ＩＰＣＣ第４次報告書の要点・解説

The sixth major <scp>IPCC</scp> assessment report and its implications: 15 September 2021

The Intergovernmental Panel on Climate Change (IPCC) has recently released its Third Assessment Report (TAR), in which new projections are given for global-mean warming in the absence of policies to limit climate change. The full warming range over 1990 to 2100, 1.4 degrees to 5.8 degrees C, is substantially higher than the range given previously in the IPCC Second Assessment Report. Here we interpret the new warming range in probabilistic terms, accounting for uncertainties in emissions, the climate sensitivity, the carbon cycle, ocean mixing, and aerosol forcing. We show that the probabilities of warming values at both the high and low ends of the TAR range are very low. In the absence of climate-mitigation policies, the 90% probability interval for 1990 to 2100 warming is 1.7 degrees to 4.9 degrees C.

Flooding is one of the most devastating natural events and leads to enormous and recurring loss of life, properties, and resources around the globe. With climate change and accelerating urbanization, flood disasters in China have increasingly affected the sustainable development of metropolitan areas. Risk assessment is an essential step in flood management and disaster mitigation, which provide a quantitative measure of flood risk. However, the difficulty of flood risk zoning is dealing with the uncertainty of the evaluation process and the complicated non-linear relationship between indicators and risk levels. To address this issue, a fuzzy synthetic evaluation (FSE) method based on combined weight (CW) was utilized in this paper to generate flood risk maps at a grid-scale (1 × 1 km). For the case study in the Beijing-Tianjin-Hebei metropolitan area (BTH) in China, fourteen indicators were selected to construct the flood risk assessment model based on the FSE approach integrated with ArcGIS. The research demonstrates that moderate, high, and very high risk zones are distributed in the southeast fluvial plain of the BTH area, accounting for 31.36% of the total land area. Meanwhile, low and very-low risk zones occupy 68.64% of the total land area, and are primarily located in the high plateau and mountain regions in the northwest. We analyzed the risk level of each county and proposed risk mitigation measures based on field investigations. The verified risk assessment results were spatially consistent with the historical flood disaster records and loss positions, indicating the accuracy and reliability of the risk assessment map using the FSE approach. Compared with the IPCC (Intergovernmental Panel on Climate Change) TAR (Third Assessment Report) and AR5 (Fifth Assessment Report) methods, FSE has significant advantages in handling uncertainty, complexity, and the non-linear relationship between indices and risk grades. This study provides a novel quantitative method for flood risk assessment in metropolitan areas and practical implications for urban flood management.

Better information on greenhouse gas (GHG) emissions and mitigation potential in the agricultural sector is necessary to manage these emissions and identify responses that are consistent with the food security and economic development priorities of countries. Critical activity data (what crops or livestock are managed in what way) are poor or lacking for many agricultural systems, especially in developing countries. In addition, the currently available methods for quantifying emissions and mitigation are often too expensive or complex or not sufficiently user friendly for widespread use.The purpose of this focus issue is to capture the state of the art in quantifying greenhouse gases from agricultural systems, with the goal of better understanding our current capabilities and near-term potential for improvement, with particular attention to quantification issues relevant to smallholders in developing countries. This work is timely in light of international discussions and negotiations around how agriculture should be included in efforts to reduce and adapt to climate change impacts, and considering that significant climate financing to developing countries in post-2012 agreements may be linked to their increased ability to identify and report GHG emissions (Murphy et al 2010, CCAFS 2011, FAO 2011).

The objectives of this study were to carry out a review of mitigation scenarios that have emerged since the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR), to update the current Emissions Scenarios Database with these scenarios, and to analyze emissions and mitigation scenarios. This article first discusses the characterization of mitigation scenarios and systematically classifies mitigation scenarios. Second, quantitative analyses on gross domestic product (GDP), population, carbon intensity, energy intensity, and carbon taxes are conducted at the regional level in the four regional aggregations used by the IPCC Special Report on Emissions Scenarios. Results show that the range of emissions trajectories is extensive and that the maximum potential mitigation of global CO2 emissions from the baseline level by 2100 is around 95%. There is a correlation between GDP growth and energy intensity improvement. The relationship between energy intensity improvement and carbon intensity reduction changes over the 21st century, with energy intensity improvement outweighing carbon intensity reduction in the first half of the century and carbon intensity reduction becoming more dominant in the latter half. Predicted carbon tax levels for 2100 range from around 50 to 1400 US$/t-C, although a uniform level of carbon tax brings about widely varying CO2 mitigation outcomes across different regions. The range of GDP loss, resulting from CO2 emissions mitigation, varies from −10% to 40% in 2100, with GDP losses in developing regions more evident than those in developed regions.

This comparative review of three assessment reports, the Intergovernmental Panel on Climate Change, (IPCC), The National Research Council (NRC), and United States Global Change Research Program (USGCRP), respectively is presented in response to comments in the press suggesting that the three reports varied substantially in their assessments of associations between global climate and infectious disease in humans. Comparisons of the assessment teams, approach, reports' findings, views on predictive modeling, recommendations to policymakers and future research are presented. All teams were interdisciplinary, two international, one US-based. Although their approaches differed somewhat, all addressed the role of climate change, El Nino and climate variability, and ultimately, human health, especially infectious disease. The panels agreed that a paucity of long-term data and complexity of relationships among factors affecting climate variability and change and human health rendered projections of current predictive models inadequate as the basis for policy decisions. Each team suggested further study of associations among climate variability/climate change and human infectious disease and downscaled models to project regional and subregional outcomes. Each added additional areas for investigation, e.g., mathematical modeling, effects of socioeconomic factors, emergence of zoonotic disease in humans, transmission dynamics of disease agents. Rather than disagreements, there were differences in emphasis on known components and on hypothesized additional contributing factors and relationships among climate and human infectious disease variables.

It is usually necessary to apply incomplete and uncertain information to inform policy and decision making, creating the need to characterize the state of knowledge and identify when more certain information may be available. After all, some information is better than none and conversely, even perfect information is of no use if it is available only after a decision has been made. In scientific assessments for global change, the challenges are particularly acute because of scientific complexity, long time horizons, and large political and economic stakes, among other factors. Moss and Schneider prepared uncertainty guidelines for the Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC) that recommended a process to make expert judgments of levels of confidence and uncertainty more systematic and transparent. The guidance provided calibrated uncertainty terms to improve communication of findings to users and urged preparation of a traceable account of the authors’ assessment of the evidence for each major finding. This article reviews the recommendations and their effectiveness and highlights ensuing critiques and the evolution of uncertainty guidance for subsequent assessment reports. It discusses emerging challenges in providing science for decision making in the era of increasing model resolution and complexity and burgeoning interest in information to inform adaptation and mitigation at regional and finer scales.

We simulated the carbon dioxide (CO2) emissions from a great Amazonian hydroelectric reservoir under future climate and land use land cover conditions using a three-dimensional ecological model. Future scenarios were developed taking into account the Representatives Concentrations Pathway (RCP) adopted by the Intergovernmental Panel for Climate Change (IPCC) in its fifth Assessment Report (AR5). To investigate the possible effects of future climate and land use changes on CO2 emissions, we compared our results with a previous study that simulated the carbon emissions under present climate conditions. The results showed that under moderate climatic changes scenario associated to the recuperation of natural land covers in the watershed (i.e., increase in forestry areas) the CO2 emissions are estimated to be more than 100% higher than the current emissions in a specific season. On the other hand, in a more extreme climatic changes scenario associated to the expansion of agriculture and pasture areas, the estimates of CO2 emissions along the year decrease of 5% compared to current emissions. Our findings indicate that the processes such as eutrophication, mixing and stratification of water column and the water retention time will be key elements controlling the CO2 emission from Amazonian reservoirs in the future. We highlight that the CO2 emissions from future planed Amazonian hydroelectric reservoirs are uncertain and will be highly dependent of regional climate and LULC changes. Decision makers must to consider these two important factors in the environmental impact studies and comparisons with CO2 emission from other energy sources.

Climate Change and Health: Strengthening the Evidence Base for Policy

On 17 September 2021, the Grantham Institute hosted a follow-up to the Royal Meteorological Society's virtual event on the Intergovernmental Panel on Climate Change (IPCC) 6th assessment report (AR6). The event focused on the response to the climate crisis and taking actions from AR6. Three sectors were covered, including 'School leaders and educators', led by Science, Technology, Engineering and Mathematics (STEM) Learning Network & London Schools Climate Summit; 'Business and Industry - Environmental, social and corporate governance', chaired by Anita Punwani, Deputy Chair NED, Institute of Risk Management; and 'Geologists, earth scientists and energy experts', led by the European Federation of Geologists and Imperial College London researchers. Panel members were from British Standards Institution, 11 https://www.bsigroup.com/ Save the Children UK, 22 https://www.savethechildren.org.uk/ University College London 33 https://www.ucl.ac.uk/ and Resurgence. 44 https://www.resurgence.io/ Dr Alex Brown (STEM learning) and Malini Mehra (Globe International) chaired a session on the implications of AR6 for school leaders and educators. Participants agreed that we now have an opportunity for collaboration, as the UK Prime Minister recently appointed a new Education Secretary (Nadhim Zahawi) and Schools Minister (Robin Walker). With COP26 (Smith et al., 2021) at the time just five weeks away, it was emphasised that now is the time to put climate education on the agenda and embedded in the green recovery. There was a feeling that teachers are constrained by the curriculum and do not have the skills, capacity, or appropriate resources to apply climate issues to their own subjects. Recommendations were given to address this through exam bodies and quality assurance organisations, and to provide better training for teachers, so they are empowered to embed climate change into their lessons. A curriculum reform should also include green skills for students, to ensure the next generation is equipped to apply for green jobs in the future. Further discussion focussed on climate risk and adaptation. Few educational leaders recognise that the most harmful impacts of climate change to the educational sector are likely to be physical, such as flooding and extreme heat. It is important to find ways to communicate this effectively with school leaders, drawing on what has been learned from COVID-19. The session ended with discussion about the next steps, starting with a letter to the Education Secretary and Schools Minister regarding an enquiry into whether the current education system is fit for purpose in relation to the government's net zero commitments. Nuha Eltinay's (Middle East and North Africa representative) 55 https://www.resurgence.io/team/ key messages included the need to build bridges between existing communities and weather forecasters. The need to communicate weather information and climate change to grassroots were essential for progress. Specifically, what the IPCC meant to her organisation was centred around vulnerabilities in Middle East and Northern African regions. It was emphasised that compound and cascading hazards after natural events are often not reported and under-addressed, despite their ability to produce further catastrophic hazards that propagate through socio-economic systems (e.g. Alexander and Pescaroli, 2019). Kit Vaughan (Save the Children) mentioned the importance of dealing with the disruption arising from climate change. Kit also explained the interrelationship between other global issues including COVID-19 which led us to recognise global inequality. Kit raised the important point that children born in 2020 are subject to a seven-fold increase in climate events when compared with their grandparents born in the 1960s (Thiery et al., 2021). This is further exacerbated by the fact that one billion children are living in high-risk areas. This discussion raised important issues of climate change with regard to children. These stakeholders require a specific focus of support and integration at every level with effective communication. Gianluca Pesacaroli (University College London) expressed issues pertaining to operational silos whereby private companies operate independently from public bodies. This becomes problematic when addressing and meeting mutual climate mitigation targets. There is a need for the co-production of information between private and public entities, scientists and non-scientists, which can facilitate important discourses allowing for effective policy making. Lesley Wilson (British Standards Foundation, BSI) emphasised the need to have a common benchmark of sustainability that organisations should employ in their environmental agendas. The BSI works collaboratively across sectors to foster such common standards. Katrina Ramage (World Values Day) highlighted the need to communicate climate change to young children in layperson terms so that they can understand the issues facing them and how the government aims to support the future generation. Discourses in the realm of decision making, be that public or private, regarding the next generation, often do not directly involve young people. Moreover, the complexities of such discourses are rarely understood by children and more needs to be done to explain the ramifications of climate change to them. Examples of this include encouraging children to debate climate change in educational establishments and visiting schools to educate children and facilitating such discussions. Hannah Wood (UBS Foundation) identified that there is a funding gap between climate and environmental issues. There is growing concern that within corporate settings there is untapped capital which can be used to support financing the global environmental agenda (Clark et al., 2018). Funding is not disseminated appropriately with little communication between corporate and public entities. Therefore, there is a serious need to trigger funding for climate change initiatives and move capital to where it is more needed. Glen Burridge (European Federation of Geologists) led the breakout session 'Earth Sapience: How can Earth Scientists work together to address the climate crisis?'. Dr Yves Plancherel (Imperial College London) started by highlighting that much of the new IPCC reports are not novel, raising the debate of how the information in the IPCC should be delivered in the future. Cedric John (Imperial College London) and Dr Edward Gryspeerdt (Imperial College London) agreed with the sentiment but added that the IPCC reports do pave the way for more platforms to discuss the IPCC, beyond the short periods that it is popularised by the news media (Pearce et al., 2014; Sanford et al., 2019). Dr Isabelle Fernandez (European Federation of Geologists) continued this concept of communication, highlighting that involving people – both the general public and companies – is an important solution to reducing greenhouse gas emissions. Dr Edward Gryspeerdt followed this saying that geologists can develop such solutions at economic cost, with the key being to find a way where it is cheaper not to emit, but to leave the CO2 in the ground. Magnus Johansson (SGU) was the last panellist in the group and highlighted that there also needs to be resilience built into everyday life, as well as a push for mitigation measures. At present, Magnus Johansson said, there is a disconnect between those planning climate mitigation and resilience measures and those applying it on the ground. The session was then opened up for general input, where carbon capture and storage (CCS) was heavily discussed. Highlighted as a sustainable opportunity, CCS needs to be implemented as soon as possible to ensure CO2 is utilised, not wasted (Martin-Roberts et al., 2021). Yves highlights that, due to the cost of implementation, oil and gas companies might be in a unique position to spearhead the transition over to CCS by converting their assets (infrastructure, knowledge and workforce) over. The breakout room concluded on discussions around the importance of investigating other energy sources and alternate forms of carbon storage. Renewable and thermal energy are important clean energy options but must also be discussed alongside a candid conversation about their accompanying issues, such as raw material supply. Forest restoration is hugely valuable in tackling both the biosphere crisis, as well as providing a nature-based solution to the carbon issue (Seddon et al., 2020). The event was concluded with a large discussion of all three sectors and the key points that were brought up in the breakout rooms. Melina Mehra clarified that one overarching message that came through was the need to be clear with messages that are being communicated, ensuring those messages are accessible in terms of the capabilities of that person, group or industry. There needs to be clarity on questions such as: What is being asked to be done? How is the success of it measured? Katrina Ramage highlighted how societal tolerance of climate injustice has reduced and that works in favour of better communication, but it does not lessen the complexity of the issue being communicated. COVID-19, as a potentially climate-induced zoonotic 66 An infectious disease which has spread from animals to humans. pandemic, and the rise in extreme weather events, has made it clear that the impacts of climate change are happening now. Glen Burridge summarised that clear communication of complex issues alongside de-biased and practically analysed decisions will allow these issues to be addressed effectively, in the present rather than in the future.

The island of Astypalea (Greece), known for its rich and pristine archeological sites, encompasses a semi-enclosed silled basin that has been very susceptible to global sea levels and regional climate changes due to its relatively modern shallow sill of 4.7 m water deep that connects the Vathy bay with the adjacent Aegean Sea. To identify the causal relationship between regional climate, sea-level trajectories, and environmental change and their potential impact on hominine habitats on the island, we investigated a high-resolution seismic profile together with sediment, stable isotope, geochemical, and biotic proxies retrieved from a marine sediment core (ASTC1). Our results show that the basin was once isolated, and a marine inundation occurred at around 7.3 ka BP, which is older than expected, based on global sea level reconstructions. The entire transition from isolation to full marine conditions was accomplished in three major phases: (1) non-marine isolated conditions between 9–7.3 ka BP, (2) semi-isolated hypersaline marsh and lagoonal conditions between 7.3 and 4.1 ka BP, and (3) semi-isolated shallow marine conditions of today (4.1 ka BP to present). High water alkalinity, elevated organic content, and heavier isotopic signals indicate relatively arid conditions in the region that favored Sr-rich carbonate precipitation within the 7.3–6 ka BP interval. On the other hand, freshwater biota, along with a high Corg/N ratio and lighter isotopic signal, showed wetter conditions, at least for the intervals 8–7.3 ka and 6–5.4 ka BP, in contrast to the aridification trend seen as 4.1 ka to present. Finally, the hominine habitat evolution at around 6 ka BP might be attributed to the wetter conditions and the freshwater source provided by the bay at that time.

Relationship between environmental change on Geoje Island, southern coast of Korea, and regional monsoon and temperature changes during the late Holocene

Assessment of plausible changes in Climatic Impact-Drivers relevant for the viticulture sector: A storyline approach with a climate service perspective

In this paper, we critically reflect on the ability of spatial and sectoral planning approaches to deal with regional climate change, especially sea level rise, and analyze the potential of ecosystem service assessments in regional coastal climate change adaptation planning. We present two concrete but contrasting case studies that focus on coastal realignment and wetland restoration as well as seaside tourism and resort development on the German Baltic Sea coast. The ecosystem service assessments compare past, present and potential future local development scenarios. Complementary, we apply the InVest and the Matrix ecosystem service assessment approaches. Despite some shortcomings, the proactive German hierarchical planning system seems suitable to deal with climate change and provide a framework for adaptation measures in coastal zones. It largely prevents a shift of climate change risks between municipalities and stakeholders. Comparative ecosystem service assessments seem well suited to play a role in the planning process by raising awareness about problems, possible solutions and consequences. On a local level, they can provide comprehensive insight into consequences of alternative measures. Our examples show that, in principle, potential future situations can be addressed with comparative ecosystem service approaches. We discuss whether the results of hypothetical future scenarios, with inherent uncertainties, might be misleading and counterproductive.

In Paris on 2 February 2007, while this book was at its page-proof stage prior to press, the IPCC launched the first part of its Fourth Assessment Report. The announced summary report was itself yet to be checked editorially, but its core message was clear: it gave a more assured statement, compared to the previous assessments, that human activity was in all probability affecting the global climate. Its summary statements included the following. The understanding of anthropogenic warming and cooling influences on climate has improved since the Third Assessment Report (TAR), leading to very high confidence that the globally averaged net effect of human activities since 1750 has been one of warming, with a radiative forcing of + 1.6 [+ 0.6 to + 2.4] W m − 2 . Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level. At continental, regional, and ocean basin scales, numerous long-term changes in climate have been observed. These include changes in Arctic temperatures and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and aspects of extreme weather including droughts, heavy precipitation, heat waves and the intensity of tropical cyclones. Anthropogenic warming and sea level rise would continue for centuries due to the timescales associated with climate processes and feedbacks, even if greenhouse gas concentrations were to be stabilized.