Vulnerability of Primary Production to Climate Extremes Lessons from the 2003 heatwave in Europe

Transcription

1 Vulnerability of Primary Production to Climate Extremes Lessons from the 2003 heatwave in Europe Ph. Ciais, M. Reichstein, N. Viovy A. Granier, J. Ogée, V. Allard, M. Aubinet, Chr. Bernhofer, A. Carrara, F. Chevallier, N. De Noblet, A. Friend, T. Grünwald, B. Heinesch, P. Keronen, A. Knohl, D. Loustau, G. Manca, G. Matteucci, F. Miglietta, J.M. Ourcival, K. Pilegaard, S. Rambal, G. Seufert, J.-F. Soussana, M.-J. Sanz, E.D. Schulze, T. Vesala, and R. Valentini

2 Interannual variations in CO 2 growth rate

3 Linking with bottom up observations The 2003 European heatwave

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5 Will the greening continue with more frequent climate extremes? % per year Nemani et al., Science 2003 Secular increase in primary productivity from satellite NDVI over the past years

6 Coupled Climate-Carbon models Predict an Increase in NPP and in carbon storage in Temperate Regions Tropical soil drying Longer growing seasons Berthelot et al., GBC 2003 See also Cox et al., Nature 2001

7 Precipitation history in Bavaria Historical temperature records in Switzerland Summer temperature reconstruction from harvest dates in Burgundy Shär et al., Nature 2003 Chuine et al., Nature, 2003

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9 Temperate and Mediterranean forests

10 2003 modelling system Tower Tower Climate Climate hourly hourly hourly space time ORCHIDEE model Tower fluxes Measured NEE, ET Derived GPP, NPP Grid point Global Climate Hourly km Model LAI Model FAPAR Model GPP, TER Model ET Model NPP Spatial average EOS-MODIS Crop Yield FAPAR Spatial average Country Average / species

11 Global biospheric model ORCHIDEE meteorological forcing rain, température, humidity, incoming radiation, wind, CO2 SECHIBA energy & water cycle photosynthesis output variables sensible & latent heat fluxes, CO2 flux, net radiation ORCHIDEE Dt = hour LAI, roughness, albedo STOMATE vegetation & soil carbon cycle phénologie, allocation, Dt = day soil water, surface temperature, GPP NPP, biomass, litterfall vegetation types LPJ spatial distribution of vegetation competition, fire, Dt = year prescribed vegetation

12 Comparing gross and net fluxes during summer 2002 and 2003

13 Abnormal Climate and Productivity in 2003 Model verification with EOS- MODIS FAPAR

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15 Verification against crops yield national data

16 2003 is the largest productivity crash of the past 100 years -%

17 How abnormal is 2003? 0.80 avg fapar Jul-Sep GIMMS MODIS GIMMS avg ± 5 standard deviations MODIS avg ± 5 standard deviations Year

18 Independent inversion estimate Inversion / stations / interannual winds / resolved on each model grid point Peylin et al. In prep

19 Uniquely dense eddy covariance network to map climate-carbon-water interactions at the regional level Severe drop of transpiration and GPP Respiration tailed off with the GPP drop rather than increasing with temperature ; forests became net CO2 sources to the atmosphere in summer! Anomalous source of 0.5 PgC y -1, undoing years of mean sink, enough to explain 50% of the global CO2 growth rate anomaly

20 Processes Soil water content variation model and observations indicate large water stress at all sites in 2003 with Root Extractable Water REW < Vielsalm extractable water (mm) DOY (2003) Hyytiala Hainich Hesse SorØ Tharandt Braschaat Fougères Bray Lille Grillenburg Loobos Breda et al.

21 water-stress controls on stomatal conductance Hesse daily canopy conductance gc* (cm s -1 ) gc* REW REW ,0 DOY (2003) 0,8 gc (cm s-1) 0,6 0,4 gc_2002 gc_2003 0,2 Granier et al. submitted 0, DOY

22 Response of ecosystem fluxes to high temperatures and precipitation deficits

23 No Changes in water use efficiency GPP [ gc m -2 month -1 ] Ha02 Th02 So02 Vi02 So03 Ha03 He03 Th03 Vi03 He02 Sa02 Ro02 Ca02 Ca03 Hy03 Hy02 Br02 Sa03 Ro03 Br Pi03 Pi Evapotranspiration [mm month -1 ]

24 Unprecedented decrease in NPP during the past century No intrinsic change in water use efficiency Delayed impact on carbon balance may be extended over several years via mortality, insect attacks, tree damage

25 Vulnerability of carbon stocks to climate extremes

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27 Take home In the future, adverse impacts of climate extremes may cancel out any benefits of moderate climate change European temperate productivity may be durably reduced if extremes become more frequents In the long run, conifer forest may be more adapted to European future climate conditions

28 Heat Drought Atmospheric water stress + Transpiration + +/- + - Soil water limitations GtCy - anomaly NEE - TER - -0% - Stomatal closure GPP -0%

29 Independent tree ring verification!c (mm) Hesse: seasonal variation of tree circumference as measured on 11 beech trees among the dominant and codominant crown classes during the period (the same trees were measured each year) DOY A. Granier pers. Comm

30 GPP modelled vs measured anomaly