SOIL MOISTURE INCREASES IN A TROPICAL SAVANNA UNDER FREE AIR CO2 ENRICHMENT
Description:
Soil
moisture measurements in an Australian tropical savanna show accumulating soil
water under three years of Free Air CO2 Enrichment (FACE). Most of this accumulation is occurring below
the rooting depth of grasses. Although
this increase in stored soil water is only a fraction (< 0.3% yr-1)
of annual rainfall, it is cumulative and may advantage deep-rooted woody
plants.
Author's Names: C.J. Stokes, A.J. Ash, and J.A.M. Holtum
Filesize: 93.97 Kb
Added on: 08-Aug-2005 Downloads: 20
Home Page | Comment on Proceeding | Details
CLIMATE AND DISTURBANCE EFFECTS ON GROSS ECOSYSTEM FLUXES ASSESSED BY MODEL-DATA FUSION
Description:
We
implement a model-data fusion method to determine the gross flux components
contributing to the net ecosystem exchange of a Ponderosa pine forest in Oregon. This site-level
investigation represents a test-run of the method, which will later be applied
to all of Oregon and north California.
Author's Names: J.M. Styles, B.E. Law, D. Turner, W. Cohen, and G. Whitley
Filesize: 48.86 Kb
Added on: 08-Aug-2005 Downloads: 51
Home Page | Comment on Proceeding | Details
OBSERVED RESPONSE OF THE CO2 GROWTH RATE TO CLIMATE VARIATIONS
Description:
The world is moving in a direction of managing the carbon
cycle in order to limit the forcing of earth's climate by CO2 as
well as to limit acidification of the oceans.
We may expect limitations on emissions, sequestration of carbon and
enhancements of natural sinks. It would
be important to be able to observe and quantify the impact of any such measures
on the growth rate of CO2. Until now it has been difficult to
quantify changes of the growth rate of CO2 with confidence due to
the large year to year variations that are caused by climate variations. A statistical method has been developed to
predict the growth rate of CO2 based on observed variations of
climate parameters.
Author's Names: Pieter Tans
Filesize: 16.25 Kb
Added on: 08-Aug-2005 Downloads: 24
Home Page | Comment on Proceeding | Details
CLIMATE-INDUCED CHANGES IN OCEAN CO2 UPTAKE MEDIATED BY CHANGES IN THE SUPPLY OF IRON-BEARING DUST
Description:
The effect of changes in iron supply to the ocean on
CO2 uptake is examined. Dust deposition fields from a dust model
driven by output from a future climate simulation of a coupled general
circulation model (GCM) were used as input to an ocean GCM with an embedded
ecosystem model. In simulations using dust produced in a future climate the
primary productivity of the ocean increased by 56% compared to simulations
using dust from the present climate. The sinking particle flux of carbon at 100
m depth increased by 46%. The net air-to-sea flux of CO2 was 4.1
PgC/y greater in the future dust simulation. Most of these changes occurred in
the Equatorial Pacific Ocean, where the model ecosystem was iron-limited with
present-day dust inputs but which received a large increase in the dust
supplied from the Amazon
Basin. These
perturbations to the marine biogeochemical system are large compared to other
potential climate effects that have been observed in the model. Although these
results are preliminary, they could form a large negative feedback on global
warming.
Author's Names: I.J. Totterdell, J. Gunson and S. Woodward
Filesize: 21.88 Kb
Added on: 08-Aug-2005 Downloads: 26
Home Page | Comment on Proceeding | Details
CARBON-CLIMATE INTERACTIONS: RESULTS FROM THE CSIRO GLOBAL CLIMATE MODEL
Description:
Using
the CSIRO global climate model (CCAM)
coupled with a terrestrial carbon cycle model, we carried out two simulations
using the protocol of C4MIP (Coupled Carbon Cycle Climate Model Intercomparison Project) Phase I to study the
influences of increasing atmospheric CO2 concentration and changes
in sea surface temperature over the last 100 years on CO2 between
atmosphere and 11 biomes. It was found that the inter-annual variation of net
ecosystem prediction of global terrestrial biosphere is significantly
correlated to the variation of land surface temperature from 1980 to 1999, and
the increase in net ecosystem production can be largely explained by the
increase in net primary production from CO2 fertilization from 1970
to 1999 in our model. The response of net ecosystem production to CO2
fertilization is strongest in tropical rainforest and not significant in
tundra. Our estimates of net ecosystem production of global terrestrial
biosphere in 1990’s agree well with the results from an inversion study by
Allison et al. [this volume].
Author's Names: Y.P. Wang, E.A. Kowalczyk, and R.M. Law
Filesize: 55.91 Kb
Added on: 08-Aug-2005 Downloads: 55
Home Page | Comment on Proceeding | Details
CLIMATE VARIABILITY IN THE PACIFIC NORTHWEST, USA AND THE IMPACT ON CARBON EXCHANGE IN AN ...
Description: Long-term micrometeorological measurements
(1998-2004) show high interannual variability in the atmosphere-ecosystem
exchange of carbon for a Pacific Northwest
coniferous old-growth forest. Earlier
work [Wharton et al. 2004] has shown that net ecosystem exchange of carbon (NEE)
in this forest is highly sensitive to any perturbations in climate, and in
particular, in precipitation and temperature anomalies. Here we present results
from the ACASA (Advanced Canopy Atmosphere-Soil Algorithm) model to investigate
NEE as it relates to various climate forcings, including a shift in precipitation
pattern and increase in air temperature.
Author's Names: S. Wharton, R.D. Pyles, M. Falk, E. González, and K.T. Paw U
Filesize: 71.00 Kb
Added on: 09-Aug-2005 Downloads: 22
Home Page | Comment on Proceeding | Details
CO2 UPTAKE OF THE BIOSPHERE: FEEDBACKS BETWEEN THE CARBON CYCLE AND CLIMATE CHANGE USING A ...
Description:
Different CO2 stabilization scenarios and CO2
emission scenarios have been carried out with an earth system model to
investigate feedbacks between future climate change and carbon cycle. The model
predicts a sensitivity of 1.6±0.1 K for an increase of 280 ppm in atmospheric
CO2 concentration. The decrease of the thermohaline circulation is
predominantly controlled by an enhanced atmospheric moisture transport to high
latitudes by global warming. Overall, the simulated effect of atmospheric CO2
concentration on climate change reduces the total carbon uptake of the ocean
and the land is reduced by 24-29%.
Author's Names: A. Winguth, U. Mikolajewicz, M. Gröger, et al
Filesize: 84.81 Kb
Added on: 09-Aug-2005 Downloads: 139
Home Page | Comment on Proceeding | Details
WHAT ARE THE MOST IMPORTANT FACTORS FOR CLIMATE CARBON CYCLE COUPLING
Description: Data
from long-term measurements of carbon balance in boreal, mid-latitude and
tropical ecosystems are used to assess the mechanisms that drive changes in
ecosystem carbon balance in response to a changing climate. We find that most
model parameterizations overestimate the temperature sensitivity of ecosystem
respiration and underestimate the role of soil water balance in controlling
respiration and flammability. We conclude that model assessments of
climate—carbon feedbacks must carefully simulate regional precipitation,
evaporation, evapotranspiration, and water balance, including factors leading
to fires (e.g. sources of ignition), in addition to assessing changes in
temperature. Covariances among these drivers of ecosystem respiration and
vegetation change may be critically important for these simulations.
Author's Names: S. C. Wofsy, J. W. Munger, S. P. Urbanski, et al
Filesize: 686.66 Kb
Added on: 09-Aug-2005 Downloads: 159
Home Page | Comment on Proceeding | Details
ENSO, DRAUGHT AND INTERANNUAL CO2 VARIABILITY
Description: The
interannual variability of atmospheric CO2 growth rate shows
remarkable correlation with the El Niño Southern Oscillation (ENSO).
Here we present results from mechanistically based terrestrial carbon cycle
model VEgetation-Global-Atmosphere-Soil (VEGAS) and the Hamburg Ocean Carbon
Cycle Model (HAMOCC), both forced by observed climate fields such as
precipitation and temperature. Land is found to contribute to most of the
interannual variability with a magnitude of about 5 Pg y-1 and the
simulated land-atmosphere flux shows a correlation of 0.59 with the CO2
growth rate observed at Mauna Loa from 1965 to
2000. Ocean-atmosphere flux varies by about 1 Pg y y-1, and is
largely out of phase with land flux. On land, much of the change comes from the
tropical regions such as the Amazon and Indonesia where ENSO related climate anomalies are in the same
direction across much of the tropics. The sub-continental variations over North
America and Eurasia are comparable to the
tropics but the total interannual variability is about 1 Pg y-1 due
to the cancellation from the sub-regions. This has implication for flux
measurement network distribution.
Author's Names: N. Zeng
Filesize: 12.64 Kb
Added on: 09-Aug-2005 Downloads: 28
Home Page | Comment on Proceeding | Details
THE GLACIAL BURIAL HYPOTHESIS – MISSING LINK IN THE GLACIAL CO2 PROBLEM?
Description:
Organic carbon buried under the great ice sheets of
the Northern Hemisphere is suggested to be the missing link in the atmospheric
CO2 change over the glacial-interglacial cycles. At glaciation, the
advancement of continental ice sheets buries vegetation and soil carbon
accumulated during warmer periods. At deglaciation, this burial carbon is
released back into the atmosphere. In a simulation over two
glacial-interglacial cycles using a synchronously coupled atmosphere-land-ocean
carbon model forced by reconstructed climate change, I found a 547 Gt
terrestrial carbon release from glacial maximum to interglacial, resulting in a
60 Gt (about 30 ppmv) increase in the atmospheric CO2, with the
remainder absorbed by the ocean in a scenario in which ocean acts as a passive
buffer. This is in contrast to previous estimates of a land uptake at deglaciation.
This carbon source originates from glacial burial, continental shelf and other
land areas in response to changes in ice cover, sea level, and climate. The
input of light isotope enriched terrestrial carbon causes atmospheric Δ13C to drop by about 0.3permil at deglaciation,
followed by rapid rise towards a high interglacial value in response to oceanic
warming and regrowth on land. Together with other ocean based mechanisms such
as change in ocean temperature, the glacial burial hypothesis may offer a full
explanation of the observed 80-100 ppmv atmospheric CO2 change.
Author's Names: N. Zeng
Filesize: 58.69 Kb
Added on: 09-Aug-2005 Downloads: 24
Home Page | Comment on Proceeding | Details