The Importance of Dynamic Iron Deposition in Projecting Climate Change Impacts on Pacific Ocean Biogeochemistry

Abstract

AbstractDeposition of mineral dust plays an important role in upper‐ocean biogeochemical processes, particularly by delivering iron to iron‐limited regions. Here we examine the impact of dynamically changing iron deposition on tropical Pacific Ocean biogeochemistry in fully coupled earth system model projections under several emissions scenarios. Projected end‐of‐21st‐century increases in central tropical Pacific dust and iron deposition strengthen with increasing emissions/radiative forcing, and are aligned with projected soil moisture decreases in adjacent land areas and precipitation increases over the equatorial Pacific. Increased delivery of soluble iron results in a reduction in, and eastward contraction of, equatorial Pacific phytoplankton iron limitation and shifts primary production and particulate organic carbon flux projections relative to a high emissions projection (SSP5‐8.5) wherein soluble iron deposition is prescribed as a static climatology. These results highlight modeling advances in representing coupled land‐air‐sea interactions to project basin‐scale patterns of ocean biogeochemical change.