Ph. Ciais , M. Reichstein, N. Viovy

A. Granier , J. Ogée , V. Allard , M. Aubinet , Chr. Bernhofer , A.Carrara , F. Chevallier , T. Conway, N. De Noblet , A. Friend , T.

Grünwald , B. Heinesch , G. Inoue, P. Keronen, A. Knohl, D.Loustau , G. Manca , T. Machida, G. Matteucci , F. Miglietta , J.M.

Ourcival , K. Pilegaard , P. Peylin, S. Rambal , P. Rayner, G.Seufert , J.-F. Soussana , M.-J. Sanz ,

E.D. Schulze , T. Vesala, and R. Valentini

Europe-wide reduction in primary productivitycaused by the heat and drought in 2003

Linking the 2003 European heatwavewith carbon observations

Secular increase in primary productivityfrom satellite NDVI over the past 20 years Nemani et al., Science 2003

% per year

Will the greening trends continue with morefrequent climate extremes ?

Can positive carbon-climate feedbacks come fromtemperate regions ?

Shär et al., Nature 2003

Historical temperaturerecords in Switzerland

Summer temperature reconstructionfrom harvest dates in Burgundy

Chuine et al., Nature, 2003

Precipitation history in BavariaEurope-wide climateSpell : heat & drought

Temperate and Mediterranean forestsshow reduced, GPP, TER, NEE

Towerfluxes

Measured NEE, ETDerived GPP, NPP

Model GPP, TERModel ETModel NPP

Model LAI

ORCHIDEEmodel

Global Climate1900-2003

Hourly 30 -100 km

TowerClimate

hourly

TowerClimate

hourly

TowerClimate

2003-2003hourly

space

time

EOS-MODIS FAPAR

Spatial average

Crop Yield Country

Average / species

Spatialaverage

Model FAPAR

Gridpoint

modelling system

30 min

Climate, andcarbon fluxes insummer 2002

vs.summer 2003

AbnormalClimate and

ModelledProductivity in

2003

EOS-MODISFAPARanomaly

How abnormal is 2003 ?

Verificationagainst

crops yieldnational

data

Interannual variations in CO2 growth rate

70 sitesGrid based inversion(3.5 x 2.5°)

LMDZ model

Interannual winds

Spatial correlations

Anomalies vs. mean97-03

Atmosphere-based inversion estimate

See Peylin et al. Posteralso Patra, Roedenbeck…

Breda et al. 2004

Soil water content variation model andobservations indicate large water stress atall sites in 2003 with Root ExtractableWater REW < 0.

0

50

100

150

200

0 60 120 180 240 300 360

DOY (2003)e

xtra

cta

ble

wa

te

r

(m

m)

Vielsalm

Hyytiala

Hainich

Hesse

SorØ

Tharandt

Braschaat

Fougères

Bray

Lille

Grillenburg

Loobos

Processes

Small Changes in water use efficiency

Effects of high ozone exposure

JJA 2002JJA 2002 JJA 2003JJA 2003

Carboncrashesin therecentpast

• Uniquely dense eddy covariance network to understandclimate-carbon-water interactions at the sub-continentallevel

• Severe drop of transpiration and GPP

• Respiration tailed off with GPP drop rather than increasedwith warming

• forests became net CO2 sources to the atmosphere in July-Aug !

• Anomalous source of 0.5 PgC y-1, undoing years of meansink, enough to explain 50% of the global CO2 growth rateanomaly during 2003

Conclusions (1)

Conclusions (2)

• In the future, adverse impacts of climateextremes may cancel out the benefits ofmoderate climate change

• Forest productivity may be durably reduced ifextremes become more frequent

• In the long run, conifer forest may be moreadapted to future climate conditions in Europe

• And so large uncertainties !

Implications for the future

SummertemperaturesObserved &Modelledby IPSL GCM

2003 2005

FPAR anomalies & recent droughts