Carbon dioxide content in the atmospheric thickness over central Eurasia (Issyk Kul Monitoring Station)

The refined data obtained from the spectroscopic measurements of carbon dioxide in the column of the continental atmosphere over the Issyk Kul Monitoring Station during the period 1980–2006 and the results of their comparison with the data obtained from the measurements of carbon dioxide in air samples and with the mean zonal empirical model of the Climate Monitoring and Diagnostics Laboratory (CMDL) are given. Seasonal variations and a long-term trend of carbon dioxide concentration in the atmospheric thickness over a 25-year period of measurements are analyzed. The monthly mean concentration of CO₂ is increased by ～40.5 ppm, and the linear-trend index is 1.62 ppm per year. The results of the aircraft measurements of CO₂ concentration in air samples are, on the average, in agreement with the data obtained from the spectroscopic measurements of carbon dioxide concentration in the atmospheric column. The CO₂ concentration in the surface air varies from day to day, and only its minimum values coincide with the CO₂ concentration in the atmospheric thickness. The results of measurements of CO₂ concentration in the atmospheric thickness and in the atmospheric surface layer over the KZD and KZM stations nearest to each other are, on the whole, in disagreement; moreover, the KZD and KZM data are inconsistent. The CO₂ concentration in the atmospheric thickness is, on the average, 1–2% higher than that obtained with the CMDL model for 42.6° N latitude. The coefficient of correlation between the measurement results and model data is high (r= 0.95).     

Variations in nitrogen dioxide in the atmosphere over central Eurasia (Issyk Kul Monitoring Station)

The results of an analysis of data on the total content of nitrogen dioxide in a vertical atmospheric column are given. These data have been obtained from measurements with the twilight method over a period of 25 years. The monthly and annual means (the arithmetic means of both morning and evening values) of NO₂, on the whole, have increased by ～6% in spite of its rapid decrease in 1991–1995 due to the Pinatubo eruption. The linear-trend index amounts to 0.23% per year. The annual mean over the entire observation time is equal to (3.18 ± 0.05) × 10¹⁵ mol/cm², and the amplitude of seasonal variations amounts to (2.39 ± 0.04) × 10¹⁵ mol/cm². Spectral analysis of the experimental data has revealed compound oscillations with periods of 6 to 253 months, the values of which do not contradict published data. Most of these oscillations are nonharmonic. A simple statistical model satisfactorily describes time variations in the monthly and annual means of NO₂ with rms deviations of ～4% and 1%, respectively.     

Interannual variability in the wintertime air–sea flux of carbon dioxide in the northern North Atlantic, 1981–2001

Gridded fields of sea surface temperature (SST), sea level pressure (SLP), and wind speed were used in combination with data for the atmospheric mole fraction of CO₂ and an empirical relationship between measured values of the fugacity of carbon dioxide in surface water and SST, to calculate the air–sea CO₂ flux in the northern North Atlantic. The flux was calculated for each of the months October–March, in the time period 1981 until 2001, allowing for an assessment of the interannual variations in the region. Locally and on a monthly time scale, the interannual variability of the flux could be as high as ±100% in regions seasonally covered by sea ice. However, in open-ocean areas the variability was normally between ±20% and ±40%. The interannual variability was found to be approximately halved when fluxes averaged over each winter season were compared. Summarised over the whole northern North Atlantic, the air to sea carbon flux over winter totalled 0.08 Gton, with an interannual variability of about ±7%. On a monthly basis the interannual variations were slightly higher, about ±8% to ±13%. Changes in wind speed and atmospheric fCO₂ (the latter directly related to SLP variations) accounted for most of the interannual variations of the computed air–sea CO₂ fluxes. A tendency for increasing CO₂ flux into the ocean with increasing values of the NAO index was identified.     

Estimation of the uncertainty of future changes in atmospheric carbon dioxide concentration and its radiative forcing

An ensemble experiment with the IAP RAS CM was performed to estimate future changes in the atmospheric concentration of carbon dioxide, its radiative forcing, and characteristics of the climate-carbon cycle feedback. Different ensemble members were obtained by varying the governing parameters of the terrestrial carbon cycle of the model. For 1860–2100, anthropogenic CO₂ emissions due to fossil-fuel burning and land use were prescribed from observational estimates for the 19th and 20th centuries. For the 21st century, emissions were taken from the SRES A2 scenario. The ensemble of numerical experiments was analyzed via Bayesian statistics, which made the uncertainty range of estimates much narrower. To distinguish between realistic and unrealistic ensemble members, the observational characteristics of the carbon cycle for the 20th century were used as a criterion. For the given emission scenario, the carbon dioxide concentration expected by the end of the 21st century falls into the range 818 ± 46 ppm (an average plus or minus standard deviation). The corresponding global instantaneous radiative forcing at the top of the atmosphere (relative to the preindustrial state) lies in the uncertainty range 6.8 ± 0.4 W m^?2. The uncertainty range of the strength of the climate-carbon cycle feedback by the end of the 21st century reaches 59 ± 98 ppm in terms of the atmospheric carbon dioxide concentration and 0.4 ± 0.7 W m^?2 in terms of the radiative forcing.     

Temporal variations in carbon dioxide and methane concentrations under urban conditions

Temporal variations in the surface concentrations of two greenhouse gases (carbon dioxide and methane) in the atmosphere over a large city are studied on the basis of the data obtained during the 2003–2005 observations at a Moscow station for environmental monitoring. This station is based on the TROICA mobile observatory and located at the meteorological station of the Faculty of Geography, Moscow State University, on Vorob’evy gory. The methods of isolating the background concentrations of greenhouse gases under urban conditions are proposed, and the excess concentrations of CO₂ and CH₄ over their background values are estimated for different seasons and times of day. The CO₂ and CH₄ concentrations are shown to have more pronounced diurnal cycles in summer than in winter. The main causes of temporal variations in the surface concentrations of CO₂ and CH₄ under urban conditions and the differences between the mean concentrations of these greenhouse gases in Moscow and other areas of Russia are analyzed. It is shown that variations in the surface concentrations of carbon dioxide and methane on different time scales are caused by different atmospheric processes (global circulation, mesoscale gravity waves, surface temperature inversions, etc.)     

Atmosphere-ocean general circulation model with the carbon cycle

Results from numerical experiments with an atmosphere-ocean general circulation model coupled to the carbon evolution cycle are analyzed. The model is used to carry out an experiment on the simulation of the climate and carbon cycle change in 1861–2100 under a specified scenario of the carbon dioxide emission from fossil fuel and land use. The spatial distribution of vegetation, soil, and oceanic carbon in the 20th century is generally close to available estimates from observational data. The model adequately reproduces the observed growth of atmospheric CO₂ in the 20th century and the uptake of excess carbon by land ecosystems and by the ocean in the 1980s and 1990s. By 2100, the atmospheric CO₂ concentration is calculated to reach 742 ppmv under emission and land-use scenario A1B. The feedback between climate change and the carbon cycle in the model is positive, with a coefficient close to the mean of all the current models. The ocean and land uptakes of the CO₂ emission by 2100 in the model are 25 and 19%, which are also close to the mean over all models.     

Methane, carbon monoxide, and carbon dioxide concentrations measured in the atmospheric surface layer over continental Russia in the TROICA experiments

The principal statistical regularities typical of the behaviors of the CH₄, CO, and CO₂ concentrations in the atmospheric surface layer over the continental Russian territory are revealed from the measurements performed in 1997–2004 along the Trans-Siberian Railroad from Moscow to Khabarovsk with a mobile laboratory. The data obtained under the conditions of the atmosphere free of anthropogenic pollutants are analyzed. For near-background conditions, the typical continental methane, carbon monoxide, and carbon dioxide concentrations and characteristic features of their large-scale spatial distributions and daily variations, including those caused by surface inversions, are determined. Variations in the concentrations of these trace gases over industrial regions are analyzed. Our results are compared to the data obtained at background stations of the world network of atmospheric monitoring and to the data of a numerical simulation.     

Carbon oxide in the surface air (Obninsk monitoring station)

The results of measurements of the concentration of carbon oxide (CO) in the atmospheric surface layer over the town of Obninsk (in European Russia, 105 km to the southwest of Moscow) are presented. Air samples were analyzed with the aid of a measuring system consisting of a Fourier-spectrometer and an optic multipass cell. The CO concentration was measured simultaneously with the measurements of air temperature up to a height of 300 m. The measurement data obtained from February 1998 to January 2009 suggest the presence of variations within the range 100–450 ppb (∼80% of all the data) and nonperiodic relatively short-term and anomalously high CO concentrations that reach several ppm. The highest concentrations are due to CO accumulated in the surface air in the presence of temperature inversion and during forest fires. The measurements of the concentration of CO throughout a day revealed its morning and evening maxima, which coincide in time with the increased traffic current. The maxima and minima of seasonal variations in the monthly mean concentrations of CO, which are due to variations in the sources and sinks of CO that happen within a year, are observed in January and June, respectively. The amplitudes of seasonal variations amounted to (53 ± 10)% of the annual mean. The annual mean concentration of CO decreased by ∼12% over the measurement period. A comparison was made with observational data obtained at five monitoring stations located in the latitudes that are close to the latitude of Obninsk. Over the European continent, the concentration of CO tends to decrease with a longitude decrease as it goes from east to west.     

Concentration of surface ozone, Obninsk, 2004–2010

The results of measurements of surface ozone in central European Russia in 2004–2010 are presented. The variation coefficient for hourly, monthly, and annual mean ozone concentrations is 78, 26, and 12%, respectively. The measurements established a link between increased (>60 μg/m³) and minimum (<12 μg/m³) hourly mean ozone concentrations with the existence of a temperature inversion in the lower 300-m atmospheric layer. Sixty-seven percent of the total number of increased hourly mean ozone concentrations over the 2004–2010 period took place in 2010. A maximum hourly mean ozone concentration of 218.5 μg/m³ was recorded at 17:00 on August 1, 2010. The annual mean ozone concentration in a climatically significant range of hourly mean concentrations from 12 to 60 μg/m³ increased by 45% in a linear approximation over the period of record. The spectral analysis of monthly mean concentrations of surface ozone identified composite oscillations with periods from 3 to 60 months. To approximate the temporal dynamics of ozone, a statistical model was used. This model satisfactorily describes the experimental monthly and annual mean concentrations.     

Modelling the monthly sea surface fCO2 fields in the Indian Ocean

In order to construct monthly fields of sea surface fugacity of carbon dioxide (f_CO2) on a large scale in the Indian Ocean, we use a one-dimensional model which takes into account the main physical and biogeochemical processes controlling f_CO2 variations in the ocean. Physical and biogeochemical processes are constrained by the monthly variations of sea surface temperature, salinity, chlorophyll concentration, wind speed and mixed-layer depth. The model is applied to four locations in the Indian Ocean and it well predicts observed temporal variations in f_CO2 at these locations. Regarding to monthly f_CO2 observations, the model also well simulates the f_CO2 distribution and its temporal variations along a track located between 20 ° and 50 °S with a maximal error of + 10 μatm. The model is also used to predict f_CO2 for 2 ° × 2 ° grids over the entire Indian Ocean and simulates seasonal cycles that are consistent with observations. The monthly f_CO2 fields derived from the model are used to estimate a global air-sea CO₂ flux over the Indian Ocean basin. We estimate a net sink of 0.5 Gt/yr C for the Indian Ocean (20 °N-50 °S), with the main sink located between 20 ° and 50 °S.     

Measurements of carbon dioxide in the Seto Inland Sea of Japan

The carbon dioxide in seawater (pCO₂) was measured in the Seto Inland Sea of Japan using newly developed equilibrator instrument designed to be free from the correction for addition or extraction of the carbon dioxide from carrier gas. The temperature dependence of pCO₂ was about 4.5%pCO₂/°C for a single seawater sample which was processed as free from biological activity and change in total carbon dioxide content during an experiment. The decrease in pCO₂ during daylight hours due to the photosynthetic fixation was about 30% of the daily mean of pCO₂ during warm months and about 15% during cold months. The effect of carbon dioxide exchange between air and seawater on pCO₂ was about 0.6 ppm in August and about 0.1 ppm in March. This is negligible small compared with the daily oscillation of carbon dioxide in seawater.     

Carbon dioxide partial pressures in North Pacific surface waters. 2. General late summer distribution

Observations of the equilibrium partial pressure of carbon dioxide in the surface waters of the North Pacific Ocean and Bering Sea indicate conditions of local upwelling or vertical mixing near the Aleutian Island passes, seasonal depletion of CO₂ in the sea surface by photosynthesis, and conditions of CO₂ supersaturation in the surface waters off the mouths of large rivers. Horizontal mixing has a large effect on the P_CO2 distribution. The area distribution of carbon dioxide in the surface waters of the Pacific Ocean from 19°N to 55°N latitude and in the Bering Sea is presented.     

Variations in the column-average dry-air mole fractions of CO2 in the vicinity of St. Petersburg

The results obtained from ground-based spectroscopic measurements of column-average dry-air mole fractions of CO₂ in the atmosphere over the St. Petersburg region are given for the period April 2009–October 2011 (～900 measurement runs, 151 measurement days). These results show significant variations in the CO₂ mixing ratio in the atmosphere over the St. Petersburg region. The minimum value of this mixing ratio (373.1 ppm) was observed on April 27, 2011, and its maximum value (420.8 ppm) was observed on February 10, 2010. The typical seasonal behavior of the CO₂ mixing ratio with its summer minimum was observed in 2009. In July 2010 and 2011, the values of the CO₂ mixing ratio increased apparently due to high air temperatures. In 2010 an additional contribution to this increase in the CO₂ mixing ratio could have been made by strong natural fires.     

Seasonal dissolved inorganic carbon variations in the Greenland Sea and implications for atmospheric CO2 exchange

During the 1993–1995 period of minimal deep convection in the Greenland Sea, the dissolved inorganic carbon concentration within the surface waters varied dramatically on the seasonal time scale, with average summer and winter values of 2064 (±10) and 2150 (±5) μmol kg⁻¹, respectively, indicative of a vigorous annual carbon cycle. In contrast, there was very little interannual variability throughout these three years. While primary production largely depleted the surface nutrient supplies in spring and summer, generating a strong seasonal CO₂ drawdown, a combination of relatively shallow remineralization and mixed-layer deepening brought essentially all of the carbon consumed by photosynthesis back into contact with the atmosphere before winter. This re-release of the inorganic carbon that had been consumed by phytoplankton earlier in the year was more than sufficient to counteract the cooling-induced increase in the carbon carrying capacity of the water during fall and winter, reducing the potential for atmospheric carbon dioxide absorption by the Greenland Sea over the same period.     

海洋酸化模拟控制系统及其在珊瑚生理研究中的应用

Due to the elevated atmospheric carbon dioxide, ocean acidification(OA) has recently emerged as a research theme in marine biology due to an expected deleterious effect of altered seawater chemistry on calcification. A system simulating future OA scenario is crucial for OA-related studies. Here, we designed an OA-simulated system(OASys) with three solenoid-controlled CO2 gas channels. The OASys can adjust the pH of the seawater by bubbling CO2 gas into seawaters via feedback systems. The OASys is very simple in structure with an integrated design and is new-user friendly with the instruction. Moreover, the OASys can monitor and record real-time pH values and can maintain pH levels within 0.02 pH unit. In a 15-d experiment, the OASys was applied to simulate OA in which the expected target pH values were 8.00, 7.80 and 7.60 to study the calcifying response of Galaxea fascicularis. The results showed daily mean seawater pH values held at pH 8.00±0.01, 7.80±0.01 and 7.61±0.01 over15 d. Correspondingly, the coral calcification of G. fascicularis gradually decreased with reduced pH.     

<Emphasis Type="Italic">In situ</Emphasis> Enclosure Experiment Using a Benthic Chamber System to Assess the Effect of High Concentration of CO<Subscript>2</Subscript> on Deep-Sea Benthic Communities

In order to evaluate the environmental impact associated with sequestration of carbon dioxide in the deep sea, a free fall type field experimental device, the benthic chamber, was developed. In situ experiments to expose deep-sea communities to elevated concentrations of carbon dioxide (average of 20,000 ppm, 5,000 ppm and control) were carried out using this device 3 times, viz., in the winter of 2002 and in the spring and the summer of 2003, in the Kumano Trough at a depth of 2,000 m. In the long-term experiments (about two weeks in winter of 2002 and summer of 2003), the abundance of meiobenthos declined whereas that of bacteria increased under the condition of 20,000 ppm carbon dioxide compared with the control. Among meiofauna, the abundance of foraminifers at the same concentration of carbon dioxide became less than the control even in the short-term (3 days in spring of 2003) experiment, suggesting that organisms with a calcium carbonate exoskeleton are more sensitive to the raised concentration of carbon dioxide. The respiration rate of the benthic community exposed to 20,000 ppm was lower in the early stage of the experiment than in the latter half, whereas it was opposite under the condition of 5,000 ppm. The increase of biological activity in the 20,000 ppm exposure group is probably due to an increase of bacteria adapted to high carbon dioxide concentrations. The present results suggest that the influence of carbon dioxide on the deep-sea benthic ecosystem does not follow a simple, linear relationship with concentration.     

Background component of methane concentration in surface air (Obninsk monitoring station)

We present measurement data from February 1998 to January 2014 obtained by Fourier spectroscopy for bulk methane concentrations in surface air samples. We have excluded the results of individual measurements of high methane concentrations arising at a temperature inversion and during fires to separate the monthly mean concentrations into the regional natural background concentration of methane and its anthropogenic addition. A seasonal concentration has been separated from the background concentration. Spectral analysis reveals a large number of composite oscillations of variations in the background methane concentra- tion with periods of 3 to 126 months. A model with the use of empirical parameters of these oscillations describes the temporal changes in the methane concentration with an error of less than 3%. The anthropogenic addition of CH₄ in the atmosphere is largely of a random character. Over 16 years of observations, its increase was ~23.7 ppb, which has resulted in an increase in the total CH₄ concentration by the same amount.     

Estimation of changes in characteristics of the climate and carbon cycle in the 21st century accounting for the uncertainty of terrestrial biota parameter values

ensemble simulations with the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS) climate model (CM) for the 21st century are analyzed taking into account anthropogenic forcings in accordance with the Special Report on Emission Scenarios (SRES) A2, A1B, and B1, whereas agricultural land areas were assumed to change in accordance with the Land Use Harmonization project scenarios. Different realizations within these ensemble experiments were constructed by varying two governing parameters of the terrestrial carbon cycle. The ensemble simulations were analyzed with the use of Bayesian statistics, which makes it possible to suppress the influence of unrealistic members of these experiments on their results. It is established that, for global values of the main characteristics of the terrestrial carbon cycle, the SRES scenarios used do not differ statistically from each other, so within the framework of the model, the primary productivity of terrestrial vegetation will increase in the 21st century from 74 ± 1 to 102 ± 13 PgC yr⁻¹ and the carbon storage in terrestrial vegetation will increase from 511 ± 8 to 611 ± 8 PgC (here and below, we indicate the mean ± standard deviations). The mutual compensation of changes in the soil carbon stock in different regions will make global changes in the soil carbon storage in the 21st century statistically insignificant. The global CO₂ uptake by terrestrial ecosystems will increase in the first half of the 21st century, whereupon it will decrease. The uncertainty interval of this variable in the middle (end) of the 21st century will be from 1.3 to 3.4 PgC yr⁻¹ (from 0.3 to 3.1 PgC yr⁻¹). In most regions, an increase in the net productivity of terrestrial vegetation (especially outside the tropics), the accumulation of carbon in this vegetation, and changes in the amount of soil carbon stock (with the total carbon accumulation in soils of the tropics and subtropics and the regions of both accumulation and loss of soil carbon at higher latitudes) will be robust within the ensemble in the 21st century, as will the CO₂ uptake from the atmosphere only by terrestrial ecosystems located at extratropical latitudes of Eurasia, first and foremost by the Siberian taiga. However, substantial differences in anthropogenic emissions between the SRES scenarios in the 21st century lead to statistically significant differences between these scenarios in the carbon dioxide uptake by the ocean, the carbon dioxide content in the atmosphere, and changes in the surface air temperature. In particular, according to the SRES A2 (A1B, B1) scenario, in 2071–2100 the carbon flux from the atmosphere to the ocean will be 10.6 ± 0.6 PgC yr⁻¹ (8.3 ± 0.5, 5.6 ± 0.3 PgC yr⁻¹), and the carbon dioxide concentration in the atmosphere will reach 773 ± 28 ppmv (662 ± 24, 534 ± 16 ppmv) by 2100. The annual mean warming in 2071–2100 relatively to 1961–1990 will be 3.19 ± 0.09 K (2.52 ± 0.08, 1.84 ± 0.06 K).     

Sub-Lethal Effects of Elevated Concentration of CO<Subscript>2</Subscript> on Planktonic Copepods and Sea Urchins

Data concerning the effects of high CO₂ concentrations on marine organisms are essential for both predicting future impacts of the increasing atmospheric CO₂ concentration and assessing the effects of deep-sea CO₂sequestration. Here we review our recent studies evaluating the effects of elevated CO₂ concentrations in seawater on the mortality and egg production of the marine planktonic copepod, Acartia steueri, and on the fertilization rate and larval morphology of sea urchin embryos, Hemicentrotus pulcherrimus and Echinometra mathaei. Under conditions of +10,000 ppm CO₂ in seawater (pH 6.8), the egg production rates of copepods decreased significantly. The survival rates of adult copepods were not affected when reared under increased CO₂ for 8 days, however longer exposure times could have revealed toxic effects of elevated CO₂ concentrations. The fertilization rate of sea urchin eggs of both species decreased with increasing CO₂ concentration. Furthermore, the size of pluteus larvae decreased with increasing CO₂ concentration and malformed skeletogenesis was observed in both larvae. This suggests that calcification is affected by elevated CO₂ in the seawater. From these results, we conclude that increased CO₂ concentration in seawater will chronically affect several marine organisms and we discuss the effects of increased CO₂ on the marine carbon cycle and marine ecosystem. This revised version was published online in July 2006 with corrections to the Cover Date.     

西沙大气二氧化碳浓度变化特征研究

CO2是引起全球气候变暖的最重要温室气体。大气中过量CO2被海水吸收后将改变海水中碳酸盐体系的组成,造成海水酸化,危害海洋生态环境。本文采用局部近似回归法对2013年12月—2014年11月期间西沙海洋大气CO2浓度连续监测数据进行筛分,得到西沙大气CO2区域本底浓度。结果表明,西沙大气CO2区域浓度具有明显的日变化和季节变化特征。4个季节西沙大气CO2区域本底浓度日变化均表现为白天低、夜晚高,最高值405.39×10-6(体积比),最低值399.12×10-6(体积比)。西沙大气CO2区域本底浓度季节变化特征表现为春季和冬季高,夏季和秋季低。CO2月平均浓度最高值出现在2013年12月,为406.22×10-6(体积比),最低值出现在2014年9月,为398.68×10-6(体积比)。西沙大气CO2区域本底浓度日变化主要受本区域日照和温度控制。季节变化主要控制因素是南海季风和大气环流,南海尤其是北部海域初级生产力变化和海洋对大气CO2的源/汇调节作用。