• Energy Research

AbstractClimate change is widely recognized as a major risk to societies and natural ecosystems but the high end of the risk, i.e., where risks become existential, is poorly framed, defined, and analyzed in the scientific literature. This gap is at odds with the fundamental relevance of existential risks for humanity, and it also limits the ability of scientific communities to engage with emerging debates and narratives about the existential dimension of climate change that have recently gained considerable traction. This paper intends to address this gap by scoping and defining existential risks related to climate change. We first review the context of existential risks and climate change, drawing on research in fields on global catastrophic risks, and on key risks and the so-called Reasons for Concern in the reports of the Intergovernmental Panel on Climate Change. We also consider how existential risks are framed in the civil society climate movement as well as what can be learned in this respect from the COVID-19 crisis. To better frame existential risks in the context of climate change, we propose to define them as those risks that threaten the existence of a subject, where this subject can be an individual person, a community, or nation state or humanity. The threat to their existence is defined by two levels of severity: conditions that threaten (1) survival and (2) basic human needs. A third level, well-being, is commonly not part of the space of existential risks. Our definition covers a range of different scales, which leads us into further defining six analytical dimensions: physical and social processes involved, systems affected, magnitude, spatial scale, timing, and probability of occurrence. In conclusion, we suggest that a clearer and more precise definition and framing of existential risks of climate change such as we offer here facilitates scientific analysis as well societal and political discourse and action.

Abstract Large Language Models (LLMs) have made significant progress in recent years, achieving remarkable results in question-answering tasks (QA). However, they still face two major challenges at inference time: hallucination and outdated information. These challenges take center stage in critical domains like climate change, where obtaining accurate and up-to-date information from reliable sources in a timely fashion is essential. To overcome these barriers, one potential solution is to provide LLMs with access to external, scientifically accurate, and robust sources (long-term memory). This access assists LLMs in continuously updating their knowledge and preventing the propagation of inaccurate, incorrect, or outdated information. In this study, we enhanced GPT-4 by providing it access to the Sixth Assessment Report of the Intergovernmental (IPCC-AR6), the most comprehensive, up-to-date, and reliable source in this domain. We present our conversational AI prototype, available at www.chatclimate.ai. The product answers challenging questions accurately in three different QA scenarios: asking from 1) GPT-4, 2) ChatClimate, and 3) hybrid ChatClimate. The answers and their sources were evaluated by a team of IPCC authors, who used their expert knowledge to score the accuracy of the answers from 1 (very-low) to 5 (very-high). The evaluation showed that the Standalone assistant provided more accurate answers.

AbstractRecent evidence shows that climate change is leading to irreversible and existential impacts on vulnerable communities and countries across the globe. Among other effects, this has given rise to public debate and engagement around notions of climate crisis and emergency. The Loss and Damage (L&D) policy debate has emphasized these aspects over the last three decades. Yet, despite institutionalization through an article on L&D by the United Nations Framework Convention on Climate Change (UNFCCC) in the Paris Agreement, the debate has remained vague, particularly with reference to its remit and relationship to adaptation policy and practice. Research has recently made important strides forward in terms of developing a science perspective on L&D. This article reviews insights derived from recent publications by the Intergovernmental Panel on Climate Change (IPCC) and others, and presents the implications for science and policy. Emerging evidence on hard and soft adaptation limits in certain systems, sectors and regions holds the potential to further build momentum for climate policy to live up to the Paris ambition of stringent emission reductions and to increase efforts to support the most vulnerable. L&D policy may want to consider actions to extend soft adaptation limits and spur transformational, that is, non-standard risk management and adaptation, so that limits are not breached. Financial, technical, and legal support would be appropriate for instances where hard limits are transgressed. Research is well positioned to further develop robust evidence on critical and relevant risks at scale in the most vulnerable countries and communities, as well as options to reduce barriers and limits to adaptation.

<p>The consequences of climate change in South and Central America are already widespread and take on many forms. Albeit there is an increasing number of studies focusing on specific climate change-related risks in the region, a synthesis of risks for the 21<sup>st</sup> century, together with current and future adaptation options is lacking. This study synthesizes major climate related risks in South and Central America, while also looking at implications for adaptation measures and (un)avoidable loss and damage. A review of over 100 peer-reviewed articles published since 2013 was completed to examine the current and projected state of the risks. We identify eight key risks in South and Central America that have the potential to become severe with climate change during the 21<sup>st</sup> century. The criteria for a severe risk relate to the number of people potentially affected, the severity of the negative effects of the risk, the importance of the affected systems, and the irreversibility versus potential to reduce the risk. The risks are analysed in relation to different climate scenarios, and changes in associated hazards, exposure, and/or vulnerability. The risks include 1: risk of food insecurity due to repeated and/or extreme drought conditions; 2: risk to life and infrastructure due to floods and landslides; 3: risk of water insecurity in Central America and the Andes region; 4: systemic risks of surpassing infrastructure and public service system capacities due to cascading impacts of storms, floods and epidemics; 5: risk of severe health effects due to increasing epidemics (in particular vector-borne diseases); 6: risk of large-scale ecological transformation of the Amazon forest; 7: risk to coral reef ecosystems due to coral bleaching in Central America; 8: risk to coastal socio-ecological systems due to sea level rise, intensification of upwelling and ocean acidification. In addition, we focus on already implemented and possible adaptation measures for each of the risks. Subsequently, we draw conclusions of the potential losses and damages caused by each risk. Our assessment of risks in the Central and South America region show that several risks have the potential to become severe already in the near future. The extent of the severity is driven by the specific region’s exposure, vulnerability and adaptation capacity. Adaptation capacity is in turn dependent on physical as well as socio-economic systems. Inequalities, corruption, and poor communication between decision makers, stakeholders and the scientific community together with a lack of available data can critically limit adaptation options. Still, many adaptation options are available, and efforts to thoroughly research further adaptation measures should be of highest priority. This will undoubtedly save both lives and severe economic damage as South and Central America face the consequences of climate change.</p>

Changes in the mountain cryosphere impact the water security of downstream societies and the resilience of water-dependent ecosystems and their services. However, assessing mountain water security requires better understanding of the complex interaction between glacial meltwater and coupled human–natural systems. In this context, we call for a refocusing from glacio-hydrological monitoring and modelling to a more integrated social-ecological perspective of the wider catchment hydrology. This shift requires locally relevant knowledge-production strategies and the integration of such knowledge into a collaborative science–policy–community framework. This approach, combined with hydrological risk assessment, can support the development of robust, locally tailored and transformational adaptation strategies.

Abstract. Despite recent research identifying a clear anthropogenic impact on glacier recession, the effect of recent climate change on glacier-related hazards is at present unclear. Here we present the first global spatio-temporal assessment of glacial lake outburst floods (GLOFs) focusing explicitly on lake drainage following moraine dam failure. These floods occur as mountain glaciers recede and downwaste and many have an enormous impact on downstream communities and infrastructure. Our assessment of GLOFs associated with the collapse of moraine-dammed lakes provides insights into the historical trends of GLOFs and their distributions under current and future global climate change. We observe a clear global increase in GLOF frequency and their regularity around 1930, which likely represents a lagged response to post-Little Ice Age warming. Notably, we also show that GLOF frequency and their regularity – rather unexpectedly – has declined in recent decades even during a time of rapid glacier recession. Although previous studies have suggested that GLOFs will increase in response to climate warming and glacier recession, our global results demonstrate that this has not yet clearly happened. From assessment of the timing of climate forcing, lag times in glacier recession, lake formation and moraine dam failure, we predict increased GLOF frequencies during the next decades and into the 22nd century.