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Evolution of wetlands since the Last Glacial Maximum

Evolution of wetlands since the Last Glacial Maximum. Pirita Oksanen University of Bristol. Wetland synthesis - distribution, extent, type and accumulation Public database Maps Data – model comparisons Since ca. 21 000 BP Phase 1. Northern extratropics. Phase 2. Tropics.

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Evolution of wetlands since the Last Glacial Maximum

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  1. Evolution of wetlands since the Last Glacial Maximum Pirita Oksanen University of Bristol

  2. Wetland synthesis - distribution, extent, type and accumulation • Public database • Maps • Data – model comparisons • Since ca. 21 000 BP • Phase 1. Northern extratropics. • Phase 2. Tropics.

  3. Peatlands net sink of CO2 – vegetation sequesters from the atmosphere • Wetlands net source of CH4 – methanogenesis in waterlogged environment • ca. 5 million km2 natural wetlands • over 1 million km2 irrigated cultivation • 400-500 Gt C in peat • 100-150 Tg CH4/a from natural wetlands • ca. 40 Tg CH4/a from rice paddies • estimates for the LGM 80-110 Tg CH4/a

  4. temperature, water table and vegetation control CH4 production and flux • wide variation of CH4 fluxes both between and within wetlands and seasons Mean values (Aselmann & Crutzen -89) • Bogs – 15 (1-50) CH4/m2/day • Fens – 80 (28-216) • Swamps – 84 (57-112) • Marshes – 253 (137-399) • Floodplains – 100 (50-200) • Lakes – 43 (17-89) • Rice paddies – 310 (179-438)

  5. Wetland vegetation plant functional types

  6. Mires today, sites with bottom dates Previous databases used: Oksanen 2005, Gorham et al. 2005, McDonald et al. 2006, PAIN. Lappalainen et al. 1996

  7. Basal peat dates 50 000 – 21 000 BP Continental and ice-sheet outlines by Patrick Bartlein, University of Oregon

  8. Mires at 13000 BP Experimental ice-sheet data by W.R Peltier, University of Toronto

  9. Mires at 11000 BP

  10. Mires at 10000 BP

  11. Mires at 9000 BP

  12. Mires at 6000 BP, sites with basal peat dates Continental and ice-sheet outlines by Patrick Bartlein, University of Oregon

  13. Mire initiation in arctic/boreal regions 0 2000 5000 8000 11000 15000 >21000

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