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  MINERAL CARBON DIOXIDE SEQUESTRATION: STILL A VIABLE OPTION  Popular
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This paper provides background and summarizes evidence supporting the possibility of developing a low-cost mineral carbon dioxide sequestration technology.


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Category: Abstracts/Managing the Carbon Cycle

  LONG-TERM CONSEQUENCES OF CONTINUED CARBON DIOXIDE EMISSION TO THE ATMOSPHERE  Popular
Description:

Continued emissions of carbon dioxide to the atmosphere will affect climate and ocean chemistry. These consequences can be anticipated by consideration of basic physical principles, past climates, and calculations. Emission of 5,000 PgC (= amount of carbon in conventional fossil-fuel resources) over a few centuries could produce radiative forcing of climate of about 10 W m­-2 which could be expected to produce global mean warming of ~4 to 12 °C. Warming in this range would have large biological and human consequences. It could threaten the ice sheets and lead to a long-term sea-level rise of 70 m. Ocean pH could decrease by 0.7 units, making the oceans more corrosive to carbonate minerals than they have been for many millions of years. From the perspective of geology and biological evolution, these changes would occur rapidly, overwhelming most natural processes that would buffer CO2 changes occurring over longer time intervals, and thus may produce changes at a rate and of a magnitude that exceed the adaptive capacity of at least some biological systems. To find comparable events in Earth history, we need to look back tens of millions of years to rare catastrophic events.


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Category: Opening Talks

  IMPACT OF CLIMATE-CARBON CYCLE FEEDBACKS ON EMISSIONS SCENARIOS TO ACHIEVE STABILISATION  Popular
Description:

At present, approximately half of anthropogenic CO2 emissions are absorbed by the land and oceans [Jones and Cox, 2005], but climate changes may act to reduce this uptake, leading to higher CO2 levels for a given emission scenario [Cox et al., 2000, Friedlingstein et al., 2005, in prep.]. Less attention has been paid to the potential impact of carbon cycle feedbacks on the emissions reductions required to achieve stabilisation (the so called “permissible emissions”), although this is arguably more pertinent to the issue of avoiding dangerous climate change in the context of the United Nations Framework Convention on Climate change.


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Category: Abstracts/Managing the Carbon Cycle

  GREENHOUSE GAS CO2, CH4 AND CLIMATE EVOLUTION SINCE 650KYRS DEDUCED FROM ANTARCTIC ICE CORES  Popular
Description:

Ice cores are unique archives of past climatic and atmospheric conditions through the isotopic composition of the ice and the analysis of the air bubbles trapped. In 1999 Petit et al published the reconstruction of the Antarctic climate and atmospheric composition over the last 420 000 years from the Vostok ice core. This record covered the last four glacial inter glacial cycles back to the end of the marine interstadial 11 (MIS 11). It has revealed the close relationship between the atmospheric part of the carbon cycle and the climate. With CO2 concentration oscillating between 180 and 280 ppmv during the last 4 climatic cycles. In a similar way the methane concentration followed closely temperature on glacial interglacial time scales, with millennial-scale structures during glacial times which appear out of phased with Antarctic temperature but, at least for the last glaciation, in phase with the Greenland rapid climatic oscillations, as revealed by the GISP and GRIP ice cores.


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Category: Abstracts/Carbon Cycle Response to Environmental Change

  SUBSTRATE INDUCED GROWTH RESPONSE OF SOIL AND RHIZOSPHERE MICROBIAL COMMUNITIES UNDER ELEVATED CO2  Popular
Description:

The maximal specific growth rate of microorganisms from rhizospheres of Populus deltoides grown under normal CO2 concentration in the atmosphere (400 ppm) was lower compared to the assessments made for plots under elevated CO2 (800 and 1200 ppm). A similar conclusion was made for microbial communities from soil under winter wheat and sugar beets grown under 370 and 550 ppm CO2 in the atmosphere. Three to four years fumigation of field plots with elevated CO2 has been shown to result in the formation of rhizosphere microbial communities characterized by faster specific growth rates as compared to microbial community under control plants.


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Category: Abstracts/Impacts of High CO2 on Land and Ocean Ecosystems

  FREQUENT MEASUREMENTS OF ATMOSPHERIC CO2 AND OTHER TRACE SPECIES USING COMMERCIAL AIRLINES  Popular
Description:

A new research project has started in 2003 to develop Continuous CO2 Measurement Equipment (CME) and Automatic Air Sampling Equipment (ASE) for commercial airlines. CMEs are planning to be installed on five aircrafts and fly to South East Asia, East Asia, Europe, North America, Pacific and Australia. Routine air sampling by ASE will be done twice a month between Japan and Australia. After issuing the certification, first observation flight by Boeing 747-400 will be conducted in October, 2005. Preliminary observation by small research aircraft indicates that CME produces reasonable results.


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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  DECADAL CHANGES IN OCEAN CARBON UPTAKE  Popular
Description:

There is growing evidence that the rate of anthropogenic CO2 uptake in the ocean is changing over time. Several programs are poised to assess current and future ocean CO2 uptake rates, but there are issues with how to extrapolate these measurements to decadal-scale changes over entire ocean basins. One possibility is to exploit the growing network of ARGO floats that are collecting profiles throughout the global oceans. We explore the viability of this approach and make recommendations for how the ARGO network might be made more useful for biogeochemical applications.


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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  NEW COUPLED CLIMATE-CARBON SIMULATIONS WITH THE IPSL MODEL: FROM VALIDATION WITH ATMOSPHERIC ...  Popular
Description:

We have developed a Climate-Carbon coupled model based on the IPSL OAGCM and on two biogeochemical models, ORCHIDEE for the continent and PISCES for the ocean, to investigate the coupling between climate change and the global carbon cycle. We have performed four climate-carbon simulations over the 1860-2100 period in which atmospheric CO2 is interactively calculated. They are :

§ A control coupled simulation with no anthropogenic emissions.

§ A coupled simulation with anthropogenic emissions.

§ A coupled simulation with anthropogenic emissions including non-CO2 greenhouse and sulfate aerosols.

§ An uncoupled carbon simulation with the same anthropogenic emissions as second simulation but for which atmospheric CO2 change has no impact on climate.

Compared to the first IPSL Climate-Carbon coupled model [Dufresne, et al., 2002], the simple carbon models have been replaced by IPSL advanced ocean and land biogeochemical models, respectively PISCES and ORCHIDEE. CO2 is transported in the atmosphere and compared with observations. Comparison with satellite data is also done. We then analyze the coupled and uncoupled simulations, highlight the importance of the climate change both on the oceanic and biosphere sink and estimate the climate-carbon feedback. The results are also compared to the outputs of other models participating in the C4MIP inter-comparison project. Finally, off-line simulations are carried out to perform sensitivity tests (fire, dynamics of land and ocean ecosystems, soil respiration) in order to identify the key processes which govern the simulated response.


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Category: Abstracts/Carbon Cycle Response to Environmental Change

  EUROPEAN-WIDE REDUCTION IN PRIMARY PRODUCTIVITY CAUSED BY THE HEAT AND DROUGHT IN 2003  Popular
Description:

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, and their impact on terrestrial carbon cycling is unclear. Europe experienced a particularly extreme climate anomaly during 2003, with July temperatures up to 6°C above long-term means, and annual precipitation deficits up to 300 mmy-1, that is 50% below the average. We used the 2003 heatwave as a ‘laboratory assistant’ to estimate the impact on terrestrial carbon cycling.


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Category: Abstracts/Carbon Cycle Response to Environmental Change

  ROLE OF AGRICULTURAL MANAGEMENT IN MITIGATING GREENHOUSE EMISSIONS  Popular
Description:

Analyses of Northern Hemisphere carbon fluxes indicate that a number of ecosystem processes jointly contribute to source and sink exchanges of CO2 which affect the net carbon sequestered from the atmosphere. These processes (e.g., CO2, N2O, CH4, and H2O dynamics) exhibit high variability in time and space with the largest variability corresponding to human land management events. Therefore, the spatial and temporal incorporation of land management information is needed to properly represent net carbon and other GHG fluxes.


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Category: Abstracts/Managing the Carbon Cycle

  HAZARDS OF TEMPERATURE ON FOOD AVAILABILITY IN CHANGING ENVIRONMENTS  Popular
Description:
Global temperatures are predicted to increase from rising levels of atmospheric carbon dioxide (CO2) and other greenhouse gases. We conducted experiments in sunlit, controlled-environment chambers and temperature-gradient greenhouses to determine effects of elevated temperature and doubled CO2 concentration on pollination and yield of rice, soybean, dry bean, peanut, and grain sorghum. Photosynthesis and vegetative growth were more tolerant of increasing temperatures than reproductive processes. Rice seed yields were optimum at 25°C mean daily temperature and decreased with increasing temperature (typically about 10% decline for each 1°C rise in temperature). Grain sorghum yield response to temperature was similar to rice, but dry bean was more sensitive, and soybean and peanut were more tolerant. Pollen viability followed a temperature response similar to seed yield. Comparisons of 43 rice cultivars in temperature-gradient greenhouses showed genetic variation in percent seed-set in response to a 4.5°C increase above ambient temperatures in Florida. Thus, there appears to be a range of adaptation of seed crops to temperature. Elevated CO2 did not prevent high temperature decline in yield; in dry bean it made pollination more sensitive to high temperature. In summary, global warming will be a greater threat to crop seed yields than to photosynthesis and vegetative growth. However, crop genetic improvements might ameliorate part, but not all, of the high temperature hazards for seed yields and global food security.

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Category: Abstracts/Carbon Cycle Response to Environmental Change

  PERSISTENCE OF NITROGEN LIMITATION OVER TERRESTRIAL CARBON UPTAKE  Popular
Description:

Because vegetation growth in the Northern Hemisphere is typically nitrogen-limited, increased nitrogen deposition could have attenuating effect on rising atmospheric CO2 by stimulating the accumulation of biomass. Given the high carbon to nitrogen ratios and long lifetimes of carbon in wood, a most significant effect of nitrogen fertilization is expected in forests. Forest inventories indicate that the carbon content of northern forests have increased concurrently with increased nitrogen deposition since the 1950s [Spiecker et al., 1996]. In addition, variations in atmospheric CO2 indicate a globally significant carbon sink in northern mid-latitude forest regions [Schimel et al., 2001]. It is unclear however, whether elevated nitrogen deposition or other factors are the primary cause of carbon sequestration in northern forests. We argue that the elevated nitrogen deposition is unlikely to enhance vegetation carbon sink significantly because of its differentiating effect on the carbon sequestration capacity of uneven aged forests and climatic limitations on carbon sequestration in the Northern Hemisphere. We estimate the potential of forests with lifted nitrogen limitation to decelerate CO2 concentrations rise in the atmosphere and therefore to mitigate climate warming. We also outline areas of the Northern Hemisphere which are most sensitive to increased nitrogen deposition.


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Category: Abstracts/Carbon Cycle Response to Environmental Change

  TOP-DOWN REGIONAL CO2 FLUXES FOR NORTH AMERICA ESTIMATED FROM NOAA-CMDL CO2 OBSERVATIONS  Popular
Description:

We present an analysis of terrestrial net CO2 fluxes from North America for the period 2000-2004. These fluxes consist of hourly maps at ~70km×100km resolution that are consistent with observed atmospheric CO2 mixing ratios, as well as with varying climatic conditions across different ecosystems as observed from space. The flux maps are created in a newly developed ensemble data assimilation system that consists of the atmospheric Transport Model v5 (TM5), the Vegetation Photosynthesis Respiration Model (VPRM), and an efficient Bayesian least-squares algorithm to optimize the fluxes from different biomes in VPRM against CO2 mixing ratios from the NOAA-CMDL observing network. The stochastic nature of the ensemble data assimilation system allows us to consistently include uncertainty on net CO2 fluxes from the neighboring oceans and more distant continents in the flux estimates for North America.


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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  A DECREASING TREND IN NORTHERN HEMISPHERE CARBON UPTAKE SINCE 1992  Popular
Description:
Increases in the north-south gradient of atmospheric CO2 at Northern Hemisphere measurement sites of the NOAA/CMDL Global Air Sampling Network reveal a shrinking carbon sink.  14 of 16 low altitude sites show differences with South Pole increasing at a faster rate than can be explained by fossil fuel emissions, resulting in an average north-south difference at remote marine sites nearly 1 ppm larger in 2003 than in 1992.  Regardless of whether this trend will persist, it shows that large changes in the carbon cycle can occur rapidly and is a strong indication of the tenuous nature of terrestrial carbon sinks.

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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  ESTIMATION OF ATMOSPHERIC CO2 FROM AIRS INFRARED SATELLITE RADIANCES IN THE ECMWF DATA ASSIMILATION  Popular
Description:

Atmospheric CO2 concentrations have been obtained from the Atmospheric Infrared Sounder (AIRS) radiance data within the European Centre for Medium-Range Weather Forecasts (ECMWF) data assimilation system. In a first explorative configuration, a subset of channels from the AIRS instrument has been assimilated providing estimates of tropospheric column-averaged CO2 mixing ratios representative of a layer between the tropopause and about 700 hPa at observation locations only. Results show considerable geographical and temporal variability with values ranging between 370 and 382 ppmv. The 5-day mean estimated random error is about 1%, which is confirmed by comparisons with flask observations on board flights of Japanese airliners in the west-Pacific region. This study demonstrates the feasibility of global CO2 estimation using high spectral resolution infrared satellite data in a numerical weather prediction data assimilation system. Currently, the system is being improved to treat CO2 as a full three-dimensional atmospheric variable included in the forecast model. This allows more flexibility in the constraints on the CO2 estimation as well as the possibility of assimilating other data sources (e.g., near-infrared satellite data and flasks). The CO2 fields provided by the data assimilation system have great potential to assist the surface flask network in constraining current top-down carbon flux estimates.


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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  A 50 YEAR RECORD OF THE EVOLUTION OF THE MERIDIONAL GRADIENT IN ATMOSPHERIC CO2 AND ITS ...  Popular
Description:

Measurements of atmospheric CO2 began in 1957-1958 at a wide range of locations, including at fixed stations, on ice floes, on oceanic expeditions, and on aircraft flights, with logistical and financial support provided by the International Geophysical Year (IGY) program. Although the measurement effort was reduced in scope immediately following the IGY, today, measurements are made at more than 100 locations.  Over this same time interval, emissions of CO2 from fossil fuel combustion increased from 2.3 thousand million metric tons per year (GtC/yr) in 1958 to 7.1 GtC/yr in 2003 [Marland et al., 2005, and personal communication].  More than 90% of this CO2 was released into the northern hemisphere where it lingered before mixing fully world-wide.  The atmospheric CO2 concentration, in response, rose faster in the northern hemisphere than in the southern, the interhemispheric difference increasing from near zero during the IGY to about 3 parts per million (ppm) in 2003. For all northern hemisphere stations where our program has measured CO2, the gradient changes relative to the South Pole are generally proportional to the rate of fossil fuel CO2 emissions, disregarding seasonal and short term interannual variability in the CO2 data.  Here, we use this fact to diagnose how the carbon cycle has evolved over the past half century.


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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  PROPOSING A MECHANISTIC UNDERSTANDING OF ATMOSPHERIC CO2 DURING THE LATE PLEISTOCENE...  Popular
Description:

Paleo-climate records in ice cores revealed high variability in temperature, atmospheric dust content and carbon dioxide. The longest CO2 record from the Antarctic ice core of the Vostok station went back in time as far as about 410 kyr BP showing a switch of glacials and interglacials in all those parameters approximately every 100 kyr during the last four glacial cycles with CO2 varying between 180-300 ppmv [Petit et al., 1999]. New measurements of dust and the isotopic temperature proxy deuterium of the EPICA Dome C (EDC) ice core covered the last 740 kyr, however, revealed glacial cycles of reduced temperature amplitude [EPICA community members, 2004]. These new archives offer the possibility to propose atmospheric CO2 for the pre-Vostok time span as called for in the EPICA challenge [Wolff et al., 2004]. Here, we contribute to this challenge using a box model of the isotopic carbon cycle [Köhler et al., 2005] based on process understanding previously derived for Termination I. Our results show that major features of the Vostok period are reproduced while prior to Vostok our model predicts significantly smaller amplitudes in CO2 variations.


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Category: Abstracts/Carbon Cycle Response to Environmental Change

  THE POTENTIAL OF UPPER OCEAN ALKALINITY CONTROLS FOR ATMOSPHERIC CARBON DIOXIDE CHANGES  Popular
Description:

Extreme global model scenarios of complete preservation and degradation of biogenic particulate CaCO3 (calcium carbonate) in open ocean waters which are supersaturated with respect to CaCO3 were carried out. According to these experiments, the theoretical potential of upper ocean alkalinity controls for changing the atmospheric pCO2 (CO2 partial pressure) amounts to several hundred μatm on time scales of several 104 years. Up to a timescale of 103 years, however, the respective influence is minor as compared to an expected anthropogenic increase of the atmospheric pCO2 in the order of 500-1000 μatm.


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Category: Abstracts/Impacts of High CO2 on Land and Ocean Ecosystems

  INTERANNUAL VARIABILITY IN TERRESTRIAL CARBON EXCHANGE USING AN ECOSYSTEM FIRE MODEL  Popular
Description:

We have incorporated a semi-mechanistic fire model into the SEVER Dynamic Global Vegetation Model (DGVM). The model produces estimates of net primary productivity (NPP), heterotrophic respiration (HR) and fire carbon emission (FE) for the globe. This model was run for the period 1957-2002 with the NCEP climate reanalysis data as an input. Results were compared with the ATSR area burnt maps and a Time Dependent Inverse (TDI) model fluxes of CO2. We find that on interannual time scales NPP variability explains major part of flux variability simulated by the TDI model, followed by the HR and FE contributions.


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Category: Abstracts/Land Use and the Terrestrial Carbon Cycle

  THE CHANGING CARBON CYCLE  Popular
Description:

The carbon cycle has undergone changes from 1998-2003 as a result of extensive droughts.  The CO2 seasonal amplitude at MLO halted its increase, and the CO2 growth rate accelerated as a result of a slowing down of the North American carbon sink.  In a series of coupled carbon-climate model experiments, we show a greater probability of drier soils in the 21st century, especially in the tropics and in mid-latitude summers as temperature-driven evapotranspiration exceed precipitation, and a positive feedback between the carbon cycle and climate. This positive feedback reduces the land and ocean’s capacity to store fossil fuel CO­ and accelerates the warming. A fossil fuel emission accelerating rapidly as the sink capacities decrease leads to further increases in the airborne fraction of fossil fuel CO2.


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Category: Abstracts/Carbon Cycle Response to Environmental Change

  WHAT ARE THE MOST IMPORTANT FACTORS FOR CLIMATE CARBON CYCLE COUPLING  Popular
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.


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  NITROGEN REGULATION OF CARBON SEQUESTRATION IN TERRESTRIAL ECOSYSTEMS IN RESPONSE TO RISING ...  Popular
Description:

A highly controversial issue in global change research is the regulation of terrestrial carbon (C) sequestration by soil nitrogen (N) availability. The Third Assessment IPCC Report  predicts rising atmospheric CO2 alone could stimulate terrestrial carbon (C) sequestration by 350 – 980 Pg (=1015 g) C in the 21st Century. Sequestering 350 – 980 Gt C in terrestrial ecosystems requires 7.7 – 37.5 Pg (N) based on a stoichiochemical relationship that approximately 0.005 g N is required for 1 g C stored in long-lived plant biomass (i.e., wood) and 0.067 g N for 1 g C sequestered in soil organic matter (SOM).  Thus, to realistically predict future C sequestration in terrestrial ecosystems, we have to understand how closely C and N processes are coupled in response to rising Ca.­


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Category: Abstracts/Impacts of High CO2 on Land and Ocean Ecosystems

  EFFECTS OF VERTICAL DIC DISTRIBUTION ON STORAGE EFFICIENCY OF DIRECT INJECTION OF CO2 INTO THE OCEAN  Popular
Description:

We estimated the effects of initial vertical distribution of dissolved inorganic carbon (DIC) on storage efficiency of direct injection of CO2 into the ocean. Our simulations shown that the storage efficiencies could be reduced up to 10% if a relative large droplet (30 mm in diameter) was injected at depth of 1500m. The storage efficiency of CO2 ocean sequestration is strongly related with not only injection depth but also the initial CO2 droplet diameter. With a given injection rate, the larger droplets injected will produce a dilute DIC plume and thus improve the acute biological impacts but a smaller storage effective due to droplet ascending.


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Category: Abstracts/Managing the Carbon Cycle

  THE AMAZON AND THE MODERN CARBON CYCLE  Popular
Description:

Is the massive Amazon forest a CO2 sink, a source or is it in equilibrium?  

There is a large uncertainty in carbon fluxes estimates for the tropics as a whole and in particular for the Amazon region in South America, bringing the attention to the lack of information to call the region a carbon source or sink. The production of scientific consistent and long term data series for the region is a process that has to advance step by step.


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  THE AGE OF CARBON RESPIRED FROM TERRESTRIAL ECOSYSTEMS  Popular
Description:

Carbon enters ecosystems through a single process, photosynthesis, and nearly all is returned to the atmosphere through respiration, some 50-80% of which occurs below-ground. Soil (belowground) respiration integrates CO2 derived from C that has resided in the ecosystem for periods of differing duration, ranging from relatively recent photosynthetic products that fuel root metabolism, to CO2 derived from decomposition of plant and soil organic matter that may be decades to centuries old.  A comparison of the radiocarbon content of CO2 respired by roots, microbes, and soils with the record of radiocarbon in atmospheric CO2 allows direct estimation of the mean age of C being respired [Trumbore 2000; Wang et al. 2000, Cisneros Dozal et al. 2005; Borken et al. 2005]. 


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Category: Abstracts/Land Use and the Terrestrial Carbon Cycle

  AN EMPIRICAL ESTIMATE OF THE SOUTHERN OCEAN AIR-SEA CO2 FLUX  Popular
Description:

A discrepancy exists between current estimates of the Southern Ocean air-sea flux of CO2.  The most recent estimate using a combination of direct and climatologically-derived pCO2 measurements [Takahashi et al., 2002] (herein referred to as T02) suggests a Southern Ocean CO2 sink that is nearly two times greater that that suggested from general circulation models, atmospheric inverse models [Gurney et al., 2002] and oceanic inverse models [Gloor et al., 2003]. Here we employ an independent method to estimate the Southern ocean air-sea flux of CO2.  Our method exploits all available surface measurements for Dissolved Inorganic Carbon (DIC) and total alkalinity (ALK) from 1986 to 1996. We show that surface age-normalized DIC can be predicted to within ~8mmol/kg and ~10mmol/kg for ALK using standard hydrographic properties, independent of season.  The predictive equations are used in conjunction with World Ocean Atlas (2001) climatologies to estimate an annual cycle of DIC and ALK, while the pCO2 distribution is calculated using standard carbonate chemistry.  For consistency we use the same gas transfer relationship and wind product from Takahashi et al, [2002] however, we include the effects of sea-ice. We estimate a Southern Ocean CO2 sink (>40°S) of -0.19±0.26 Pg C for 1995. Our estimates are smaller than those estimated by Takahashi et al, [2002], but consistent with atmospheric / oceanic inverse methods, general circulation models and provides further evidence that the Southern Ocean CO2 sink in relation to its oceanic surface area, is moderate on a global scale.


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  A DIRECT CARBON BUDGETING APPROACH TO STUDY CO2 SOURCES AND SINKS  Popular
Description:

For the purpose of exploiting upcoming measurements of atmospheric CO2 vertical profiles by aircrafts and continuous CO2 data recorded along tall towers as part of the North American Carbon Plan (NACP), a direct carbon budgeting approach is being developed.


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  SIGNALS OF PHOTOSYNTHESIS AND RESPIRATION AT BOREAL FORESTS IN RESPONSE TO ENVIRONMENT ...  Popular
Description:

The isotopic composition of the ecosystem respiration (d13CER) and the isotopic discrimination of the ecosystem (DEco) were retrieved from intensive campaigns (1998 to 2000) and from weekly diurnal sampling (2003) at a boreal forest site (Fraserdale, Canada, 49°53'N, 81°34'W). The results show that d13CER was less sensitive to temperature (T) variation compared with DEco, suggesting that the photosynthesis CO2 flux was likely more sensitive to temperature than the ecosystem respiration CO2 flux during the same period of time at the study site.


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Category: Abstracts/Land Use and the Terrestrial Carbon Cycle

  THE UNDERPINNINGS OF LAND-USE HISTORY: THREE CENTURIES OF GLOBAL GRIDDED LAND-USE ...  Popular
Description:
To accurately assess the impacts of human land-use on the Earth System, information is needed on the current and historical patterns of land-use activities. Previous global studies have focused on developing reconstructions of the spatial patterns of agriculture. Here, we provide the first global gridded estimates of the underlying land conversions (land-use transitions), wood harvesting, and resulting secondary lands annually, for the period 1700-2000. For input, we used two existing datasets of global gridded land-use history—HYDE [Klein Goldewijk 2001] and SAGE [Ramankutty & Foley 1999], a new reconstruction of national wood harvest that we spatially disaggregated to a global gridded product, and model estimates of the spatial distribution of plant carbon density and its recovery. Since these do not fully constrain the problem, we added assumptions related to four additional factors: the residence time of agricultural land, the inclusiveness of wood harvest statistics, the priority for land conversion and logging (e.g. primary- or secondary-land), and the spatial pattern of wood harvest within countries. In order to estimate uncertainty and characterize model sensitivity, a set of 216 alternative reconstructions was derived using different assumptions. We estimate that the accumulated global wood harvest 1700-2000 was approximately 112 Pg C including slash.

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Category: Abstracts/Land Use and the Terrestrial Carbon Cycle

  SIMULATING THE GLOBAL BOMB RADIOCARBON CYCLE: CLOSING THE BUDGET  Popular
Description:

We estimated the production of bomb radiocarbon using available information on atmospheric nuclear bomb tests, the simple (radio-)carbon cycle model GRACE (Global RadioCarbon Exploration Model) and atmospheric observations as constraints. Subsequent forward simulations of the bomb radiocarbon inventory in the different carbon reservoirs turned out to be in very good agreement with recent observation-based estimates, therewith for the very first time allowing to close the global bomb radiocarbon budget. Besides confirming original stratospheric bomb 14C data published in the reports of the Health and Safety Laboratories [Telegadas, 1971, and references therein], our results confirm recent observation-based ocean bomb radiocarbon inventory estimates for the time of GEOSECS (1970s) and WOCE (1990s) from Peacock [2004] and Key et al. [2004], but refute the GEOSECS ocean inventory estimates from Broecker et al. [1985, 1995].


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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  APPARENT TRENDS IN PHOTOSYNTHETIC CAPACITY OF MONSOON ASIA FROM 1982 TO 2002  Popular
Description: The rapid economic growth of Monsoon Asia raises concerns about the future of carbon stored in the terrestrial ecosystems of the region, especially in connection with climate change [Tian et al., 2003; Canadell et al., 2002; Oikawa and Ito, 2001; Esser, 1995]. The regional carbon budget for 1980s suggests that Monsoon Asia as a whole acted as source [Tian et al., 2003], although some parts of the region acted as sink. Here we provide some evidence from satellite data that photosynthetic capacity of the region changed in the manner that suggests similar conclusion. Comparing the period 1982-1992 and the period 1992-2002, we found that the photosynthetic capacity of the territory generally decreased in the forest zone and increased in the non-forest zone of the region.
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  ESTIMATING LANDSCAPE-LEVEL CARBON FLUXES FROM TOWER CO2 MIXING RATIO DATA  Popular
Description:

Variations of the CO2 mixing ratio in the atmosphere near the surface result from several processes, including photosynthesis and respiration of the underlying ecosystems, vertical mixing near the surface and in the planetary boundary layer (PBL), and entrainment of air above the PBL. We developed a novel approach for isolating ecosystem metabolism signals at the landscape scale (102-104 km2) in an hourly CO2 record using a vertical diffusion scheme coupled with an ecosystem model.


Filesize: 33.38 Kb
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Category: Abstracts/Land Use and the Terrestrial Carbon Cycle

  IN AND OUT OF AFRICA: ESTIMATING THE CARBON EXCHANGE OF A CONTINENT  Popular
Description:

Understanding the diverse elements of the global carbon cycle has been the focus of much recent research [Prentice et al. 2001, Schimel et al. 2001, Gurney et al. 2002, House et al. 2003]; research that is vital to our understanding of the missing sink, future atmospheric carbon dioxide concentrations, and future climate [Fan et al. 1998, Houghton et al. 1998]. Much research has concentrated on carbon dynamics of the large ocean basins [Lee et al. 1998, Le Quéré et al. 2003] and terrestrial exchange in North America and Eurasia [Pacala et al. 2000, Schimel et al. 2000]. Despite representing 20% of the global land mass, Africa has thus far been largely neglected in these studies. We will examine current understanding of carbon stocks and fluxes within Africa and discuss how uncertainty in global carbon dynamics arises in part from uncertainty in the African components. We outline areas where new measurements and research in Africa can contribute to understanding at both continental and global scales.


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  NEW VIEWS OF THE OCEANIC CARBON CYCLE FROM AUTONOMOUS EXPLORERS  Popular
Description:
A new paradigm for ocean carbon observations is emerging with the rapid advances in autonomous measurements of carbon systems with the success of robotic ocean profiling Carbon Explorers, autonomous sensors for particulate organic and inorganic carbon (POC and PIC), and new instruments which will measure year-long high frequency records of POC and PIC sedimentation in the very observation-poor but biologically-active upper kilometers of the ocean. The new observing capability described here is critical for improved prediction of the substantial biotic carbon flows in the ocean. There are excellent prospects for an enhanced ocean carbon observing system fully capable of autonomous real time monitoring, measurement, and verification of ocean carbon sequestration.

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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  THE EXPRESSION OF BIOSPHERE RESPONSE TO LIGHT LEVEL CHANGES ON 18O OF ATMOSPHERIC CO2  Popular
Description:

Observations suggest the global reflectivity of Earth changed during recent decades. Although there is some ambiguity surrounding these findings, it is clear that, should there be changes in clouds or scattering aerosols, a change in the total solar radiation received at the surface and the fraction of diffuse light could result. Intriguingly, the d18O of CO2 time series measured at Mauna Loa shows variability during the 1990s that does not match secular trends in CO2 concentration or d13C. While a decrease in total solar radiation alone would reduce biospheric productivity, an increase in diffuse light can increase productivity, as has been argued for the period following the eruption of Pinatubo. Moreover, since the changes in radiation affect the surface latent energy exchange, the isotopic composition of terrestrial water with which CO2 interacts (specifically leaf and soil water) will be modified and can thus drive a change in isotopic fluxes.


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Category: Abstracts/Carbon Cycle Response to Environmental Change

  LONG-TERM OBSERVATION OF CO2 CONCENTRATION AND ITS ISOTOPE RATIO OVER THE WESTERN PACIFIC  Popular
Description:
Air was collected systematically from 1995 to 2005 over the Pacific from 30S to 55N in latitude by ships-of-opportunity to monitor global trend of CO2 concentration and its variation in the atmosphere.  The monitoring results showed that three El Niño events during 10 years mostly affected regional and temporal variation of CO2 growth rate and its budget. Variation of carbon isotope ratio showed that the CO2 flux from terrestrial biosphere seemed to rapidly increase at that time, correlated with global temperature anomaly. Oxygen isotope ratio had increasing trend in this period, similar to the variation of temperature. Atmospheric 14CO2 variation also seemed to be influenced by El Niño event.   

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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  UNRAVELING THE DECLINE IN HIGH-LATITUDE SURFACE OCEAN CARBONATE  Popular
Description:
For perhaps 25 million years, surface waters throughout the ocean have remained saturated with respect to calcium carbonate (CaCO3).  Yet increasing atmospheric CO2 reduces ocean pH and carbonate ion concentration [CO32-] and thus the level of saturation.  Despite this acidification, it has been estimated that all surface waters will remain saturated for centuries. However, marine calcifiers are still expected to suffer reductions in the rate at which they form their exoskeletons out of CaCO3. Here we show with ocean data and models that the anthropogenic acidification will actually cause some surface waters to become undersaturated within decades, thus exacerbating the problem for marine calcifiers [Orr et al., 2005]. For instance, by 2050 when atmospheric CO2 reaches 550 ppmv under the IS92a business-as-usual scenario, Southern Ocean surface waters begin to become undersaturated with respect to aragonite, a metastable form of CaCO3. By 2100 as atmospheric CO2 reaches 788 ppmv under the same scenario, undersaturation extends throughout the entire Southern Ocean (all ocean south of 60°S) and into the surbarctic Pacific.

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Category: Abstracts/Impacts of High CO2 on Land and Ocean Ecosystems

  CO2 UPTAKE OF THE BIOSPHERE: FEEDBACKS BETWEEN THE CARBON CYCLE AND CLIMATE CHANGE USING A ...  Popular
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%.


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Category: Abstracts/Carbon Cycle Response to Environmental Change

  VARIABILITY OF OCEAN CO2 PARTIAL PRESSURE AND AIR-SEA CO2 FLUXES IN THE SUBANTARCTIC ZONE ...  Popular
Description:

Seven CARIOCA lagrangian buoys drifted in the Subantarctic Zone, SAZ, of the Indian and Pacific Ocean between 2001 and 2005. Measurements indicate that pCO2 in sea water is undersaturated with respect to the atmospheric value and consequently the subantartic zone of the Southern Ocean acts as a sink for atmospheric CO2 during all seasons. Large observed pCO2 variability is associated with mixing close to the subantarctic front, with biological activity and local warming. These variabilities are higher than the seasonal cycle in the studied areas.


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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  EVALUATION OF CO AND SF6 AS QUANTITATIVE TRACERS FOR FOSSIL FUEL CO2: THE MODELLERS VIEW  Popular
Description:

Simulations with a regional transport model are evaluated in order to determine to which extend the indirect fossil fuel combustion tracer CO or the purely anthropogenic tracer SF6 can be used to retrieve the contribution of fossil fuel emissions in the atmospheric CO2 signal.


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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  METRICS TO ASSESS THE MITIGATION OF GLOBAL WARMING BY CARBON CAPTURE AND STORAGE  Popular
Description:

Different metrics to assess mitigation of global warming by carbon capture and storage are discussed. The climatic impact of capturing 30% of the anthropogenic carbon emission and its storage in the ocean or in a geological reservoir are evaluated for different stabilization scenarios using a reduced-form carbon cycle-climate model. The accumulated Global Warming Avoided (GWA) remains, after a ramp-up during the first ~50 years, in the range of 15 to 30% over the next millennium for deep ocean injection and for geological storage with annual leakage rates of up to about 0.001. For longer time scales, the GWA may approach zero or become negative for storage in a reservoir with even small leakage rates, accounting for the CO2 associated with the energy penalty for carbon capture. For an annual leakage rate of 0.01, surface air temperature becomes higher than in the absence of storage after three centuries only.


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Category: Abstracts/Managing the Carbon Cycle

  STABILIZING ATMOSPHERIC CO2 CONCENTRATIONS: CAN GEOLOGIC STORAGE HELP?  Popular
Description:

One option for reducing emissions of CO2 to the atmosphere as a result of combustion of fossil fuels is to capture CO2 and inject it into porous subsurface geologic formations.  High pressure CO2 has been used for the last three decades as an agent for enhanced oil recovery, and hence considerable experience in the technical issues associated with predicting the movement of CO2 in the subsurface has been accumulated.  Significant additional quantities of CO2 could be stored in depleted oil and gas reservoirs if CO2 were available at low cost.  These formations are appealing as storage sites because the subsurface is known to have a trap and seal that contains the buoyant oil or gas.


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  RADIATIVE FORCING FROM A BOREAL FOREST FIRE  Popular
Description:

We report measurements of energy and carbon fluxes from a boreal forest fire chronosequence. Taking into account greenhouse gas emissions and post-fire changes in the surface radiation budget, a boreal forest fire in interior Alaska caused the climate to cool. This result suggests that management of forests in northern countries to preserve carbon sinks may have the opposite effect on climate as that intended.


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Category: Abstracts/Land Use and the Terrestrial Carbon Cycle

  ATMOSPHERIC CO2, CARBON ISOTOPES, THE SUN AND CLIMATE CHANGE OVER THE LAST MILLENNIUM  Popular
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.

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  INFORMATION NEEDS FOR ADAPTIVE MANAGEMENT OF THE CARBON CYCLE: FROM REGIONAL CARBON BUDGETS TO A HO  Popular
Description:

During the past two centuries, human activities have undertaken a vast earth system modification of the carbon (C) cycle. Early during this period, humans have converted native vegetation to croplands. Such land use changes have mobilized massive amounts of C. During the past century, increased use of fossil energy sources, primarily coal and oil, have resulted in the rapid expansion of industry and technology throughout the world.  The resulting impact has been to greatly increase the atmospheric concentration of C dioxide (CO2) to where in 2004 it is estimated to 375ppm, nearly 100 pm greater than the pre-industrial levels. Fossil fuel emissions and land use change have moved the global C cycle out of balance.


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  IMPORTANCE OF RECENT SHIFTS IN SOIL THERMAL DYNAMICS ON GROWING SEASON LENGTH, PRODUCTIVITY, ...  Popular
Description:

In terrestrial high-latitude regions, observations indicate recent changes in snow cover, permafrost, and soil freeze-thaw transitions due to climate change.  These modifications may result in temporal shifts in the growing season and the associated rates of terrestrial productivity. Changes in productivity will influence the ability of these ecosystems to sequester atmospheric CO2. We use the Terrestrial Ecosystem Model (TEM), which simulates the soil thermal regime, in addition to terrestrial carbon, nitrogen and water dynamics, to explore these issues over the years 1960-2100 in extratropical regions (30˚-90˚ N).  Our results reveal noteworthy changes in snow, permafrost, growing season length, productivity, and net carbon uptake, indicating that prediction of terrestrial carbon dynamics from one decade to the next will require that large-scale models adequately take into account the corresponding changes in soil thermal regimes.


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Category: Abstracts/Land Use and the Terrestrial Carbon Cycle

  MODELING THE HISTORY OF TERRESTRIAL CARBON SOURCES AND SINKS  Popular
Description:

We report modeling experiments with a new global dynamic land model (LM3V), to reconstruct possible causes of the terrestrial carbon sources and sinks over the past century.  The model is unique, in that it is capable of representing the global history of land use, including the management of secondary forests (those forests that have re-grown at least once following harvest). Several published carbon inventories attribute the majority of the carbon sink caused by land use in the temperate zone to the management of secondary forests.


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  CH4 TOTAL COLUMNS FROM SCIAMACHY - COMPARISON WITH ATMOSPHERIC MODELS  Popular
Description:

A detailed comparison of global atmospheric CH4 retrievals from the space-borne spectrometer SCIAMACHY onboard the European environmental satellite ENVISAT is presented with the atmospheric transport models TM4 and TM5.


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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  WHAT CAN WE LEARN FROM INTENSIVE ATMOSPHERIC SAMPLING FIELD PROGRAMS?  Popular
Description:

Intensive atmospheric sampling field programs are envisioned as a key component of integrated research programs such as the North American Carbon Program (NACP) [Sarmiento and Wofsy, 1999; Wofsy and Harriss, 2002].  The intensive sampling provides unique information about the spatial distribution of CO2 as well as imposes tight constraints on regional budgets that are difficult to obtain from other means. We summarize what we have learned from the numerous COBRA (CO2 Budget and Rectification Airborne study) experiments [Gerbig et al., 2003a] that have taken place in 2000, 2003, and 2004.  We present the observed spatial variability of CO2 [Gerbig et al., 2003a; Lin et al., 2004a] and regional budgets derived from regional air parcel-following experiments [Lin et al., 2004b].  These observations are also used as a critical testbed for modeling frameworks [Gerbig et al., 2003b]. We draw conclusions about ways to maximize the value of intensive atmospheric sampling experiments and the role that such experiments should play within programs like the NACP.


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Category: Abstracts/The Fate of Fossil-Fuel Carbon Emissions

  THE ROLE OF WATER RELATIONS IN DRIVING GRASSLAND ECOSYSTEM RESPONSES TO RISING ATMOSPHERIC CO2  Popular
Description:

While rising atmospheric carbon dioxide (CO2) is known to be an important contributor to radiative forcing of Earth’s climate, more direct effects of this gas on photosynthesis and plant water relations have been underway for more than a century, and likely have already contributed to important ecosystem changes. Experiments conducted in native and semi-natural grasslands in which ambient CO2 concentrations have been artificially increased have shown that increasing CO2 often increases photosynthesis, results in higher soil and plant water content, and can enhance plant water use efficiency, the ratio of plant biomass produced per unit water transpired back to the atmosphere. While these responses may appear beneficial, there are long-term responses of ecosystems to CO2 such as alterations in the cycling and availability of critical plant nutrients like nitrogen (N) which are likely to change over time and may significantly alter CO2-enhanced production and forage quality. Herein we discuss these phenomena and speculate on the implications and the importance for world grasslands.


Filesize: 31.72 Kb
Added on: 02-Aug-2005 Downloads: 122
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Category: Abstracts/Impacts of High CO2 on Land and Ocean Ecosystems


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     Talk History
Friday, September 30
· Discussion Panel
· Nitrogen Regulation of Carbon Sequestration in Terrestrial Ecosystems in Respons
· The Role of Water Relations in Driving Grassland Ecosystem Responses to Rising A
· Unraveling the Decline in High-latitude Surface Ocean Carbonate
Thursday, September 29
· Hazards of Temperature on Food Availability in Changing Environments (HOT-FACE)
· The Amazon and the Modern Carbon Cycle
· New Coupled Climate-carbon Simulations from the IPSL Model
· The Changing Carbon Cycle
· What are the Most Important Factors for Climate-carbon Cycle Coupling?
· CO2 Uptake of the Marine Biosphere
· European-wide Reduction in Primary Productivity Caused by the Heat and Drought i
· Persistence of Nitrogen Limitation over Terrestrial Carbon Uptake
· Atmospheric CO2, Carbon Isotopes, the Sun, and Climate Change over the Last Mill
· Proposing a Mechanistic Understanding of Atmospheric CO2 During the late Pleist
· Greenhouse Gas (CO2, CH4) and Climate Evolution since 650 kyrs Deduced from Anta
Wednesday, September 28
· (In and) Out of Africa: Estimating the Carbon Exchange of a Continent
· Recent Shifts in Soil Dynamics on Growing Season Length, Productivity, and...
· Interannual Variability in the Carbon Exchange Using an Ecosystem-fire Model
· Photosynthesis and Respiration in Forests in Response to Environmental Changes
· Seasonal and Interannual Variability in Net Ecosystem CO2 Exchange in Japan
· Estimating Landscape-level Carbon Fluxes from Tower CO2 Mixing Ratio Measurement
· Monitoring Effects in Climate and Fire Regime on Net Ecosystem Production
· Radiative Forcing from a Boreal Forest Fire
· The Influence of Soil and Water Management on Carbon Erosion and Burial
· Spatial and Temporal Patterns of CO2, CH4, and N2O Fluxes in Ecosystems
· Modeling the History of Terrestrial Carbon Sources and Sinks
· The Age of Carbon Respired from Terrestrial Ecosystems
· Discussion Panel
· The Underpinnings of Land Use History
Tuesday, September 27
· Regional CO2 Fluxes for North America Estimated from NOAA/CMDL Observatories

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The 7th International CO2 Conference

The Omni Interlocken Resort
September 25th - 30th
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