Ocean Biogeochemistry and Climate Feedbacks

Primary tabs

The Ocean is a key player in the climate system, buffering changes in the atmopheric composition. Changes in the ocean carbon cycle affect the marine ecosystem producing feedbacks on climate. Our research line focuses on ocean biogeochemical processes and the effects on the climate system of their alteration.

Summary

Atmospheric levels of CO2 and other greenhouse gases (CH4 and N2O) have increased substantially above preindustrial levels due to human activities. Carbon dioxide is continuously exchanged between the atmosphere and the ocean. Carbon dioxide entering the surface ocean immediately reacts with water to form bicarbonate (HCO3) and carbonate (CO32–) ions by means of the physical and the biological pump. These two pumps maintain a vertical gradient in CO2 regulating the exchange of CO2 between the atmosphere and the ocean. The strength of the solubility pump depends globally on the strength of the MOC, surface ocean temperature, salinity, stratification and ice cover. The efficiency of the biological pump depends on the fraction of photosynthesis exported from the surface ocean as sinking particles. Nowadays the oceans take ∼2.6 PgC/yr. However, models and observations suggest that, the rate of growth of this sink may have slowed down producind sever feedbacks on the climate system.

  • Changes in CO2 solubility:

CO2 solubility is a function of the temperature, therefore as the ocean’stemperature increases the solubility of CO2 decreases and consequently the uptake of the CO2 is reduced.

  • Changes in the ocean stratification:

Increased the sea surface temperatures (SST) and increased precipitation at high latitudes lead to an increase in the ocean’s surface stratification. This causes a shallower mixing layer and a reduction in the vertical exchange and transport of anthropogenic CO2 to the deep ocean. The stratification reduces the supply of DIC and nutrients, which are needed for biological activity.

  • Changes in the marine productivity:

Warming and other environmental changes (e.g. ocean acidification) can lead to further changes in marine productivity

  • Changes in the ocean circulation:

On centennial time scales the ocean carbon sink may also be affected by climate-driven changes in the ocean circulation such as the slowing down of the Thermohaline Circulation

Using state of the art earth system model  (EC-Earth) and the experience on climate prediction gained in the Climate Prediction Group, the aim of the ocean biogeochemistry and climate feedbacks research line is to study the response of the ocean in a changing climate and their feedbacks.

Objectives

  • To study the ocean biogeochemical impacts due to climate change and climate variability
  • To quantify feedbacks between ocean biogeochemistry in the climate system
  • To understand the impacts on the marine ecosystem due the changes of the main ocean biogochemical cycles in a changing climate
    • RAFFAELE BERNARDELLO's picture
    • Contact
    • RAFFAELE BERNARDELLO
    • Research Scientist
    • raffaele [dot] bernardello [at] bsc [dot] es