Dynamics and Predictability of Marine Ecosystem Stressors

Abstract

Anthropogenic climate change is driving long-term ocean warming, acidification, and deoxygenation with ramifications for marine organisms and ecosystems. Alongside long-term changes, there is growing interest in the effects of short-term variability which can lead to extreme events that rapidly alter marine conditions, including marine heatwaves (MHW) and ocean acidification extremes (OAX). Relatively limited biogeochemical observations make these short-term changes hard to study, leading to the use of Earth System Models (ESMs) which provide valuable insights into biogeochemical changes and predictability. Here we focus on three research questions: (1) How do MHW affect regional biogeochemistry? (2) Can ESMs forecast surface and subsurface marine stressors? and (3) Can ESMs forecast marine extreme events (MHW, OAX)? We first focus on the regional biogeochemical impacts of the Blob, a notable MHW in the Northeast Pacific, using a combination of in-situ observations, observation-based products, and ESM reconstructions. We then use model output to estimate the dynamical drivers of biogeochemical changes associated with these MHWs. Next, we assess the ability of the Community Earth System Model (CESM) Seasonal-to-Multiyear Large Ensemble (SMYLE) to predict anomalies of surface and subsurface marine ecosystem stressors in Large Marine Ecosystems. Finally, we assess the ability of CESM SMYLE to skillfully forecast global MHW and OAX over the historical period and determine drivers of skill. We then utilize a CESM SMYLE forecast generated in late 2023 to assess the evolution of marine extremes in 2024. This work helps contextualize the impacts and predictability of marine ecosystem stressors and extremes in a changing climate.