Showing papers on "Atmospheric carbon cycle published in 1980"

Predicted shift in the 13 C/12 C ratio of atmospheric carbon dioxide

Abstract: Knowledge of recent global changes in the rare isotopic species 13CO2 in atmospheric carbon dioxide does not now distinguish whether the land biosphere is a source or sink for fossil fuel carbon dioxide. The question is critically dependent on isotopic fractionation between the atmosphere and ocean water: if the isotopic fractionation factor for CO2 uptake at the air-ocean boundary, αam, is approximately 0.986, as is the case for strongly alkaline solutions, the 13CO2 content of atmospheric CO2 is insensitive to changes in the biosphere; if αam is approximately unity, as now seems likely for ocean water, very accurate measurements, over the next decade or longer, will permit an estimate to be made of the net global loss or gain of biospheric carbon.

New attention for atmospheric carbon

Abstract: Elemental carbon particles are widespread; they absorb and scatter light, thus creating a visibility-reducing haze; they may alter the radiation balance of the atmosphere, intensifying urban inversions and disrupting the arctic climate; and their surfaces are chemical webs that can catalyze, or even take part directly in, many important atmospheric reactions. Problems of defining and measuring elemental carbon releases and understanding the processes that control the cycle of elemental carbon through the atmosphere are discussed. A common nomenclature and comparable analytical methods must be developed to better define and measure elemental carbon in the atmosphere, and to understand its effects of atmospheric conditions.

The greenhouse effect of planetary atmospheres

Abstract: The greenhouse effect of the atmosphere is the main factor of possible climate changes of anthropogenic origin. The growing pollution of the atmosphere leads to an increase of the concentration of such gaseous components as sulphur and carbon dioxides, carbon oxide, halocarbons, nitrous oxides, etc. Of great importance is also the consideration of the aerosols, both injected directly into the atmosphere and formed as a result of the conversion of chemical gas into particles (first of all, it concerns the sulphate aerosol). All the above gaseous components, as well as aerosols, have the absorption bands in the IR spectral range, which determines their contribution to the greenhouse effect of the atmosphere, mainly governed by water vapour and carbon dioxide. The traditional attention to the problem of the CO2 contribution to the greenhouse effect has somewhat overshadowed the significance of the different components. The data characterizing the significance of the different components of the greenhouse effect are considered. The results of studying the absorption spectra of methane, nitrous oxides, sulphuric gas, ammonia, nitric-acid vapours and other components are discussed. The assessments of their contribution to the greenhouse effect are given. The important role of the small-size fraction of the atmospheric aerosols as a factor of the greenhouse effect is discussed. Both the analysis of the causes of the Earth's climate variability and the relevant investigation of the atmospheric greenhouse effect determine the expediency of analysing the conditions of the greenhouse effect formation on other planets, that is the consideration of different planetary atmospheres as the specific models of the greenhouse effect formation. To solve such a problem, data are needed on the composition and structural parameters of the atmospheres and the quantitative characteristics of the absorption spectra associated with the specific conditions of various atmospheres. In connection with this, laboratory studies of the IR absorption spectra of the synthetical CO2 atmospheres were carried out. Some results from these studies are discussed. Calculations of the thermal-emission fluxes' spectral distribution in the atmospheres of Mars, Venus and Jupiter were performed to analyse the conditions of the greenhouse effect formation in the atmospheres of these planets. Calculations were made which concern the optical properties of Venus clouds and dust aerosols of Mars,i.e. the contribution of clouds and aerosols into the greenhouse effect was analysed. The conditions favourable to the antigreenhouse effect formation are specified.

The carbon cycle: sources and sinks of atmospheric CO2

Abstract: In this contribution we try to give a synopsis of the more important processes within the global C cycle. Special attention is paid to the mechanisms by which atmospheric CO2 is interchanged between the biosphere and the oceans, and existing qualitative and quantitative uncertainties are pointed out.

Carbon dioxide and the greenhouse effect

Abstract: The large releases of carbon dioxide into the atmosphere from the burning of fossil fuels may present a special problem. Carbon dioxide is not a pollutant in the normal sense of the word. It is an essential constituent of the environment and plays a key role in plant growth being converted by photosynthesis in plants to hydrocarbons. The burning of fossil fuel returns to the atmosphere carbon which was fixed by plants in primeval times, when the CO2 concentration in the atmosphere was higher, about 450 ppm compared with about 325 ppm at present. The concern arises in that the rapid increase in the rate of burning of fossil fuels has produced CO2 at a greater rate than can be absorbed under equilibrium conditions in the oceans and by plants and as a result the CO2 concentration in the atmosphere has shown a steady rise over recent years (Figure 51).1

The effect of the ocean on the global carbon cycle

Abstract: The fate of fossil fuel CO2 in the ocean is discussed and a comparison is made with the natural oceanic cycle of carbon. The oceanic share of fossil fuel carbon, pressently about 40%, will decrease in the future. Much of the fossil fuel carbon will remain in the atmosphere, and will stay there for many centuries. In the long run, however, the ocean will bring to an end the fossil fuel excursion of atmospheric CO2-firstly by dissolution as bicarbonate and ultimately by burial in ocean sediments.

Carbon Dioxide Effects Research and Assessment Program. The role of temperate zone forests in the world carbon cycle: problem definition and research needs

Abstract: The continuing rise in the CO/sub 2/ content of the atmosphere has produced concern that in the next half-century, climatic, ecological and societal effects may occur throughout the world which will not easily be reversed. This prospect has encouraged a critical assessment of the many elements of the global carbon cycle and the influence of man on it. The role of the terrestrial biosphere has been underscored by recent evidence that reduction of the world's biota may be adding as much or more carbon to the atmosphere as combustion of fossil fuels. The diversity of world ecosystems, and the lack of data on carbon content in many of them, have led to different interpretations of how much the terrestrial biosphere contributes to carbon accumulation in the atmosphere. A detailed review is needed of the principal elements of biospheric influence on the carbon cycle, of where the accumulating atmospheric carbon is originating, and of the options there may be to control it. The Office of Carbon Dioxide Effects Research and Assessment of the US Department of Energy has funded The Institute of Ecology to evaluate three terrestrial biospheric components which may be important in the world carbon cycle. These components are:more » the temperate zone forest, particularly over the past 100 years; organic soils of the world; and freshwater systems subject to eutrophication. From 10 to 12 researchers have participated in each panel. Data review, problem definition and recommendations for research have been the focus in each workshop. The results reported here cover the temperate forest component.« less