两种不同减排情景下21世纪气候变化的数值模拟

利用国家气候中心最新发展的气候系统模式BCC-CSM1.0模拟了相对于B1排放情景,两种不同减排情景(De90和De07,表示按照B1情景排放到2012年,之后线性递减,至2050年时CO_2排放水平分别达到1990和2007年排放水平一半的情景)对全球和中国区域气候变化的影响.结果表明:两种减排情景下模式模拟的全球平均地表气温在21世纪40年代以后明显低于Bl情景,比减排情景浓度低于B1的时间延迟了20年左右;尽管De90减排情景在2050年所达到的稳定排放水平低于De07情景,但De90情景下的全球增温在2070年以后才一致低于De07情景,这种滞后町能与耦合系统(主要足海洋)的惯性有关;至21世纪末,De90和De07情景下的全球增温幅度分别比B1情景降低了0.4和0.2℃;从全球分布来看,B1情景下21世纪后30年的增温幅度在北半球高纬度和极地地区最大,减排情景能够显著减少这些地区的增温幅度,减排程度越大,则减少越多;在中国区域,B1情景下21世纪末平均增温比全球平均高约1.2℃,减排情景De90和De07分别比B1情景降低了0.4和0.3℃,中国北方地区增温幅度高于南方及沿海地区,减排情景能够显著减小中国西部地区的增温幅度;B1情景下21世纪后30年伞球增温在冬季最高,De90和De07情景分别能够降低各个季节全球升温幅度的17%和10%左右.     

不同气候变化情景下未来中国热相关死亡风险的预估

预估气候变化背景下中国未来近期、中期及远期温度热相关人群超额死亡风险,为未来热相关人群健康风险防范提供科学依据。基于中国网格化日均气温数据集与3种排放情景下未来日均气温数据、历史人口数据与3种生育率情景下未来人口数据以及死因数据资料计算的热效应暴露-反应关系,计算每日热相关死亡人数。结果表明:（1）未来中国平均气温将持续升高,且北方地区升温幅度较大。（2）1986—2005年中国热相关非意外总死亡人数约为7.1（95%置信区间:5.7—8.5）万。（3）RCP2.6、RCP4.5情景下未来中国热相关非意外总死亡人数均呈现先升后降的变化趋势。21世纪末,不同情景下的热相关非意外总死亡人数均高于基准年代。（4）未来不同情景下中国热相关非意外总死亡人数在黄淮海地区以及成渝地区均呈上升趋势,在RCP2.6、RCP4.5情景下北方地区热相关非意外总死亡人数呈下降趋势,东南沿海地区在21世纪30年代后开始呈下降趋势。总体而言在全球变暖的背景下未来中国热相关死亡风险将上升,而在RCP2.6情景下可以有效抑制其上升趋势。      

Representing global climate change,adaptation and mitigation

The diagrammatic representation of climate change, adaptation and mitigation is important in conceptualizing the problem, identifying important feedbacks, and communicating between disciplines. The Synthesis Report of the IPCC's Third Assessment Report, 2001, uses a “cause and effect” approach developed in the integrated assessment literature. This viewpoint reviews this approach and suggests an alternative, based on stocks and flows. The alternative gives a much richer representation of the problem so that it includes the enhanced greenhouse effect, ancillary benefits of mitigation, the distinction between climate-change and other stresses on natural systems, and a more refined distinction between adaptation and mitigation.     

The use of scenarios as the basis for combined assessment of climate change mitigation and adaptation

Scenarios are used to explore the consequences of different adaptation and mitigation strategies under uncertainty. In this paper, two scenarios are used to explore developments with (1) no mitigation leading to an increase of global mean temperature of 4 °C by 2100 and (2) an ambitious mitigation strategy leading to 2 °C increase by 2100. For the second scenario, uncertainties in the climate system imply that a global mean temperature increase of 3 °C or more cannot be ruled out. Our analysis shows that, in many cases, adaptation and mitigation are not trade-offs but supplements. For example, the number of people exposed to increased water resource stress due to climate change can be substantially reduced in the mitigation scenario, but adaptation will still be required for the remaining large numbers of people exposed to increased stress. Another example is sea level rise, for which, from a global and purely monetary perspective, adaptation (up to 2100) seems more effective than mitigation. From the perspective of poorer and small island countries, however, stringent mitigation is necessary to keep risks at manageable levels. For agriculture, only a scenario based on a combination of adaptation and mitigation is able to avoid serious climate change impacts.     

Economics of climate change mitigation forest policy scenarios for Ukraine

Abstract

This article reveals the contribution of woodland expansion in Ukraine to climate change mitigation policies. The opportunities for climate change mitigation of three policy scenarios: (1) carbon storage in forests, (2) carbon storage and additional wood-for-fuel substitution, and (3) carbon storage with additional sink policy for wood products, are investigated by using a simulation technique, in combination with cost—benefit analysis. The article concludes that the Ukraine's forests and their expansion offer a low-cost opportunity for carbon sequestration. Important factors that influence the results are the discount rate and the time horizon considered in the models. The findings provide evidence that the storage climate change mitigation forest policy scenario is most viable for the country, under the assumptions considered in this research.     

Global socio-economic and climate change mitigation scenarios through the lens of structural change

This paper analyses structural change in the economy as a key but largely unexplored aspect of global socio-economic and climate change mitigation scenarios. Structural change can actually drive energy and land use as much as economic growth and influence mitigation opportunities and barriers. Conversely, stringent climate policy is bound to induce specific structural and socio-economic transformations that are still insufficiently understood. We introduce Multi-Sectoral macroeconomic Integrated Assessment Models as tools to capture the key drivers of structural change and we conduct a multi-model study to assess main structural effects – changes of the sectoral composition and intensity of trade of global and regional economies – in a baseline and 2°C policy scenario by 2050. First, the range of baseline projections across models, for which we identify the main drivers, illustrates the uncertainty on future economic pathways – in emerging economies especially – and inform on plausible alternative futures with implications for energy use and emissions. Second, in all models, climate policy in the 2°C scenario imposes only a second-order impact on the economic structure at the macro-sectoral level – agriculture, manufacturing and services - compared to changes modelled in the baseline. However, this hides more radical changes for individual industries – within the energy sector especially. The study, which adopts a top-down framing of global structural change, represents a starting point to kick-start a conversation and propose a new research agenda seeking to improve understanding of the structural change effects in socio-economic and mitigation scenarios, and better inform policy assessments.     

Integrated assessment of biomass supply and demand in climate change mitigation scenarios

Biomass is often seen as a key component of future energy systems as it can be used for heat and electricity production, as a transport fuel, and a feedstock for chemicals. Furthermore, it can be used in combination with carbon capture and storage to provide so-called “negative emissions”. At the same time, however, its production will require land, possibly impacting food security, land-based carbon stocks, and other environmental services. Thus, the strategies adopted in the supply, conversion, and use of biomass have a significant impact on its effectiveness as a climate change mitigation measure. We use the IMAGE 3.0 integrated assessment model to project three different global, long term scenarios spanning different socioeconomic futures with varying rates of population growth, economic growth, and technological change, and investigate the role of biomass in meeting strict climate targets. Using these scenarios we highlight different possibilities for biomass supply and demand, and provide insights on the requirements and challenges for the effective use of this resource as a climate change mitigation measure. The results show that in scenarios meeting the 1.5 °C target, biomass could exceed 20% of final energy consumption, or 115–180 EJ_Prim/yr in 2050. Such a supply of bioenergy can only be achieved without extreme levels land use change if agricultural yields improve significantly and effective land zoning is implemented. Furthermore, the results highlight that strict mitigation targets are contingent on the availability of advanced technologies such as lignocellulosic fuels and carbon capture and storage.     

Shoreline evolution under climate change wave scenarios

This paper investigates changes in shoreline evolution caused by changes in wave climate. In particular, a number of nearshore wave climate scenarios corresponding to a ??present?? (1961?C1990) and a future time-slice (2071?C2100) are used to drive a beach evolution model to determine monthly and seasonal statistics. To limit the number of variables, an idealised shoreline segment is adopted. The nearshore wave climate scenarios are generated from wind climate scenarios through point wave hindcast and inshore transformation. The original wind forcing comes from regional climate change model experiments of different resolutions and/or driving global climate models, representing different greenhouse-gas emission scenarios. It corresponds to a location offshore the south central coast of England. Hypothesis tests are applied to map the degree of evidence of future change in wave and shoreline statistics relative to the present. Differential statistics resulting from different global climate models and future emission scenarios are also investigated. Further, simple, fast, and straightforward methods that are capable of accommodating a great number of climate change scenarios with limited data reduction requirements are proposed to tackle the problem under consideration. The results of this study show that there are statistically significant changes in nearshore wave climate conditions and beach alignment between current and future climate scenarios. Changes are most notable during late summer for the medium-high future emission scenario and late winter for the medium-low. Despite frequent disagreement between global climate change models on the statistical significance of a change, all experiments agreed in future seasonal trends. Finally, a point of importance for coastal management, material shoreline changes are generally linked to significant changes in future wave direction rather than wave height.     

Robustness of pattern scaled climate change scenarios for adaptation decision support

Pattern scaling offers the promise of exploring spatial details of the climate system response to anthropogenic climate forcings without their full simulation by state-of-the-art Global Climate Models. The circumstances in which pattern scaling methods are capable of delivering on this promise are explored by quantifying its performance in an idealized setting. Given a large ensemble that is assumed to sample the full range of variability and provide quantitative decision-relevant information, the soundness of applying the pattern scaling methodology to generate decision relevant climate scenarios is explored. Pattern scaling is not expected to reproduce its target exactly, of course, and its generic limitations have been well documented since it was first proposed. In this work, using as a particular example the quantification of the risk of heat waves in Southern Europe, it is shown that the magnitude of the error in the pattern scaled estimates can be significant enough to disqualify the use of this approach in quantitative decision-support. This suggests that future application of pattern scaling in climate science should provide decision makers not just a restatement of the assumptions made, but also evidence that the methodology is adequate for purpose in practice for the case under consideration.     

The ocean response to climate change guides both adaptation and mitigation efforts

The ocean's thermal inertia is a major contributor to irreversible ocean changes exceeding time scales that matter to human society. This fact is a challenge to societies as they prepare for the consequences of climate change, especially with respect to the ocean. Here the authors review the requirements for human actions from the ocean's perspective. In the near term (～2030), goals such as the United Nations Sustainable Development Goals (SDGs) will be critical. Over longer times (～2050–2060 and beyond), global carbon neutrality targets may be met as countries continue to work toward reducing emissions. Both adaptation and mitigation plans need to be fully implemented in the interim, and the Global Ocean Observation System should be sustained so that changes can be continuously monitored. In the longer-term (after ～2060), slow emerging changes such as deep ocean warming and sea level rise are committed to continue even in the scenario where net zero emissions are reached. Thus, climate actions have to extend to time scales of hundreds of years. At these time scales, preparation for “high impact, low probability” risks — such as an abrupt showdown of Atlantic Meridional Overturning Circulation, ecosystem change, or irreversible ice sheet loss — should be fully integrated into long-term planning.摘要在全球变化背景下, 海洋的很多变化在人类社会发展的时间尺度上 (百年至千年) 具有不可逆转性, 海洋巨大的热惯性是造成该不可逆性的主要原因. 这个特征为人类和生态系统应对海洋变化提出一系列挑战. 本文从海洋变化的角度总结了人类应对气候变化的要求, 提出需要进行多时间尺度的规划和统筹. 在近期 (到2030年) , 实现联合国可持续发展目标至关重要. 在中期 (2050–2060年前后) , 全球需要逐步减排并实现碳中和目标. 同时, 适应和减缓气候变化的行动和措施必须同步施行; 全球海洋观测系统需要得以维持并完善以持续监测海洋变化. 在远期 (在2060年之后) , 即使全球达到净零排放, 包括深海变暖和海平面上升在内的海洋变化都将持续, 因此应对全球变化的行动需持续数百年之久. 在该时间尺度, 应对“低概率, 高影响”气候风险 (即发生的可能性较低, 但一旦发生影响极大的事件带来的风险, 例如: 大西洋经圈反转环流突然减弱, 海洋生态系统跨过临界点, 无可挽回的冰盖质量损失等) 的准备应充分纳入长期规划.     

Vulnerability and adaptability of wheat production in different climatic zones of Pakistan under climate change scenarios

Ten wheat production sites of Pakistan were categorized into four climatic zones i.e. arid, semi-arid, sub-humid and humid to explore the vulnerability of wheat production in these zones to climate change using CSM-Cropsim-CERES-Wheat model. The analysis was based on multi-year (1971–2000) crop model simulation runs using daily weather series under scenarios of increased temperature and atmospheric carbon dioxide concentration (CO₂) along with two scenarios of water management. Apart from this, sowing date as an adaptation option to offset the likely impacts of climate change was also considered. Increase in temperature resulted in yield declines in arid, semi-arid and sub-humid zone. But the humid zone followed a positive trend of gain in yield with rise in temperature up to 4°C. Within a water regime, increase in CO₂ concentration from 375 to 550 and 700 ppm will exert positive effect on gain in wheat yield but this positive effect is significantly variable in different climatic zones under rainfed conditions than the full irrigation. The highest response was shown by arid zone followed by semi-arid, sub-humid and humid zones. But if the current baseline water regimes (i.e. full irrigation in arid and semi-arid zones and rainfed in sub-humid and humid zones) persist in future, the sub-humid zone will be most benefited in terms of significantly higher percent gain in yield by increasing CO₂ level, mainly because of its rainfed water regime. Within a CO₂ level the changes in water supply from rainfed to full irrigation shows an intense degree of responsiveness in terms of yield gain at 375 ppm CO₂ level compared to 550 and 700 ppm. Arid and semi-arid zones were more responsive compared to sub-humid and humid zones. Rise in temperature reduced the length of crop life cycle in all areas, though at an accelerated rate in the humid zone. These results revealed that the climatic zones have shown a variable intensity of vulnerability to different scenarios of climate change and water management due to their inherent specific and spatial climatic features. In order to cope with the negative effects of climate change, alteration in sowing date towards cooler months will be an appropriate response by the farmers.     

不同情景达到碳中和下中国区域气候变化的预估

利用第6次耦合模式比较计划(CMIP6)中的9个全球气候模式的模拟结果,通过CO₂浓度达峰时间确定SSP1-1.9和SSP1-2.6两种情景下的全球碳中和时间,预估了全球碳中和下中国区域气候较历史参考期(1995—2014年)的未来变化,分析不同时间达到碳中和下气候响应差异,并与未实现碳中和的SSP2-4.5情景下的气候变化对比。结果表明,SSP1-1.9和SSP1-2.6情景下全球达到碳中和的时间分别为2041年和2063年,相较于历史参考期,SSP1-1.9/SSP1-2.6下中国区域平均年气温上升1.22/1.58℃,平均年降水量增加7.1%/9.9%。SSP1-2.6(晚碳中和)较SSP1-1.9(早碳中和)情景下年均温增高约0.36℃,最大升温区位于西南及高原地区。对降水而言,晚碳中和较早碳中和全国平均年降水量增加约2.7%。全年及夏季降水量显著增加区主要在西北,新疆地区出现降水增加超过8%的大值区,冬季则集中于黄河中下游,增幅也超过8%。未碳中和的SSP2-4.5情景下中国区域的升温显著强于SSP1-2.6(碳中和)情景,年平均气温高约0.61℃,西北...     

Harmonising climate change adaptation and mitigation: The case of tourist resorts in Fiji

Tourism in island states is vulnerable to climate change because it may result in detrimental changes in relation to extreme events, sea level rise, transport and communication interruption. This study analyses adaptation to climate change by tourist resorts in Fiji, as well as their potential to reduce climate change through reductions in carbon dioxide emissions. Interviews, site visitations, and an accommodation survey were undertaken. Many operators already prepare for climate-related events and therefore adapt to potential impacts resulting from climate change. Reducing emissions is not important to operators; however, decreasing energy costs for economic reasons is practised. Recommendations for further initiatives are made and synergies between the adaptation and mitigation approaches are explored.     

气候变化条件下雅砻江流域未来径流变化趋势研究

雅砻江为我国重要的水电基地,未来气候变化条件下流域径流变化将直接影响雅砻江梯级水库群运行安全和发电调度,因此研究气候变化对雅砻江流域径流的影响十分必要。首先建立了流域月尺度的SWAT模型,然后使用统计降尺度模型（SDSM）模拟未来2006—2100年流域内各站点的气象数据,最后使用流域SWAT模型对未来2006—2100年月径流进行模拟。结果表明,未来雅砻江流域径流呈上升趋势,且增幅随着辐射强迫的增加同步增大,RCP2.6、RCP4.5、RCP8.5这3种典型浓度路径下年平均径流增幅分别为8.9%、12.5%、16.7%,且2020S（2006—2035年)、2050S（2036—2065年)、2080S（2066—2100年）这3个时期年径流量呈现不同的变化趋势,其中RCP2.6浓度路径下为先逐步增加达到峰值后略有减少,RCP4.5浓度路径下为先逐步增加达到峰值后趋于稳定,RCP8.5浓度路径下为持续增加。流域径流年内分配方面,3种典型浓度路径下汛期径流占全年比例在2020S、2050S、2080S这3个时期均为先降后升趋势,整个预测期总体为降低趋势,RCP2.6、RCP4.5及RCP8.5这3种浓度路径下整个预测期的均值分别由基准期的75.9%降低为72.9%、72.0%、71.2%。径流增加会对流域洪水特性产生较大影响,为此应该修正流域设计洪水计算结果和调整防洪调度方案,以降低雅砻江流域梯级水库群因气候变化而产生的运行风险,并提高发电调度效率。