Showing papers on "Carbon dioxide in Earth's atmosphere published in 1990"

Effects on carbon storage of conversion of old-growth forests to young forests.

Abstract: Simulations of carbon storage suggest that conversion of old-growth forests to young fast-growing forests will not decrease atmospheric carbon dioxide (CO2) in general, as has been suggested recently. During simulated timber harvest, on-site carbon storage is reduced considerably and does not approach old-growth storage capacity for at least 200 years. Even when sequestration of carbon in wooden buildings is included in the models, timber harvest results in a net flux of CO2 to the atmosphere. To offset this effect, the production of lumber and other long-term wood products, as well as the life-span of buildings, would have to increase markedly. Mass balance calculations indicate that the conversion of 5 x 109 to 1.8 x 109 megagrams of carbon to the atmosphere.

Evidence from chronosequence studies for a low carbon-storage potential of soils

Abstract: OVER most of the Earth's land surface, the amount of carbon stored in soil organic matter exceeds by a factor of two or three the amount stored in living vegetation. This pool of soil carbon is large (1.5 × 1018 g)1,2 and plays a dynamic part in the geochemical carbon cycle. Prentice and Fung3 have suggested that terrestrial vegetation and soils would act as a large sink for atmospheric carbon dioxide if its concentration were twice the present level. Here I use data from chronosequence studies to show that the production of refractory humus substances in soils sequesters only ∼0.4 × 1015 g C yr−1 from the atmosphere, accounting for just 0.7% of terrestrial net primary production. Moreover, agricultural practices tend, on balance, to cause a release of soil carbon to the atmosphere4,5. Thus if the terrestrial biosphere is indeed to act as a carbon sink under future elevated levels of carbon dioxide, this would be more likely to be the result of changes in the distribution and biomass of terrestrial vegetation than of changes in the accumulation of soil organic matter.

Atmospheric carbon dioxide levels over phanerozoic time.

Abstract: A new model has been constructed for calculating the level of atmospheric CO2 during the past 570 million years. A series of successive steady states for CO2 is used in order to calculate CO2 level from a feedback function for the weathering of silicate minerals. Processes considered are: sedimentary burial of organic matter and carbonates; continental weathering of silicates, carbonates, and organic matter; and volcanic and metamorphic degassing of CO2. Sediment burial rates are calculated with the use of an isotope mass-balance model and carbon isotopic data on ancient seawater. Weathering rates are calculated from estimates of past changes in continental land area, mean elevation, and river runoff combined with estimates of the effects of the evolution of vascular land plants. Past degassing rates are estimated from changes in the rate of generation of sea floor and the shift of carbonate deposition from platforms to the deep sea. The model results indicate that CO2 levels were high during the Mesozoic and early Paleozoic and low during the Permo-Carboniferous and late Cenozoic. These results correspond to independently deduced Phanerozoic paleoclimates and support the notion that the atmospheric CO2 greenhouse mechanism is a major control on climate over very long time scales.

Increases in terrestrial carbon storage from the last glacial maximum to the present

Abstract: EVIDENCE from ice cores1 indicates that concentrations of atmospheric carbon dioxide were lower by about 75 p.p.m. during the Last Glacial Maximum (LGM; ∼18,000 years ago) than during the present interglacial (10,000 years ago to the present). The causes of such large changes in atmospheric CO2 remain uncertain. Using a climate model, Prentice and Fung2 have estimated that there was approximately the same amount of carbon in vegetation and soils during the LGM as there was during the present (pre-industrial) interglacial. In contrast, we present here results based on palynological, pedological and sedimentological evidence which indicate that in fact the amount of carbon in vegetation, soils and peatlands may have been smaller during the LGM by ∼1.3x 1012 tonnes. Thus, organic carbon in vegetation and soils has more than doubled (from 0.96 to 2.3 x 1012 tonnes) since the LGM. Oceanic CO2 reservoirs seem to be the only possible source of this large quantity of carbon that has entered the terrestrial biosphere since the LGM (in addition to that which has entered the atmosphere to give the higher interglacial CO2 levels).

Intensification of recycling of organic matter at the sea floor near ocean margins

Abstract: QUANTIFICATION of the flux of organic carbon from the ocean surface to the deep ocean and sea floor is crucial to the prediction of future levels of atmospheric carbon dioxide and the interpretation of organic carbon variations in marine sediments. We report here the results of a study of benthic exchange and metabolism based on in situ benthic flux-chamber, in situ oxygen microelectrode and shipboard pore-water measurements performed off the central California continental shelf. At the base of the continental slope, the rates of benthic carbon mineralization exceed 0.8 mol C m−2 yr−1. Seaward of the slope and rise, however, rates decrease to <0.05 mol C m−2yr−1 in the North Pacific central gyre. These results indicate that, across the northeast Pacific, about half of the input of organic carbon to the sea floor occurs within 500 km of the continental slope. Measured rates of benthic carbon oxidation near the continental margin exceed the fluxes of organic carbon determined from previous sediment-trap studies by a factor of about three. In this region, therefore, either traps significantly underestimate the mean flux of vertically sinking particulate organic carbon (perhaps by under-sampling important episodic events) or more than half of the organic-carbon input is due to processes that by-pass traps, such as near-bottom lateral or active biological transport.

Transient response of a global ocean-atmosphere model to a doubling of atmospheric carbon dioxide

Abstract: The transient response of climate to an instantaneous increase in the atmospheric concentration of carbon dioxide has been investigated by a general circulation model of the coupled ocean-atmosphere-land system with global geography and annual mean insulation. An equilibrium climate of the coupled model is perturbed by an abrupt doubling of the atmospheric carbon dioxide. The evolution of the model climate during the 60-year period after the doubling is compared with the result from a control integration of the model without the doubling. The increase of surface air temperature in middle and high latitudes is slower in the Southern Hemisphere than the Northern Hemisphere The large thermal inertia of the ocean-dominated hemisphere is partly responsible for this difference. The effective thermal inertia of the oceans becomes particularly large in high southern latitudes. Owing to the absence of meridional barriers at the latitudes of the Drake Passage. a wind-driven. deep cell meridional circulatio...

Coherence established between atmospheric carbon dioxide and global temperature

Abstract: The hypothesis that the increase in atmospheric carbon dioxide is related to observable changes in the climate is tested using modern methods of time-series analysis. The results confirm that average global temperature is increasing, and that temperature and atmospheric carbon dioxide are significantly correlated over the past thirty years. Changes in carbon dioxide content lag those in temperature by five months.

Sensitivity of the equilibrium surface temperature of a GCM to systematic changes in atmospheric carbon dioxide

Abstract: The equilibrium response of surface temperature to atmospheric CO2 concentration, for six values between 100 and 1000 ppm, is calculated from a series of GCM experiments. This response is nonlinear, showing greater sensitivity for lower values of CO2 than for the higher values. It is suggested that changes in CO2 concentration of a given magnitude (e.g., 100 ppm) played a larger role in the Pleistocene ice-age-type temperature variations than in causing global temperature changes due to anthropogenic increases.

Balancing atmospheric carbon dioxide.

Abstract: Rising carbon dioxide and global temperatures are causing increasing worldwide concern, and pressure towards an international law of the atmosphere is rapidly escalating, yet widespread misconceptions about the greenhouse effect's inevitability, time scale, and causes have inhibited effective consensus and action. Observations from Antarctic ice cores, Amazonian rain forests, and Caribbean coral reefs suggest that the biological effects of climate change may be more severe than climate models predict. Efforts to limit emissions from fossil-fuel combustion alone are incapable of stabilizing levels of carbon dioxide in the atmosphere. Stabilizing atmospheric carbon dioxide requires coupled measures to balance sources and sinks of the gas, and will only be viable with largescale investments in increased sustainable productivity on degraded tropical soils, and in long-term research on renewable energy and biomass product development in the developing countries. A mechanism is outlined which directly links fossil-fuel combustion sources of carbon dioxide to removal via increasing biotic productivity and storage. A preliminary cost-benefit analysis suggests that such measures are very affordable, costing far less than inaction.

Geochemical evolution of the northern Plains of Mars: early hydrosphere, carbonate development, and present morphology.

Abstract: It is likely that early in Mars' history, abundant liquid water was available. Under a thick (several bars) carbon dioxide atmosphere, this water could have formed an ocean, located primarily in the lowlands of the northern hemisphere. An equilibrium geochemical model of this ocean and its interactions with the atmosphere and regolith of Mars was developed, and the results of this model were used to discuss the evolution of the volatile budget of Mars, including the deposition of large carbonate beds on the northern plains. Differential solutional weathering of these carbonate beds may have caused the formation of some of the enigmatic features seen on the northern plains of Mars, such as the thumbprint terrain and enclosed depressions.

Anthropogenic climatic change

Abstract: It has been believed for many years that the modern global climate is more or less stable and that there are no grounds to expect noticeable changes in the immediate future. Proposals made by scientists since the late 19th century as to the possible climatic effects of increasing amounts of carbon dioxide in the atmosphere due to burning carbon fuel were not credited and met no support.

Biogeochemical modeling at mass extinction boundaries: Atmospheric carbon dioxide and ocean alkalinity at the K/T boundary

Abstract: The causes of mass extinctions and the importance of major bio-events in the history of life are subjects of considerable scientific interest. A large amount of geological, geochemical, and paleontological information now exists for the Cretaceous/Tertiary (K/T) boundary (66 Myr BP). These data are used here to constrain a newly developed time-dependent biogeochemical cycle model that is designed to study transient behavior of the earth system. Model results suggest significant fluctuations in ocean alkalinity, atmospheric CO2, and global temperatures at the K/T boundary, brought about by the extinction of calcareous plankton and reduction in pelagic CaCO3 and organic carbon sedimentation rates. Oxygenisotope analyses and other paleoclimatic data provide some evidence that such climatic fluctuations may have occurred, but stabilizing feedback processes may have acted to reduce the ocean-alkalinity and carbon dioxide fluctuations.

Overview of the greenhouse effect. Global change syndrome; general outlook.

Abstract: Accumulation of cosmic dust and planetesimals was most likely the mechanism that created our planet. Due to dominance of hydrogen, the extruded gases produced a primordial reducing atmosphere, enriched with methane and ammonia. Then, after a slow start, continued oxidation with oxygen, released from photolysis of water, and the later development of life from photosynthesis caused the atmosphere to become dominated by CO 2 , water vapor and N. The two former components were able to trap IR radiation and to produce a warming greenhouse effect of 33°C, shifting the surface temperature to +15°C. Oxygen from photosynthesis (at present yearly ca 330 bil t from terrestrial photosynthesis) was used over at least 2 billion years, for sustaining respiration of the various facets of life and for iron oxidation in marine and terrestrial sediments. During the last billion years oxygen began to enrich in the atmosphere, parallel to reducing CO 2 concentration, due to its consumption by photosynthesis, chemical weathering and the carbonate precipitating pumping effect of the oceans. CO 2 replenishment occurs via volcanism and release from subduction zones. The faster biochemical cycle of smaller pool size (organic matter production, respiration, humification, kerogene formation, and biotic-abiotic-photochemical organic matter turnover) and over longer geological periods especially the slow but very large geochemical cycle (exchange of carbon between atmosphere, ocean, biosphere, and sediments), are decisive for CO 2 concentration and its contribution to temperature. Some features of the biochemical cycle against the background of climate changes, including those due to Pangaea/Gondwana shifting, are discussed. Life is on a carbon trip. Wasteful consumption of fossil C based fuel, due to rising living standard and population explosion in conjunction with increasing release of greenhouse active (radiatively active) gases – which are fingerprinted – threatens to exert climate changes detrimental to our life conditions and civilization. Arguments to characterize the situation are assessed, also those expressing potential advantages of increasing CO 2 concentration for crop yields and expansion of the farmland area, doomed to shrinking at the present level of population explosion. The need for a change from the carbon trip to a mixed carbon – hydrogen trip is evident.

Climate Monitoring and Diagnostics Laboratory No. 18. Summary report, 1989

Abstract: Contents: CMDL station information; observatory reports; aerosols and radiation monitoring group; carbon cycle group; ozone group; acquisition and data management; air quality group; nitrous oxide and halocarbons group; a joint U.S./U.S.S.R. experiment for the study of desert dust and its impact on local meteorological conditions and climate; annual ozone cycle and decade trend at South Pole; wintertime black carbon aerosol measurements over the southwestern United States, December 1989; cooperative programs; precipitation chemistry; continuous aerosol monitoring with the epiphaniometer at mlo; antarctic ultraviolet spectroradiometer monitoring program; chemical resolution of fine aerosol mass at mlo: the role of organic matter; artificial windshielding of precipitation gauges in the arctic; UVB monitoring data from Rockville, Maryland; Robertson-Berger UVB meter; the CSIRO latitudinal gradient study: methane data from air samples collected at Cape Grim, Tasmania; secular variation in the carbon-13 content of atmospheric carbon dioxide; snow bunting nesting study at Barrow, Alaska; optical depth retrieval with the sunphotometer; tropospheric nitrogen oxide during spring at Barrow; chemical analyses of atmospheric particulates and gases at mlo; a temperature inversion climatology for barrow: 1976-1985; the global precipitation chemistry project; radioactivity in the surface air at brw, mlo, smo, and spo; total nitrate variations at Mauna Loa; seasonal andmore » latitudinal trends in the (13)c/(12)c ratio of methane; aerosol constituents at American Samoa, November 1989; update on the o-ring bias; trends of the carbon isotopi composition of atmospheric methane in the southern hemisphere; bromine and surface ozone atmospheric chemistry at Barrow, Alaska, during spring 1989; USGS Barrow Observatory; radon from distant continents detected at the Mauna Loa Observatory.« less

Short-rotation woody crop opportunities to mitigate carbon dioxide buildup

Abstract: Short-rotation woody crops (SRWC) have a significant potential for permanently mitigating carbon dioxide buildup in the atmosphere. The greatest benefit can be derived from growing large amounts of woody crops dedicated to substitute for fossil energy resources. Assuming current production and conversion technologies and a conservative estimate of the viable US land base (35 million acres), SRWC energy could displace 34 to 67 million tons of fossil carbon releases, 3 to 5% of current annual US emissions. Assuming predicted technology advancements and a high estimate of the US land base available for SRWC (103 million acres), SRWC energy could displace 272 to 470 million tons of annual fossil fuel carbon releases. The carbon mitigation potential of SRWC-based electricity production would be equivalent to about 7.5% of current global fossil fuel emissions and 35% of current total US fossil fuel emissions. This document discusses the strategies to mitigate carbon dioxide in the atmosphere. Topics include planting new trees, managing forests, improving forest utilization and using wood as a renewable energy source to replace fossil fuels. 16 refs., 2 figs., 4 tabs.

The warm Cretaceous climate: Role of the long‐term carbon cycle

Abstract: An annual energy-balance model is coupled to a steady state formulation of the long-term CO{sub 2} cycle to investigate the possible sources of the global warming at the Cretaceous. It is found that paleogeography solely is an insufficient factor but that the different latitudinal distribution of continental masses 100 My ago influenced the CO{sub 2} cycle and favored a larger content of the atmospheric CO{sub 2} level. A larger rate of tectonic activity and the possible influence of the vegetation in a CO{sub 2} richer atmosphere provide further sources of atmospheric carbon dioxide increase. The combination of these factors, together with a more vigorous poleward heat transport, provides CO{sub 2} levels 5 to 15 times larger than today and a global surface warming within the 6-12C estimated from paleoindicators.

Evolution of the Earth's atmosphere and its geological impact

Abstract: Current problems with the ozone layer and rising carbon dioxide levels have highlighted the importance of the atmosphere, with its delicate balance of gases. In fact, the atmosphere has been changing since the Earth formed. From anoxic beginnings to its current oxygenated state, it has influenced depositional processes on the Earth's surface and helped the development of active, oxygen-breathing life forms that culminated in ourselves. Evidence for changes in the atmosphere is found in the sediments accumulated on the Earth's surface, where fossils are also preserved. In this article the major geological aspects of the atmosphere's evolution are considered; in particular, the role of oxygen is aired.

Photosynthesis of plants in relation to resource availability in the field

Abstract: Photosynthesis is the process that provides energy to all anabolic and catabolic processes in ecosystems. The rate at which plants assimilate CO2 in the field may be quite different from optimal conditions in the test tube or in growth cabinets. The rate depends on the environmental conditions of the habitat which determine to what extent the genetic capability of a plant can actually be used for photosynthesis. The main factor restricting photosynthesis in the field is the availability of light. But, other factors my become just as rate 1imitating, such as atmospheric carbon dioxide concentration, air humidity and temperature, and water or nutrient supply from the soil. Time is an additional important factor which influences the carbon balance via plant age but also by deterimining the dose of stress.

Possible Effects of Man on the Carbon Cycle in the Past and in the Future

Abstract: On a global scale, vegetation belts are the natural expression of the response of major ecosystems to climatic parameters. Environmental conditions are mainly controlled by air temperature and water availability. For Example, in herbaceous savannas and steppes a direct linear to exponential relation exists between total vegetation weight (biomass in dry matter or in carbon) and rainfall (Le Houerou, 1990). In high latitudes or high altitudes temperature is the limiting factor.

Chemical evolution of the early Martian hydrosphere

Abstract: The chemical evolution of the early Martian hydrosphere is discussed The early Martian ocean can be modeled as a body of relatively pure water in equilibrium with a dense carbon dioxide atmosphere The chemical weathering of lavas, pyroclastic deposits, and impact melt sheets would have the effect of neutralizing the acidity of the juvenile water As calcium and other cations are added to the water by chemical weathering, they are quickly removed by the precipitation of calcium carbonate and other minerals, forming a deposit of limestone beneath the surface of the ocean As the atmospheric carbon dioxide pressure and the temperature decrease, the Martian ocean would be completely frozen Given the scenario for the chemical evolution of the northern lowland plains of Mars, it should be possible to draw a few conclusions about the expected mineralogy and geomorphology of this regions

The Greenhouse Effect, Stratospheric Ozone, Marine Productivity, and Global Hydrology: Feedbacks in the Global Climate System

Abstract: The problems of greenhouse warming, ozone depletion and changes in global hydrology are inter-related through a number of feedback mechanisms. Recognized feedbacks act through two important loops involving changes in atmospheric chemistry, UV-B radiation at the earth’s surface, and marine productivity. Reliable predictions of future changes in global and regional climate require an understanding of the direction, magnitude and time constants of the various climatic and biochemical feedback processes. Changes in the amount and distribution of precipitation can also have important feedback effects on soil moisture, vegetation, cloudiness, ground and cloud albedo, ocean salinity (through changes in evaporation and runoff), bottom water formation and productivity. Model studies incorporating these and other feedbacks should be useful in determining the sensitivity of the climate system and anthropogenic changes.

Production of vegetable powder

Abstract: PURPOSE:To shorten the time for producing vegetable powder and regulate the particle diameter of powder and amount of lipids without carrying out pretreatment by exposing a plant to an atmosphere of high-pressure carbon dioxide, reducing the pressure, pulverizing the plant, reincreasing the pressure and extracting the lipids. CONSTITUTION:A plant (e.g. almond) is exposed to an atmosphere of high- pressure carbon dioxide and the pressure in the above-mentioned atmosphere is then reduced at >=0.1kg/cm per min rate to pulverize the plant. The pressure of the aforementioned atmosphere is then increased to extract lipids in the plant. Furthermore, the pressure of the carbon dioxide atmosphere is regulated to 300kg/cm and the temperature is kept at 40 deg.C. After keeping the atmosphere under the condition for 30min, the pressure is preferably reduced to 100kg/cm at 5kg/cm per min rate to pulverize the plant. The pressure is preferably returned to 300kg/cm to carry out extraction of the lipids.

A hydrologist's plan to combat the Greenhouse effect

Abstract: Some of the gases that industrial society routinely spews into the air by burning fossil fuel sami cooling our buildings are trapping heat in the earth's atmosphere and warming the planet. This is called the greenhouse effect. This decade has seen the four hottest years of the last century and the first five months of 1988 were the warmest on record. Since 1880, mean global temperatures have increased more than 0.78 Celsius degrees. James Hansen of NASA'S Goddard Institute for space studies declared that he is certain that the greenhouse effect is here and will continue to increase: however, this view is not shared by many atmospheric scientists who have not detected the greenhouse ‘signal’ in the global temperature data. Since 1958 concentrations of carbon dioxide in the atmosphere have increased 25 percent, mostly the result of burning oil and coal. North America. Western Europe, the U.S.S.R and Soviet-block countries are responrible for about 67 percent of the emissions. The level of carbon di...

Energy Options and Climatic Effects

Abstract: There are many uncertainties surrounding the climate change issue, but the two most important are 1. What quantity of greenhouse gases will be added to the atmosphere and at what rate? and 2. How will the climate system respond?