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See detailCurrent systematic carbon-cycle observations and the need for implementing a policy-relevant carbon observing system
Ciais, P.; Dolman, A. J.; Bombelli, A. et al

in Biogeosciences (2014), 11(13), 3547--3602

A globally integrated carbon observation and analysis system is needed to improve the fundamental understanding of the global carbon cycle, to improve our ability to project future changes, and to verify ... [more ▼]

A globally integrated carbon observation and analysis system is needed to improve the fundamental understanding of the global carbon cycle, to improve our ability to project future changes, and to verify the effectiveness of policies aiming to reduce greenhouse gas emissions and increase carbon sequestration. Building an integrated carbon observation system requires transformational advances from the existing sparse, exploratory framework towards a dense, robust, and sustained system in all components: anthropogenic emissions, the atmosphere, the ocean, and the terrestrial biosphere. The paper is addressed to scientists, policymakers, and funding agencies who need to have a global picture of the current state of the (diverse) carbon observations.We identify the current state of carbon observations, and the needs and notional requirements for a global integrated carbon observation system that can be built in the next decade. A key conclusion is the substantial expansion of the ground-based observation networks required to reach the high spatial resolution for CO2 and CH4 fluxes, and for carbon stocks for addressing policy-relevant objectives, and attributing flux changes to underlying processes in each region. In order to establish flux and stock diagnostics over areas such as the southern oceans, tropical forests, and the Arctic, in situ observations will have to be complemented with remote-sensing measurements. Remote sensing offers the advantage of dense spatial coverage and frequent revisit. A key challenge is to bring remote-sensing measurements to a level of long-term consistency and accuracy so that they can be efficiently combined in models to reduce uncertainties, in synergy with groundbased data. Bringing tight observational constraints on fossil fuel and land use change emissions will be the biggest challenge for deployment of a policy-relevant integrated carbon observation system. This will require in situ and remotely sensed data at much higher resolution and density than currently achieved for natural fluxes, although over a small land area (cities, industrial sites, power plants), as well as the inclusion of fossil fuel CO2 proxy measurements such as radiocarbon in CO2 and carbon-fuel combustion tracers. Additionally, a policy-relevant carbon monitoring system should also provide mechanisms for reconciling regional top-down (atmosphere-based) and bottom-up (surface-based) flux estimates across the range of spatial and temporal scales relevant to mitigation policies. In addition, uncertainties for each observation data-stream should be assessed. The success of the system will rely on long-term commitments to monitoring, on improved international collaboration to fill gaps in the current observations, on sustained efforts to improve access to the different data streams and make databases interoperable, and on the calibration of each component of the system to agreed-upon international scales. [less ▲]

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See detailCO2 balance of boreal, temperate, and tropical forests derived from a global database
Luyssaert, S.; Inglima, I.; Jung, M. et al

in Global Change Biology (2007), 13(12), 2509-2537

Terrestrial ecosystems sequester 2.1 Pg of atmospheric carbon annually. A large amount of the terrestrial sink is realized by forests. However, considerable uncertainties remain regarding the fate of this ... [more ▼]

Terrestrial ecosystems sequester 2.1 Pg of atmospheric carbon annually. A large amount of the terrestrial sink is realized by forests. However, considerable uncertainties remain regarding the fate of this carbon over both short and long timescales. Relevant data to address these uncertainties are being collected at many sites around the world, but syntheses of these data are still sparse. To facilitate future synthesis activities, we have assembled a comprehensive global database for forest ecosystems, which includes carbon budget variables (fluxes and stocks), ecosystem traits (e.g. leaf area index, age), as well as ancillary site information such as management regime, climate, and soil characteristics. This publicly available database can be used to quantify global, regional or biome-specific carbon budgets; to re-examine established relationships; to test emerging hypotheses about ecosystem functioning [e.g. a constant net ecosystem production (NEP) to gross primary production (GPP) ratio]; and as benchmarks for model evaluations. In this paper, we present the first analysis of this database. We discuss the climatic influences on GPP, net primary production (NPP) and NEP and present the CO2 balances for boreal, temperate, and tropical forest biomes based on micrometeorological, ecophysiological, and biometric flux and inventory estimates. Globally, GPP of forests benefited from higher temperatures and precipitation whereas NPP saturated above either a threshold of 1500 mm precipitation or a mean annual temperature of 10 degrees C. The global pattern in NEP was insensitive to climate and is hypothesized to be mainly determined by nonclimatic conditions such as successional stage, management, site history, and site disturbance. In all biomes, closing the CO2 balance required the introduction of substantial biome-specific closure terms. Nonclosure was taken as an indication that respiratory processes, advection, and non-CO2 carbon fluxes are not presently being adequately accounted for. [less ▲]

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See detailReduction Of Ecosystem Productivity And Respiration During The European Summer 2003 Climate Anomaly: A Joint Flux Tower, Remote Sensing And Modelling Analysis
Reichstein, M.; Ciais, P.; Papale, D. et al

in Global Change Biology (2007), 13(3),

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See detailTowards A Standardized Processing Of Net Ecosystem Exchange Measured With Eddy Covariance Technique: Algorithms And Uncertainty Estimation
Papale, D.; Reichstein, M.; Aubinet, Marc ULg et al

in Biogeosciences (2006), 3(4),

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See detailEurope-Wide Reduction In Primary Productivity Caused By The Heat And Drought In 2003
Ciais, P.; Reichstein, M.; Viovy, N. et al

in Nature (2005), 437(7058),

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See detailDiurnal Centroid Of Ecosystem Energy And Carbon Fluxes At Fluxnet Sites
Wilson, Kb.; Baldocchi, D.; Falge, E. et al

in Journal of Geophysical Research. Atmospheres (2003), 108(D21),

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See detailEnergy Balance Closure At Fluxnet Sites
Wilson, K.; Goldstein, A.; Falge, E. et al

in Agricultural and Forest Meteorology (2002), 113(1-4),

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See detailSeasonality Of Ecosystem Respiration And Gross Primary Production As Derived From Fluxnet Measurements
Falge, E.; Baldocchi, D.; Tenhunen, J. et al

in Agricultural and Forest Meteorology (2002), 113(1-4),

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See detailCarbon balance gradient in European forests: should we doubt 'surprising' results? A reply to Piovesan & Adams
Jarvis, P. G.; Dolman, A. J.; Schulze, E. D. et al

in Journal of Vegetation Science (2001), 12(1), 145-150

This paper responds to the Forum contribution by Piovesan & Adams (2000) who criticized the results obtained by the EUROFLUX network on carbon fluxes of several European forests. The major point of ... [more ▼]

This paper responds to the Forum contribution by Piovesan & Adams (2000) who criticized the results obtained by the EUROFLUX network on carbon fluxes of several European forests. The major point of criticism was that the data provided by EUROFLUX are inconsistent with current scientific understanding. It is argued that understanding the terrestrial global carbon cycle requires more than simply restating what was known previously, and that Piovesan & Adams have not been able to show any major conflicts between our findings and ecosystem or atmospheric-transport theories. [less ▲]

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See detailProductivity Overshadows Temperature In Determining Soil And Ecosystem Respiration Across European Forests
Janssens, Ia.; Lankreijer, H.; Matteucci, G. et al

in Global Change Biology (2001), 7(3),

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See detailRespiration As The Main Determinant Of Carbon Balance In European Forests
Valentini, R.; Matteucci, G.; Dolman, Aj. et al

in Nature (2000), 404(6780),

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See detailEstimates of the annual net carbon and water exchange of forests: the EUROFLUX methodology.
Aubinet, Marc ULg; Grelle, A.; Ibrom, A. et al

in Advances in Ecological Research (1999), 30

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See detailNew estimate of the carbon sink strength of EU forests integrating flux measurements, field surveys, and space observations: 0.17-0.35 Gt(C)
Martin, Philippe; Valentini, R.; Jacques, M. et al

in AMBIO : A Journal of the Human Environment (1998), 27(7), 582-584

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