time, there was a forced tendency for an El Nino event to occur that also caused significant anomalous carbon uptake in the equatorial Pacific.

This work demonstrates that the global mean forced response of the ocean carbon sink to Mt. Pinatubo was an additional uptake of 0.3 PgC/yr into the surface ocean. This result is consistent with our previous study in which we used a box model to propose a significant influence of Mt. Pinatubo on the ocean carbon sink of the 1990s.

In this new study, we do not find a strong response in the Southern Ocean to Mt. Pinatubo, a region where observations suggest there were large air-sea CO2 flux anomalies in the early 1990s. Just recently we’ve learned that the volcanic aerosol forcing used in CESM-LENS was too weak in the southern hemisphere, and this may have impacted our results. We are following up with new experiments that bring the southern hemisphere aerosol loading closer to observed values. We hope to be able to share more soon!