基于IPCC AR4耦合模式的南极涛动和北极涛动的模拟及未来变化预估

评估了参加政府间气候变化委员会第4次评估报告(IPCCAR4)的耦合模式对南极涛动和北极涛动的模拟能力。分析了24个模式对1970—1999年南极涛动和北极涛动的模拟效能,并与两套再分析资料ERA-40和NCEP-1进行了对比分析。结果表明,模式的模拟能力具有一定的季节依赖性,冬季模拟能力最好。大多数模式对南极涛动空间结构和时间序列趋势的模拟好于北极涛动。根据Taylor图选出具有较好模拟能力的模式并做集合分析,发现经过选取的模式集合可以明显改善模式的模拟能力。分析SRESA1B情景下的南极涛动和北极涛动的模拟、预估结果表明:1970—2099年,南极涛动和北极涛动指数均呈持续上升趋势,北极涛动指数增长略显平稳。相对于1970—1999年、2060—2089年两半球的海平面气压场均呈现极区气压降低、中纬度气压升高的形态,同样表明南、北极涛动在后一时段更强。因此,在气候变暖背景下,南、北极涛动将持续增强,21世纪中期的臭氧恢复可能不会显著影响这种趋势。     

Synthesizing a policy-relevant perspective from the three IPCC “Worlds”—A comparison of topics and frames in the SPMs of the Fifth Assessment Report

The paper investigates topics, emphases, frames and absences in the Summary for Policymakers parts of the three Working Group reports in the IPCC 5th Assessment Report and the Summary for Policymakers of the Synthesis Report. It explores similarities and differences by using various tools of lexical and discourse analysis, combining quantitative and qualitative methods. The main results are these: First, each Working Group’s Summary reflects not only the Working Group’s distinctive mandate but also a distinctive intellectual framing. Second, although there are some significant differences in the emphases given to different themes from the Working Groups, the Synthesis Summary covers the main topics of the three other Summaries, and constitutes a relatively integrated summary of the complete Assessment Report. Third, we find though that the Synthesis Summary centrally follows up the risk framing and language which are prominent in Working Group II but semi-absent in the other Working Groups, as part of constructing a policy-relevant statement from the three distinctive reports. In addition, the Synthesis Summary makes use of linguistic devices which contribute to ‘amplify’ the strength of statements, as part of transferring messages effectively from the scientific context to a policy-maker audience. Fourth, we find that the style and tone of the IPCC Summaries conduce also to important absences and imbalances in emphasis: main victims of climate change (particular groups of vulnerable people) remain virtually invisible in the Summaries, unlike the impacts in nature and ecological systems or the aggregate economic impacts, and correspondingly the challenges, options and opportunities for action remain relatively underdeveloped in the analysis.     

Some Opinions on Rock-Weathering-Related Carbon Sinks from the IPCC Fifth Assessment Report

Many recent researches show that rock-weathering-related carbon sink, especially carbonate-weathering-related carbon sink, actively takes part in the modern global carbon cycle, which might greatly contribute to balancing global carbon budget. Some new opinions on flux, time scale and effect of rock-weathering-related carbon sink were released in IPCC fifth Assessment Report (AR5). The flux of global rock-weathering-related carbon sink is about 0.4 Pg C/a in AR5 report, which accounts for about 1/2~1/3 of unbalanced global carbon budget. New time scale of global rock-weathering-related carbon sink was released. Time scale of silicate-weathering-related carbon sink is 10⁴~ 10⁶ year, while carbonate-weathering-related carbon sink (karst processes) is 10³~10⁴ year. A highlight is that rock-weathering-related carbon sink is listed as one of four carbon dioxide removal methods in AR5 report, whose time scale is 10²~ 10³ year. Although AR5 report released these new opinions, it is still thought that the rate of global rock-weathering-related carbon sink is currently too small to offset the rate at which fossil fuel CO₂ is being emitted. According to many researches in the field of rock weathering science in the past decades, this review discussed the shortage in carbon flux, time scale and effect of rock-weathering-related carbon sink in AR5 report. Many recent researches indicated that the carbon sink originated from carbonate rock weathering was a fast and sensitive geochemical process, which showed multiple time scales (diel, seasonal, annual or storm event). A new model based on H₂O carbonate-CO₂-aquatic phototroph interaction was established, which coupled geological, land surface water, and submerged phototroph carbon cycle process. The global carbon sink from carbonate rock weathering in new model is 0.477 Pg C/a,which accounts for about 39%~59% of unbalanced global carbon budget. Some key scientific issues on rate, stability, controlling mechanisms and scaling of rock-weathering-related carbon sink should be vitally concerned in the future, which could greatly contribute to balancing the global carbon budget.     

Climate-induced change of environmentally defined floristic domains: A conservation based vulnerability framework

Global climate change is having marked influences on species distributions, phenology and ecosystem composition and raises questions as to the effectiveness of current conservation strategies. Conservation planning has only recently begun to adequately account for dynamic threats such as climate change. We propose a method to incorporate climate-dynamic environmental domains, identified using specific environmental correlates of floristic composition, into conservation strategies, using the province of KwaZulu-Natal, South Africa as a case study. The environmental domains offer an approach to conservation that conserves diversity under current and future climates, recognising that the species constituting diversity may change through time. We mapped current locations of domains by identifying their positions in a multi-dimensional environmental space using a non-hierarchical iterative k-means clustering algorithm. Their future locations were explored using an ensemble of future climate scenarios. The HadCM2 and GFDL2.1 models represented the extreme ranges of the models. The magnitude of change in each environmental domain was calculated using Euclidean distances to determine areas of greatest and least stability for each future climate projection. Domains occurring in the savanna biome increase at the expense of domains occurring in the grassland biome, which has significant negative consequences for the species rich grasslands. The magnitude of change maps represents areas of changed climatic conditions or edaphic disjunctions. The HadCM2 model predicted the greatest overall magnitude of change across the province. Species with specific soil requirements may not be able to track changing climatic conditions. A vulnerability framework was developed that incorporated climatic stability and habitat intactness indices. The mean magnitude of change informed the potential speed of transition of domains between the vulnerability quadrants. The framework informs appropriate conservation actions to mitigate climate change impacts on biodiversity. The study explicitly links floristic pattern and climate variability and provides useful insights to facilitate conservation planning for climate change.     

《对2006 IPCC国家温室气体清单指南的2013增补:湿地》的解析

为了填补《2006 IPCC国家温室气体清单指南》有关湿地的温室气体排放与吸收清单编制方法学指南的空缺,IPCC于2014年2月底发布了《对2006IPCC国家温室气体清单指南的2013增补:湿地》。该指南在考虑人类活动影响以及对湿地定义进行重新梳理的基础上,给出了湿地排干、还湿的温室气体排放与吸收的估算方法;同时,也增补了滨海湿地、用于污水处理人工湿地的温室气体排放与吸收的估算方法。该指南的发布为清单编制者估算人类活动所导致的湿地温室气体排放与吸收提供了较全面的方法学。当然,受到科学认识水平与文献的限制,该指南在随排水流失的颗粒有机碳损失量的估算、随还湿来自于湿地外其他生态系统有机碳的进入所产生排放量估算等方面存在着需进一步完善的内容。     

Streamflow response of Belgian catchments to IPCC climate change scenarios

The IRMB (Integrated Runoff Model—F. Bultot) daily step conceptual model has been applied to eight Belgian catchments with areas ranging from 100 to 1200 km². These catchments are characterized by various infiltration rates and ground water storage capacities. The outputs of six GCMs (General Circulation Model) distributed by the IPCC (Intergovernmental Panel on Climate Change) and an earlier scenario have been used to perturb time series of hydrometeorological input data relevant to simulate the water cycle. This paper focuses on the impacts on streamflow and its surface and underground components, as well as on the occurrence of flood days and low flow days. Impacts are shown to be catchment and scenario dependent. Due to the scenario diversity, streamflow impacts are found to be either positive or negative. The trends are common to scenarios with the same patterns or to catchments with similar characteristics. For all but two scenarios, all the catchments present an increase of flood frequency. Nevertheless, for all the scenarios, catchments with prevailing surface flow are undergoing an increase in flood frequency during winter months.     

Knowing like a global expert organization: Comparative insights from the IPCC and IPBES

In this paper we draw on Science and Technology (STS) approaches to develop a comparative analytical account of the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental science-policy Platform on Biodiversity and Ecosystem Services (IPBES). The establishment of both of these organizations, in 1988 and 2012 respectively, represented important ‘constitutional moments’ in the global arrangement of scientific assessment and its relationship to environmental policymaking. Global environmental assessments all share some similarities, operating at the articulation between science and policy and pursuing explicit societal goals. Although the IPCC and IPBES have different objectives, they are both intergovernmental processes geared towards the provision of knowledge to inform political debates about, respectively, climate change and biodiversity loss. In spite of these similarities, we show that there are significant differences in their knowledge practices and these differences have implications for environmental governance. We do this by comparing the IPCC and IPBES across three dimensions: conceptual frameworks, scenarios and consensus .We argue that, broadly speaking, the IPCC has produced a ‘view from nowhere’, through a reliance on mathematical modelling to produce a consensual picture of global climate change, which is then ‘downscaled’ to considerations of local impacts and responses. By contrast IPBES, through its contrasting conceptual frameworks and practices of argumentation, appears to seek a ‘view from everywhere’, inclusive of epistemic plurality, and through which a global picture emerges through an aggregation of more placed-based knowledges. We conclude that, despite these aspirations, both organizations in fact offer ‘views from somewhere’: situated sets of knowledge marked by politico-epistemic struggles and shaped by the interests, priorities and voices of certain powerful actors. Characterizing this ‘somewhere’ might be aided by the concept of institutional epistemology, a term we propose to capture how particular knowledge practices become stabilized within international expert organizations. We suggest that such a concept, by drawing attention to the institutions’ knowledge practices, helps reveal their world-making effects and, by doing so, enables more reflexive governance of both expert organizations and of global environmental change in general.     

Understanding the latest progress in mitigating climate change and facilitating carbon neutrality北大核心CSCD

The Intergovernmental Panel on Climate Change (IPCC) released the report of Working Group III of the Sixth Assessment Report "climate change 2022: mitigating climate change". The report accessed and summarized the latest research progress on climate change mitigation since the release of the Fifth Assessment Report, which will provide an important reference for the international community to further understand climate change mitigation actions, system transformation, and the pursuit of sustainable development. The report pointed out that human activities had cumulatively emitted about 2.4 trillion tons of CO2 from 1850 to 2019, of which 58% was emitted before 1990. In order to control the level of global temperature rise in the future, deep and immediate mitigation actions are required. In both low and minimum emission scenarios, fossil energy needs to be greatly reduced; renewable energy will be the mainstay of future energy supply; achieving carbon neutrality requires relying on negative emission technologies and increasing carbon sinks. Technological progress is one of the key conditions for helping the world combat climate change. Accelerated and equitable climate action is critical to sustainable development. The report's conclusions once again show that China's carbon neutrality target is in line with the mitigation path of the Paris Agreement's temperature rise target of less than 2 °C and striving to achieve 1.5°C. In the future, China should strengthen special research programs on the national concerns and key contents covered in the report. While strengthening scientific interpretation and effective use of the report's conclusions, it is also necessary to actively participate in the IPCC scientific assessment process, actively contribute Chinese wisdom, and contribute to the international dissemination of Chinese climate governance concepts. © 2022 Chinese Journal of Digestive Endoscopy All rights reserved.     

IPCC AR6报告关于气候变化适应措施的解读

适应举措对降低人类和生态系统的气候变化风险有着积极的影响。IPCC第六次评估报告（AR6）第二工作组（WGII）报告全面评估了适应的可行性和有效性,深入评估了适应局限性和不良适应。报告认为,个人、地方、区域和国家各级的适应行动都在增加,但是在做决策时需考虑不良适应的风险。报告从经济、技术、制度、社会、环境和地球物理这6个维度,对23个适应措施的可行性进行了评估;这些适应措施分布在陆地、海洋与生态系统,城乡与基础设施系统,能源系统以及跨部门等四大系统,其中,基于森林的适应、具有恢复力的电力系统、能源可靠性等适应措施具有高信度的高可行性。适应措施的可行性和有效性会随着气候变暖的增加而降低,需要采用多种措施来降低未来气候变化风险。