The latest iteration of IPCC uncertainty guidance—an author perspective

The latest iteration of Intergovernmental Panel on Climate Change (IPCC) uncertainty guidance is simpler and easier to use than the previous version. However, its primary focus remains assessing “what is at risk” under climate change, thus is most suitable for dealing with the scientific uncertainties in Working Group I and part of Working Group II findings. I distinguish between tame and complex risks, arguing that the guidance is most suited to assessing tame risks. Climate change is a complex risk, and as such as can be divided into idealized, calculated and perceived risks. While science has claims to objectivity, risk has a specific value component: when measuring gain and loss, calculated risks compete with risky options to manage those risks. The IPCC is charged with calculating risk (IPCC 2007, p22) but the communication of key findings takes place in an environment of competing perceived risks. Recommendations for managing this complex environment include separating scientific and risk-based findings, treating uncertainties for each separately; strengthening the philosophical basis of uncertainty management; application of a methodical scientific research program; clearly communicating competing findings, especially in the social sciences; and application of multiple frame to policy-relevant findings as reflected in the literature.     

Improving conveyance of uncertainties in the findings of the IPCC

Authors of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) received guidance on reporting understanding, certainty and/or confidence in findings using a common language, to better communicate with decision makers. However, a review of the IPCC conducted by the InterAcademy Council (2010) found that “the guidance was not consistently followed in AR4, leading to unnecessary errors . . . the guidance was often applied to statements that are so vague they cannot be falsified. In these cases the impression was often left, quite incorrectly, that a substantive finding was being presented.” Our comprehensive and quantitative analysis of findings and associated uncertainty in the AR4 supports the IAC findings and suggests opportunities for improvement in future assessments.     

Treatment of uncertainties in IPCC Assessment Reports: past approaches and considerations for the Fifth Assessment Report

The assessments of the Intergovernmental Panel on Climate Change (IPCC), since the First Assessment Report, have involved calibrated uncertainty language and other methods aimed towards clear communication of the degree of certainty in findings of the assessment process. There has been a continuing tradition of iterative improvement of the treatment of uncertainties in these assessments. Here we consider the motivations for the most recent revision of the uncertainties guidance provided to author teams of the Fifth Assessment Report (AR5). We first review the history of usage of calibrated language in IPCC Assessment Reports, along with the frameworks for treatment of uncertainties that have been provided to IPCC author teams. Our primary focus is the interpretation and application of the guidance provided to author teams in the Fourth Assessment Report, with analysis of the successes and challenges in the application of this guidance and approaches taken in usage of its calibrated uncertainty language. We discuss the ways in which the AR5 Guidance Note attempts to refine the calibrated uncertainty metrics and formalize their interrelationships to improve the consistency of treatment of uncertainties across the Working Group contributions.     

Climate change 1992: The supplementary report to the IPCC impacts assessment: edited by W.J. McG. Tegart, G.W. Sheldon and J.H. Hellyer Australian Government Publishing Service, Canberra, 1993, 112 pp

The Intergovernmental Panel on Climate Change (IPCC) completed its first round of assessments of the science, impacts and response to climate change in 1990. In 1992, the IPCC pulled together updates to the first round of reports (J. Houghton, G.J. Jenkins and J.J. Ephraums, eds, Climate Change: The IPCC Scientific Assessment, Cambridge University Press, Cambridge, 1990; W.J. McG. Tegart, G.W. Sheldon and D.C. Griffiths, eds, Climate Change: The IPCC Impacts Assessment, Australian Government Publishing Service, Canberra, 1990). At the same time, the literature on the potential impacts of climate change has expanded enormously. Four volumes are reviewed here.     

Progress and evaluation of international climate change cooperation北大核心CSCD

气候变化是当前世界面临的巨大挑战,应对气候变化需要国际间合作已成为普遍共识。IPCC第六次评估报告(AR6)第三工作组(WGⅢ)报告第十四章回顾了IPCC第五次评估报告(AR5)以来气候变化国际合作的进展,基于所提出的评价体系对进展进行了系统评估。报告认为,AR5以来气候变化国际合作最重要的进展是基于《巴黎协定》建立的以国家自主贡献为核心的全球行动模式;除《巴黎协定》外,国际上也形成了多种形式的合作机制,其中,气候俱乐部是国际气候合作研究的新热点。对于《巴黎协定》的有效性,目前国际社会存在正反两种观点,并认为《巴黎协定》能否达成既定目标取决于是否有能力强化全球下一步的集体气候行动目标和实施。     

未来气候变化科学研究的主要方向和挑战

2014年9月,IPCC联合世界气候研究计划（WCRP）,在瑞士伯尔尼大学召开了一次特别的研讨会,总结过去几年气候变化科学研究中所取得的经验教训。此次会议针对IPCC最新评估报告中的关键不确定性,梳理并总结了未来气候变化研究的主要科学方向和面临的主要挑战,讨论了如何与WCRP计划结合并解决这些问题,以期在未来更好地应对这些挑战。在此次会议上,与会专家提出,未来气候变化科学研究的重大挑战应包括如下8个主题。云、环流与气候敏感度;理解和预测极端天气气候事件;冰冻圈变化;区域气候信息;区域海平面上升及其对沿海地区的影响;水资源可利用量;生物地球化学、气溶胶和大气化学;理解年代际变化：归因与预测。这些主题涵盖了WCRP计划的六大挑战和其他被认为具有挑战性的主题。本文将在此次会议报告的基础上,对相关内容进行介绍,以供当前的气候变化工作参考。     

IPCC第六次气候变化评估中的气候约束预估方法

得益于第五次评估报告（AR5）以来约束预估研究的迅速发展,观测约束成为政府间气候变化专门委员会（IPCC）第一工作组（WGI）第六次评估报告（AR6）提升对未来预估约束的证据链中的重要一环。IPCC第一工作组第六次评估报告首次利用包括根据历史模拟温度升高幅度得到的观测约束、多模式预估以及第六次评估报告中更新的气候敏感度在内的多条证据链来约束全球地表温度未来变化的预估,减小了多模式预估的不确定性。文中回顾并介绍了IPCC第一工作组第六次评估报告中涉及的几种主要观测约束方法（多模式加权方法、基于归因结论的约束方法（ASK方法）、萌现约束方法）及其应用情况。在IPCC第一工作组第六次评估报告以及很多针对不同区域不同变量的预估研究中,观测约束方法均显示出了订正模式误差、改善模式预估的潜力。相比而言,目前中国在观测约束预估方面的研究还不多,亟待加强观测约束方法研究以及在中国区域气候变化预估中的应用,为中国应对气候变化的政策制定和适应规划提供更丰富、不确定性更小的未来气候信息。      

气候反馈对温度空间模态的依赖性:IPCC AR6解读

依据政府间气候变化专门委员会(IPCC)第六次评估报告(AR6)第一工作组(WGI)报告第七章的内容,详细解读了气候反馈对温度空间模态的依赖性。与第五次评估报告(AR5)相比,AR6对于地表温度空间模态演变在驱动气候反馈变化中作用的理解已有了较大提升。AR6认为,在温室气体强迫下,北极在21世纪的增温幅度很可能大于全球平均水平,南极在百年时间尺度上的增温要强于热带地区;同时,在百年时间尺度上热带太平洋东部的变暖幅度大于西部,即热带太平洋东-西向海表温度梯度减弱。极地放大效应(尤其是南半球)和热带太平洋东-西向海表温度梯度随时间的变化是影响未来气候反馈如何演变的关键因素。随着地表增温空间模态的演变,气候反馈(尤其云反馈)预计将在未来几十年的时间尺度上逐渐增加,对气候变化更多是起放大作用。     

全球气候变暖:浅谈从AR5到AR6的认知进展

自政府间气候变化专门委员会（IPCC）第五次评估报告（AR5）发布以来,国际科学界在气候系统变化领域取得显著进展,有关气候变化的科学认识不断深入。IPCC第六次评估报告（AR6）第一工作组（WGI）报告对这些科学进展和最新认识作了综合评估。温度是全球变化最直接的指示器。本文从温度变化视角,对从AR5到AR6的科学进展进行了梳理和简要评述,主要聚焦观测的变化、归因以及未来预估三个方面。与AR5相比,AR6以更强有力的证据进一步确证了近百年全球气候变暖的客观事实,人类活动对气候变暖影响的信号更为清晰,未来变暖幅度取决于温室气体减排力度。     

IPCC-AR4 climate simulations for the Southwestern US: the importance of future ENSO projections

Future climate trends for the Southwestern US, based on the climate models included in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report, project a more arid climate in the region during the 21st century. However, future climate variability associated with El Niño Southern Oscillation (ENSO)—an important driver for winter climate variability in the region—have not been addressed. In this work we evaluate future winter ENSO projections derived from two selected IPCC models, and their effect on Southwestern US climate. We first evaluate the ability of the IPCC coupled models to represent the climate of the Southwest, selecting the two models that best capture seasonal precipitation and temperature over the region and realistically represent ENSO variability (Max Planck Institute’s ECHAM5 and the UK Met Office HadCM3). Our work shows that the projected future aridity of the region will be dramatically amplified during La Niña conditions, as anomalies over a drier mean state, and will be characterized by higher temperatures (~0.5°C) and lower precipitation (~3 mm/mnt) than the projected trends. These results have important implications for water managers in the Southwest who must prepare for more intense winter aridity associated with future ENSO conditions.     

气候变化影响的最新认知

政府间气候变化专门委员会（IPCC）第二工作组于2007年4月6日正式发布了第四次评估报告,该报告客观、全面而审慎地评估了气候变化已有的和未来的可能影响。现有观测证据表明,人为增暖可能已对许多自然和生物系统产生了可辨别的影响,但由于适应以及非气候因子的作用,许多影响还难以辨别。21世纪中期,某些中纬度和热带干旱地区年平均河流径流量和可用水量会减少10%～30%;如果全球平均温度增幅超过1.5～2.5℃,目前所评估的20%～30%动植物物种可能面临灭绝的风险会增大;从全球角度看,局地平均温度增加1～3℃,预计粮食生产潜力会增加,但若超过这一范围,则会减少。兼顾适应和减缓的措施能够降低气候变化相关风险。     

气候变化科学的最新认知

 政府间气候变化专门委员会（IPCC）第一工作组于2007年2月2日发布的第四次评估报告明确指出,近100 a（1906-2005年）地球表面平均温度上升了0.74℃,近50 a的线性增温速率为0.13℃/10 a,1850年以来最暖的12个年份中有11个出现在近期的1995-2006年。全球变暖已经是不争的科学事实,报告认为人类活动是近50 a全球气候系统变暖的主要原因。 IPCC评估报告是国际科学界对气候变化问题最权威、最全面的认识,代表了目前全球气候变化研究的科学认识水平,是国际上制定相关政策的重要依据。     

Projected changes in the physical climate of the Gulf Coast and Caribbean

As the global climate warms due to increasing greenhouse gases, the regional climate of the Gulf of Mexico and Caribbean region will also change. This study presents the latest estimates of the expected changes in temperature, precipitation, tropical cyclone activity, and sea level. Changes in temperature and precipitation are derived from climate model simulations produced for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4), by comparing projections for the mid- and late-21st century to the late 20th century and assuming a “middle-of-the-road” scenario for future greenhouse gas emissions. Regional simulations from the North America Regional Climate Change Program (NARCCAP) are used to corroborate the IPCC AR4 rainfall projections over the US portion of the domain. Changes in tropical cyclones and sea level are more uncertain, and our understanding of these variables has changed more since IPCC AR4 than in the case of temperature and precipitation. For these quantities, the current state of knowledge is described based on the recent peer-reviewed literature.     

“Reasons for concern” (about climate change) in the United States

Article 2 of the United Nations Framework Convention on Climate Change commits its parties to stabilizing greenhouse gas concentrations in the atmosphere at a level that “would prevent dangerous anthropogenic interference with the climate system.” Authors of the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC 2001a, b) offered some insight into what negotiators might consider dangerous by highlighting five “reasons for concern” (RFC’s) and tracking concern against changes in global mean temperature; they illustrated their assessments in the now iconic “burning embers” diagram. The Fourth Assessment Report reaffirmed the value of plotting RFC’s against temperature change (IPCC 2007a, b), and Smith et al. (2009) produced an unpated embers visualization for the globe. This paper applies the same assessment and communication strategies to calibrate the comparable RFC’s for the United States. It adds “National Security Concern” as a sixth RFC because many now see changes in the intensity and/or frequency of extreme events around the world as “risk enhancers” that deserve attention at the highest levels of the US policy and research communities. The US embers portrayed here suggest that: (1) US policy-makers will not discover anything really “dangerous” over the near to medium term if they consider only economic impacts that are aggregated across the entire country but that (2) they could easily uncover “dangerous anthropogenic interference with the climate system” by focusing their attention on changes in the intensities, frequencies, and regional distributions of extreme weather events driven by climate change.     

An antipodean climate of uncertainty?

Climatic impact assessment is generally conducted by reference to numerical models, from which most estimates of climatic change are derived, and to the policy developers, by whom the impact assessments are demanded. The propagation of estimates derived from numerical climate model predictions of greenhouse-induced climate change through impact models into policy advice is a precariously uncertain process which compounds the considerable uncertainties already inherent in policy development. Clear statements of scientific confidence in the greenhouse phenomenon in the mid-1980s prompted demands for policy, and hence for policy advice. In Australia, as in many other countries, public and political awareness of the possibility of greenhouse-induced climatic change increased. These developments led to the formation of the Intergovernmental Panel on Climate Change (IPCC); to the Framework Convention on Climate Change, signed at the United Nations Conference on Environment and Development (UNCED) in June 1992; and to the review of the World Climate Programme in April 1993. This special issue ofClimatic Change illustrates some aspects of the difficulties surrounding projections of climatic impacts at a national scale where policy development almost always occurs under conditions of uncertainty. It may be valuable to identify uncertainty issues which could benefit from additional research and also sensitive points in the policy development process at which uncertainty can be used and abused. In this paper, the role of uncertainty in the greenhouse debate is reviewed from the perspective of a natural scientist working in a developed country. The aim is to offer a framework for the rest of this special issue ofClimatic Change. Uncertainty is by no means the only factor which influences views on climate change but increased understanding and more informed debate of all aspects of the uncertainties relating greenhouse-induced climatic change to policy development and implementation would be beneficial.     

Severe climate-induced water shortage and extremes in Crete

Climate change is expected to have a significant impact on the hydrologic cycle, creating changes in freshwater resources. The Intergovernmental Panel on Climate Change (IPCC) predicts that, as a result, floods and prolonged droughts will take place at increasingly frequent periods. The Mediterranean has been described as one of the main climate change “hot-spots”, with recent simulations showing a collective picture of substantial drying and warming. This effect appears more pronounced during warm periods, when the seasonal decrease of precipitation can exceed control climatology by 25–30%. Despite the decreasing annual rainfall trend, an increase in the amount and intensity of wintertime rainfall is evident. However, the scientific question on the quantitative impact of these signals to small scale coastal watersheds and Mediterranean islands has not been answered. The state-of-the-art Ensembles dataset was employed to assess the impact of the changing climate on the water availability of the island of Crete at basin scale. Here, the Ensembles precipitation and temperature data is used as input for a rainfall–runoff model previous calibrated for the whole island with the principle of regionalization. Data analysis for the period 1970–2100 reveals an overall decreasing precipitation trend which, combined with a temperature rise, leads to substantial reduction of water availability. Quantitative results of hydrological change provide the data required to improve knowledge and adaptation policy to water shortages.     

Key themes in the Working Group II contribution to the Intergovernmental Panel on Climate Change 5th assessment report

Assessments conducted by the Intergovernmental Panel on Climate Change (IPCC) are significant undertakings that require input from experts and practitioners in multiple scientific disciplines, integrating local to international information across spatial and temporal scales. An IPCC report is a unique collaboration between the scientific community and policymakers, with governments (through their Focal Points) providing guidance and input to the scientists conducting an assessment at several stages during the process. This commentary reviews the IPCC mandate and process; summarizes key themes to be addressed in the Working Group II contribution to the 5th assessment report; discusses challenges for the WGII report when assessing qualitative literature, incorporating local knowledge, and identifying particularly vulnerable groups; and touches on the expertise and commitment of the WGII authors. Active engagement of the wider scientific community in IPCC assessments through publication and review will enhance their relevance to decision- and policy-makers.     

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.     

A Regional, Multi-sectoral And Integrated Assessment Of The Impacts Of Climate And Socio-economic Change In The Uk

Policy makers and stakeholders are increasingly demanding impact assessments which produce policy-relevant guidance on the local impacts of global climate change. The ‘Regional Climate Change Impact and Response Studies in East Anglia and North West England’ (RegIS) study developed a methodology for stakeholder-led, regional climate change impact assessment that explicitly evaluated local and regional (sub-national) scale impacts and adaptation options, and cross-sectoral interactions between four major sectors driving landscape change (agriculture, biodiversity, coasts and floodplains and water resources). The ‘Drivers-Pressure-State-Impact-Response’ (DPSIR) approach provided a structure for linking the modelling and scenario techniques. A 5 × 5 km grid was chosen for numerical modelling input (climate and socio-economic scenarios) and output, as a compromise between the climate scenario resolution (10 × 10 km) and the detailed spatial resolution output desired by stakeholders. Fundamental methodological issues have been raised by RegIS which reflect the difficulty of multi-sectoral modelling studies at local scales. In particular, the role of scenarios, error propagation in linked models, model validity, transparency and transportability as well as the use of integrated assessment to evaluate adaptation options to climate change are examined. Integrated assessments will provide new insights which will compliment those derived by more detailed sectoral assessments.