A nonlinear impulse response model of the coupled carbon cycle-climate system (NICCS)

 Impulse-response-function (IRF) models are designed for applications requiring a large number of climate change simulations, such as multi-scenario climate impact studies or cost-benefit integrated-assessment studies. The models apply linear response theory to reproduce the characteristics of the climate response to external forcing computed with sophisticated state-of-the-art climate models like general circulation models of the physical ocean-atmosphere system and three-dimensional oceanic-plus-terrestrial carbon cycle models. Although highly computer efficient, IRF models are nonetheless capable of reproducing the full set of climate-change information generated by the complex models against which they are calibrated. While limited in principle to the linear response regime (less than about 3 ^∘C global-mean temperature change), the applicability of the IRF model presented has been extended into the nonlinear domain through explicit treatment of the climate system's dominant nonlinearities: CO₂ chemistry in ocean water, CO₂ fertilization of land biota, and sublinear radiative forcing. The resultant nonlinear impulse-response model of the coupled carbon cycle-climate system (NICCS) computes the temporal evolution of spatial patterns of climate change for four climate variables of particular relevance for climate impact studies: near-surface temperature, cloud cover, precipitation, and sea level. The space-time response characteristics of the model are derived from an EOF analysis of a transient 850-year greenhouse warming simulation with the Hamburg atmosphere-ocean general circulation model ECHAM3-LSG and a similar response experiment with the Hamburg carbon cycle model HAMOCC. The model is applied to two long-term CO₂ emission scenarios, demonstrating that the use of all currently estimated fossil fuel resources would carry the Earth's climate far beyond the range of climate change for which reliable quantitative predictions are possible today, and that even a freezing of emissions to present-day levels would cause a major global warming in the long term. Received: 28 January 2000 / Accepted: 9 March 2001     

The geography of global urban greenhouse gas emissions: an exploratory analysis

The purpose of this paper is to describe global urban greenhouse gas emissions by region and sector, examine the distribution of emissions through the urban-to-rural gradient, and identify covariates of emission levels for our baseline year, 2000. We use multiple existing spatial databases to identify urban extent, greenhouse gas emissions (CO₂, N₂O, CH₄ and SF₆) and covariates of emissions in a “top-down” analysis. The results indicate that urban activities are significant sources of total greenhouse gas emissions (36.8 and 48.6 % of total). The urban energy sector accounts for between 41.5 and 66.3 % of total energy emissions. Significant differences exist in the urban share of greenhouse gas emissions between developed and developing countries as well as among source sectors for geographic regions. The 50 largest urban emitting areas account for 38.8 % of all urban greenhouse gas emissions. We find that greenhouse gas emissions are significantly associated with population size, density, growth rates, and per capita income. Finally, comparison of our results to “bottom-up” estimates suggest that this research’s data and techniques are best used at the regional and global scales.     

Implications of alternative metrics for global mitigation costs and greenhouse gas emissions from agriculture

100-year Global Warming Potentials (GWPs) are used almost universally to compare emissions of greenhouse gases in national inventories and reduction targets. GWPs have been criticised on several grounds, but little work has been done to determine global mitigation costs under alternative physics-based metrics . We used the integrated assessment model MESSAGE to compare emission pathways and abatement costs for fixed and time-dependent variants of the Global Temperature Change Potential (GTP) with those based on GWPs, for a policy goal of limiting the radiative forcing to a specified level in the year 2100. We find that fixed 100-year GTPs would increase global abatement costs (discounted and aggregated over the 21^st century) under this policy goal by 5–20 % relative to 100-year GWPs, whereas time-varying GTPs would reduce costs by about 5 %. These cost differences are smaller than differences arising from alternative assumptions regarding agricultural mitigation potential and much smaller than those arising from alternative radiative forcing targets. Using the land-use model GLOBIOM, we show that alternative metrics affect food production differently in different world regions depending on regional characteristics of future land-use change to meet growing food demand. We conclude that under scenarios of complete participation, the choice of metric has a limited impact on global abatement costs but could be important for the political economy of regional and sectoral participation in collective mitigation efforts, in particular changing costs and gains over time for agriculture and energy-intensive sectors.     

碳中和愿景下的污水处理厂温室气体排放情景模拟研究

污水处理厂运行过程中大量释放甲烷(CH4)和氧化亚氮(N2O),是重要的人为温室气体排放源.基于2005—2015年统计资料和IPCC核算方法,估算了2005—2015年中国生活污水处理厂CH4和N2O排放,分析了其排放特征和影响因素;依据碳中和愿景设定3种减排情景(低减排、中减排和高减排),并预估了2020—2050...     

Global and regional trends in greenhouse gas emissions from livestock

Following IPCC guidelines (IPCC 2006), we estimate greenhouse gas emissions related to livestock in 237 countries and 11 livestock categories during the period 1961–2010. We find that in 2010 emissions of methane and nitrous oxide related to livestock worldwide represented approximately 9 % of total greenhouse gas (GHG) emissions. Global GHG emissions from livestock increased by 51 % during the analyzed period, mostly due to strong growth of emissions in developing (Non-Annex I) countries (+117 %). In contrast, developed country (Annex I) emissions decreased (?23 %). Beef and dairy cattle are the largest source of livestock emissions (74 % of global livestock emissions). Since developed countries tend to have lower CO₂-equivalent GHG emissions per unit GDP and per quantity of product generated in the livestock sector, the amount of wealth generated per unit GHG emitted from the livestock sector can be increased by improving both livestock farming practices in developing countries and the overall state of economic development. Our results reveal important details of how livestock production and associated GHG emissions have occurred in time and space. Discrepancies with higher tiers, demonstrate the value of more detailed analyses, and discourage over interpretation of smaller-scale trends in the Tier 1 results, but do not undermine the value of global Tier 1 analysis.     

Principles of monitoring of anthropogenic greenhouse gas emissions and sinks

Principles and substantiation of a system of monitoring anthropogenic greenhouse gas emissions and sinks are considered. The basic task of the system is to estimate the anthropogenic contribution to the atmospheric greenhouse gas concentrations and possible climate effect. The major attention is paid to the system of indirect or “computational” monitoring of anthropogenic greenhouse gases. A multifunctional information system is described in the context of its application for solving a number of other ecological problems. It can be used as an instrumental basis for estimating ecological efficiency of measures aimed at reducing emissions and increasing greenhouse gas uptake. The effect should be considered in totality for all greenhouse gases and most hazardous pollutants. Monitoring of anthropogenic greenhouse gas emissions and sinks includes observations (using modeling) of integral indicators of ecosystems and can be used as part of ecological monitoring (for example, dynamics of soil carbon balance of agroecosystems and forest cenoses). The connection of the monitoring of anthropogenic greenhouse gas emissions and sinks with the satellite monitoring enlarges the possible applications of this information system.     

Communicating uncertainty in the IPCC’s greenhouse gas emissions scenarios

The issue of climate change required the development of the Special Report on Emission Scenarios (SRES) by the IPCC. The complexity of the subject and the unique science-policy relation resulted in confusion and discussions appeared in popular media like The Economist. This paper reviews scenario literature and SRES, identifies the most vulnerable elements in the communication of SRES. In the communication of GHG emission scenarios through SRES, the weaknesses that have been identified by the authors of this paper are the normative character of climate change assessment, the plausibility of the scenarios, and the risk of simplification of complex messages. The causes of these communicative issues have been identified as the intrinsic difficulties of interdisciplinary science, the uniqueness of the science-policy relation, and the need for a high degree of transparency. This paper suggests improving future communication of complex messages from scientists to their audience by means of clear reasoning when communicating with non-scientists, explicitly normative emission scenarios, and increased stakeholder participation in scenario development. Based on a presentation at the “IIASA-YSSP uncertainty seminars,” 22 July 2004, and the discussions thereafter.     

全球碳排放格网化格局的变化

基于世界各国年碳排放总量数据和人口密度数据,将人口密度作为一项经济-人口综合指标来对碳排放进行空间分配,运用ArcGIS空间分析工具,做出了1950年、1980年、2014年共3期的全球碳排放空间分布格局图 （0.1?×0.1?),并对各期分布格局及变化进行了比较分析。结果显示：1950年主要碳排放区为美国的东部和欧洲地区,1980年新增中国东部、日本、韩国等为全球碳排放的主要区域,2014年新增印度、东南亚为主要排放区。各碳排放区的排放量总体上大幅增加,少数地区略有减少,这与其工业发展所处的不同阶段有关。该数据能够反映当前全球不同区域的碳排放水平的空间格局,为全球变化研究提供基础数据。     

Exponential analysis in assessing the contribution of greenhouse gases emissions to global warming

Several carbon cycle models listed in the IPCC materials are used for assessing the atmospheric CO₂ response to various scenarios for the CO₂ anthropogenic emission into the atmosphere. The same materials present the Green function expressions of these models in terms of this exponential approximation, i.e., in the form of a sum of exponents. The uncertainties that occur when the Green function is substituted by its exponential approximation are investigated. The reason of such an analysis is a classic conclusion that a general problem of the exponential approximation refers to the class of inconsistent problems.     

Sudden stratospheric warmings and tropospheric blockings in a multi-century simulation of the IPSL-CM5A coupled climate model

The relation between sudden stratospheric warmings (SSWs) and blocking events is analyzed in a multi-centennial pre-industrial simulation of the Institut Pierre Simon Laplace coupled model (IPSL-CM5A), prepared for the fifth phase of the coupled model intercomparison project. The IPSL model captures a fairly realistic distribution of both SSWs and tropospheric blocking events, albeit with a tendency to overestimate the frequency of blocking in the western Pacific and underestimate it in the Euro-Atlantic sector. The 1000-year long simulation reveals statistically significant differences in blocking frequency and duration over the 40-day periods preceding and following the onset of SSWs. More specifically, there is an enhanced blocking frequency over Eurasia before SSWs, followed by an westward displacement of blocking anomalies over the Atlantic region as SSWs evolve and then decline. The frequency of blocking is reduced over the western Pacific sector during the life-cycle of SSWs, while the model simulates no significant relationship with eastern Pacific blocks. Finally, these changes in blocking frequency tend to be associated with a shift in the distribution of blocking lifetime toward longer-lasting blocking events before the onset of SSWs and shorter-lived blocks after the warmings. This study systematically verifies that the results are consistent with the two pictures that (1) blockings produce planetary scale anomalies that can force vertically propagating Rossby waves and then SSWs when the waves break and (2) SSWs affect blockings in return, for instance via the effect they have on the North Atlantic Oscillation.     

Cloud albedo feedback and the super greenhouse effect in a global coupled GCM

Two competing cloud-radiative feedbacks identified in previous studies i.e., cloud albedo feedback and the super greenhouse effect, are examined in a sensitivity study with a global coupled ocean-atmosphere general circulation model. Cloud albedo feedback is strengthened in a sensitivity experiment by lowering the sea-surface temperature (SST) threshold in the specified cloud albedo feedback scheme. This simple parameterization requires coincident warm SSTs and deep convection for upper-level cloud albedos to increase. The enhanced cloud albedo feedback in the sensitivity experiment results in decreased maximum values of SST and cooler surface temperatures over most areas of the planet. There is also a cooling of the tropical troposphere with attendant global changes of atmospheric circulation reminiscent of those observed during La Niña or cold events in the Southern Oscillation. The strengthening of the cloud albedo feedback only occurs over warm tropical oceans (e.g., the western Pacific warm pool), where there is increased albedo, decreased absorbed solar radiation at the surface, stronger surface westerlies, enhanced westward currents, lower temperatures, and decreased precipitation and evaporation. However, the weakened convection over the tropical western Pacific Ocean alters the large-scale circulation in the tropics such that there is increased upper-level divergence over tropical land areas and the tropical Indian Ocean. This results in increased precipitation in those regions and intensified monsoonal regimes. The enhanced precipitation over tropical land areas produces increased clouds and albedo and wetter and cooler land surfaces. These additional contributions to decreased absorbed solar input at the surface combine with similar changes over the tropical oceans to produce the global cooling associated with the stronger cloud albedo feedback. Increased low-level moisture convergence and precipitation over the tropical Indian Ocean enhance slightly the super greenhouse effect there. But the stronger cloud albedo feedback is still the dominant effect, although cooling of SSTs in that region is less than in the tropical western Pacific Ocean. The sensitivity experiment demonstrates how a regional change of radiative forcing is quickly transmitted globally through a combination of radiative and dynamical processes in the coupled model. This study points to the uncertainties involved with the parameterization of cloud albedo and the major implications of such parameterizations concerning the maximum values of SST, global climate sensitivity, and climate change.Support is provided by the Office of Health and Environmental Research of the U.S. Department of Energy, as part of its Carbon Dioxide Research Program.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

Costs and global impacts of black carbon abatement strategies

Abatement of particulate matter has traditionally been driven by health concerns rather than its role in global warming. Here we assess future abatement strategies in terms of how much they reduce the climate impact of black carbon (BC) and organic carbon (OC) from contained combustion. We develop global scenarios which take into account regional differences in climate impact, costs of abatement and ability to pay, as well as both the direct and indirect (snow-albedo) climate impact of BC and OC. To represent the climate impact, we estimate consistent region-specific values of direct and indirect global warming potential (GWP) and global temperature potential (GTP). The indirect GWP has been estimated using a physical approach and includes the effect of change in albedo from BC deposited on snow. The indirect GWP is highest in the Middle East followed by Russia, Europe and North America, while the total GWP is highest in the Middle East, Africa and South Asia. We conclude that prioritizing emission reductions in Asia represents the most cost-efficient global abatement strategy for BC because Asia is (1) responsible for a large share of total emissions, (2) has lower abatement costs compared to Europe and North America and (3) has large health cobenefits from reduced PM₁₀ emissions.     

Non-Kyoto radiative forcing in long-run greenhouse gas emissions and climate change scenarios

Climate policies must consider radiative forcing from Kyoto greenhouse gases, as well as other forcing constituents, such as aerosols and tropospheric ozone that result from air pollutants. Non-Kyoto forcing constituents contribute negative, as well as positive forcing, and overall increases in total forcing result in increases in global average temperature. Non-Kyoto forcing modeling is a relatively new component of climate management scenarios. This paper describes and assesses current non-Kyoto radiative forcing modeling within five integrated assessment models. The study finds negative forcing from aerosols masking (offsetting) approximately 25 % of positive forcing in the near-term in reference non-climate policy projections. However, masking is projected to decline rapidly to 5–10 % by 2100 with increasing Kyoto emissions and assumed reductions in air pollution—with the later declining to as much as 50 % and 80 % below today’s levels by 2050 and 2100 respectively. Together they imply declining importance of non-Kyoto forcing over time. There are however significant uncertainties and large differences across models in projected non-Kyoto emissions and forcing. A look into the modeling reveals differences in base conditions, relationships between Kyoto and non-Kyoto emissions, pollution control assumptions, and other fundamental modeling. In addition, under climate policy scenarios, we find air pollution and resulting non-Kyoto forcing reduced to levels below those produced by air pollution policies alone—e.g., China sulfur emissions fall an additional 45–85 % by 2050. None of the models actively manage non-Kyoto forcing for climate implications. Nonetheless, non-Kyoto forcing may be influencing mitigation results, including allowable carbon dioxide emissions, and further evaluation is merited.     

Dietary greenhouse gas emissions of meat-eaters,fish-eaters,vegetarians and vegans in the UK

The production of animal-based foods is associated with higher greenhouse gas (GHG) emissions than plant-based foods. The objective of this study was to estimate the difference in dietary GHG emissions between self-selected meat-eaters, fish-eaters, vegetarians and vegans in the UK. Subjects were participants in the EPIC-Oxford cohort study. The diets of 2,041 vegans, 15,751 vegetarians, 8,123 fish-eaters and 29,589 meat-eaters aged 20–79 were assessed using a validated food frequency questionnaire. Comparable GHG emissions parameters were developed for the underlying food codes using a dataset of GHG emissions for 94 food commodities in the UK, with a weighting for the global warming potential of each component gas. The average GHG emissions associated with a standard 2,000 kcal diet were estimated for all subjects. ANOVA was used to estimate average dietary GHG emissions by diet group adjusted for sex and age. The age-and-sex-adjusted mean (95 % confidence interval) GHG emissions in kilograms of carbon dioxide equivalents per day (kgCO₂e/day) were 7.19 (7.16, 7.22) for high meat-eaters (?>?=?100 g/d), 5.63 (5.61, 5.65) for medium meat-eaters (50-99 g/d), 4.67 (4.65, 4.70) for low meat-eaters (?<?50 g/d), 3.91 (3.88, 3.94) for fish-eaters, 3.81 (3.79, 3.83) for vegetarians and 2.89 (2.83, 2.94) for vegans. In conclusion, dietary GHG emissions in self-selected meat-eaters are approximately twice as high as those in vegans. It is likely that reductions in meat consumption would lead to reductions in dietary GHG emissions.     

交通运输温室气体核算边界和测算方法研究

交通运输行业是温室气体排放的主要来源之一。“双碳”目标对交通领域碳减排工作提出了更高的要求。我国交通运输行业能源消耗统计和温室气体排放测算的统计数据基础较为薄弱,目前国家层面尚未公布统一的交通运输温室气体核算方法,温室气体排放存在底数不清的问题,其核算边界、范围、方法都有待进一步明确。文中通过梳理国内外交通运输领域温室气体核算边界及测算方法,提出了适用于我国交通运输不同子领域温室气体的测算研究思路。并针对我国交通运输温室气体核算工作现存问题,从健全行业能耗与排放核算方法体系、建立交通运输能耗与碳排放数据共享机制、加强交通能耗与碳排放核算方法培训、强化数据质量管理等方面提出相应的政策建议,为我国交通运输行业温室气体排放核算工作的持续开展提供参考。     

Exploring future copper demand,recycling and associated greenhouse gas emissions in the EU-28

Copper is widely used in modern technology, but declining ore grades and depletion of natural deposits have raised concerns regarding sustainable demand-supply balance in the long term. The vulnerability to primary copper supply restrictions amplifies for countries dependant on imports, notably many EU Member States. Recycling of post-consumer scrap can provide a valuable source of essential material to the European industry. However, a considerable fraction of collected and processed copper old scrap is exported, while the remaining fraction is either not recovered or lost due to nonfunctional recycling undermining the implementation of a circular economy. In this work, material flow analysis, regression analysis, and life cycle assessment are combined to explore the possible evolution of four scenarios of copper demand in Europe to year 2050 and the potentials for greenhouse gas emissions reduction under material circularity conditions.The results show that for three of the four scenarios, secondary production would not comply with the carbon dioxide emissions reduction target of 50% below 2000 levels neither in case of combined aggressive recycling, moderate decarbonization of electricity, and energy efficiency improvements. In particular, for the scenario that describes a “business as usual” approach, the modelled future domestic demand can only be met by increasing primary inputs and, despite strong efforts to improve recycling at end-of-life, the fraction of old scrap in total metal demand seems likely to achieve 65% at best. Should that scenario ensue, the GHG emissions embodied in EU copper demand might result in an emissions gap of more than 15 TgCO₂eq or about +260% the carbon dioxide reduction target. In contrast, the lowest environmental impacts are associated with a scenario emphasizing green technology and more equitable lifestyles. In that scenario, the secondary copper flows will gradually approach the expected demand, laying the foundation for achieving a circular economy with considerable potential for preserving natural capital and mitigating climate change. This possible future, however, requires dramatic changes in the current pattern of material production and consumption, as we discuss.