Siberian CO2 efflux in winter as a CO2 source and cause of seasonality in atmospheric CO2

Over three years, we found a consistent CO₂ efflux from forest tundra of the Russian North throughout the year, including a large (89 g C m^–2 yr^–1) efflux during winter. Our results provide one explanation for the observations that the highest atmospheric CO₂ concentration and greatest seasonal amplitude occur at high latitudes rather than over the mid-latitudes, where fossil fuel sources are large, and where high summer productivity offset by winter respiration should give large seasonal oscillations in atmospheric CO₂. Winter respiration probably contributed substantially to the boreal winter CO₂ efflux. Respiration is an exothermic process that produces enough heat to warm soils and promote further decomposition. We suggest that, as a result of this positive feedback, small changes in surface heat flux, associated with human activities in the North or with regional or global warming, could release large quantities of organic carbon that are presently stored in permafrost.     

大气二氧化碳对CO2激光辐射各谱线的吸收

本文给出了大气二氧化碳对CO_2激光辐射各谱线吸收的计算公式,并利用标准大气资料计算了各谱线的吸收值。发现在P支谱线中,P(16)线吸收最大;在R支谱线中,R(16)线为最大。当转动量子数J大于或小于16时,吸收值随J值的增大或减小几乎成指数减小。为了验证计算公式的可靠性,在实验室中进行了模拟大气测量,其测量结果和理论计算结果具有较好的一致性。     

Effect of increasing CO2 on the stratospheric level of CO and O3

Production and destruction processes of carbon monoxide (CO) and ozone (O3) are examined in the light of increasing amount of atmospheric carbon dioxide (CO2). It is found that doubling of CO2 will increase the stratospheric concentration of CO and will have positive effect on O3 concentration.     

Managing atmospheric CO2

A coupled carbon cycle-climate model is used to compute global atmospheric CO₂ and temperature variation that would result from several future CO₂ emission scenarios. The model includes temperature and CO₂ feedbacks on the terrestrial biosphere, and temperature feedback on the oceanic uptake of CO₂. The scenarios used include cases in which fossil fuel CO₂ emissions are held constant at the 1986 value or increase by 1% yr^–1 until either 2000 or 2020, followed by a gradual transition to a rate of decrease of 1 or 2% yr^–1. The climatic effect of increases in non-CO₂ trace gases is included, and scenarios are considered in which these gases increase until 2075 or are stabilized once CO₂ emission reductions begin. Low and high deforestation scenarios are also considered. In all cases, results are computed for equilibrium climatic sensitivities to CO₂ doubling of 2.0 and 4.0 °C.Peak atmospheric CO₂ concentrations of 400–500 ppmv and global mean warming after 1980 of 0.6–3.2 °C occur, with maximum rates of global mean warming of 0.2–0.3 °C decade^–1. The peak CO₂ concentrations in these scenarios are significantly below that commonly regarded as unavoidable; further sensitivity analyses suggest that limiting atmospheric CO₂ to as little as 400 ppmv is a credible option.Two factors in the model are important in limiting atmospheric CO₂: (1) the airborne fraction falls rapidly once emissions begin to decrease, so that total emissions (fossil fuel + land use-induced) need initially fall to only about half their present value in order to stabilize atmospheric CO₂, and (2) changes in rates of deforestation have an immediate and proportional effect on gross emissions from the biosphere, whereas the CO₂ sink due to regrowth of forests responds more slowly, so that decreases in the rate of deforestation have a disproportionately large effect on net emission.If fossil fuel emissions were to decrease at 1–2% yr^–1 beginning early in the next century, emissions could decrease to the rate of CO₂ uptake by the predominantly oceanic sink within 50–100 yrs. Simulation results suggest that if subsequent emission reductions were tied to the rate of CO₂ uptake by natural CO₂ sinks, these reductions could proceed more slowly than initially while preventing further CO₂ increases, since the natural CO₂ sink strength decreases on time scales of one to several centuries. The model used here does not account for the possible effect on atmospheric CO₂ concentration of possible changes in oceanic circulation. Based on past rates of atmospheric CO₂ variation determined from polar ice cores, it appears that the largest plausible perturbation in ocean-air CO₂ flux due to changes of oceanic circulation is substantially smaller than the permitted fossil fuel CO₂ emissions under the above strategy, so tieing fossil fuel emissions to the total sink strength could provide adequate flexibility for responding to unexpected changes in oceanic CO₂ uptake caused by climatic warming-induced changes of oceanic circulation.     

On geoengineering and the CO2 problem

The problem of CO₂ control in the atmosphere is tackled by proposing a kind of fuel cycle for fossil fuels where CO₂ is partially or totally collected at certain transformation points and properly disposed of.CO₂ is disposed of by injection into suitable sinking thermohaline currents that carry and spread it into the deep ocean that has a very large equilibrium capacity.The Mediterranean undercurrent entering the Atlantic at Gibraltar has been identified as one such current; it would have sufficient capacity to deal with all CO₂ produced in Europe even in the year 2100.     

Comparison of eddy-covariance measurements of CO2 fluxes by open- and closed-path CO2 analysers

Eddy fluxes of CO₂ estimated using a sonic anemometer and a closed-path analyser were, on average, 16% lower than those obtained with the same anemometer and an adjacent open-path CO₂ analyser. Covariances between vertical windspeed and CO₂ density from the closed-path analyser were calculated using data points for CO₂ that were delayed relative to anemometer data by the time required for a parcel of air to travel from the tube inlet to the CO₂ sensor. Air flow in the intake tube was laminar. Densities of CO₂ that had been corrected for spurious fluctuations arising from fluctuations in temperature and humidity were used in the flux calculations. Corrections for the cross-sensitivity of CO₂ analysers to water vapour were also incorporated. Spectral analysis of the corrected CO₂ signal from the closed-path analyser showed that damping of fluctuations in the sampling tube at frequencies f > 0.1 Hz caused the apparent loss in flux. The measured losses can be predicted accurately using theory that describes the damping of oscillations in a sampling tube. High-frequency response of the closed-path system can be improved substantially by ensuring turbulent flow in the tube, using a combination of high volumetric flow rate and small tube diameter. The analysis of attenuation of turbulent fluctuations in flow through tubes is applicable to the measurement of fluxes of other minor atmospheric constituents using the eddy covariance method.     

基于生产与消费视角的CO2环境库茨涅兹曲线的实证研究

 基于生产和消费视角,对人均GDP和单位GDP的CO₂排放之间的内在关系进行了实证分析。对1990-2004年44个国家的人均GDP与生产型和消费型的单位GDP的CO₂排放进行面板数据的单位根检验和协整分析,在此基础上,对CO₂环境库茨涅兹曲线（EKC）进行模拟。结果显示：无论是从生产视角还是从消费视角,单位GDP的CO₂排放量都具有显著的倒"U"形状,符合环境库茨涅兹曲线特征。但对于多数发展中国家,消费型单位GDP的CO₂排放量总是低于生产型单位GDP的CO₂排放量,表明多数发展中国家在国际贸易中存在着内涵CO₂排放的净出口,这对从生产角度核算国家温室气体排放体系提出了挑战。最后,分析了CO₂环境库茨涅兹曲线对中国应对气候变化的启示。     

Aspects of CO2 advection measurements

Observations of vegetation–atmosphere exchange of carbon dioxide (CO₂) by the eddy covariance (EC) technique are limited by difficult conditions such as nighttime and heterogeneous terrain. Thus, advective flux components are included into the net ecosystem exchange (NEE) budget. However, advection measurements are experimentally challenging and do not always help to solve the night flux problem of the EC technique. This study investigates alternative methods for the observation of horizontal advection, in particular horizontal concentration gradients, as well as different approaches to coordinate rotation and vertical advection. Continuous high-frequency measurements of the horizontal CO₂ concentration field are employed and compared to the often used discontinuous sequential sampling. Significant differences were found in the case of 30-min mean concentration values between the conventional discontinuous sampling approach and the complete observation of the time series by continuous sampling. Estimates of vertical advection rely on accurate estimates of vertical wind velocity ( $\emph{w}$ ). Therefore, different approaches to the planar fit coordinate rotation have been investigated. Sector-wise rotation was able to eliminate directional dependencies of mean $\emph{w}$ . Furthermore, the effect of the data set length used for rotation (window length) was investigated and was found to have significant impact on estimates of vertical advection, with larger window lengths yielding about 50% larger vertical advection. A sequential planar fit with controlled window length is proposed to give reproducible results. The different approaches to the measurement and calculation of horizontal and vertical advection presented are applied to data obtained during the exchange processes in mountainous region experiment at the FLUXNET site Waldstein–Weidenbrunnen (DE-Bay). Estimates of NEE including advection are compared to NEE from turbulent and storage flux alone without advection. NEE including vertical advection with sector-wise planar fit rotation and controlled window length and including horizontal advection from continuous gradient measurements, which were comprehensively bias corrected by a new approach, did compare well with the expected night flux error, with meteorological drivers of the fluxes and with soil chamber measurements. Unrealistically large and noisy values of horizontal advection from the conventional discontinuous sampling approach, which lead to unrealistic values of NEE, could be eliminated by the alternative approaches presented. We therefore suggest the further testing of those approaches at other sites in order to improve the accuracy of advection measurements and, subsequently, estimates of NEE.     

A robust sequential CO2 emissions strategy based on optimal control of atmospheric CO2 concentrations

This paper formally introduces the concept of mitigation as a stochastic control problem. This is illustrated by applying a digital state variable feedback control approach known as Non-Minimum State Space (NMSS) control to the problem of specifying carbon emissions to control atmospheric CO₂ concentrations in the presence of uncertainty. It is shown that the control approach naturally lends itself to integrating both anticipatory and reflexive mitigation strategies within a single unified framework. The framework explicitly considers the closed-loop nature of climate mitigation, and employs a policy orientated optimisation procedure to specify the properties of this closed-loop system. The product of this exercise is a control law that is suitably conditioned to regulate atmospheric CO₂ concentrations through assimilating online information within a 25-year review cycle framework. It is shown that the optimal control law is also robust when faced with significant levels of uncertainty about the functioning of the global carbon cycle.     

CO2地下埋存分布状况及环境影响的监测

 CO₂的地质埋存处理是减缓温室效应的现实选择之一。要保证埋存的有效性、安全性和持久性,需要对钻井（主要包括注入井和废弃井）、CO₂地下分布运移状况以及因CO₂渗漏所造成的环境影响等方面实施严格的监测管理。通过对以上各方面文献的查阅和综合分析,系统阐述了世界范围内目前CO₂地质埋存过程中所采用的各项主要监测技术。     

On the effect of decreasing CO2 concentration in the atmosphere

In the present paper the effect of an abrupt change of the atmospheric radiative forcing is investigated by means of a global climate model that includes a mixed layer ocean. In assessing if, under such a change, the model response has a bifurcation point, the steady solution is studied for a sudden decrease of CO₂ concentration from its actual value. It is found that there is a critical threshold for CO₂ content below which the model ends up to a snowball Earth. It occurs for a few percentage changes of CO₂ concentration around the threshold because the model strongly depends on the relationship among atmospheric temperature, water vapor content and the sudden ice-albedo feedback activation, even in the subtropical regions. Moreover, results suggest that the transition to ice-covered Earth is clearly favoured when Q-flux corrections (i.e. the parameterization of ocean heat transports) are removed.     

Impact of anthropogenic CO 2 on the next glacial cycle

The model of Paillard and Parrenin (Earth Planet Sci Lett 227(3–4):263–271, 2004) has been recently optimized for the last eight glacial cycles, leading to two different relaxation models with model-data correlations between 0.8 and 0.9 (García-Olivares and Herrero (Clim Dyn 1–25, 2012b)). These two models are here used to predict the effect of an anthropogenic CO ₂ pulse on the evolution of atmospheric CO ₂, global ice volume and Antarctic ice cover during the next 300 kyr. The initial atmospheric CO ₂ condition is obtained after a critical data analysis that sets 1300 Gt as the most realistic carbon Ultimate Recoverable Resources (URR), with the help of a global compartmental model to determine the carbon transfer function to the atmosphere. The next 20 kyr will have an abnormally high greenhouse effect which, according to the CO ₂ values, will lengthen the present interglacial by some 25 to 33 kyr. This is because the perturbation of the current interglacial will lead to a delay in the future advance of the ice sheet on the Antarctic shelf, causing that the relative maximum of boreal insolation found 65 kyr after present (AP) will not affect the developing glaciation. Instead, it will be the following insolation peak, about 110 kyr AP, which will find an appropriate climatic state to trigger the next deglaciation.     

大气中CO2浓度增加对大气顶射出辐射影响的监测

本文分析了大气中CO2浓度增加对2380-2400 cm-1范围大气顶射出辐射的影响，对温度和其它一些大气成分可能的干扰也进行了考察，提出了可以从卫星上对CO2浓度增加的辐射影响进行监测的通道。     

Reservoir timescales for anthropogenic CO2 in the atmosphere

Non-steady state timescales are complicated and their application to specific geophysical systems requires a common theoretical foundation. We first extend reservoir theory by quantifying the difference between turnover time and transit time (or residence time) for time-dependent systems under any mixing conditions. We explicitly demonstrate the errors which result from assuming these timescales are equal, which is only true at steady state. We also derive a new response function which allows the calculation of age distributions and timescales for well-mixed reservoirs away from steady state, and differentiate between timescales based on gross and net fluxes. These theoretical results are particularly important to tracer-calibrated "box models" currently used to study the carbon cycle, which usually approximate reservoirs as well-mixed. We then apply the results to the important case of anthropogenic CO2 in the atmosphere, since timescales describing its behavior are commonly used but ambiguously defined. All relevant timescales, including lifetime, transit time, and adjustment time, are precisely defined and calculated from data and models. Apparent discrepancies between the current, empirically determined turnover time of 30-60 years and longer model-derived estimates of expected lifetime and adjustment time are explained within this theoretical framework. We also discuss the results in light of policy issues related to global warming, in particular since any comparisons of the "lifetimes" of different greenhouse gases (CO2, CH4, N2O, CFC's etc.) must use a consistent definition to be meaningful.     

A load-based CO2 cap in the power sector

Oregon's governor has proposed a load-based cap and trade programme that limits carbon dioxide (CO₂) emissions to 10% below 1990 levels by 2020. A load-based programme is different from the source-based European Union Emissions Trading Scheme (EU ETS), as it regulates emissions sources, located outside the state, that serve Oregon's electricity load. This article describes the stakeholder process that developed the legislative proposal for the load-based cap. The Oregon Clean Energy Planning Model©, a modified capacity expansion model of annual load resource balances, is used to estimate programme costs. The net present value of the climate policy to Oregon ranges from a $518 million benefit to a $414 million cost under various load growth scenarios. Programme benefits are possible under low and medium load growth because the societal returns of energy efficiency exceed its cost over the life of the programme. CO₂ allowance prices in 2017–2020 are estimated in the medium case at approximately $21 per tonne. Low energy efficiency deployment could raise allowance costs to $36, while an aggressive efficiency programme could reduce them to $13.50. Competition for Northwest renewable resources could increase allowance prices in final phase to $37, indicating the interdependence in programme design among state climate policies.     

A commentary on the recent CO2-climate controversy

Suggestions have persisted over the past few years that, contary to conventional estimates, increasing levels of atmospheric carbon dioxide will produce negligible warming of the earth's surface, or might even result in surface cooling. In the present paper we reexamine several aspects of these suggestions and illustrate that they are either founded in various violations of the first law of thermodynamics, or that they are based upon misinterpretations of historical data.     

CO2大气透过率的统计算法

红外CO2吸收带大气透过率算法的改进,是将物理反演法用于业务反演系统所必须突破的最大障碍之一,本文基于McMillin和Fleming的工作而进行的回归变量调整和谱通道宽度的非确定性修正两个算法试验,结果表明:利用前两个算法计算的透过率精度明显地优于后者。     

Interannual variation of atmospheric CO2 concentration

A method is described for the analysis of the interannual variability of background atmospheric carbon dioxide concentration. The analysis is carried out on the data from 6 observatories for which records of >8 years were available.A global-scale interannual variation of CO₂ concentration in the troposphere with a characteristic time-scale of 2–3 years has been confirmed throughout the period of the records. These variations are estimated to be associated with carbon cycle imbalances of 2–3 Gt or annual net exchanges between the atmosphere and another carbon reservoir(s) at a rate of about 1.2 Gt of carbon per year. Lag correlations and amplitude comparisons between the records suggests a low latitude southern hemisphere origin to this phenomenon.The interannual variations of CO₂ increase are found to be correlated with those observed in data for Pacific sea surface temperatures and Pacific witd stress, the Southern Oscillation Index and the Quasi-Biennial Oscillation. However multiple regression studies found that once the Southern Oscillation index is used as an explanatory variable for CO₂ variations, the inclusion of additional geophysical variables does not give any significant improvement in the regression.     

Detection of the CO2 effect upon the climate of Western Europe

Summary In this paper climate changes were examined for the detection of climate modification, expected from the rising CO₂ concentration in the atmosphere.The behaviour of temperature, precipitation and air pressure in the summers of De Bilt during this century was investigated. Each variable displayed a stepwise behaviour on a time scale of about 20 years, which could not be ascribed to chance and is possibly connected with periodicities in the influence of the sun.From the beginning of this century till about 1930 there was a period of cool and wet summers with heights of the barometer which were below normal on an average; the same holds for a period which lasted from approximately 1950 till the end of the sixties. Between these periods the summers were relatively warm and dry with comparatively high pressure values; the same holds for the period that began at the end of the sixties and still continues. The two jumps upwards were more strongly significant than the jump downward and the second jump towards a climate optimum was larger than the first. The CO₂ effect may be imagined to be superimposed upon the stepwise behaviour that is present by nature. Apparently, the behaviour of the summer climate in De Bilt does not run counter to an already-present CO₂ effect. The summers of the next few years to come may give a further confirmation of the assumed CO₂ influence.

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Zusammenfassung In dieser Arbeit werden Klimaschwankungen zum Nachweis einer Änderung untersucht, wie sie von der steigenden CO₂-Konzentration zu erwarten ist. Das Verhalten von Temperatur, Niederschlag und Luftdruck während des Sommers in De Bilt in diesem Jahrhundert wurde bearbeitet. Jedes Element zeigt eine stufenweise Veränderung in Zeitschritten von etwa 20 Jahren, die nicht dem Zufall zugeschrieben werden kann und möglicherweise mit Periodizitäten im Einfluß der Sonne zusammenhängt.Vom Beginn des Jahrhunderts bis etwa 1930 waren die Sommer kühl und feucht bei unternormalen Luftdruckwerten; das gleiche gilt für den Zeitraum von 1950 bis zum Ende der sechziger Jahre. Dazwischen waren die Sommer relativ warm und trocken; was auch für die Zeit nach dem Ende der sechziger Jahre bis heute gilt. Die beiden Sprünge hinauf waren signifikanter als der Sprung hinunter, wobei die zweite Änderung in Richtung auf ein Klimaoptimum größer war als die erste. Der CO₂-Effekt ist möglicherweise diesem natürlichen stufenartigen Verhalten überlagert. Offenkundigerweise widersprechen die Sommer in De Bilt einem schon spürbaren CO₂-Effekt nicht. Die Sommer der nächsten Jahre geben vielleicht eine weitere Bestätigung des angenommenen CO₂-Einflusses.

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二氧化碳红外吸收带透过率的计算

本文较简单而系统地说明了大气中CO_2及类似于CO_2的线形分子的红外吸收带透过率公式及计算方法。在不伤害物理本质的前提下采用分子光谱模型处理。在计算P、R两支谱线的吸收时,采用艾尔萨斯模型并加上弱谱线吸收订正。当有Q支谱线时则在靠近Q支吸收有影响的波段计及Q支谱线的吸收,对它也采用相应的模型处理。