Understanding the variability and projecting future changes of biogeochemistry in the California Current Upwelling System

 In the California Current System (CCS), variability in both surface and
subsurface biogeochemical variables affects the dynamics of economically important living marine
resources. Future variability and trends in the biogeochemistry of the CCS upwelling ecosystem may
be driven by several potentially confounding factors that span a range of spatiotemporal scales.
Physical factors include both local processes, such as changes in along-shore wind magnitude and
stratification, and remote processes, such as changes in the relative contributions of different source
waters and in their biogeochemical properties. However, most future climate projections are based
on Earth System Models (ESMs) with resolutions too coarse to properly resolve coastal winds and
upwelling dynamics. Therefore, more accurate representations of upwelling dynamics and
biogeochemical variability from high-resolution models are needed to provide actionable
information to those managing living marine resources. The main goal of this project is to
understand and quantify the variability of the physical mechanisms that drive changes in
the biogeochemistry of the California Current Upwelling System in response to
anthropogenic climate change. We will analyze biogeochemical variables (e.g., oxygen, nutrients,
pH, Chl-a) from historical observations and a set of high-resolution biogeochemical reanalyses, and
produce future projections from an eddy-permitting regional ocean circulation model (ROMS)
coupled with a biogeochemical model and forced with bias-corrected CMIP6 output to accomplish
three objectives: (1) Quantify and examine how future climate change will alter the relative
contribution of source water masses to the CCS and the biogeochemical properties within those
source waters; (2) Quantify and examine local changes in coastal upwelling and biogeochemistry in
response to future climate change; and (3) Quantify the relative contributions of local vs. remote
forcing to future changes in the biogeochemistry of the CCS.

Relevance to the Competition and NOAA’s Long-Term Climate Goal and Broader impacts:
The proposed research will directly address Priority Area A of the competition, “Identify key
climate/oceanic processes that affect ocean biogeochemistry of relevance to fisheries and other living marine resources in NMFS areas of interest across climate timescales”, in that it explores and quantifies future changes in physical drivers (local vs. remote) affecting the biogeochemistry in the California Current Upwelling System, which impacts the ecosystem across all trophic levels through changing oxygen, nutrient and pH levels. It also addresses the Priority Area C “Improve the modeling of climate-ocean predictability pathways and its representation in prediction/projection systems”, by producing a set of high-resolution coupled physical-biogeochemical projections forced by CMIP6 output. This project will also address a number of priorities identified in the NMFS National Climate Science Strategy, including “understanding mechanisms of change”, “projecting future conditions”, and “tracking change to provide early warnings”.

Climate Risk Area: Marine Ecosystems