Climate change impacts on the distribution and cycling of essential micronutrients

Camille Richon, United States and Alessandro Tagliabue, University of Liverpool, Liverpool, United Kingdom
Abstract:
Trace metals are important micronutrient for marine microbial life. They support many metabolic reactions necessary for bacteria, phytoplankton and zooplankton, however, some trace metals such as Cu or Zn may have toxic effects at high concentrations. The processes shaping trace metals distribution and cycling in the ocean are still poorly understood. Furthermore, the evolution of trace metals distributions as a consequence of climate change has never been investigated.

This work aims at characterizing the potential impacts of climate change on the global biogeochemical cycling of essential trace metals. We use a state-of-the-art global ocean biogeochemical model representing a suite of trace elements (Fe, Cu, Zn, Co) to investigate how their distribution and inventories may change in response to the RCP8.5 climate change scenario. The changing ocean circulation in this scenario may result in surface stratification, resulting in changes in biological pump strength, oxygen distribution and particle loadings. In regions affected by external inputs, surface concentration of micronutrient may increase as a result of surface stratification. On the other hand, surface micronutrient concentrations may decrease in the open ocean as a result of the decline in vertical supply of nutrients. Moreover, the changes in oxygen distribution could affect cobalt exchange with the sediments, and the change in particle loadings may strongly impact copper scavenging, changing the global inventory of these trace elements and potentially resulting in changes in the micronutrient limitations for phytoplankton.