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Global warming and abrupt ocean circulation changes at the Paleocene/Eocene boundary (55 Ma)

Global warming and abrupt ocean circulation changes at the Paleocene/Eocene boundary (55 Ma). Malte Heinemann. Mentor: Jochem Marotzke. [m]. 3000. 3000. -6000. 0. motivation. motivation. PETM: Paleocene/Eocene Thermal Maximum (55 Ma b.p.).

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Global warming and abrupt ocean circulation changes at the Paleocene/Eocene boundary (55 Ma)

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  1. Global warming and abrupt ocean circulation changes at the Paleocene/Eocene boundary (55 Ma) Malte Heinemann Mentor: Jochem Marotzke

  2. [m] 3000 3000 -6000 0 motivation motivation PETM: Paleocene/Eocene Thermal Maximum (55 Ma b.p.) global warming due to GHG increase - source unclear results I: temperature hypothesis: ocean circulation switch caused methane hydrate release results II: ocean circulation tool: AO-GCM with P/E boundary conditions summary& outlook MPI-OM ECHAM5 OASIS

  3. [oC] 12 18 24 30 36 0 6 P/E control simulation motivation GHG concentrations poorly constrained by data CO2=560ppm, preindustrial CH4 already yields warm climate: results I: temperature surface temperature: results II: ocean circulation summary& outlook

  4. P/E control simulation Atlantic deepwater track fits with that inferred from δ13C for the PETM, but not the pre-PETM: motivation results I: temperature our simulation(690m-2650m): reconstruction (Nunes & Norris 2006): results II: ocean circulation pre-PETM summary& outlook PETM

  5. summary & outlook motivation we performed a coupled atmosphere-ocean GCM simulation with Paleocene/Eocene boundary conditions; results I: temperature even using a moderate GHG forcing, the simulated P/E climate is very warm (mostly due to a low surface albedo); results II: ocean circulation Atlantic deepwater formation occurs in the proto-Labrador Sea; summary& outlook next step: investigate climate and ocean circulation sensitivity to greenhouse gas forcing. THANK YOU!

  6. spares 12 0 10 temperature [oC] (for an ice-free ocean) 8 1 6 4 2 benthic δ18O [‰] 3 4 5 30 60 50 20 40 0 10 Million years ago motivation results I: temperature results II: ocean circulation summary& outlook 65 million years of climate change: global deep-sea oxygen isotope ratio based on more than 40 DSDP and ODP sites; modified from Zachos et al. (2001);

  7. spares time [years] time [years] 1000 1500 2000 [oC] 0 500 [oC] 1000 1500 2000 0 500 18 18 1 1 15 15 2 2 12 depth [km] 12 3 3 9 9 4 4 Atlantic 6 6 Pacific 5 3 5 3 [oC] 1000 1500 2000 [oC] 0 500 1000 1500 2000 0 500 10 18 1 1 15 9 2 2 12 depth [km] 3 3 9 8 4 4 6 Arctic Ocean ‘Wedell’ Sea 5 5 3 7 motivation results I: temperature results II: ocean circulation summary& outlook

  8. spares convective depth: [m] 1500 900 1200 0 300 600 motivation results I: temperature results II: ocean circulation summary& outlook

  9. spares motivation P/E results I: temperature results II: ocean circulation summary& outlook preind.

  10. spares motivation upper 690m: results I: temperature results II: ocean circulation summary& outlook bathymetry [m] 0 4000 2000

  11. spares motivation 690m-2650m: results I: temperature results II: ocean circulation summary& outlook bathymetry [m] 6000 4000 2000 0

  12. [oC] 12 18 24 30 36 0 6 P/E control simulation motivation GHG concentrations poorly constrained by data CO2=560ppm, preindustrial CH4 already yields warm climate: results I: temperature zonal mean land surface temperature: surface temperature: results II: ocean circulation [oC] 40 30 summary& outlook 20 10 0 -10 90 60 30 30 0 60 -90 latitude [deg. North]

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