How Does Dust Modify Marine Heatwave-Low Chlorophyll Compound Extremes?

Marine heatwaves (MHW) and low-chlorophyll (LChl) extremes have been increasing in frequency and intensity over the satellite record. Ecosystem damage can be amplified when multiple extreme events overlap, creating a compound event. Since compound MHW-LChl extremes can be driven by changes in the availability of light and nutrients, adding dust to the system may impact the formation or progression of MHW-LChl events. Dust fertilizes the sea surface with iron, nitrogen, and phosphorus and has been linked to phytoplankton blooms. However, at very high AOD values, the light-blocking effects of dust may inhibit phytoplankton growth and cool SST. We assess when and where dust is associated with MHW-LChl compound extremes, how those effects differ with the effects on single MHW and LChl extremes, and whether those effects are caused by dust or controlled by other dynamics. In a changing climate, where dust distributions may change and MHW-LChl events are expected to become more frequent, understanding these phenomena could have implications for fisheries and other resource management during, and in the recovery after, compound extreme events.

Recommended citation: Quigley et al.