CONTRASTING RESPONSE IN CARBON UPTAKE OF TWO BEECH FORESTS TO EUROPEAN DROUGHT 2003
Description:
Here
we use the severe heat and drought event in Europe
from summer 2003 as a natural experiment to study the impact of a climatic
extreme event on ecosystem physiology and its feedback to the atmosphere. The
combination of continuous eddy covariance and tree growth measurements at two nearby
located deciduous forests showed a large reduction in carbon uptake during the
drought (-30%) and a strong carry-over effect into the next year. Both forests,
however, responded differently, although climatic forcing was almost identical.
Species composition and site condition of the ecosystems seemed to play a major
role in the ecosystems response to the drought.
Author's Names: A. Knohl, W. Kutsch, M. Mund, P. Anthoni, O. Kolle, et al
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ASSESSMENT OF WINTER FLUXES OF CO2 AND CH4 IN BLACK SPRUCE FOREST SOILS OF CENTRAL ...
Description:
This
research was carried out to estimate the winter fluxes of CO2 and CH4
by the concentration
profile method (indirect) and the chamber method (direct) at black spruce
forest soils of central Alaska during the winter 2004/5. The average winter
fluxes of CO2 and CH4 by the indirect and direct methods
were 0.24±0.06 (SE; standard error) and 0.21±0.06 gCO2-C/m2/d,
and 21.4±5.6 and 21.4±14 µgCH4-C/m2/h, respectively. The fluxes estimated by two methods are not a
significant difference based on a one-way ANOVA with a 95% confidence
level. The winter CO2 flux
corresponds to 30% of the annual CO2 emitted from Alaskan black
spruce forest soils. The average winter
emissions of CO2 and CH4 were 49±13 gCO2-C/m2
and 4.5±3.0 mgCH4-C/m2, respectively. This suggests that the winter emissions of CO2
and CH4 are an important part of the annual carbon budget in
seasonally snow-covered terrain.
Author's Names: Yongwon Kim, Masa Ueyama, Noriyuki Tanaka, et al
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DEVELOPMENT OF THE COUPLED CLIMATE-TERRESTRIAL CARBON CYCLE MODEL
Description:
The terrestrial
ecosystem carbon cycle model, Sim-CYCLE, was combined with the CCSR/NIES/FRCGC
AGCM5.7b (including a land surface model: MATSIRO). That coupled model shows a
reasonable distribution of the LAI, NPP and other carbon storages after the
1000yrs spin-up run. This presentation introduces the preliminary results of
the coupled run in 20th century.
Author's Names: T. Kato and A. Ito
Filesize: 54.22 Kb
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THE INTERPLAY BETWEEN SOURCES OF METHANE AND BIOGENIC VOCS IN GLACIAL-INTERGLACIAL FLUCTUATIONS ...
Description: Recent analyses of ice core methane
concentrations have suggested that methane emissions from wetlands were the
primary driver for prehistoric changes in atmospheric methane. However, these
data conflict as to the location of wetlands, magnitude of emissions, and the
environmental controls on methane oxidation. The flux of other reactive trace
gases to the atmosphere also controls apparent atmospheric methane
concentrations because these compounds compete for the hydroxyl radical (OH),
which is the primary atmospheric sink for methane. In a series of coupled
biosphere-atmosphere chemistry-climate modelling experiments, we simulate the
methane and biogenic volatile organic compound emissions from the terrestrial
biosphere from the Last Glacial Maximum (LGM) to present. Using an atmospheric
chemistry-climate model, we simulate the atmospheric concentrations of methane,
the hydroxyl radical, and numerous other reactive trace gas species. Over the
past 21,000 years methane emissions from wetlands increased slightly to the end
of the Pleistocene, but then decreased again, reaching levels at the
preindustrial Holocene that were similar to the LGM.
Author's Names: Jed O. Kaplan, Gerd Folberth, and Didier A. Hauglustaine
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SIMULATED CHANGES IN VEGETATION DISTRIBUTION, LAND CARBON STORAGE, AND ATMOSPHERIC CO2 IN ...
Description:
It is investigated how abrupt changes in the
North Atlantic (NA) thermohaline circulation (THC)
affect the terrestrial carbon cycle. The Lund-Potsdam-Jena Dynamic Global
Vegetation Model is forced with climate perturbations from freshwater
experiments with the ECBILT-CLIO ocean-atmosphere model. A reorganization of
the marine carbon cycle is not addressed. Modeled NA THC
collapsed and recovered after about a millennium in response to prescribed
freshwater forcing. The initial cooling of several Kelvin over Eurasia causes a reduction of extant boreal and temperate
forests and a decrease in carbon storage in high northern latitudes, whereas
improved growing conditions and slower soil decomposition rates lead to enhanced
storage in mid-latitudes. The magnitude and evolution of global terrestrial
carbon storage in response to abrupt THC
changes depends sensitively on the initial climate conditions. These were
varied using results from time slice simulations with the Hadley climate model
for different periods over the past 21,000 years. Terrestrial storage varies
between -67 and +50 PgC for the range of experiments with different initial
conditions. Simulated peak-to-peak differences in atmospheric CO2
and d13C are 6 and 18 ppmv for
glacial and early Holocene conditions. Simulated changes in d13C are between 0.18 and 0.30 permil. The small CO2 changes
modelled for glacial conditions are compatible with available evidence from
marine studies and the ice core CO2 record. The latter shows CO2
variations of up to 20 ppmv broadly in parallel with the Antarctic warm events
A1 to A4.
Author's Names: F. Joos, P. Köhler, S. Gerber, and R. Knutti
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ATMOSPHERIC CO2, CARBON ISOTOPES, THE SUN AND CLIMATE CHANGE OVER THE LAST MILLENNIUM
Description: The records of atmospheric CO2 and of NH surface temperature
covering the past millennium hold information on the strength of the
sensitivity of the global carbon cycle to climate changes. This sensitivity is
defined as the change in atmospheric CO2 in response to a given
change in NH temperature in units of ppm K-1. The magnitude of the
sensitivity is estimated for modest (< 1 K) temperature variations from
simulations with the Bern Carbon Cycle Climate model driven with solar and
volcanic forcing over the last millennium and from simulations with the range
of C4MIP models over the industrial periods. The model results are broadly
compatible with the data-deduced range.
Author's Names: F. Joos, S. Gerber, S.A. Müller, R. Muscheler
Filesize: 25.84 Kb
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SIMULATIONS OF VARIATIONS OF TROPOSPHERIC CO2 CONCENTRATION OVER JAPAN
Description:
In order to investigate the long-term and
inter-annual variations in the atmospheric CO2 concentration record
obtained by aircraft measurements over Japan, we have conducted numerical
experiments using a transport model with a process-based ecosystem model. The
climate-induced anomalies of net biospheric flux account for a significant part
of the inter-annual variations in the CO2 growth rate. The results
indicate that year-to-year change in observed vertical CO2 gradient
is mainly caused by the inter-annual variability in atmospheric transport,
likely related to El Niño events.
Author's Names: M. Ishizawa, S. Maksyutov, T. Nakazawa, and S. Aoki
Filesize: 83.09 Kb
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ANALYSIS, INTEGRATION AND MODELING OF THE EARTH SYSTEM: INTEGRATING HUMAN PROCESSES WITH ...
Description: There is a growing recognition that the Earth itself
is a single system within which the biosphere is an active component. Human
activities are now so pervasive and profound in their consequences that they
affect the Earth at a global scale in complex, interactive and apparently
accelerating ways. The new IGBP project, Analysis, Integration and Modeling of
the Earth System (AIMES) is charged with integrating human processes with Earth
system processes.
Author's Names: K.A. Hibbard and D.S. Schimel
Filesize: 12.08 Kb
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OBSERVED RELATIONSHIPS BETWEEEN LARGE-SCALE ATMOSPHERIC VARIABILITY AND THE CARBON CYCLE
Description:
Various patterns of large-scale
climate variability have exhibited trends over the past few decades. These
patterns of variability are known to have contributed substantially to recent
trends in, for example, surface temperatures and precipitation. However, it is
less clear to what extent the climate impacts of these patterns extend to the
carbon cycle. Here we summarize the observed relationships between monthly and
daily mean variations in concentrations of atmospheric carbon dioxide and the
dominant pattern of variability in the extratropical circulations, the
so-called Northern and Southern Hemisphere Annular Modes. The observed
relationships are compared with results derived from surface flux estimates
from the Atmospheric Tracer Transport Model Intercomparison Project (TransCom).
Author's Names: A.K. Hawes, and D.W.J. Thompson
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THE SOIL CARBON CO2 FERTILIZATION FACTOR: THE MEASURE OF AN ECOSYSTEM’S CAPACITY TO INCREASE ...
Description:
This research introduces the concept of a “CO2
fertilization factor for soil carbon” (SigmaCF). The SigmaCF is a measure of an
ecosystem’s capacity to increase soil carbon storage in response to elevated
carbon dioxide levels. This research describes the mathematical derivation of
SigmaCF and illustrates how SigmaCF can be determined experimentally, using
data from three different CO2 enrichment experiments. I have
developed this concept to compare the results of carbon dioxide enrichment
experiments having different soil carbon turnover times, different levels of CO2
enrichment, and different lengths of exposure to elevated carbon dioxide
levels. The SigmaCF can also be used to estimate increases in soil carbon
uptake due to observed contemporary increases in atmospheric carbon dioxide
levels. This approach approximates the extent to which elevated carbon dioxide
levels increase soil carbon storage. I calculated SigmaCF for three
experimental settings—a mixed forest, and stands of loblolly pine and white oak
trees—by measuring changes in carbon inventories and radiocarbon ratios. The
forest had a SigmaCF of 1.8, which would imply a global sequestration of 5.5
billion tons C/year during the 1990's (in the highly-unlikely event that all
terrestrial vegetation shows this same response to elevated carbon dioxide
levels). The loblolly pine stand had a SigmaCF of 0.9 (2.8 billion tons C/year)
and the white oak stand had a SigmaCF of 1.18 (3.5 billion tons C/year). These
results show that elevated carbon dioxide levels in the atmosphere are
increasing the flux of carbon from the atmosphere to soil.
Author's Names: K.G. Harrison
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