U41B-0006
A Description of the Global, Monthly, Fossil-Fuel Carbon Dioxide Time Series Based on National Estimates
Increased analysis has led to the realization that a detailed, mechanistic understanding of the global carbon
cycle needs more detailed description in multiple dimensions (e.g., finer spatial scales, finer temporal scales,
more accurate and precise mass fluxes, isotopic descriptions, ...). Carbon dioxide emissions from fossil fuels
are central to the increased interest in the carbon cycle and are critical toward a more detailed
understanding of other fluxes in the carbon cycle. This presentation describes recent efforts that have
produced a more detailed description of fossil-fuel-derived carbon dioxide emissions at finer spatial and
temporal scales. The efforts describe, explicitly, a majority of the total fossil-fuel-derived carbon dioxide
emission flux and, via extrapolation, the entire fossil-fuel-derived carbon dioxide emission flux. The
extrapolation is based on selecting representative monthly descriptions from among the 21 countries studied
in detail to represent the monthly distribution of emissions for the remaining countries of the world. These
selections are based on similarities in economy and climate. Emission fluxes will be characterized in both
mass and stable carbon isotope space. These results, when combined with global carbon cycle models,
should lead to a better understanding of the global carbon cycle.
Monte Carlo simulations will be applied to the individual, national, monthly time series to generate possible,
future, monthly time series. The domain of inputs to the Monte Carlo simulation will be the actual monthly
time series generated for each of the 21 countries examined in detail. For most of these countries, monthly
time series that span multiple years were constructed, although some of the data series are quite short. In
addition, each of these 21 countries has individual time series for gas, liquid and solid fuels; each of which
will be subjected to Monte Carlo analysis. The national results will then be aggregated into a global, monthly
time series. The resultant global time series of emissions estimates will cover an extended time period even
though the individual, national data sets are of varying length and not necessarily synchronous. The results
of the Monte Carlo analysis should be useful to the larger community for representing the historic or
estimating the future patterns of fossil-fuel use and their resulting carbon dioxide emissions.
Past analyses of the monthly time series for individual countries have shown significant differences in the
month-to-month emissions as opposed to a 1/12 distribution (a typical default distribution pattern obtained by
dividing annual emissions equally among the 12 months). The global monthly time series shows statistically
significant differences from the 1/12 distribution.
Past analyses of the stable carbon isotope signature (del 13C) of the monthly time series for individual
countries have shown significant changes in the month to month signatures. This is due to the distinct
isotopic signatures of solid, liquid and gaseous fuels and the monthly variations in the mass of each fuel
consumed. These signatures will now be applied to the global, monthly time series and similar, significant
changes are expected to be revealed in the month to month signatures.
http://cdiac.esd.ornl.gov/
U41B-0007
Multi-instrumental Analysis and Assimilation of Carbon Monoxide Data
Challenges and perspectives of data fusion studies with the space-borne CO retrievals in the troposphere and lower stratosphere are discussed in this paper. The combined chemical data assimilation and inverse modeling scheme that analyze the MOPITT CO retrievals with assumption of the bias-free data are outlined and year-to-year variations of analyzed regional CO concentrations and optimized surface CO emissions are presented. Uncertainties of CO and quantification of the NH boreal fire emissions (May-September) in chemical transport model forecasts and analysis are examined employing data from three thermal infrared CO sensors (AIRS, TES, MOPITT). Paper evaluates and discusses differences between the multi- instrumental CO products characterized by resolution kernels and a priori. For chemical data assimilation studies the perspectives to combine the multi-sensor information from the CO sensitive radiances (microwave, MLS, near-infrared, SCIAMACHY, and thermal channels, MOPITT, AIRS, TES) to optimize the partial CO sub-columns between the surface and the tropopause are considered. The possible data quality controls, model and data bias correction schemes, along with scale-dependent retrieval/assimilation algorithms are proposed to unify analysis of the multi-sensor CO measurements (radiances and/or retrievals) in the single data assimilation (CO concentrations) and inverse modeling (CO sources) system.
U41B-0008
Modeling Seasonal to Decadal Variability in Global Ocean Carbon
A 3D ocean model is used to estimate seasonal, interannual and decadal variability of carbon in the global oceans. The model, called the NASA Ocean Biogeochemical Model (NOBM) contains an explicit prognostic ecosystem model, that is coupled with a carbon model, including dissolved organic carbon, dissolved inorganic carbon, and pCO2. We track the variability of carbon and ecosystem components from 1997 through 2005. This period includes several major and minor ENSO events. Seasonal variability of ecosystem and carbon components is pronounced, as is interannual variability of ecosystem and particularly primary production. Interannual carbon variability is less pronounced. Assimilation of satellite ocean chlorophyll into the model provides substantially improved representation of simulated chlorophyll, but carbon components are less affected. A multi-variate approach to nutrient further improves them, but again changes in carbon components are modest. Statistical comparisons with in situ and satellite data are encouraging.
U41B-0009
Methane on the Move: natural greenhouse gas emissions over geological time
The mass of organic carbon in sedimentary basins amounts to a staggering 1016 tons, dwarfing the mass contained in coal, oil, gas and all living systems by ten thousand-fold. The changing fate of this giant mass during subsidence and uplift, via chemical, physical and biological processes, is known to ultimately control fossil energy resource occurrence worldwide. But what has been overlooked and/or ignored until now is its enormous capacity for driving global climate: only a tiny degree of leakage, particularly when focussed through the clathrate cycle, can result in high greenhouse gas emissions. Understanding the workings of sedimentary basins in time and space is fundamental to gaining insights into Earth's climate. Here we shall present an integrated framework based on petroleum system modelling that will ultimately quantify methane migration and emission from one hundred of the world's most prolific petroliferous sedimentary basins. Timing of hydrocarbon generation from globally occurring prolific Jurassic and Cretaceous source rocks is regarded to be the key factor in quantifying gas release. Combined thermogenic and biogenic methane fluxes are the base for prediction of gas hydrate formation through time and space, by application of kinetics developed in the laboratory to geological scenarios. Results are calibrated in basin scale by emission structure evaluation (mud volcanoes, carbonate mounds, pockmarks) and on a global scale by proxy data from sedimentary archives and local atmospheric data. Identifying potential climate feedback processes over a geological time line that spans the Cenozoic requires a comprehensive understanding of source-sink relationships by coupling these feedstock fluxes with gas hydrate stability considerations, deep biosphere activity, ocean and atmosphere modelling
U41B-0010
On the Vertical Gradient in CO2
Attempts to constrain surface fluxes of carbon from atmospheric measurements of carbon dioxide have primarily focused on surface boundary layer measurements, because information about surface fluxes is least diluted close to the locations where the fluxes occur. However, errors in model ventilation of air in the vertical can be misinterpreted as local surface fluxes. Satellites which measure column integrated CO2 are expected to represent a major advance in part because they observe the entire atmospheric column. Recent work has highlighted the fact that vertical gradients in carbon concentrations can give us information about where vertical mixing errors are likely to be misinterpreted as local surface fluxes, but passive tracer evidence suggests that models that capture vertical profiles on the ocean do poorly on the land (and vice versa), suggesting that the problem of correctly treating vertical mixing in inverse studies is more fundamental than picking the "best" model. We consider observations of the vertical gradient in CO2 from aircrafts and from a comparison of satellites that observe in the near infrared (which observe the column integrated CO2 field) and the thermal infrared (which observe the upper troposphere). We evaluate the feasibility of using these satellites for determining the vertical gradient in CO2. We examine how observations of the vertical gradient of CO2 allow us to differentiate the imprint of vertical mixing and the imprint in surface fluxes on the observed field of atmospheric CO2.
U41B-0011
Carbon Cycle Simulations for the East Coast Continental Shelf of North America
We are presenting a nested physical-biogeochemical ocean model for the North American East Coast continental shelf and adjacent deep ocean that includes organic and inorganic carbon species and describes physical and biogeochemical processes driving air-sea exchange of CO2. While occupying only 28% of the global ocean area, continental margins are of disproportionate importance for ocean carbon cycling with elevated levels of primary and secondary production, significant benthic-pelagic coupling and much larger amplitude air-sea CO2 fluxes than found in open ocean waters. As the interface between land and ocean, these regions are also expected to be more sensitive to the anticipated impacts of climate change. Yet, continental shelves are poorly represented in current global models, mostly due to numerical constraints that hinder the adequate resolution of relevant spatial and temporal scales. Our presentation is aimed at illustrating (1) the importance of biogeochemical constraints on coastal carbon fluxes and their global relevance, (2) the challenges posed by temporal and spatial variability, and (3) the utility of nesting approaches for future inclusion of continental margin processes in global Earth System Models. Specifically, we are focusing on the biogeochemical constraints on carbon fluxes imposed by the nitrogen cycle and on interannual variability. Model simulations are critically evaluated in comparisons with available in situ and remote sensing data sets.
U41B-0012
Large-Scale Controls of Methanogenesis Inferred From Satellite Observations of Methane and Gravity
Wetlands are the single largest source of CH4 but the magnitude and temporal and spatial distributions of this source are poorly understood on continental scales. We isolated the wetland contribution to satellite observations of CH4 from SCIAMACHY over 2003-2005 using satellite observations of gravity anomalies from GRACE, a measure of water-table depth, and NCEP/NCAR surface temperature analyses. Tropical CH4 variations are largely determined by variations in water-table depth, where we find a concurrent decline in CH4 and water-table depth, suggesting that tropical wetlands have recently played a smaller role in determining the global CH4 budget. At higher latitudes, we find that CH4 variations are determined by variations in surface temperature. We find that the tropics represent 25% of the wetland source, with the remainder from the extra-tropics, 16% of which is from Arctic latitudes. We find that that the normalized distribution of CH4 emissions, inferred from our analysis, is in broad agreement with bottom-up emission estimates.
U41B-0013
Intra-annual Variability of the Carbon Cycle in the Drake Passage
The Southern Ocean plays a vital role in the global carbon cycle by acting as a major sink for anthropogenic CO2. It is very important to understand what controls surface ocean pCO2 in the Southern Ocean, as it governs the CO2 exchange with the atmosphere. We develop a high-resolution (1/6°) ocean biogeochemical model as a tool to better understand the mechanisms of the intra-annual variations in surface pCO2 in the Drake Passage. The physical circulation fields are from the Southern Ocean State Estimate, which is constrained by a suite of satellite and in-situ observations, and the biogeochemical processes are parameterized using an OCMIP-type model. The model is tested against in-situ pCO2 observations from 8 cruises in 2005/6. The analysis of model fields can offer an opportunity to quantify how much of the pCO2 variability is driven by biology, horizontal and vertical advection, and gas exchange. In particular, our analysis focuses on the role of mesoscale eddies which are explicitly represented in the high resolution model.
U41B-0014
Estimates of carbon sources and sinks using new NIES transport model
The NIES08, new version of the NIES transport model, has improved by increasing spatial resolution (1.25 deg × 1.25 deg) and more accurate advection (Van Leer, 1977) from former version (NIES99) with the spatial resolution of 2.5 deg × 2.5 deg and semi-Lagrangian advection. In this study, we estimate CO2 sources and sinks using NIES08, and study the influence of transport algorithms on inverse modeling by comparing NIES08 and other transport models. The NIES08 predicting stronger vertical mixing produces seasonal amplitudes which are closer to the observed seasonality. The interhemispheric difference (IHD) of surface mean CO2 concentration which is overestimated by NIES99 decreases in NIES08, and the IHD of NIES08 is lower as compared to average of transport models used in TransCom 3. The NIES08 estimates weaker northern land uptake (-1.3 Gt C year-1), which falls within standard deviation of the averaged flux of three models which estimate closest to the annual-mean vertical gradients of the atmospheric CO2 in results of Stephens et al. (2007). The northern land flux by NIES08 is estimated reasonably reflecting a seasonality and vertical gradient of CO2. In tropics, the NIES08 estimates strong land emission when compared with the difference between the northern land uptake and the tropical land emission in NIES99. There are still uncertainties because the tropical fluxes are less constrained by atmospheric CO2 measurements and because compensating variations in the tropical land fluxes are estimated in inversion.
U41B-0015
Emission Flux of CO2 Through an Active Fault Zone in SW Taiwan
CO2 is well-known as a greenhouse gas, which is identified as a species affecting the Earth climate. CO2 could account for more than 60 percent of all greenhouse gas generated globally. Although CO2 is very important to the climate system, its nature flux at fault zone was seldom quantified. Chunglun mud pool is located in the southwest Taiwan and is cut by the active Tsu-Ko Fault. The main component of its bubbling gas is CO2 (more than 75 percnet) with minor CH4 (10 percent). The CO2 is considered to the eruption products of Miocene magmatism in West Taiwan and might be stored in the reservoir and started degassing due to fault activity. A general survey of soil CO2 flux along the fault zone was conducted using the closed chamber method. Meanwhile, a continuous monitoring system was setup to record the gas flow at Chunglun mud pool, using a big funnel (1m x 1m) to cover the bubbling gas of the mud pool. The results show that the average CO2 flux from mud pool is ca. 0.2 t/m2/day and soil CO2 emission from fault zone is ca. 29 g/m2/day. The total CO2 emission flux and the mount of CO2 in the reservoir and the residual time in the reservoir will be discussed in present study.
U41B-0016
Assessing Error in Modelled Ocean Carbon Uptake Resulting From Uncertainty in Biogeochemical Parameters
Estimates of the air-sea CO2 flux produced by ocean biogeochemical models are uncertain due to poorly constrained model parameters. Here, we present the results of an analysis into the biochemical parameters that influence air-sea CO2 flux, and the error that results from uncertainties in these parameters in GCMs. A sensitivity analysis is performed on the Hadley centre Ocean Carbon Cycle (HadOCC) NPZD biogeochemical model used in the HadCM3 GCM. This uses a 1D test bed with forcing from different locations and identifies the parameters that control phytoplankton growth, formation of calcite and the sinking of organic matter to have greatest effect on the calculated air-sea CO2 flux. These parameters are tuned to data at sites with very different biochemical cycles and are then used to explore the resulting error in global ocean carbon fluxes within GCMs.
U41B-0017
The Influence of El Nino/Southern Oscillation and Volcanic Aerosols on Tropical Terrestrial Carbon Flux
The relationship between the El Nino/Southern Oscillation and the carbon cycle has been explored in analysis of atmospheric CO2, biogeochemical modeling studies and recently through inverse estimation. The influence of volcanic aerosols on the relationship has been noted as interrupting the strong correlation between ENSO and net carbon exchange. This paper is a first attempt at a systematic quantification of the relationship between ENSO, volcanic aerosols and net carbon exchange using the results of the TransCom inverse estimate intercomparison. A new index (ENSO-τa) is created by combining aerosol optical depth with ENSO and performing correlation analysis with the aggregated and regional terrestrial carbon flux estimates from the TransCom experiment. Northern Africa and Tropical Asia show statistically significant positive lagged correlations (r=0.61, p<0.02; r=0.55, p<0.05, respectively) with the ENSO-τa index (flux follows ENSO-τa at 1 month and 4 months, respectively) and these relationships are dominated by the El Nino phase. Northern Africa and Tropical Asia respond most strongly to Jan-Mar ENSO-τa anomalies while Tropical Asia also responds to June-Aug ENSO- τa anomalies. A significant relationship is also found with the Temperate Asia region and this relationship is stronger without inclusion of the volcanic aerosol optical depth and is related to the La Nina phase. The relationship suggests that anomalies of 0.37 GtC/year result from a typical (one standard deviation) El Nino event across the tropical land regions and anomalies of 0.17 due to La Nina in the Temperate Asia region.The relationship between the El Nino/Southern Oscillation and the carbon cycle has been explored in analysis of atmospheric CO2, biogeochemical modeling studies and recently through inverse estimation. The influence of volcanic aerosols on the relationship has been noted as interrupting the strong correlation between ENSO and net carbon exchange. This paper is a first attempt at a systematic quantification of the relationship between ENSO, volcanic aerosols and net carbon exchange using the results of the TransCom inverse estimate intercomparison. A new index (ENSO-τa) is created by combining aerosol optical depth with ENSO and performing correlation analysis with the aggregated and regional terrestrial carbon flux estimates from the TransCom experiment. Northern Africa and Tropical Asia show statistically significant positive lagged correlations (r=0.61, p<0.02; r=0.55, p<0.05, respectively) with the ENSO-τa index (flux follows ENSO-τa at 1 month and 4 months, respectively) and these relationships are dominated by the El Nino phase. Northern Africa and Tropical Asia respond most strongly to Jan-Mar ENSO-τa anomalies while Tropical Asia also responds to June-Aug ENSO- τa anomalies. A significant relationship is also found with the Temperate Asia region and this relationship is stronger without inclusion of the volcanic aerosol optical depth and is related to the La Nina phase. The relationship suggests that anomalies of 0.37 GtC/year result from a typical (one standard deviation) El Nino event across the tropical land regions and anomalies of 0.17 due to La Nina in the Temperate Asia region.
U41B-0018
Contact Metamorphism and the Global Carbon Cycle
The understanding of past global warming events may help predict the consequences of today's anthropogenic climate change. In this contribution, we show that the 183 Ma old Karoo Large Igneous Province vented greenhouse gases into the atmosphere at rates and with a carbon isotopic compositions similar to today's emissions. The emplacement of magmatic intrusions in sediments with abundant organic carbon is the mechanism of greenhouse gases production, and involves the sudden exposure of organic matter to temperatures as high as 600°C in metamorphic contact aureoles. The organic-rich Ecca Group forms the base of the Karoo sedimentary succession and contains thousands of degassing pipe structures rooted in contact aureoles around sill intrusions. Numerical and analogue modelling shows that these piercement structures form during violent eruptions releasing the overpressure. In the present study, we focus on the devolatilization processes in a contact aureole by evaluating the effects of thermal alteration on the carbon isotopic composition of organic-rich sediments. We compared thermally affected and unaffected borehole sections intersecting organic-rich black shale from South Africa. A series of bulk-geochemical analyses (total organic carbon, organic maturity and stable carbon isotopes) were carried out on both borehole sections. The results show that the aureole thickness is best defined by organic matter maturity. With decreasing distance from the sill intrusion contacts, the thermal maturity increases, the total organic carbon decreases and the carbon isotopic composition measured on bitumen is enriched in 13C. These results demonstrate that the 2.8t/m2 of organic carbon escapes the contact aureole during devolatilization processes involving the generation of light carbon gases. The calculated isotopic composition of the carbon released is similar whether using the batch devolatilization or the Rayleigh distillation model, and ranges from the background values to 1-2 permil lighter values with decreasing distance from the contact. The extrapolation of our results to the portion of the sedimentary basin intruded by magma suggests that contact metamorphism of organic-rich sediments, synchronous with the formation of the Karoo continental flood basalts, triggered massive release of isotopically light carbon gas to the atmosphere, thus perturbing the global carbon cycle at the beginning of the Toarcian. In conclusion, contact metamorphism and venting is an efficient way of transferring carbon from the sedimentary to atmospheric reservoirs.
U41B-0019
Global Carbon Cycle Inside GISS ModelE GCM: Results of Equilibrium and Transient Simulations.
We present simulation results for a fully coupled carbon cycle inside the ModelE General Circulation Model (GCM) developed at the NASA Goddard Institute for Space Studies (GISS). The current implementation utilizes the GISS dynamical atmospheric core coupled to the HYCOM ocean model. The atmospheric core uses a Quadratic Upstream Scheme (QUS) for advection of gas tracers, while HYCOM has its own built-in algorithm for advection of ocean tracers. The land surface part of the model consists of the GISS ground hydrology model coupled to the Ent dynamic global terrestrial ecosystem model. The ocean biogeochemistry model based on Watson Gregg's model was implemented inside the HYCOM ocean model. Together with ocean tracer transport, it describes all aspects of the carbon cycle inside the ocean and provides CO2 fluxes for exchange with the atmosphere. CO2 fluxes from land vegetation are provided by the Ent model, which employs well-known photosynthesis relationships of Farquhar, von Caemmerer, and Berry and stomatal conductance of Ball and Berry. Soil CO2 fluxes are also computed by the Ent model according to the CASA soil biogeochemistry model. We present results of fully coupled GCM simulations as well as off-line tests for different components. For GCM simulations, we present results of both equilibrium and transient runs and discuss implications of biases in GCM-predicted climate for accurate modeling of the carbon cycle.