WP 11

- Biogeochemical Impacts -

Kick-off meetingNice 10 – 13/06/2008

Objectives:

Determine impacts of ocean acidification on C and other key element

cycles as well as climate relevant gases (CO2, DMS, N2O) from regional to

global scales.

Assess the impact of emission scenarios on simulated ecosystem

structure and function.

Quantify the changing role of marine sediments as sinks and sources of

macro- and micro-nutrients (P, Fe) under future ocean acidification and

climate change scenarios and investigate the impact of these changes on

shelf and open ocean ecosystems and biogeochemistry.

Assess the potential of different long-term observation approaches

(radionuclides, alkalinity changes, sediment traps) for detecting impacts

due to ocean acidification.

Kick-off meetingNice 10 – 13/06/2008

Approach:

Use a hierarchy of regional to global biogeochemical-ecosystem models,

some of which include not only the water column but also couple that to

an interactive benthic compartment

Kick-off meetingNice 10 – 13/06/2008

Tasks:

1/3

Model Development: to incorporate new process knowledge from WP9 in

order to better evaluate how ocean acidification affects individual

processes and improve 3-D ocean biogeochemical and ecosystem

models.Where we start from:

pH sensitive processes taken into account in large scale models …

BIOLOGICAL PUMPS

CaCO3 COUNTER PUMPORGANIC C PUMPSOLUTION PUMP

AIR

SURFACE OCEAN

TWILIGHT ZONE

DEEP OCEAN

coldfresh

warmhaline

SOLUBILITY HIGH LOW

PHOTO-SYNTHESIS

Nutrient &CO2 uptake

REMINERALISATIONNutrient &CO2 release

SEDIMENT

BENTHIC REMIN.Nutrient & CO2 release

CALCIFICATIONCO2 release

ALK consumption

CaCO3 dissolutionALK release

BENTHIC DISS.ALK release

POC flux CaCO3 flux

Tasks:

2/3

Model Performance Assessment: to evaluate the capability of models to

reproduce existing and new datasets of dissolved properties (e.g.,

carbonate system parameters [WP10], O2, nutrients);

Kick-off meetingNice 10 – 13/06/2008

+ Model output will be compared to relevant data, particularly where

model domains overlap (e.g. the North West African upwelling system).

+ New data for the biogeography of calcifying organisms from WP3 will be

exploited.

Tasks: 3/3

Model-based assessment of impacts of ocean acidification on key

biogeochemical and ecosystem processes, including sediment

biogeochemistry

- remineralization of

organic

- particle aggregation

- ballasting

- CaCO3 dissolution- rain ratio- bioavailability of

nutrients

(including sediment

source)

- ecosystem structure &

productivity

- stoichiometry of C fix

- export production- CaCO3 production- air-sea fluxes

CO2N2ODMS

Deliverables:

Link to monitoring :

Report on potential methods for detecting the impact of ocean acidification on

marine particle fluxes (rain ratio effect)

Model perfomance assessment :

Report evaluating the performance of all models and their developments in terms

of their capability to reproduce past and present observations

Impacts of ocean acidification :

… on the global fluxes of climate relevant gases

… and climate change on the sea floor as a source of macro- and micro-

nutrients to the oceans (P, Fe)

… on individual biogeochemical processes at the regional, basin & global scales :

report on future uncertainties and thersholds (input to WP13)

Impacts of anthropogenic C emissions (past, present, future) :

… on ocean biogeochemistry and ecosystems

Kick-off meetingNice 10 – 13/06/2008

Participation teams :

(1)shelf seas : ETH Zürich

Plymouth Marine Laboratory

Universiteit Utrecht

(2) regional scale : Alfred Wegener Institut für Polar- u.

Meeresforschung

ETH Zürich

(3) global scale/ : Laboratoire des Sciences et de l’Environnement

and Earth Syst. University of Bergen

Universität Bern

Max-Planck-Institut für Meteorologie

University of Bristol (model of intermediate

complexity)

Kick-off meetingNice 10 – 13/06/2008

Tasks:

Model-based assessment of impacts of ocean acidification on key

biogeochemical and ecosystem processes, including sediment

biogeochemistry: (i) the photic zone: ecosystem structure and

productivity, stoichiometry of C fixation and export production, CaCO3

production, global fluxes of climate relevant gases, changes in

bioavailability of macro-and micronutrients including sediment

biogeochemistry in shelf areas

(ii) the aphotic zone (remineralization of organic carbon, particle

aggregation and ballasting, CaCO3 dissolution, and the rain ratio).

The relative importance of physical versus biological-biogeochemical

processes and their uncertainties will be identified by using sensitivity

studies and probabilistic approaches.

Kick-off meetingNice 10 – 13/06/2008