首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
In Thailand, the world's largest rice exporter, rice constitutes a major export on which the economy of the whole country depends. Climate change could affect rice growth and development and thus jeopardize Thailand's wealth. Current climatic conditions in Thailand are compared to predictions from four general circulation models (GCMs). Temperature predictions correlate well with the observed values. Predictions of monthly rainfall correlate poorly. Virtually all models agree that significant increases in temperature (from 1 to 7 °C) will occur in the region including Thailand following a doubling in atmospheric carbon dioxide (CO2) concentration. The regional seasonality and extent of the rise in temperature varies with each model. Predictions of changes in rainfall vary widely between models. Global warming should in principle allow a northward expansion of rice-growing areas and a lengthening of the growing season now constrained by low temperatures. The expected increase in water-use efficiency due to enhanced CO2 might decrease the water deficit vulnerability of dryland rice areas and could make it possible to slightly expand them.The research described in this article has been funded by the U.S. Environmental Protection Agency (EPA). This document has been prepared at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract # 68-C8-0006 to ManTech Environmental Technology, Inc. It has been subjected to the Agency's peer and administrative review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.  相似文献   

2.
Presented is the assessment of the contribution that such major types of the land use in Russia as arable lands, forage lands, settlements, and peatery make to anthropogenic fluxes of carbon dioxide CO2, methane CH4, and nitrogen oxide N2O, The assessment is based on the methods of computation monitoring carried out in the period from 2000 to 2011. The results of the study demonstrated that every year arable lands cause the emission of CO2 and N2O of about 117.0 and 74.9 million t CO2 equiv, and peatery, 0.54 and 105.4 thousand t CO2 equiv, respectively. The balance of soil carbon in hayfields and pastures is close to zero. The average emissions of CH4 and N2O from the manure of pasture animals amount to 0.2 and 5.0 million t CO2 equiv/year, and those from grass fires, 276.1 and 372.5 thousand t CO2 equiv/year, respectively. The carbon balance in permanent soils of settlements is also almost close to zero, and newly built-up lands are the source of CO2 (9.5 million t/year). The natural overgrowing of fallow lands leads to the accumulation of the soil carbon (about 92.4 million t CO2/year). It was revealed that the intensity of CO2 emission is defined by the soil carbon balance and that of other gases, by the amount of nitrogen fertilizers, plant residues, and manure coming to the soil. The total emission from the land use is 106.9 million t CO2 equiv/year that makes up 4.9% of the total anthropogenic emission of greenhouse gases in the Russian Federation.  相似文献   

3.
Atmospheric CO2 concentrations can be reduced by storing carbon in vegetation. However, this lowers the concentration gradient between the atmosphere and other potential carbon reservoirs, such as the oceans, and thereby reduces the subsequent inherent rate of removal of CO2 from the atmosphere. Hence, storage of carbon in temporary reservoirs can reduce atmospheric CO2 concentrations in the short term, but if the carbon is released again, it will increase concentrations in the long term. It must, therefore, be considered when, or, indeed whether, to store carbon in vegetation sinks.To determine an optimal strategy, the exact nature of climate-change impacts needs to be considered first. Impacts can be mediated by:1. the direct and instantaneous effect of CO2 and its associated temperature;2. the rate of change in CO2 and its associated temperature;3. the cumulative effect of CO2 and its associated temperature.Carbon stored in permanently maintained vegetation sinks can lower atmospheric CO2 concentrations, but this can be done most effectively if sequestration occurs close to the time when atmospheric concentrations are to be lowered. Similarly, maximal rates of change can be most effectively reduced by carbon sequestration close to the time of anticipated maximal rates of change. For reducing impacts via cumulative forcing, however, early sink activity would be more effective than delayed activity.Temporary carbon stores would only be beneficial for climate change impacts related to the cumulative impact of CO2, but it could even worsen impacts mediated via the instantaneous effect of temperature or those related to the rate of change. Hence, the planting of trees is only beneficial in reducing climate-change impacts if the most serious impacts are those related to the cumulative effect of increased temperature. If other impacts are more serious, then the planting of trees would bring greater benefits if it is delayed until closer to the time when the most severe impacts are to be expected. However, if serious land degradation would result from deforestation, or from a failure to plant trees in the near future, then trees should still be planted in order to maximise the amount of carbon stored on land.  相似文献   

4.
《Climate Policy》2013,13(1):56-70
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.  相似文献   

5.
Grassland is one of the most widespread vegetation types worldwide and plays a significant role in regional climate and global carbon cycling. Understanding the sensitivity of Chinese grassland ecosystems to climate change and elevated atmospheric CO2 and the effect of these changes on the grassland ecosystems is a key issue in global carbon cycling. China encompasses vast grassland areas of 354 million ha of 17 major grassland types, according to a national grassland survey. In this study, a process-based terrestrial model the CENTURY model was used to simulate potential changes in net primary productivity (NPP) and soil organic carbon (SOC) of the Leymus chinensis meadow steppe (LCMS) under different scenarios of climatic change and elevated atmospheric CO2. The LCMS sensitivities, its potential responses to climate change, and the change in capacity of carbon stock and sequestration in the future are evaluated. The results showed that the LCMS NPP and SOC are sensitive to climatic change and elevated CO2. In the next 100 years, with doubled CO2 concentration, if temperature increases from 2.7-3.9˚C and precipitation increases by 10% NPP and SOC will increase by 7-21% and 5-6% respectively. However, if temperature increases by 7.5-7.8˚C and precipitation increases by only 10% NPP and SOC would decrease by 24% and 8% respectively. Therefore, changes in the NPP and SOC of the meadow steppe are attributed mainly to the amount of temperature and precipitation change and the atmospheric CO2 concentration in the future.  相似文献   

6.
Summary A series of sensitivity runs have been performed with a coupled climate–carbon cycle model. The climatic component consists of the climate model of intermediate complexity IAP RAS CM. The carbon cycle component is formulated as a simple zero-dimensional model. Its terrestrial part includes gross photosynthesis, and plant and soil respirations, depending on temperature via Q 10-relationships (Lenton, 2000). Oceanic uptake of anthropogenic carbon is formulated is a bi-linear function of tendencies of atmospheric concentration of CO2 and globally averaged annual mean sea surface temperature. The model is forced by the historical industrial and land use emissions of carbon dioxide for the second half of the 19th and the whole of the 20th centuries, and by the emission scenario SRES A2 for the 21st century. For the standard set of the governing parameters, the model realistically captures the main features of the Earth’s observed carbon cycle. A large number of simulations have been performed, perturbing the governing parameters of the terrestrial carbon cycle model. In addition, the climate part is perturbed, either by zeroing or artificially increasing the climate model sensitivity to the doubling of the atmospheric CO2 concentration. Performing the above mentioned perturbations, it is possible to mimic most of the range found in the C4MIP simulations. In this way, a wide range of the climate–carbon cycle feedback strengths is obtained, differing even in the sign of the feedback. If the performed simulations are subjected to the constraints of a maximum allowed deviation of the simulated atmospheric CO2 concentration (pCO2(a)) from the observed values and correspondence between simulated and observed terrestrial uptakes, it is possible to narrow the corresponding uncertainty range. Among these constraints, considering pCO2(a) and uptakes are both important. However, the terrestrial uptakes constrain the simulations more effectively than the oceanic ones. These constraints, while useful, are still unable to rule out both extremely strong positive and modest negative climate–carbon cycle feedback.  相似文献   

7.
Nearly all scenarios for future U.S. energy supply systems show heavy dependence on coal. The magnitude depends on assumptions as to reliance on nuclear fission, degree of electrification, and rate of GNP growth, and ranges from 700 million tons to 2300 million tons per year. However, potential climate change resulting from increasing atmospheric carbon dioxide concentrations may prevent coal from playing a major role. The carbon in the carbon dioxide produced from fossil fuels each year is about 1/10 the net primary production by terrestrial plants, but the fossil fuel production has been growing exponentially at 4.3% per year. Observed atmospheric CO2 concentrations have increased from 315 ppm in 1958 to 330 ppm in 1974 - in 1900, before much fossil fuel was burned, it was about 290–295 ppm. Slightly over one-half the CO2 released from fossil fuels is accounted for by the increase observed in the atmosphere; at present growth rates the quantities are doubling every 15–18 years. Atmospheric models suggest a global warming of about 2 K if the concentration were to rise to two times its pre-1900 value - enough to change the global climate in major (but largely unknown) ways. With the current rate of increase in fossil fuel use, the atmospheric concentration should reach these levels by about 2030. A shift to coal as a replacement for oil and gas gives more carbon dioxide per unit of energy; thus if energy growth continues with a concurrent shift toward coal, high concentrations can be reached somewhat earlier. Even projections with very heavy reliance on non-fossil energy (Neihaus) after 2000 show atmospheric carbon dioxide concentrations reaching 475 ppm.First presented to the symposium, Coal Science and our National Expectations, Annual Meeting of the American Association for the Advancement of Science, Boston, Massachusetts, February 20, 1976.  相似文献   

8.
There is growing scientific and public concern that increasing concentrations of greenhouse gases in the atmosphere will produce global warming and other climatic changes. Although economic activity is the main source of greenhouse gas emissions, information and incentive problems make it difficult to translate concern about global warming into economic behaviour and policy conducive to reducing emissions. The paper considers a set of near term (carbon tax), intermediate term (afforestation, energy efficiency) and long term (new non-fossil fuel technologies) strategies for reducing CO2 in the atmosphere. Each strategy has useful attributes, but shortcomings or limitations too. While the near term and intermediate term strategies can slow and perhaps reverse the growth of CO2 emissions, only a successful long term strategy of fostering the development of some promising non-fossil fuel technologies, such as solar and solar-hydrogen, can eventually halt the build-up of CO2 in the atmosphere. Moreover, public investment in the development of new non-fossil fuel technologies would largely obviate the information and incentive problems that currently stand in the way of an economically viable greenhouse policy.  相似文献   

9.
The Netherlands has ratified The Kyoto protocol and agreed to reduce its emissions of greenhouse gases. Since 1990 the goals were made less ambitious several times, but still the last goal for 2000 was not met. Economic growth surely has been one of the main culprits. The main reason economic growth results in higher CO2 emissions, is the fact that it causes higher energy consumption. So far policy measures to reduce CO2 emissions, including many energy efficiency and energy reduction measures, did not succeed in beating the effects of economic growth. The Netherlands did not manage to decouple economic growth and environmental pressure (measured here as CO2 emissions). Absolute decoupling will require an economy that has a fuel mix with a large proportion of renewables, and a much higher energy efficiency level, and probably some major technological breakthroughs. It is not very likely that current policy measures will lead to the Kyoto goals. Therefore, it is concluded that emission trading and levies would offer good, and efficient options for further reductions of CO2 equivalents. It might, however, make it difficult for The Netherlands to realise 50% of its reduction domestically, as CO2 reduction abroad will most likely be at least five times cheaper. The Ministry of VROM will have to invent new policy measures to meet the Kyoto goals.  相似文献   

10.
The need for atmospheric carbon dioxide(CO_2) reduction in the context of global warming is widely acknowledged by the global scientific community.Fossil fuel CO_2(CO_(2ff)) emissions occur mainly in cities,and can be monitored directly with radiocarbon(~(14) C).In this research,annual plants [Setaria viridis(L.) Beauv.] were collected from 26 sites in 2013 and2014 in the central urban district of Xi'an City.The △~(14)C content of the samples were analyzed using a 3 MV Accelerator Mass Spectrometer,and CO_(2ff) concentrations were calculated based on mass balance equations.The results showed that the CO_(2ff) mixing ratio ranged from 15.9 to 25.0 ppm(part per million,equivalent to μmol mol~(-1)),with an average of 20.5 ppm in 2013.The range of measured values became larger in 2014,from 13.9 ppm to 33.1 ppm,with an average of 23.5 ppm.The differences among the average CO_(2ff) concentrations between the central area and outer urban areas were not statistically significant.Although the year-to-year variation of the CO_(2ff) concentration was significant(P 0.01),there was a distinctly low CO_(2 ff) value observed in the northeast corner of the city.CO_(2 ff) emiissions from vehicle exhaust and residential sources appeared to be more significant than two thermal power plants,according to our observed CO_(2 ff) spatial distribution.The variation of pollution source transport recorded in our observations was likely controlled by southwesterly winds.These results could assist in the optimal placement of regional CO_2 monitoring stations,and benefit the local government in the implementation of efficient carbon emission reduction measures.  相似文献   

11.
Because of its large area of high C density forests and high deforestation rate, Brazil may play an important role in the global C cycle. The study reported here developed an estimate of Brazil's biotic CO2-C budget for the period 1990–2010. The analysis used a spreadsheet C accounting model based on three major components: a conceptual model of ecosystem C cycling, a recently completed vegetation classification developed from remote-sensing data, and published estimates of C density for each of the vegetation classes. The dynamics of the model came from estimates of disturbance to ecosystems that release C and estimates of recovery from past disturbance that store C. The model was projected into the future with three alternative estimates of the rate of future land use change. Under all three deforestation scenarios Brazil was a C source in the range of about 3–5 × 109 MgC over the 20-yr study period.The research described in this article has been funded wholly by the U.S. Environmental Protection Agency. This document has been prepared at the EPA National Health and Environmental Effects Research Laboratory in Corvallis, OR, U.S.A., through contract number 68-C8-0006 to ManTech Environmental Research Services, Corp. It has been subjected to the Agency's peer and administrative review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.  相似文献   

12.
Conditional forecasts of US economic and energy sector activity are developed using information from a dynamic, data-rich environment. The forecasts are conditional on a path for carbon dioxide emissions outlined in the US Environmental Protection Agency’s Clean Power Plan (CPP) and are estimated based on a factor-augmented autoregressive framework. Results suggest that overall growth will be slower under the CPP than it would otherwise; however, economic growth and CO2 reductions can be achieved simultaneously. There are little differences between unconditional (business-as-usual) and conditional forecasts of the variables in the early part of the forecast period; the impacts of the CPP are small while the constraints on carbon dioxide are less stringent. The results serve as a data-driven complement to structural analyses of policy change in the energy sector.  相似文献   

13.
The challenge of reversing rising atmospheric CO2 concentrations is growing with the continued expansion of CO2-emitting energy infrastructure throughout the world and with the lack of coordinated, effective measures to manage and reduce emissions. Given this situation, it is prudent for society to explore all potential carbon management options, including those with seemingly low probability for success. Recent initiatives for advancing and enhancing carbon storage options have focused primarily on the physical trapping of CO2 in underground geologic formations and on the biological uptake of CO2; less attention has been given to approaches that rely primarily on geochemical reactions that enhance transformation of CO2 gas into dissolved or solid phase carbon by liberating cations to neutralize carbonic acid. This paper provides a structured review of the technical status of these geochemical approaches, and also presents a simple framework for assessing the potential and limitations of various proposed geochemical approaches to assist prioritizing future research in this area. Despite major limitations, geochemical approaches have unique potential to contribute to CO2 reductions in ways that neither physical nor biological carbon storage can by allowing for the direct removal of CO2 from the atmosphere with minimal requirements for integrating with existing infrastructure. Recognizing the severity and urgency of the need for carbon management options, we argue for an increase in research activity related to geochemical approaches to carbon management.  相似文献   

14.
《Climate Policy》2013,13(1):71-88
Abstract

Recent analyses continue to modify our understanding of terrestrial carbon sinks. The sinks are large and variable enough to account for much of the variability in the growth rate of atmospheric CO2. They are distributed throughout both northern mid-latitudes and the tropics. Identification of the factors influencing an observed sink is extremely difficult; methods for attribution are reviewed. Although various ecological mechanisms (e.g. CO2 fertilization, nitrogen deposition, climatic variability) have been shown experimentally to have short-term effects on physiological processes controlling the amount of carbon in terrestrial ecosystems, it is unclear which of these mechanisms has been most important in the past 10–100 years and which will be most important in the future. The decades-long supposition that CO2 fertilization has been a major driver of terrestrial carbon uptake is being challenged. A major portion of the sink in the northern mid-latitudes (although probably not in the tropics) is a result of recovery from past changes in land use and management. To the extent that these direct human actions explain most of the current (and future) sink, attribution and thus accounting become more tractable, but the continued functioning of the sink is limited and largely dependent on deliberate actions (e.g. afforestation, sustainable forest management and preservation).  相似文献   

15.
One way to reduce carbon dioxide (CO2) emissions to the atmosphere is to recover it from an energy conversion process (e.g. from stack gases) and to store it in an aquifer (a permeable, mainly sandy, underground layer). The main goal of this study was a preliminary evaluation of this kind of storage.Allowing for a large uncertainty in the geological properties, we arrived at the following tentative results. The average cost of disposal is $1.4 per ton CO2 stored. The enclosing layer of most aquifers seems impermeable enough to prevent the CO2 from rising to the surface within at least 10 000 years. The main technical uncertainty is whether the water in the reservoir can be pushed aside fast enough to prevent an intolerable pressure build-up in the reservoir.The disposal of CO2 in aquifers seems to be a feasible option in the light of existing geological knowledge. If it is a practical possibility, the opportunities are large and the costs appear to be relatively low. However, uncertainties remain in the technical sphere. These uncertainties have to be studied and dispelled before the disposal of CO2 in aquifers can be said to be called technically feasible.  相似文献   

16.
This article analyses the determinants of CO2 emission for 15 post-Soviet Union independent (PSI) countries given their recent transition to market-based economies and their relatively high levels of corruption. The direct and indirect effects of economic growth on CO2 emission for the PSI countries are derived using a multiple-equation generalized method of moment (GMM) approach to account for simultaneity among corruption, growth and CO2 emission. A linear relationship between gross domestic product (GDP) and CO2 emission was observed from the analysis. Furthermore, GDP influences CO2 emission directly, but also indirectly through its impact on corruption. Similarly, corruption affects CO2 emission directly, as well as indirectly through its impact on GDP. Political democracy and economic freedom increase CO2 emission indirectly through their impact on economic growth. Improved energy efficiency and the EU climate policy reduce CO2 emission, while inflows of foreign direct investment tend to increase CO2 emission.

Policy relevance

First, PSI countries need to invest more in efficient energy technologies to mitigate CO2 emission levels significantly. Second, PSI policies aimed at reducing deforestation (thereby increasing population density) may help mitigate carbon emission. Third, PSI countries would be well served to recognize the detrimental effects of foreign direct investment before embarking on a misguided policy path that attracts such inflows at any cost.  相似文献   

17.
Abstract

A new version of the PAGE model, PAGE2002, has been used to calculate the marginal impacts of CO2, CH4 and SF6 emissions based on Scenario A2 of the IPCC. The mean marginal impact of CO2 is found to be US$19 per tonne of carbon (or about US$5 per tonne of CO2), for methane it is US$105 per tonne, and for SF6 it is US$200,000 per tonne. For each gas, the range between the 5% and 95% points is about an order of magnitude. The climate change impacts of methane are a significant proportion of its market price, and for SF6 the climate change impacts are much larger than the market price. The economics of schemes to reduce the leakage of SF6 are transformed once the climate change impacts are properly counted.  相似文献   

18.
利用GEOS-Chem全球三维大气化学传输模式,分析了北半球近地层CO2体积分数的时空变化特征及其成因。2006—2010年的5 a的模拟结果表明:北半球中纬度近地层CO2体积分数存在着两个高值中心,即亚洲东部和北美东北部。在季节尺度上,亚洲东部CO2体积分数最大值出现在春季,而北美东北区域CO2体积分数最大值出现在冬季;而两个地区的CO2体积分数最低值都出现在夏季。在年际尺度上,两个区域CO2体积分数的年际变率增幅明显高于北半球其它区域,且CO2体积分数高值出现时间的年际差异较大。另外,模拟分析发现北半球森林、农田、草原典型区域,所对应的CO2体积分数具有不同的季节变化特点,它们的CO2季节内变幅依次减小。进一步分析发现3种不同典型区域的CO2体积分数与叶面积指数(LAI)季节变化,具有很好的负相关性。可见陆地生态系统作为碳汇,对近地层CO2体积分数的季节变化具有重要的作用。而温度和降水是影响LAI的最重要的两个气象因子,它们与CO2体积分数季节变化存在内在联系,模拟结果表明北半球大部分陆地近地层CO2体积分数与温度、降水呈现显著的负相关。  相似文献   

19.
Ocean iron fertilization has been proposed as a method to mitigate anthropogenic climate change, and there is continued commercial interest in using iron fertilization to generate carbon credits. It has been further speculated that ocean iron fertilization could help mitigate ocean acidification. Here, using a global ocean carbon cycle model, we performed idealized ocean iron fertilization simulations to place an upper bound on the effect of iron fertilization on atmospheric CO2 and ocean acidification. Under the IPCC A2 CO2 emission scenario, at year 2100 the model simulates an atmospheric CO2 concentration of 965 ppm with the mean surface ocean pH 0.44 units less than its pre-industrial value of 8.18. A globally sustained ocean iron fertilization could not diminish CO2 concentrations below 833 ppm or reduce the mean surface ocean pH change to less than 0.38 units. This maximum of 0.06 unit mitigation in surface pH change by the end of this century is achieved at the cost of storing more anthropogenic CO2 in the ocean interior, furthering acidifying the deep-ocean. If the amount of net carbon storage in the deep ocean by iron fertilization produces an equivalent amount of emission credits, ocean iron fertilization further acidifies the deep ocean without conferring any chemical benefit to the surface ocean.  相似文献   

20.
全球农作物对大气CO2及其倍增的吸收量估算   总被引：15，自引：0，他引：15  
王修兰 《气象学报》1996,54(4):466-473
根据农作物产量资料（ＦＡＯ１９９２年），计算出中国和全球各种作物对ＣＯ２的吸收总量分别为５．５×１０８ｔ／ａＣ和２８．９×１０８ｔ／ａＣ。同时以不同ＣＯ２浓度下小麦、玉米、大豆等全生育期光合速率实验数据直接计算的Ｃ吸收量为对照，与相应的中国产量资料计算结果比较，两者相差２．６％。从而进一步依据作物对ＣＯ２倍增反应诊断实验结果，推算出大气ＣＯ２浓度比目前倍增（７００ｐｐｍ）条件下，中国和全球农作物吸收ＣＯ２总量将增长２１％－２６％，分别为６．６×１０８ｔ／ａ—６．９×１０８ｔ／ａ和３４．１×１０８ｔ／ａ—３６．２×１０８ｔ／ａＣ。研究还表明，单位面积作物年吸Ｃ量全球（３．２ｔ／（ｈｍ２·８））比中国（４．２ｔ／（ｈｍ２·ａ））低２５．４％，而且Ｃ４作物普遍高于同类Ｃ３作物。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号