Project aims

The overarching goal of PROCUP is to investigate the predictability of the oceanic carbon uptake with a special emphasis on the underlying mechanisms.

Project structure

We will work with the MPI-ESM decadal prediction system with the emphasis on its ocean biogeochemical component HAMOCC.

Tasks of the project

PROCUP identifies the following 3 main tasks:

1. Evaluate model simulations which also involves observation data collection and validation.
2. Investigate the predictability of the oceanic carbon uptake and the responsible mechanisms in the context of a combination of biological, chemical, and physical processes.
3. Assist establishing a decadal-prediction earth system model with good representation of the ocean biogeochemical processes.

Deliverables

The predictability of the oceanic carbon uptake.

Progress so far

The variability and predictablity of the oceanic carbon uptake reveal significant regional charateristics. Based on the state of ocean physical variables’ predictability, region such as the North Atlantic is identified for in-depth investigation. We find that the predictive skill of oceanic carbon uptake in the North Atlantic western subpolar gyre is up to 4-7 years.

We use the MPI-ESM large ensemble of 100-member simulations to investigate internal variability of the oceanic carbon sink. Our study shows that both positive and negative decadal trends of oceanic carbon sink can be captured by MPI-ESM large ensemble simulations, as well as in observations. The decadal variations of the oceanic carbon sink show that especially negative decadal trends are still found in near-future, which is not intuitive under the increase of anthropogenic CO2 emissions. In the presence of large internal variability, more than 45 ensemble members are required to capture the forced signal of global oceanic carbon sink in contemporary decades, and this number increases to 71 in future projection. Furthermore, we also find an increase of internal variability in oceanic carbon sink under a high CO2 scenario. Our insight into the internal variability provides a basis for establishing robust predictive skills of the oceanic carbon sink.