GEOF236 CHEMICAL OCEANOGRAPHY (HØST 2012) Christoph Heinze University of Bergen, Geophysical Institute and Bjerknes Centre for Climate Research Prof. in Global Carbon Cycle Modelling Allegaten 70, N-5007 Bergen, Norway Phone: Fax: Mobile phone: DEAR STUDENT AND COLLEAGUE: ”This presentation is for teaching/learning purposes only. Do not use any material of this presentation for any purpose outside course GEOF236, ”Chemical Oceanography”, autumn 2012, University of Bergen. Thank you for your attention.”

Sarmiento&Gruber 2006 Chapter 9: Calcium carbonate cycle, part 2

Heinze, C., E. Maier-Reimer, and K. Winn, 1991, Glacial pCO 2 reduction by the World Ocean - experiments with the Hamburg Carbon Cycle Model, Paleoceanography, 6, Carbon pumps SOLUBILITY

The major factor for changing TA is precipitation/dissolution of CaCO 3 : CaCO 3 solid ↔ Ca 2+ + CO 3 2- Carbon in seawater: CO 2 added, carbonate saturation calcium carbonate (calcite, aragonite) So in principle one can neutralise CO 2 gas by dissolving CaCO 3 : CaCO 3 solid + CO 2 gas + H 2 O ↔ Ca HCO 3 - Over-/undersaturation with respect to CaCO 3 is determined by the solubility product: K sp = [Ca 2+ ] sat x [CO 3 2- ] sat = const. x [CO 3 2- ] sat Therefore: By adding CO 2 we decrease the carbonate saturation. Ω = saturation state = ([CO 3 2- ] actual ∙[Ca 2+ ] actual )/K sp ≈ [CO 3 2- ] actual / [CO 3 2- ] sat

Source: Zeebe & Wolf-Gladrow, 2001 Carbon pumps

Tucker and Wright (1990) Two different concepts to discriminate between over- and undersaturated areas: Lysocline: Depth interval, where CaCO3 shell material undergoes strong signs of corrosion. Calcium carbonate compensation depth, CCD: depth level, where rain and re-dissolution balance. Therefore: Below the CCD there is no CaCO 3 available anymore.

Atlantic Pacific Model Observation GEOSECS Black dots: approximate saturation depth level, using the critical CO 3 2- concentration)

CaCO 3 top sediment coverage:

Diagenesis model: Model to predict: -solid concentrations in the bioturbated zone -porewater concentrations in the bioturbated zone -flux of dissolved constituents between water column and porewaters -Burial of solid material to “stone” SEE ARCHER ET AL. 1993

Diagenesis modelling: Heinze et al., 2009, Paleoceanography

Diagenesis modelling: Heinze et al., 2009, Paleoceanography

long-term variations (past)

CaCO 3 from Eq. Pac. Atmosph. CO 2 Farrell&Prell 1989 Siegenthaler et al., 2005 last 130,000 years

Tracer signals – example Atlantic Balsam 1983 Pazific Farrell & Prell 1989

Zachos et al.,

T anomaly across the Paleocene-Eocene boundary (Winguth et al., 2010)

Van Andel, 1975

future evolution

Caldeira and Wickett, 2003

Direct measurements of C ant in the ocean: Sarmiento&Gruber, 2006

Direct measurements of C ant in the ocean: Santana-Casiano et al., GBC, 2007

Potential alterations in biological cycling of carbon with circulation and pCO 2 change: 350 μatm (green) 700 μatm (grey) 1050 μ atm (red) Apparent decrease of dissolved inorganic C with pCO 2 Apparent increase of organically bound C with pCO 2 Apparent increase of nutrient utilisiation efficiency with pCO 2 Mesocosm facilities at Espegrend, Bergen Mesocosm experiments at differing atmospheric pCO 2 : ”Captering natural ecosystem communities in plastic bags and watching their behavior for changes in forcing under controlled conditions ” Riebesell, Schulz, Bellerby, Botros, Fritsche, Meyerhöfer, Neill, Nondal, Oschlies, Wohlers & Zöllner, Nature, 2007

PTEROPODS (small snails) (aragonite producers) Antarctic pteropod, Fabry et al., Oceanography, 2009 CORALS (aragonite producers) Hoegh-Guldberg et al., Science, 2007

Anthroogenic CO 2 emssion scenarios: Raupach et al., 2007, PNAS

Aragonite saturation according to future climate projections:

Steinacher et al., Biogeosciences, 2009 Aragonite saturation according to future climate projections:

Gehlen et al., 2008 CaCO 3 sediment can start to dissolve close to deep-water production areas due to anthropogenic CO 2 :

Gehlen et al., 2008 CaCO 3 sediment can start to dissolve close to deep-water production areas due to anthropogenic CO 2 :

Gehlen et al., 2008 CaCO 3 sediment can start to dissolve close to deep-water production areas due to anthropogenic CO 2 :

CaCO 3 sediment neutralises IPCC AR4, Ch. 7, following Archer, 2005 Archer, 1996 Core top CaCO 3 Ocean is central for long-term uptake and storage of anthropogenic CO 2 : without with CaCO 3 sediment

Warm water corals Guinotte&Fabry, 2008

Deep water corals Guinotte&Fabry, 2008