Martin Heimann Max-Planck-Institute for Biogeochemistry, Jena, Germany

Transcription

1 Martin Heimann Max-Planck-Institute for Biogeochemistry, Jena, Germany 1

2 Northern Eurasia: winter: enhanced warming in arctic, more precip summer: general warming in center, wetter in east, dryer in southwest IPCC AR4,

3 IPCC AR4,

4 What is the regional contribution to the global trace gas budgets (CO2 and CH4)? Can we separate and quantify the direct versus the indirect (feedback) fluxes? What is the recent history of the regional trace gas budgets? Are there thresholds in the forcing which will negatively impact vulnerable pools or processes? How will the regional budgets evolve over the next 100 years? 4

5 Warming lengthening of vegetation period increase in carbon uptake Warming enhanced soil decomposition enhanced CO 2 release Warming drying wetland degradation Warming drying changes in fire regimes Warming permafrost carbon degradation CO 2, CH4 Warming hydrological regime shifts ecosystem composition changes shifts in carbon balance Warming hydrological regime shifts carbon export by runoff Antropogenic impacts: Logging, fire, agriculture 5

6 Climate CO2 Atmosphere Emissions from burning of fossil fuels and cement production Changes in landuse and land management Landbiosphere Ocean Climate response T, P,... CO2, CH4 Antropogenic emissions Climate driven feedback sources Y coupled = f Y uncoupled 6

7 Air Temperature CO 2 concentration Growing season length Photosynthesis - Heterotrophic respiration - Vegetation carbon stocks Soil carbon stocks Heimann and Reichstein,

8 Piao et al.,

9 Climate CO2 Atmosphere Emissions from burning of fossil fuels and cement production Changes in landuse and land management Landbiosphere Ocean Simulated global carbon stock increases in atmosphere, ocean and land biosphere Carbon uptake by land and ocean Difference coupled - uncoupled simulation ( ) PgC Climate feedback: atmospheric land biosphere carbon content Year kgc m -2 Raddatz et al.,

10 Cox et al.,

11 11 models, SRES-A2 emission profile C 4 MIP Simulations, Friedlingstein et al.,

12 10 8 Global land uptake 6 PgC yr Land uptake 60N-90N PgC yr models, SRES-A2 emission profile Decadal averages, smoothed C 4 MIP Simulations, Friedlingstein et al.,

13 0 PgC yr Land - global 6 PgC yr N-90N models, SRES-A2 emission profile Decadal averages, smoothed C 4 MIP Simulations, Friedlingstein et al.,

14 Global 60N-90N Model No. 6 Model No PgC yr PgC yr 1 C 4 MIP Simulations, Friedlingstein et al.,

15 20 A2-SRES Emissions PgC yr C 4 MIP Simulations: Global climate-carbon cycle feedback factor: 1.18±0.11 Climate feedbacks Total uptake by land and ocean Decadal averages, smoothed C 4 MIP Simulations, Friedlingstein et al.,

16 Ocean: Uncertainty due to different mixing and circulation characteristics Relatively small climate feedback Land: Models assume substantial CO2 fertilization : ΔNPP NPP Effective β = 0 = ΔC C 0 Strong climate feedback Carbon cycle - climate feedback factor, range of C 4 MIP models: 4-20% (10 models), 31% (HadCM3LC) 16

17 Air Temperature CO 2, CH 4 concentration Soil Temperature Soil carbon release (CO 2, CH 4 ) Soil thawing depth Microbial metabolic activty Heat production 17

18 Fo Figure 1. Scheme of the permafrost carbon cycle model Khvorostyanov et al., Tellus,

19 eer R Khvorostyanov et al., Tellus,

20 With metabolic heat generation For Peer Without metabolic heat generation Fo (a) Soil temperature ( C): talik formation when decomposition heat is On. Contour interval is 4 C Talik formation (c) Soil temperature ( C): no talik formation when decomposition heat is Off. Contour interval is 4 C Khvorostyanov et al., Tellus,

21 Soil carbon budget no metabolic heat generation with metabolic heat generation Khvorostyanov et al., Tellus,

22 Soil carbon very likely Terrestrial Biomass likely unlikely Wetlands & Peatlands LAND 1 PgC release highly unlikely ~0.25 ppm atmospheric CO2 increase (100yr time scale) Permafrost PgC Gruber et al.,

23 Warming lengthening of vegetation period increase in carbon uptake Warming enhanced soil decomposition enhanced CO 2 release Warming drying wetland degradation Warming drying changes in fire regimes Warming permafrost carbon degradation CO 2, CH4 Warming hydrological regime shifts ecosystem composition changes shifts in carbon balance Warming hydrological regime shifts carbon export by runoff Antropogenic impacts: Logging, fire, agriculture Represented in current ecosystem/climate models 23

24 Current models exhibit still large differences Indication of insufficient process knowledge Many vulnerable pools and biogeochemical processes not yet represented in current Earth system models (a.o. permafrost, wetlands, fire, nutrients, ozone, CH4,...) Effects of changes in land use and management not yet included Comprehensive assessment: Biogeochemical biophysical feedbacks! 100yr time scale carbon cycle - climate feedbacks: positive, globally a ~20% effect 24