title: Europe-wide reduction in primary productivity caused by the heat and drought in 2003.
abstract: Future climate warming is expected to enhance plant growth in temperate ecosystems and to increase carbon sequestration. But although severe regional heatwaves may become more frequent in a changing climate, their impact on terrestrial carbon cycling is unclear. Here we report measurements of ecosystem carbon dioxide fluxes, remotely sensed radiation absorbed by plants, and country-level crop yields taken during the European heatwave in 2003. We use a terrestrial biosphere simulation model to assess continental-scale changes in primary productivity during 2003, and their consequences for the net carbon balance. We estimate a 30 per cent reduction in gross primary productivity over Europe, which resulted in a strong anomalous net source of carbon dioxide (0.5 Pg C yr(-1)) to the atmosphere and reversed the effect of four years of net ecosystem carbon sequestration. Our results suggest that productivity reduction in eastern and western Europe can be explained by rainfall deficit and extreme summer heat, respectively. We also find that ecosystem respiration decreased together with gross primary productivity, rather than accelerating with the temperature rise. Model results, corroborated by historical records of crop yields, suggest that such a reduction in Europe's primary productivity is unprecedented during the last century. An increase in future drought events could turn temperate ecosystems into carbon sources, contributing to positive carbon-climate feedbacks already anticipated in the tropics and at high latitudes.
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement, LSCE, F-91191, Gif sur Yvette, France. philippe.ciais@cea.fr
authors.forename: Ph
authors.initials: P
authors.lastname: Ciais
authors.forename: M
authors.initials: M
authors.lastname: Reichstein
authors.forename: N
authors.initials: N
authors.lastname: Viovy
authors.forename: A
authors.initials: A
authors.lastname: Granier
authors.forename: J
authors.initials: J
authors.lastname: Ogée
authors.forename: V
authors.initials: V
authors.lastname: Allard
authors.forename: M
authors.initials: M
authors.lastname: Aubinet
authors.forename: N
authors.initials: N
authors.lastname: Buchmann
authors.forename: Chr
authors.initials: C
authors.lastname: Bernhofer
authors.forename: A
authors.initials: A
authors.lastname: Carrara
authors.forename: F
authors.initials: F
authors.lastname: Chevallier
authors.forename: N
authors.initials: N
authors.lastname: De Noblet
authors.forename: A D
authors.initials: AD
authors.lastname: Friend
authors.forename: P
authors.initials: P
authors.lastname: Friedlingstein
authors.forename: T
authors.initials: T
authors.lastname: Grünwald
authors.forename: B
authors.initials: B
authors.lastname: Heinesch
authors.forename: P
authors.initials: P
authors.lastname: Keronen
authors.forename: A
authors.initials: A
authors.lastname: Knohl
authors.forename: G
authors.initials: G
authors.lastname: Krinner
authors.forename: D
authors.initials: D
authors.lastname: Loustau
authors.forename: G
authors.initials: G
authors.lastname: Manca
authors.forename: G
authors.initials: G
authors.lastname: Matteucci
authors.forename: F
authors.initials: F
authors.lastname: Miglietta
authors.forename: J M
authors.initials: JM
authors.lastname: Ourcival
authors.forename: D
authors.initials: D
authors.lastname: Papale
authors.forename: K
authors.initials: K
authors.lastname: Pilegaard
authors.forename: S
authors.initials: S
authors.lastname: Rambal
authors.forename: G
authors.initials: G
authors.lastname: Seufert
authors.forename: J F
authors.initials: JF
authors.lastname: Soussana
authors.forename: M J
authors.initials: MJ
authors.lastname: Sanz
authors.forename: E D
authors.initials: ED
authors.lastname: Schulze
authors.forename: T
authors.initials: T
authors.lastname: Vesala
authors.forename: R
authors.initials: R
authors.lastname: Valentini
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D018556:Crops, Agricultural / Q000378:metabolism*; D004190:Disasters; D017753:Ecosystem; D005060:Europe; D017752:Greenhouse Effect; D006358:Hot Temperature; D011891:Rain; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide; D002244:Carbon