Carbon Dioxide Variations Research Articles

Regional and temporal variation in pH, alkalinity and carbon dioxide in Danish streams, related to soil type and land use

SUMMARY 1. The Weichsel glaciation has divided Denmark into two regions with different susceptibility to acidification. East of the Weichselian terminal moraine, soils are usually clayey and calcareous, and the streams are alkaline (mean alkalinity 2.24 mmol 1‐‐1) and resistant to inputs of acidifying substances.2. Trend analysis of pH and alkalinity of water samples taken over 15 years in two streams with alkalinities above 1.5 mmol 1−1 in eastern Jutland, showed no trends of acidification.3. West of the terminal moraine the soils are sandy and leached and alkalinity is lower (mean 0.59 mmol 1−1). Although such streams with medium alkalinity are believed not to be vulnerable to acidification, we have documented significant decreases in their pH and alkalinity over 12 years.4. Trends of pH and alkalinity in four western streams with mean alkalinities between 0.05 and 0.79 mmol 1−1 showed annual decreases of 0.027 pH units and 4.7 nmol 1−1 in alkalinity.5. Overall, Danish streams contain about 7.9 times more calculated free CO2 (pCO2=10−2.6 atm) than water in equilibrium with air (pCO2= 10−3.5 atm). The calculated free CO2 content has increased significantly in western Danish streams over the study period (6.9 μmol 1−1 yr‐1). This increase cannot be explained by the prevailing global increase in atmospheric pCO2 which only can account for 0.54 pmol 1−1 yr−1 at maximum.6. Reasons for the ongoing stream acidification in the western part of Denmark are discussed. We suggest that atmospheric deposition causes stream acidification in a heath‐covered catchment without agriculture. In heavily cultivated regions the main acidification factor is argued to be proton production in the soil through nitrification of ammonium‐containing fertilizers.

A first-order global model of late Cenozoic climatic change II. Further analysis based on a simplification of CO2 dynamics

A model developed recently for the long-term variations of global ice mass, carbon dioxide, and mean ocean temperature through the late Cenozoic is simplified by hypothesizing a new equation for the CO2 variations containing one less adjustable parameter, but retaining the essential physical content of the previous equation (including nonlinearity and the potential for instability). By assuming plausible time constants for the glacial ice mass and global mean ocean temperature, and setting the values of six adjustable parameters (rate constants), a solution for the last 5 My is obtained displaying many of the features observed over this period, including the transition to the near-100 ky major ice-age oscillations of the late Pleistocene. In obtaining this solution it is also assumed that variations in tectonic forcing lead to a reduction of the equilibrium CO2 concentration (perhaps due to increased weathering of rapidly uplifted mountain ranges over this period). As a consequence of this CO2 reduction, the model dynamical system can bifurcate to a free oscillatory ice-age regime that is under the “pacemaker” influence of earthorbital (Milankovitch) forcing. Expanded discussions are given of the surface temperature variations accompanying the evolution of ice, CO2, and ocean temperature, and of the bifurcation properties of the model from both mathematical and physical viewpoints.

Temporal and spatial variations of upper tropospheric and lower stratospheric carbon dioxide

Temporal and spatial variations of upper tropospheric and lower stratospheric carbon dioxide

Climate variations and the Appalachians from the late paleozoic to the present: Results from model simulations

A series of climate model simulations are utilized to examine the climate evolution of the Appalachians from the Carboniferous to the Present through consideration of large scale changes in paleogeography and potential variations in carbon dioxide on long time scales. The model simulations predict considerable variations in temperature and precipitation through time. In addition, a number of shorter time scale phenomena may influence the climatic record of the Appalachians. In particular Milankovitch orbital variations can produce rhythmic climate and weathering. Particular geographic configurations since the Carboniferous tend to promote sensitivity to orbital variations. Although far from comprehensive, the model simulations provide independent predictions of climate which can be utilized to investigate the evolution of the Appalachians deductively.

The effect on Earth's surface temperature from variations in rotation rate, continent formation, solar luminosity, and carbon dioxide.

Proposed evolutionary histories of solar luminosity, atmospheric carbon dioxide amounts, Earth rotation rate, and continent formation have been used to generate a time evolution of Earth's surface temperature. While speculative because of uncertainties in the input parameters, such a study does help to prioritize the areas of most concern to paleoclimatic research while illustrating the relationships and mutual dependencies. The mean temperature averages about 5 K higher than today over most of geologic time; the overall variation is less than 15 K. The evolution of Earth's rotation rate makes a significant contribution to the surface temperature distribution as late as 0.5 b.y. ago. While there is little change in equatorial temperatures, polar temperatures decrease, being some 15 K lower 3.5 b.y. ago than with present day rotation. The effect of continent growth on albedo is of secondary importance.

Derzeitige Möglichkeiten und Grenzen der transkraniellen Dopplersonographie als zerebrales Monitoringverfahren

Transcranial Doppler Sonography (TCD) can meet some requirements for an ideal measuring device of the cerebral circulation. TCD can measure non-invasively and repeatably blood flow velocities of basal cerebral arteries. Under the assumption of constant vessel diameters can altered flow velocities reflect alterations of cerebral blood flow. TCD-measurements have been used frequently for diagnosis of cerebral vasospasm after subarachnoid hemorrhage. Furthermore TCD has been applied in cerebrovascular diseases, during operations with extracorporal circulation and in patients with increased intracranial pressure. Unchanged diameters of basal cerebral arteries have been proven only for carbon dioxide variations and some drugs; this cannot be presupposed during alterations of mean arterial or intracranial pressure. If conditions as ventilation, hemodynamics and drug therapy are kept constant, TCD may be valuable for short-term-trend-detection of cerebral blood flow and intracranial pressure.

Distribution and variations of oceanic carbon dioxide in the western North Pacific, eastern Indian, and Southern Ocean south of Australia

Distribution and variations of oceanic carbon dioxide in the western North Pacific, eastern Indian, and Southern Ocean south of Australia

Carbon cycle instability as a cause of the Late Pleistocene Ice Age Oscillations: Modeling the asymmetric response

A dynamical model of the Pleistocene ice ages, incorporating many of the qualitative ideas advanced recently regarding the possible role of ocean circulation, chemistry, temperature, and productivity in regulating long‐term atmospheric carbon dioxide variations, has been constructed. This model involves one additional term (and free parameter) beyond that included in a previous model (B. Saltzman and A. Sutera, 1987), providing the capacity for an asymmetic (for example, “saw‐toothed”) response. It is shown that many of the main features exhibited by the δ18O‐derived ice record and the Vostok core/δ13C‐derived carbon dioxide record in the late Pleistocene can be deduced as a free oscillatory solution of the model, including a rapid déglaciation during which a spike of high CO2 and a rapid surge in North Atlantic deep water production occurs. It is expected that the addition of reasonable levels of external (for example, Earth orbital) forcing will enable the model to account for a significant amount of the remaining observed variance and covariance of the slow response climatic variables over the full Pleistocene including the mid‐Pleistocene transition.

Problems of Acid-Base Balance in Rapidly Changing Intertidal Environments

SYNOPSIS. Many physical factors vary widely and rapidly in residual water bodies left on the shore by the receding tide. Whereas variations of temperature and salinity depend on climatic conditions, the changes of oxygen and carbon dioxide are mainly governed by biological activities. Typically, such waters become hypoxic-hypercapnic at night and hyperoxic-hypocapnic during the day at low tide. According to findings in single-factor laboratory experiments, all these variables can potentially disturb acid-base balance in tidepool animals. However, the whole response of the organism to the complex natural situation can hardly be predicted and must be approached in the field or in simulated environments. Measurements on crabs Carcinus maenas acclimated to an artificial tidepool show only moderate hemolymph acid-base changes, due mainly to counteracting influences of the concerted variations of water oxygen and carbon dioxide. The pH-temperature slope for these crabs was —0.016 pH unit°C−1 in agreement with an imidazole alphastat pattern of acid-base regulation.

The variations of atmospheric carbon dioxide at Alert and Sable Island, Canada

It has been observed that atmospheric carbon dioxide (CO 2) is increasing at Alert and Sable Island at a rate of about 1.25 ppm a −1. Seasonal cycles of atmospheric CO 2 are quite evident there, with the occurrence of minimum values in the late summer. Maximum values occur in the late winter at Sable Island in the mid-latitude and in April or May at Alert in the Arctic. Although anthropogenic emissions of CO 2 into the Arctic atmosphere are 2–3 orders of magnitude smaller than those at mid-latitudes, a higher concentration and larger seasonal variation are observed at Alert than at Sable Island. At Alert, a CO 2 minimum in the seasonal cycle in the summer is associated with a lower frequency of atmospheric inversions, and increased occurrence of stratus clouds, precipitation and cyclonic activities. The frequency of occurrence of relatively low values of CO 2 with precipitation and fog during the period of 1981–1985 was 64.3 % at Alert and 62.0% at Sable Island. Air parcel back-trajectory analyses have indicated that at Sable Island relatively low values of CO 2 are associated with air parcels generally coming from the N or SE (oceanic regions) to the site. In contrast, relatively high values are associated with 5-day trajectories arriving from the W or WSW, i.e. from the continent. The 5-year climatology of air parcel trajectories arriving at Alert showed that low values of atmospheric CO 2 concentrations are usually associated with S-SW airflows, while relatively high values of CO 2 are generally associated with a long trajectory originating in the Soviet Arctic. In particular, high values of CO 2 concentrations occur in the late spring under the meteorological conditions of a pronounced temperature inversion, high solar radiation and calm or light winds at the surface. These conditions are favourable for high air pollution potential in the Arctic and for CO 2 episodes at Alert. It is believed that Arctic air pollution is a cause of perturbation in radiation budgets especially during spring.

Distribution and variations of oceanic carbon dioxide in the western North Pacific, eastern Indian, and Southern Ocean south of Australia

The partial pressure of carbon dioxide (pCO2) in surface seawater was measured to clarify its time and space variation in the western North Pacific, eastern Indian and Southern Ocean south of Australia during the Southern Cross Cruise in 1968169, the BIOMASS Cruise in 1983/84 and the Ryofu-maru Cruises in 1984 and 1987. The pCO2 in surface seawater was high in high latitudes, coastal and equatorial regions and low in the subtropics. The spatial variation of pCO2 clearly reflects the general circulation of seawater, i.e., vertical mixing of seawater plays an important rijle in determining the pCO2 in surface seawater.Two kinds of periodicities during the annual cycle, which are caused by the variations in seawater temperature, vertical mixing and biological activities, were found off Japan's coast. The pCO2 in surface seawater obtained in the boreal winters of 1969 and 1984 suggests an increase due to the enhancement of CO2 flux from air to sea. The apparent increase was 20.0 f 10.6 ppm in the western North Pacific, and 24.4 8.3 ppm in the Southern Ocean, south of Australia.

Seasonal and meridional variations of atmospheric carbon dioxide in the lower troposphere of the northern and southern hemispheres

Systematic collection of air samples over the Pacific Ocean was begun in March 1982 on board a container ship sailing between Japan and Australia. A current picture of seasonal and meridional varia...

Time and space variations of tropospheric carbon dioxide over Japan

Aircraft measurements of atmospheric CO2 concentration over Japan, initiated in January 1979, have been continued to the present. The average seasonal variation of atmospheric CO2 showed maximum co...

Carbon dioxide and the ?18O record of late-Quaternary climatic change: a global model

A dynamical model for the late-Quaternary global variations of δ18O, mean ocean surface tempeature τ, ice mass I, deep ocean temperature θ, and atmospheric carbon dioxide concentration μ, is constructed. This model consists of two diagnostic equations (for δ18O and τ), and three prognostic equations (for I, θ, and μ) of a form studied extensively in previous articles. The carbon dioxide equation includes forcing by a representation of the Milankovitch earth-orbital radiation effects, and contains a basic instability that drives a free oscillation of period near 100,000 years. The system is constrained to conserve mass and energy, contain physically plausible feedbacks including a system time constant no greater than 10.000 years, and be robust (i. e., structurally stable in the presence of expected noise levels and uncertainties in values of coefficients). Within the limits of these constraints, coefficients are chosen such that (i) the solution gives a good fit to the observed SPECMAP δ18O variations, and (ii) the ice mass variations are qualitatively similar to the δ18O variations. The predicted long term variations of sea surface temperature and atmospheric carbon dioxide are in reasonably good agreement with the limited observational evidence available for these quantities, while the predicted variations of deep ocean temperature remain to be verified when paleoclimatic estimates of this quantity become available. The relative contributions of ice mass changes and surface water temperature changes to the variations of δ18O at any time are given by the model.

Time and space variations of tropospheric carbon dioxide over Japan

Aircraft measurements of atmospheric CO2 concentration over Japan, initiated in January 1979, have been continued to the present. The average seasonal variation of atmospheric CO2 showed maximum co...

Seasonal and meridional variations of atmospheric carbon dioxide in the lower troposphere of the northern and southern hemispheres

Systematic collection of air samples over the Pacific Ocean was begun in March 1982 on board a container ship sailing between Japan and Australia. A current picture of seasonal and meridional variations of lower tropospheric CO2 was derived from the measurement of these samples and supplementary information from several other observational programs. It was concluded that: (1) the amplitude of the seasonal variation was about 15 ppmv in high and mid-latitudes of the northern hemisphere and decreased southward to low values of about 1 ppmv in the southern hemisphere; (2) the maximum and minimum concentrations of the seasonal variation in the mid-latitudes of the northern hemisphere appeared early in April and in mid-August, respectively, and their occurrences were delayed gradually southward and northward from that latitude; (3) the annual mean CO2 concentration was high in the midnorthern hemisphere, decreased gradually southward to low values in the mid-southern hemisphere and increased slightly again in the Antarctic region, the concentration difference between the mid-northern hemisphere and the Antarctic region being about 3 ppmv; (4) the year-to-year changes of annual mean CO2 concentrations in all latitudes covered by this measurement were 1.3 and 1.7 ppmv yr-1, for 1982-1983 and 1983-1984, respectively.

沖縄における大気中の二酸化炭素濃度の時間的変動

沖縄における大気中の二酸化炭素濃度の時間的変動

Global ice-sheet system interlocked by sea level

Denton and Hughes (1983, Quaternary Research 20, 125–144) postulated that sea level linked a global ice-sheet system with both terrestrial and grounded marine components during late Quaternary ice ages. Summer temperature changes near Northern Hemisphere melting margins initiated sea-level fluctuations that controlled marine components in both polar hemispheres. It was further proposed that variations of this ice-sheet system amplified and transmitted Milankovitch summer half-year insolation changes between 45 and 75°N into global climatic changes. New tests of this hypothesis implicate sea level as a major control of the areal extent of grounded portions of the Antarctic Ice Sheet, thus fitting the concept of a globally interlocked ice-sheet system. But recent atmospheric modeling results ( Manabe and Broccoli, 1985, Journal of Geophysical Research 90, 2167–2190) suggest that factors other than areal changes of the grounded Antarctic Ice Sheet strongly influenced Southern Hemisphere climate and terminated the last ice age simultaneously in both polar hemispheres. Atmospheric carbon dioxide linked to high-latitude oceans is the most likely candidate ( Shackleton and Pisias, 1985, Atmospheric carbon dioxide, orbital forcing, and climate. In “The Carbon Cycle and Atmospheric CO 2: Natural Variations Archean to Present” (E. T. Sundquest and W. S. Broecker, Eds.), pp. 303–318. Geophysical Monograph 32, American Geophysical Union, Washington, D.C.), but another potential influence was high-frequency climatic oscillations (2500 yr). It is postulated that variations in atmospheric carbon dioxide acted through an Antarctic ice shelf linked to the grounded ice sheet to produce and terminate Southern Hemisphere ice-age climate. It is further postulated that Milankovitch summer insolation combined with a warm high-frequency oscillation caused marked recession of Northern Hemisphere ice-sheet melting margins and the North Atlantic polar front about 14,000 14C yr B.P. This permitted renewed formation of North Atlantic Deep Water, which could well have controlled atmospheric carbon dioxide ( W. S. Broecker, D. M. Peteet, and D. Rind, 1985, Nature ( London) 315, 21–26). Combined melting and consequent sea-level rise from the three warming factors initiated irreversible collapse of the interlocked global ice-sheet system, which was at its largest but most vulnerable configuration.

Reassessment of late 19th century atmospheric carbon dioxide variations in the air of western Europe and the British Isles based on an unpublished analysis of contemporary air masses by G. S. Callendar

Reassessment of late 19th century atmospheric carbon dioxide variations in the air of western Europe and the British Isles based on an unpublished analysis of contemporary air masses by G. S. Callendar

Reassessment of late 19th century atmospheric carbon dioxide variations in the air of western Europe and the British Isles based on an unpublished analysis of contemporary air masses by G. S. Callendar

We have reassessed measurements of the concentration of atmospheric carbon dioxide made during the 19th century by examining original data published between 1880 and 1905 and an interpretation of these data carried out during the 1930’s by C. S. Callendar, a British engineer. We have perused an unpublished notebook of Callendar which contains a detailed analysis of air masses and wind velocities attending some of these 19th century analyses. We find new evidence to support Callendar’s contention that the concentration of C0 2 in the late nineteenth century was close to 290 ppm. Of particular interest are the observations of J. A. Reiset made on the coast of France from 1871 to 1880 which we show to be consistent with the seasonal cycle of CO 2 as known from modern measurements. From Reiset’s data, we deduce that the mean annual concentration of atmospheric CO 2 circa 1880 in uncontaminated air at 5O°N latitude was 292 ppm. DOI: 10.1111/j.1600-0889.1986.tb00092.x