Interpretation of high projections for global-mean warming.

This article outlines the latest scientific knowledge on global warming/climate change, especially in the meteorological and climatological fields, presented in the fourth assessment report (AR4) from Intergovernmental Panel on Climate Change (IPCC) in 2007, and provides a comparison with the third assessment report (TAR). In the review of WG1 report, we summarize “Observed recent climate change” and “Future climate projection, ” referring to major events and climate variables. In the review of WG2, we summarize the results on the main potential impacts of global warming projected on the natural environment and ecosystems in the future. Finally, a review of downscaling studies is presented, which are very important as they provide a bridge between regional scale climate change information presented in WG1 and WG2.Since TAR, progress in understanding how climate is changing in space and in time has been gained through improvements and extensions of numerous datasets and data analyses, broader geographic coverage, better understanding of uncertainties, and a wider variety of measurements. Understanding of anthropogenic warming and cooling influences on climate has also improved. AR4 concludes with very high confidence (higher than TAR) that : i) climate warming is unequivocal and ii) the global average net effect of human activities since 1750 has been one of warming. In studies on the impacts of global warming, understanding of global warming risk is evaluated more quantitatively based on greatly increased studies of observed trends in the physical and biological environment and their relationships with regional climate change, as well as improved future climate projections on a regional scale.

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

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.

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.

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 recent publication of the summary for policy makers by Working Group I of the Intergovernmental Panel on Climate Change (IPCC) [1] has injected a renewed sense of urgency to address climate change. It is therefore timely to review the notion of preventing 'dangerous anthropogenic interference with the climate system' as put forward in the United Nations Framework Convention on Climate Change (UNFCCC). The article by Danny Harvey in this issue [2] offers a fresh perspective by rephrasing the concept of 'dangerous interference' as a problem of risk assessment. As Harvey points out, identification of 'dangerous interference' does not require us to know with certainty that future climate change will be dangerous—an impossible task given that our knowledge about future climate change includes uncertainty. Rather, it requires the assertion that interference would lead to a significant probability of dangerous climate change beyond some risk tolerance, and therefore would pose an unacceptable risk.

Climate Change and Health: Strengthening the Evidence Base for Policy

The Intergovernmental Panel on Climate Change (IPCC) has some agenda-setting power for global climate policy. This explains worries about the fact that the governments had decided in 2009 that the IPCC's Fifth Assessment Report (AR5) was to explicitly address geoengineering options, which could then possibly legitimate the serious consideration of such options in global climate policy negotiations. Such worries, however, neglect two factors. First, the IPCC has a long history of dealing with geoengineering and, second, the IPCC performs its assessments without endorsing any options and being based on what is available in the primary literature. It must be admitted that the assessment of geoengineering options in the AR5 of 2014 has been the most extensive of all IPCC reports, mainly because much literature has appeared in the AR5. This is a moral issue: the IPCC carries a special responsibility to give the most comprehensive and clear portrayal of uncertainties, risk, and limitations of geoengineering methods and technologies.

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.

The Intergovernmental Panel on Climate Change (IPCC) has been producing influential reports for over 35 years. As the IPCC’s Seventh Assessment Report (AR7) cycle begins, we offer our perspective as former members of the IPCC Technical Support Units from Working Groups I, II & III, and the Synthesis Report on lessons learned during the Sixth Assessment Report (AR6) cycle. We identify three broad issues that, if addressed, could reinforce and sustain the IPCC in continuing its mission to comprehensively assess the scientific understanding of human-induced climate change. These are the imperative to ensure balanced representation, the importance of author recognition, and the need for improved institutional memory. Our recommendations include addressing skill and training needs, tackling barriers to participation particularly for Global South authors, and ensuring all contributors receive appropriate recognition for their efforts. We focus, in particular, on feasible incremental changes that could be implemented during AR7 without major changes to the underlying procedures that require approval by the 195 member governments that make up the IPCC.

In its Fourth Assessment Report (AR4), the Intergovernmental Panel on Climate Change (IPCC) addresses serious risks that could undermine the living conditions of people all over the world (IPCC 2007). Impacts on food and water availability, flood and storm disasters, and large-scale events such as loss of the monsoon, breakdown of the thermohaline circulation, polar ice melting, or sea level rise could affect a considerable fraction of the global population. After publication of this report a number of studies suggested that the struggle for food and water, the impact of natural disasters, and large-scale migration could pose security risks that would destabilize social systems and aggravate existing conflicts. These concerns inspired a debate on the securitization of climate change (Wæver 1995; Brauch 2009b). The IPCC reports did not focus on the links between climate change, security, and conflict (IPCC 2007; Nordås/ Gleditsch 2009), although statements by IPCC Chair Rajendra Pachauri upon acceptance of the Nobel Peace Prize suggest such a linkage. In its planned fifth assessment report, the IPCC will include a chapter on the human security dimensions of climate change.

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.

This article contributes to Indigenous literature on Intergovernmental Panel on Climate Change (IPCC) Assessment Reports (ARs) for an exploration of the science–policy–politics interface at the global scale. It presents findings from the systematic review of the latest AR6, conducted by the Knowledge Justice Collective, that examined Indigenous content in the report and the scientific knowledge base AR6 is based upon. It shows that paying attention solely on numerical increases of Indigenous content rather than the uneven Indigenous representation in the IPCC knowledge base produced in the English language by researchers largely in environmental science-related disciplines at elite institutions limits our understanding of the nuances of Indigenous lived realities in the ARs. Therefore, without an intervention at the knowledge base level, Indigenous Peoples and Indigenous Peoples’ Knowledges will continue to be legible only through extractive relationships in the IPCC AR processes while continuing to promote epistemic Eurocentrism.

There is a heightened interest at present on the possibility of rapid melting of world-wide glaciers and ice caps (e.g., Greenland & Antarctic Ice Caps) as a result of ongoing global warming, which could lead to escalated sea level rise in future. Several stories and news items in the print & TV media and also in scientific magazines seem to strongly suggest that glaciers and ice caps are melting faster than ever and this could lead to significant rise in global and regional sea level. Recent popular Hollywood movies like An Inconvenient Truth showing big ice shelves breaking off and sliding down into cold Arctic Ocean seem to reinforce this perception that the ice caps and glaciers are indeed melting rapidly and causing sea level to rise dramatically. From a scientific perspective, satellite altimeter data (Topex/Poseidon) have estimated recent sea level rise of about 3mm/yr and possibly higher, this value being significantly higher than the traditionally held value of about 1.5 to 2 mm per yr (for most of the twentieth century) has generated sufficient interest among the scientific community about ‘escalating sea level rise’ in near future. In a recent (Journal of Climate 2007) paper, the lead author Prof (Emeritus) Carl Wunsch states that “ Modern sea level is a matter of urgent concern from a variety of points of view, but especially because of possibility of its acceleration and consequent threats to many low-lying parts of the inhabited world “. The Intergovernmental Panel on Climate Change (IPCC), a UN Body of scientists, has been making periodic review of the earth’s climate change since 1990. In its most recent climate change documents (Meehl 2007), the IPCC projects global sea level rise (SLR) for the next 100 years to be between 14 and 43 cm ( with a mean value of 29 cm) under an emission scenario A1B ( these emission scenarios have been developed using economic development indices for world countries) in which the earth’s mean temperature is projected to rise between 2.3C and 4.1C by 2100. The IPCC projects largest increase in SLR (about 230 mm by 2100) as due to thermal contribution, resulting from warming of the earth’s surface and associated expansion of water in future. The contribution due to melting of glaciers and ice caps is estimated by the IPCC to be about 60 mm over next 100 years. These two components namely thermal (or steric) and mass balance (or eustatic) are being closely examined at present in the context of several recent studies on climate sensitivity and observational evidence of increased glacier melting. In this chapter, a brief background of the global warming science is presented in section 2. This is followed by a discussion on sea level rise over the past several thousand years and