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Anthropogenic LUC & climate

Anthropogenic LUC & climate. 2 nd May 2012 Laura Batlle Bayer. Vegetation - climate. Biogeochemical impacts. Biogeophysical impacts. CO 2 release (radiative forcing). High uncertainty. Bonan et al. (2008). Biogeophysical impacts. Albedo- Radiative effect (-0.2 ± 0.2 W /m2).

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Anthropogenic LUC & climate

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  1. Anthropogenic LUC & climate 2nd May 2012 Laura Batlle Bayer

  2. Vegetation - climate Biogeochemical impacts Biogeophysical impacts CO2 release (radiative forcing) High uncertainty Bonan et al. (2008)

  3. Biogeophysical impacts • Albedo- Radiative effect (-0.2 ± 0.2 W /m2) • Aerodynamic effect (roughness) • Hydrological effect (evaporation efficiency)

  4. T in Coupled GCM simulations (Forest with grass albedo) – (forest) Globally: -1.36K High lat: ~ -4K Low lat: ~ -1K (Forest with grass roughness) – (forest) (Forest with grass evap.eff.) – (forest) Globally: +0.24 K Globally: +0.29 K Davin et al. (2010) (Grass everywhere) – (forest everywhere)

  5. Contribution of individual processes to the net biogeophysical effect Biogeophysical impacts Albedo: wider-scale influence magnitude of albedo effect increases with latitude

  6. Biogeophysical impacts • No consensus on (de Noblet-Ducoudré et al., 2012): • The scale of LULCC required to be “large enough” • How large the resulting change in the regional climate might be expected to be • How the nature of the existing climate over a region might suppress or amplify the initial impacts of LULCC • Question: Regional climate impact of large-scale LULCC

  7. LUCID intercomparison study • Goal: to determine the scale of the regional & global scale • Objective: robustness of biogeophysical impacts of historical LULCC across climate models • 7 atmosphere-land models with a common experimental design

  8. LUCID – Experimental design Change in global vegetation patterns due to LCC

  9. LUCID – Global scale for the NH summer Pitman et al. (2009) Uncertainties in climate responses to past land cover change: First results from the LUCID intercomparison study

  10. LUCID North America & Eurasia de Noblet-Decoudre et al. (2012) Determining robust impacts of landuse induced land-cover changes on surface climate over North America and Eurasia; Results from the first set of LUCID experiments

  11. LUCID North America & Eurasia de Noblet-Decoudre et al. (2012) Determining robust impacts of landuse induced land-cover changes on surface climate over North America and Eurasia; Results from the first set of LUCID experiments

  12. LUCID North America & Eurasia • Responses to changes (LULCC): 0.5(PD-PDv + PIv – PI) • Average response to GHG (SST/CO2): 0.5(PD-PIv + PDv – PI) • Surface Energy balance (W m-2): QS (1-α) + QLd QLu = QH + QE +QG • Available energy: QA = QS (1-α) + QLd • Turbulent energy flux: QT = QH + QE de Noblet-Decoudre et al. (2012) Determining robust impacts of landuse induced land-cover changes on surface climate over North America and Eurasia; Results from the first set of LUCID experiments

  13. LUCID North America & Eurasia de Noblet-Decoudre et al. (2012) Determining robust impacts of landuse induced land-cover changes on surface climate over North America and Eurasia; Results from the first set of LUCID experiments

  14. LUCID North America & Eurasia de Noblet-Decoudre et al. (2012) Determining robust impacts of landuse induced land-cover changes on surface climate over North America and Eurasia; Results from the first set of LUCID experiments

  15. LUCID North America & Eurasia de Noblet-Decoudre et al. (2012) Determining robust impacts of landuse induced land-cover changes on surface climate over North America and Eurasia; Results from the first set of LUCID experiments

  16. LUCID North America & Eurasia No consistent pattern among the various models regarding how QE and QH change from one season to another Boisier et al. (2012) Determining robust impacts of landuse induced land-cover changes on surface climate over North America and Eurasia; Results from the first set of LUCID experiments

  17. LUCID North America & Eurasia • The key uncertainty in the LULCC forcing at temperate latitudes is caused by: • QE response. • How each model calculates the seasonally and surface type dependent Bowen Ratio. • Robust common features: LULCC → ↑ α→↓ QA → ↓QE,QH • No consistanciesamong models: • QT partitioning between QE and QH • Seasonal response of QH and QE to LULCC Boisier et al. (2012) Determining robust impacts of landuse induced land-cover changes on surface climate over North America and Eurasia; Results from the first set of LUCID experiments

  18. Feedback analysis in EC-Earth (atm only) temperature response per unit albedo change Strong neg. feedback via clouds in tropics SWsurf LWsurf Small neg. feedback via clouds in mid-lat. vd Molen et al, 2010

  19. Feedback analysis in EC-Earth (atm only) temperature response per unit albedo change Less evaporative cooling in tropics H LE vd Molen et al, 2010

  20. Biogeochemical impacts Net C sink =CO2 sink > CO2 source + disturbances CO2 sink NEE = NPP - Rh CO2 sources Photosynthesis (GPP) NPP = GPP - Ra Rh Ra disturbances AG biomass litter BG biomass SOC

  21. Biogeochemical impacts World’s forest - C sink From 1990 – 2007: • Sink = 2.4 ± 0.4 PgC/yr • Source = 1.3 ± 0.7 PgC / yr Net global forest C sink = 1.1 ± 0.8 PgC/yr 12% 40% • Gross tropical deforestation = 2.9 ± 0.5 PgC/yr • Tropical forest regrowth = 1.6 ± 0.5 PgC / yr 18% 60% 70% 0% Pan et al. (Science, 2011) A Large and Persistent Carbon Sink in the World’s Forests

  22. Biogeochemical impacts Friedlingstein et al. (2006) Climate–Carbon Cycle Feedback Analysis: Results from the C4MIP Model Intercomparison

  23. Global Biogeochemical impacts of LCC Lauwrence et al. (2012) Simulating the Biogeochemical and Biogeophysical Impacts of Transient Land Cover Change and Wood Harvest in the Community Climate System Model (CCSM4) from 1850 to 2100.

  24. Global Biogeochemical impacts of LCC Global wood harvest area (106 km2) Global C harvest amount (Pg C) Global total LCC area (106 km2) Lauwrence et al. (2012) Simulating the Biogeochemical and Biogeophysical Impacts of Transient Land Cover Change and Wood Harvest in the Community Climate System Model (CCSM4) from 1850 to 2100.

  25. Global Biogeochemical impacts of LCC Lauwrence et al. (2012) Simulating the Biogeochemical and Biogeophysical Impacts of Transient Land Cover Change and Wood Harvest in the Community Climate System Model (CCSM4) from 1850 to 2100.

  26. Global Biogeochemical impacts of LCC Global historical & RCP LCC in Land unit area & LU in wood harvest area Lauwrence et al. (2012) Simulating the Biogeochemical and Biogeophysical Impacts of Transient Land Cover Change and Wood Harvest in the Community Climate System Model (CCSM4) from 1850 to 2100.

  27. Global Biogeochemical impacts of LCC Global historical & RCP C fluxes of LUC and NEE Lauwrence et al. (2012) Simulating the Biogeochemical and Biogeophysical Impacts of Transient Land Cover Change and Wood Harvest in the Community Climate System Model (CCSM4) from 1850 to 2100.

  28. Global Biogeophysical impacts of LCC • Single forcing experiment: • Prescribed transient LCC & wood harvest • All other forcings remained at 1850 control experiment values • Fulltransient historical experiment Lauwrence et al. (2012) Simulating the Biogeochemical and Biogeophysical Impacts of Transient Land Cover Change and Wood Harvest in the Community Climate System Model (CCSM4) from 1850 to 2100.

  29. Global Biogeophysical impacts of LCC Historical biogeophysical changes in annual surface albedo (1976 to 2005) – (1850 to 1879) Lauwrence et al. (2012) Simulating the Biogeochemical and Biogeophysical Impacts of Transient Land Cover Change and Wood Harvest in the Community Climate System Model (CCSM4) from 1850 to 2100.

  30. Global Biogeophysical impacts of LCC Historical biogeophysical changes in annual 2m Temp (1976 to 2005) – (1850 to 1879) Lauwrence et al. (2012) Simulating the Biogeochemical and Biogeophysical Impacts of Transient Land Cover Change and Wood Harvest in the Community Climate System Model (CCSM4) from 1850 to 2100.

  31. Biogeochemical vs Biogeophysical 20th Century: Biogeophysical Global cooling -0.03 0C Biogeochemical Global warming 0.16 – 0.18 0C Net Global warming 0.13 – 0.15 0C Pongratz et al. (2010) Biogeophysical versus biogeochemical climate response to historical anthropogenic land cover change

  32. Biogeochemical vs Biogeophysical Pongratz et al. (2010) Biogeophysical versus biogeochemical climate response to historical anthropogenic land cover change

  33. Biogeophysical and biogeochemical effects Land use change at the local scale ~ global CO2-effects Carbon-climate feedback non-significant (but uncertain) Also local feedbacks exist Summary

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