Showing papers on "Carbon dioxide in Earth's atmosphere published in 2002"

Dinitrogen fixation in the world's oceans

Abstract: The surface water of the marine environment has traditionally been viewed as a nitrogen (N) limited habitat, and this has guided the development of conceptual biogeochemical models focusing largely on the reservoir of nitrate as the critical source of N to sustain primary productivity. However, selected groups of Bacteria, including cyanobacteria, and Archaea can utilize dinitrogen (N2) as an alternative N source. In the marine environment, these microorganisms can have profound effects on net community production processes and can impact the coupling of C-N-P cycles as well as the net oceanic sequestration of atmospheric carbon dioxide. As one component of an integrated ‘Nitrogen Transport and Transformations’ project, we have begun to re-assess our understanding of (1) the biotic sources and rates of N2 fixation in the world’s oceans, (2) the major controls on rates of oceanic N2 fixation, (3) the significance of this N2 fixation for the global carbon cycle and (4) the role of human activities in the alteration of oceanic N2 fixation. Preliminary results indicate that rates of N2 fixation, especially in subtropical and tropical open ocean habitats, have a major role in the global marine N budget. Iron (Fe) bioavailability appears to be an important control and is, therefore, critical in extrapolation to global rates of N2 fixation. Anthropogenic perturbations may alter N2 fixation in coastal environments through habitat destruction and eutrophication, and open ocean N2 fixation may be enhanced by warming and increased stratification of the upper water column. Global anthropogenic and climatic changes may also affect N2 fixation rates, for example by altering dust inputs (i.e. Fe) or by expansion of subtropical boundaries. Some recent estimates of global ocean N2 fixation are in the range of 100−200 Tg N (1−2 × 1014 g N) yr −1, but have large uncertainties. These estimates are nearly an order of magnitude greater than historical, pre-1980 estimates, but approach modern estimates of oceanic denitrification.

Carbon emissions from tropical deforestation and regrowth based on satellite observations for the 1980s and 1990s.

Abstract: The increase of carbon dioxide in the atmosphere relative to emissions from fossil-fuel burning and land-use change indicates that terrestrial and marine environments are absorbing approximately one-half to three-quarters of the emitted carbon dioxide. Several lines of evidence indicate uptake of carbon dioxide in the terrestrial extratropical Northern Hemisphere including land-inventory data, atmospheric CO2 and O2 data, isotopic analyses, and ecosystem models (1–5). Regrowth on abandoned agricultural land, fire prevention, longer growing seasons, and fertilization by increased concentrations of carbon dioxide and nitrogen have been proposed as possible mechanisms responsible for the Northern Hemisphere uptake (6–8). Future atmospheric carbon-dioxide concentrations and consequent climate change depend to a large extent on the future course of the terrestrial uptake (9). If the underlying mechanisms are no longer able to sequester carbon at some point in the future, as for example would be the case once regrowing forests mature, a larger proportion of emitted carbon dioxide would remain in the atmosphere, and carbon-dioxide concentrations would increase at a greater rate for the same level of emissions. Atmospheric inversion studies, which calculate net sources and sinks of carbon dioxide from the spatial distribution of atmospheric concentrations, indicate a net land sink of 0.6–2.3 petagrams (Pg)⋅yr−1 in the extra tropics (6). In the tropics, inverse models are poorly constrained but indicate that the region, overall, is neutral or a small source of carbon to the atmosphere (10). Although inversion studies locate and quantify the net terrestrial sources or sinks, the attribution to mechanisms and their possible future trajectories depend on quantifying the gross sources and sinks. For a net sink, the mechanisms responsible for uptake of carbon dioxide must be powerful enough to offset the sources from fossil fuel and deforestation. The carbon dioxide emitted from fossil-fuel combustion is well quantified (11), but the emission from tropical land-use change is highly uncertain. Without more precise estimates of this source term, deciphering possible mechanisms sequestering the missing carbon remains problematic. The flux of carbon to the atmosphere from tropical land-use change is one of the largest uncertainties in the contemporary carbon budget (6, 12) because of the difficulties in quantifying deforestation and regrowth rates, initial biomass, and fate of carbon in areas where vegetation has been cleared. Estimates of carbon fluxes from tropical deforestation as reported by the Intergovernmental Panel on Climate Change (IPCC; ref. 12) from refs. 5 and 13 range from 0.6 to 2.5 Pg⋅yr−1 for the 1980s, based primarily on calculations using cropland statistics from the United Nations Food and Agriculture Organization (FAO) and deforestation rates from the FAO Forest Resource Assessment (FRA). The FRA information is obtained through national reporting supplemented by limited satellite analysis in the assessment for the 1990s (14–16). Participation of individual countries through national reporting is a strength from some perspectives, but it generates problems from varying definitions of forest cover among countries and time intervals (17). These problems are particularly acute in developing countries, where most tropical deforestation occurs. Comparisons of national statistics from the FRA with other country-level analyses suggest that the FRA overestimated changes in forest cover in some African countries (18), Bolivia (19), and other developing countries (20, 21). For the 1990–2000 interval, the FRA also conducted a remote-sensing survey, analyzing 10% of all tropical land area (15, 21). Forest area and deforestation rates from the FRA remote-sensing survey are generally lower than the FRA (15, 22) country reports for the 1990–2000 interval for Latin America and tropical Asia, although the differences are not statistically significant. For tropical Africa, the difference is very large (3 million ha/yr), suggesting exaggerated deforestation rates in the country data (15). For the 1980–1990 interval, on which the IPCC estimates of carbon fluxes from tropical deforestation are based, the country reports are the sole source of information for the FRA analysis. Satellite data offer the possibility of spatially and temporally consistent estimates of forest cover to complement national reports. Data acquired by the Landsat platform, with a pixel resolution of ≈30 m for the thematic mapper sensor and 60 m for the multispectral scanner sensor before the early 1980s, have provided estimates of deforestation rates for individual regions such as the Amazon basin (23). However, because of cloud coverage and limited acquisitions over the past several decades, it has not been possible to obtain comprehensive coverage for the entire tropics. Global data from the early 1980s to present acquired by the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer (AVHRR) provide daily coverage but at a coarse spatial resolution of 8 km (24). AVHRR data at the sensor resolution of ≈1 km are not available for the full time series with adequate spatial coverage. In this study we estimate changes in forest area by using an approach to estimate subpixel changes in tree cover within the coarse spatial resolution of the AVHRR data. This analysis thus provides a spatially explicit alternative to the FAO's nationally reported changes in forest area and an alternative estimate for carbon fluxes over the past two decades.

Foraminiferal Calcification Response to Glacial-Interglacial Changes in Atmospheric CO2

Abstract: A record of foraminiferal shell weight across glacial-interglacial Termination I shows a response related to seawater carbonate ion concentration and allows reconstruction of a record of carbon dioxide in surface seawater that matches the atmospheric record. The results support suggestions that higher atmospheric carbon dioxide directly affects marine calcification, an effect that may be of global importance to past and future changes in atmospheric CO2. The process provides negative feedback to the influence of marine calcification on atmospheric carbon dioxide and is of practical importance to the application of paleoceanographic proxies.

On the initiation of a snowball Earth

Abstract: [1] The Snowball Earth hypothesis explains the development of glaciation at low latitudes in the Neoproterozoic, as well as the associated iron formations and cap carbonates, in terms of a runaway ice-albedo feedback leading to a global glaciation followed by an extreme greenhouse climate. The initiation of a snowball glaciation is linked to a variety of unusual perturbations of the carbon cycle operating over different timescales, as evidenced by unusual patterns in the carbon isotopic composition of marine carbonate. Thus a theory for why multiple glaciations happened at this time, and not in the Phanerozoic nor earlier in the Proterozoic, requires a reexamination of the carbon cycle and the controls on climate stability. We propose that the concentration of continental area in the tropics was a critical boundary condition necessary for the onset of glaciation, both because the existence of substantial continental area at high latitudes may prevent atmospheric carbon dioxide from getting too low and because a tropical concentration of continental area may lead to more efficient burial of organic carbon through increased tropical river discharge. Efficient organic carbon burial sustained over tens of millions of years, required by the high carbon isotopic compositions of preglacial carbonate, may lead to the buildup of enormous quantities of methane, presumably in hydrate reservoirs. We examine how the slow release of this methane may explain the drop in δ13C values immediately before the glaciation. Moreover, the accumulation of methane in the atmosphere coupled with the response of silicate weathering to the additional greenhouse forcing can lead to a climate with methane as the major greenhouse gas. This situation is unstable because methane is not buffered by a large ocean reservoir like carbon dioxide, and so the collapse of the methane source may provide a trigger for the onset of a runaway ice-albedo feedback. A simple model of the carbon cycle is used to explore the boundary conditions that would allow this to occur.

The hydrologic cycle in deep-time climate problems.

Abstract: Hydrology refers to the whole panoply of effects the water molecule has on climate and on the land surface during its journey there and back again between ocean and atmosphere. On its way, it is cycled through vapour, cloud water, snow, sea ice and glacier ice, as well as acting as a catalyst for silicate-carbonate weathering reactions governing atmospheric carbon dioxide. Because carbon dioxide affects the hydrologic cycle through temperature, climate is a pas des deux between carbon dioxide and water, with important guest appearances by surface ice cover.

Effects of urban tree management and species selection on atmospheric carbon dioxide

Abstract: Trees sequester and store carbon in their tissue at differing rates and amounts based on such factors as tree size at maturity, life span, and growth rate. Concurrently, tree care practices release carbon back to the atmosphere based on fossil-fuel emissions from maintenance equipment (e.g., chain saws, trucks, chippers). Management choices such as tree locations for energy conservation and tree disposal methods after removal also affect the net carbon effect of the urban forest. Different species, decomposition, energy conservation, and maintenance scenarios were evaluated to determine how these factors influence the net carbon impact of urban forests and their management. If carbon (via fossil-fuel combustion) is used to maintain vegetation structure and health, urban forest ecosystems eventually will become net emitters of carbon unless secondary carbon reductions (e.g., energy conservation) or limiting decomposition via long-term carbon storage (e.g., wood products, landfills) can be accomplished to offset the maintenance carbon emissions. Management practices to maximize the net benefits of urban forests on atmospheric carbon dioxide are discussed.

Climate responses to a doubling of atmospheric carbon dioxide for a climatically vulnerable region

Abstract: [1] Global modeling studies of future climate change predict large scale climatic responses to increased atmospheric carbon dioxide (CO2). While there have been several regional climate modeling studies that produced results at spatial and temporal scales relevant for climate change impact analysis, few have employed statistical significance testing of results. In a sensitivity study that focused on mean climate states, we use a regional climate model to generate ensembles of climate scenarios under atmospheric conditions of 280 and 560 ppm CO2, for a domain centered over California. We find statistically significant responses by mean annual and monthly temperature, precipitation, and snow to CO2 doubling. Relative to the 280 ppm results, 560 ppm results show temperature increasing everywhere in the region annually (up to 3.8°C), and in every month, with the greatest monthly surface warming at high elevations. Snow accumulation decreased everywhere, and precipitation increased in northern regions by up to 23%, on a mean annual basis.

Assimilating atmospheric data into a terrestrial biosphere model: A case study of the seasonal cycle

Abstract: [1] This paper demonstrates a new method of assimilating atmospheric concentration data into terrestrial biosphere models. Using a combination of adjoint and tangent linear models of both the underlying biosphere model and the atmospheric transport model, we directly infer optimal model parameters and their uncertainties. We also compute biospheric fluxes and their uncertainties arising from these parameters. We demonstrate the method using the Simple Diagnostic Biosphere Model (SDBM) and data on the seasonal cycle of CO2 from 41 observing sites. In the model, the light-use efficiency for several biomes is well-constrained by concentration observations. Optimal values generally increase with latitude as required to match the seasonal cycle. Modeled Q10 values are poorly constrained unless local flux measurements are also used. Values also increase with latitude but are less than the commonly assumed value of 2. INDEX TERMS: 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 1640 Global Change: Remote sensing; 1615 Global Change: Biogeochemical processes (4805); 3210 Mathematical Geophysics: Modeling; KEYWORDS: carbon cycle data assimilation, inverse modeling, adjoint, terrestrial biosphere, uncertainty analysis, atmospheric carbon dioxide Citation: Kaminski, T., W. Knorr, P. J. Rayner, and M. Heimann, Assimilating atmospheric data into a terrestrial biosphere model: A case study of the seasonal cycle, Global Biogeochem. Cycles, 16(4), 1066, doi:10.1029/2001GB001463, 2002.

Atmospheric carbon dioxide levels for the last 500 million years

Abstract: The last 500 million years of the strontium-isotope record are shown to correlate significantly with the concurrent record of isotopic fractionation between inorganic and organic carbon after the effects of recycled sediment are removed from the strontium signal. The correlation is shown to result from the common dependence of both signals on weathering and magmatic processes. Because the long-term evolution of carbon dioxide levels depends similarly on weathering and magmatism, the relative fluctuations of CO2 levels are inferred from the shared fluctuations of the isotopic records. The resulting CO2 signal exhibits no systematic correspondence with the geologic record of climatic variations at tectonic time scales.

Progress made in study of ocean's calcium carbonate budget

Abstract: Many of the uncertainties in diagnostic and prognostic marine carbon cycle models arise from an imperfect understanding of the processes that control the formation and dissolution of calcium carbonate (CaCO3). On the production side of the equation, the factors that control the abundances of calcifying phytoplankton or zooplankton are largely unknown. On the dissolution side, changes in the depth of CaCO3 saturation horizons for both calcite and aragonite may produce large-scale changes in dissolution of shelf and slope sediments and reefs, with potentially significant implications for atmospheric carbon dioxide concentration and climate change, as well as for coralline organisms themselves. In recent years, concern about the long-term fate of anthropogenic CO2 in the oceans has re-ignited scientific interest in the fundamental abiotic and biotic processes that control the marine CaCO3 budget, since biological CaCO3 production and export are important mechanisms by which carbon is exported from the ocean's surface to its abyss. CaCO3 precipitation releases CO2 to solution, while CaCO3 dissolution takes up CO2 from solution.

Carbon isotope discrimination in forest and pasture ecosystems of the Amazon Basin, Brazil

Abstract: (1) Our objective was to measure the stable carbon isotope composition of leaf tissue and CO2 released by respiration (dr), and to use this information as an estimate of changes in ecosystem isotopic discrimination that occur in response to seasonal and interannual changes in environmental conditions, and land-use change (forest-pasture conversion). We made measurements in primary forest and pastures in the Amazon Basin of Brazil. At the Santarem forest site, dr values showed a seasonal cycle varying from less than 29% to approximately 26%. The observed seasonal change in dr was correlated with variation in the observed monthly precipitation. In contrast, there was no significant seasonal variation in dr at the Manaus forest site (average dr approximately 28%), consistent with a narrower range of variation in monthly precipitation than occurred in Santarem. Despite substantial (9%) vertical variation in leaf d 13 C, the average dr values observed for all forest sites were similar to the d 13 C values of the most exposed sun foliage of the dominant tree species. This suggested that the major portion of recently respired carbon dioxide in these forests was metabolized carbohydrate fixed by the sun leaves at the top of the forest canopy. There was no significant seasonal variation observed in the d 13 C values of leaf organic matter for the forest sites. We sampled in pastures dominated by the C4 grass, Brachiaria spp., which is planted after forest vegetation has been cleared. The carbon isotope ratio of respired CO2 in pastures was enriched in 13 C by approximately 10% compared to forest ecosystems. A significant temporal change occurred in dr after the Manaus pasture was burned. Burning removed much of the encroaching C3 shrub vegetation and so allowed an increased dominance of the C4 pasture grass, which resulted in higher dr values. INDEX TERMS: 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 1610 Global Change: Atmosphere (0315, 0325); 1615 Global Change: Biogeochemical processes (4805); 3309 Meteorology and Atmospheric Dynamics: Climatology (1620); KEYWORDS: carbon cycle, global change, tropical ecosystems, atmospheric carbon dioxide

Atmospheric CO2 as a Global Change Driver Influencing Plant-Animal Interactions.

Abstract: SYNOPSIS. Plants respond to changes in atmospheric carbon dioxide. To herbivores, the decreased leaf protein contents and increased C/N ratios common to all leaves under elevated atmospheric carbon dioxide imply a reduction in food quality. In addition to these fine-scale adjustments, the abundance of C3 and C4 plants (particularly grasses) are affected by atmospheric carbon dioxide. C 4 grasses currently predominate over C3 grasses in warmer climates and their distributions expand as atmospheric carbon dioxide levels decreased during glacial periods. C4 grasses are a less nutritious food resource than C3 grasses both in terms of reduced protein content and increased C/N ratios. There is an indication that as C 4-dominated ecosystems expanded 6‐8 Ma b.p., there were significant species-level changes in mammalian grazers. Today there is evidence that mammalian herbivores differ in their preference for C3 versus C4 food resources, although the factors contributing to these patterns are not clear. Elevated carbon dioxide levels will likely alter food quality to grazers both in terms of fine-scale (protein content, C/N ratio) and coarse-scale (C3 versus C4) changes. Atmospheric gas composition plays an important role in determining many aspects of animal and plant

The alkenone-CO2 proxy and ancient atmospheric carbon dioxide.

Abstract: Cenozoic climates have varied across a variety of time-scales, including slow, unidirectional change over tens of millions of years, as well as severe, geologically abrupt shifts in Earth's climatic state. Establishing the history of atmospheric carbon dioxide is critical in prioritizing the factors responsible for past climatic events, and integral in positioning future climate change within a geological context. One approach in this pursuit uses the stable carbon isotopic composition of marine organic molecules known as alkenones. The following report represents a summary of the factors affecting alkenone carbon isotopic compositions, the underlying assumptions and accuracy of short- and long-term CO(2) records established from these sedimentary molecules, and their implications for the controls on the evolution of Cenozoic climates.

Is ocean fertilization credible and creditable

Abstract: It is possible that the increase in atmospheric carbon dioxide, which drives global warming, could be partially mitigated by adding iron to ocean waters. In their Policy Forum “Dis-crediting ocean fertilization” (12 Oct., p. [309][1]), S. W. Chisholm et al. argue that “the known consequences

Influence of atmospheric carbon dioxide enrichment on induced response and growth compensation after herbivore damage in Lotus corniculatus

Abstract: 1. Plant growth and chemical defence compounds in four Lotus corniculatus genotypes exposed to factorial combinations of ambient and elevated carbon dioxide, and herbivory by caterpillars of Polyommatus icarus were measured to test the predictions of the carbon/nutrient balance hypothesis. 2. Shoot and root biomass, allocation to shoots versus roots, and carbon-based defence compounds were greater under elevated carbon dioxide. Pupal weight of P. icarus was greater and development time shorter under elevated carbon dioxide. 3. Herbivory decreased shoot growth relative to root growth and production of nitrogen-based defence (cyanide). Young leaves contained more defence compounds than old leaves, and this response depended on carbon dioxide and herbivory treatments (significant interactions). 4. Genotype-specific responses of plants to carbon dioxide and herbivory were found for the production of cyanide. Furthermore, maternal butterfly-specific responses of caterpillars to carbon dioxide were found for development time. This suggests the existence of genetic variation for important defence and life-history traits in plants and herbivores in response to rising carbon dioxide levels.

Carbon dioxide cycling through the mantle and implications for the climate of ancient Earth

Abstract: Abstract The continental cycle of silicate weathering and metamorphism dynamically buffers atmospheric CO2 and climate. Feedback is provided by the temperature dependence of silicate weathering. Here we argue that hydrothermal alteration of oceanic basalts also dynamically buffers CO2. The oceanic cycle is linked to the mantle via subduction of carbonatized basalts and degassing of CO2 at the mid-ocean ridges. Feedback is provided by the dependence of carbonatization on the amount of dissolved carbonate in sea water. Unlike the continental cycle, the oceanic cycle has no thermostat. Hence surface temperatures can become very low if CO2 is the only greenhouse gas apart from water. Currently the continental cycle is more important, but early in Earth’s history the oceanic cycle was probably dominant. We argue that CO2 greenhouses thick enough to defeat the faint early Sun are implausible and that, if no other greenhouse gases are invoked, very cold climates are expected for much of Proterozoic and Archaean time. We echo current fashion and favour biogenic methane as the chief supplement to CO2. Fast weathering and probable subduction of abundant impact ejecta would have reduced CO2 levels still further in Hadean time. Despite its name, the Hadean Eon might have been the coldest era in the history of the Earth.

A weekly cycle in atmospheric carbon dioxide

Abstract: [1] We present a new statistic called the “Mean Symmetrized Residual” (MSR) for detection and quantification of a weekly cycle in measured daily atmospheric carbon dioxide (CO2). At the Mauna Loa Observatory in Hawaii, we conclude that CO2 concentrations, on average, are significantly lower (0.022 parts per million by volume, ppmv) on weekends (Saturday–Sunday) than during the rest of the week. Over the past twenty-five years, the variation of the mean values of MSR (as a function of day of the week) has been relatively stable. We speculate that the observed weekday/weekend variation in CO2 at Mauna Loa is the result of anthropogenic emissions on Hawaii and nearby sources. We do not detect a weekly cycle in daily CO2 concentration measured at South Pole, Antarctica. This methodology has applicability to a variety of datasets.

The Annual Carbon Budget for Fen and Forest in a Wetland at Arctic Treeline

Abstract: Three separate research efforts conducted in the same wetland-peatland system in the northern Hudson Bay Lowland near the town of Churchill, Manitoba, allow a comparison of two carbon budget estimates, one derived from long-term growth rates of organic soil and the other based on shorter-term flux measurements. For a tundra fen and an open subarctic forest, calculations of organic soil accumulation or loss over the last half-century indicate that while the fen on average has lost small amounts of carbon from the ecosystem, the adjacent forest has gained larger amounts of atmospheric carbon dioxide. These longer-term data are supported by shorter-term flux measurements and estimates, which also show carbon loss by the fen and carbon uptake by the forest. The shorter-term data indicate that the fen's carbon loss is largely attributable to exceptionally dry years, especially if they are warm. The forest may gain carbon at an increased rate as it matures and during warm growing seasons. Also, the changes in relief of the dynamic hummock-hollow landscape in the fen may inhibit photosynthesis.

Method for reducing carbon dioxide in atmosphere and its device

Abstract: PROBLEM TO BE SOLVED: To reduce an atmospheric level of carbon dioxide which is a global warming greenhouse gas for prevention of global warming. SOLUTION: The method for reducing the atmospheric level of carbon dioxide comprises a step of producing decarbonated sea water by decarbonating surface ocean water, and a step of making the decarbonated sea water come in contact with the atmosphere in order for the sea water to absorb carbon dioxide in the atmosphere with chemical equilibrium effects between the atmosphere and the ocean surface. Calcium and magnesium or the like existing together in the sea water are combined with a carbonic acid without adding any additive to the sea water so that the carbonic acid contained in the sea water is separated and recovered as an insoluble carbonate. Furthermore, the carbonic acid is precipitated, separated and recovered in the form of the insoluble carbonate, which is then sunk deep under the sea and on the sea bottom. These steps can be integrated into a series of processes. COPYRIGHT: (C)2004,JPO

Studies of the global carbon cycle using atmospheric oxygen and associated tracers

Abstract: This thesis presents research into the global carbon cycle using measurements of atmospheric composition made at the Commonwealth Scientific and Industrial Research Organisation's (CSIRO) Global Atmospheric Sampling LABoratory (GASLAB). The focus is on high precision measurement of atmospheric 021N2 and its application to deduction of carbon fluxes due to surface exchange and atmospheric transport processes. A key theme is the use of multiple species (gas concentrations and isotopomer ratios) constraints to enhance both the interpretation of atmospheric data and the diagnosis of experimental artefacts. Behaviour of the linked carbon and oxygen cycles in the contemporary atmosphere is examined on three timescales, in each case addressing important but unresolved scientific issues: • The long term trend in atmospheric 02/N2 constrains the partitioning of uptake of anthropogenic CO2between the oceans and the land biosphere. The partitioning is deduced here by determination of trends at.Cape Grim, Tasmania, based on 5 years of biweekly flask sampling and by reconstruction of a 23-year record using archived air. The results favour a small net global biospheric sink, implying significant oceanic and terrestrial (after allowance for land clearing) carbon uptake between 1978 and 2001. • More than forty years of atmospheric CO2monitoring at Mauna Loa, Hawaii has revealed strong correlation in interannual variability (IAV) of CO 2growth rate with the El Nirio Southern Oscillation (ENSO). GASLAB multi-species measurements during the 1990s showed correlation of ENSO and global IAV in most of the measured species. They include CO 2 . established tracers of terrestrial carbon exchange (021N2 and 8' 3C) and other species (H2, CO and CH4) whose atmospheric budgets are not as obviously linked to CO 2 . A multi-species analysis implicates biomass burning as a major influence on IAV in all species. • Seasonal cycling in composition of background Southern Hemisphere air is investigated by ground-based flask sampling of the marine boundary layer at Cape Grim and from aircraft-based vertical profiling of the troposphere to altitudes of 6-8 km above Cape Grim. Seasonal variations in the vertical 0211•12 gradient are useful as a constraint of vertical mixing rates. Measurements of CO2, 02/N2 and other relevant tracers are used to explore the relative contributions of multiple processes (atmospheric transport, terrestrial and air-sea exchange) to seasonal signals. Measurement of 021N2 to the precision required for global carbon cycle, studies is a major challenge. Extensive consideration is therefore given to the technical aspects of this measurement program, especially in relation to the mass spectrometric analytical technique and to gas handling procedures. Numerous causes of significant 02/N2 artefacts were identified, in some cases shedding light on artefacts previously observed, but not understood, for other species (e.g. CO2).

Workshop highlights iron dynamics in ocean carbon cycle

Abstract: The role of iron in regulating the flux of carbon through the surface layer of the ocean has become increasingly apparent during the past 15 years Before that time, the analytical challenges of measuring trace (parts per trillion) iron concentrations from iron ships using gear suspended on an iron wire precluded oceanographers from making accurate measurements Laboratory experiments were invariably conducted with samples that were seriously contaminated with elevated iron concentrations We now recognize, through greatly improved methodologies, that iron is a key regulator of phytoplankton primary production throughout the ocean Small changes in iron concentration may produce large variations in the export of particulate organic carbon from the ocean's sunlit surface layer into deep-sea sediments These variations in carbon export may occur over glacial/interglacial cycles at a scale sufficient to influence the flux of carbon dioxide from the atmosphere to the ocean Such processes have been hypothesized to be an important driver of the changes in atmospheric carbon dioxide concentration that have been recorded in ice cores over the past 400,000 years

Ink composition for detecting carbon dioxide, carbon dioxide indicator using it, packaging body with carbon dioxide indicator disposed thereon, and pin hole detecting method using it

Abstract: PROBLEM TO BE SOLVED: To easily check generation of pin holes and defective sealing. SOLUTION: A carbon dioxide indicator to which an ink composition for detecting carbon dioxide containing one or more kinds of pH indicators, a binder and a solvent, and capable of easily and visually checking any color reaction of an indication unit by the carbon dioxide concentration is applied, and a vessel for chemicals which is formed of a carbon dioxide permeable plastic and stores the chemical containing bicarbonate are packaged in a gas- substituting manner in a carbon dioxide atmosphere.

Rain Might Be Leading Carbon Sink Factor

Abstract: GLOBAL WARMINGMainland U.S. ecosystems are absorbing an unexpectedly large amount of carbon dioxide, and scientists have been at a loss to explain it. Now, a study published online by Geophysical Research Letters on 28 May suggests that the increased rainfall and humidity documented in the continental United States might be the single most important factor spurring increased plant growth; this, in turn, is slowing the accumulation of carbon dioxide in the atmosphere.

Respiration and assimilation processes reflected in the carbon isotopic composition of atmospheric carbon dioxide

Abstract: It is well known that all plants assimilate from the air CO2 in preference to CO2 (see for example: [5, 12, 13]). Diffusion of light molecule (CO2) is faster than that of heavy molecule (CO2). Carbon isotope fractionation factor is equal to 1.0044 if CO2 gas diffuses in air [1, 3]. Enrichment of plant in light carbon isotope in comparison to atmospheric carbon dioxide (which has a δ13C value of about -8‰) depends on photosynthetic pathways (C3, C4, CAM), stomatal conductance and is affected by environmental factors, such as temperature and atmospheric CO2 concentration. Carbon isotopic composition (δ 13C) of C3 plants (about 90% of all plants today) is in the range from -35 to -20‰ while C4 plants δ13C have values of -16 to -9‰ [7].