Responses to future climate change: biogeochemistry

Transcription

1 Responses to future climate change: biogeochemistry Jean-Pierre Gattuso Laboratoire d Océanographie de Villefranche (LOV) CNRS - Université Pierre et Marie Curie - Paris 6 Villefranche-sur-mer, France

2 Time-series of ocean acidification 8.15 BATS HOT ESTOC ph T Year Orr (2011) )

3 Barker & Ridgwell (2012) Long-term perspective

4 Rapid progression of ocean acidification in the California Current System (EBUS) Gruber et al. (in press)

5 Assessment B I OLOGY ocean acidification 15 declarative statements assessed: Chemical aspects Biological and biogeochemical responses Policy and socio-economic aspects Guidance)Note)for)Lead)Authors)of)the) Jean-Pierre Gattuso and Lina Hansson 647)July)2010 C Mastrandrea et al. (2010)

6 Summary on statements Chemical effects: robust evidence and high certainty Biological and ecological effects: much less certain calcification, primary production, nitrogen fixation and biodiversity will be altered but with an unknown magnitude some cannot be assessed Biogeochemistry, society and the economy may change; whether it will be significant or not is also unknown

7 Systems at risk Polar areas Deep-sea environments Coral reefs Nearshore ecosystems

8 Warming up, turning sour, losing breath: ocean biogeochemistry under global change Hotspots OA not acting in isolation Warming increases oxygen loss and stratification (deoxygenation) Warming, acidification, and deoxygenation in 21st century Only begun to fathom ecological and biogeochemical effects Aragonite undersaturation Lower productivity Deoxygenation Aragonite undersaturation Deoxygenation Lower productivity The triumvirate of ocean change (Gruber, 2011)

9 Changes in biogenic carbon flow in response to sea surface warming Normal temperature Elevated temperature DIC P E DOC POC A DIC P E DOC POC A R S R S Thermocline Wholers et al. (2009)

10 Changes in biogenic carbon flow in response to sea surface warming Normal temperature Elevated temperature DIC P E DOC POC A DIC P E DOC POC A R S R S Thermocline Wholers et al. (2009)

11 Very limited impact of climate change on the carbonate system Cao et al. (2007)

12 Interaction between ocean warming and acidification C Calcification (%dw d -1 ) C 25.2 C 28.2 C 0.0 Normal pco 2 Elevated pco 2 Coral perturbation experiments (Reynaud et al., 2003)

13 Interaction between ocean warming and acidification Calcification (%dw d -1 ) C 28.2 C 25.2 C 28.2 C Calcification A Extension 0.0 Normal pco 2 Elevated pco Coral perturbation experiments (Reynaud et al., 2003) Reconstruction of coral calcification on the GBR (De ath et al., 2011)

14 Changes -> possible changes? Ocean Temperatures, frontal positions, circulation and connectivity, mixed layer depths, variability (SAM, Ozone, Greenhouse?), eddies? Sea ice Extent, timing, thickness, drift, variability Murphy & Hofmann Biogeochemistry CO2, upwelling, iron inputs, ph?

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