Collisionless evaporation from cluster elliptical galaxies

We describe a particular aspect of the effects of the parent cluster tidal field (CTF) on stellar orbits inside cluster Elliptical galaxies. In particular we discuss, with the aid of a simple numerical model, the possibility that collisionless stellar evaporation from elliptical galaxies is an effective mechanism for the production of the recently discovered intracluster stellar populations. A preliminary investigation, based on very idealized galaxy density profiles (Ferrers density distributions), showed that over an Hubble time, the amount of stars lost by a representative galaxy may sum up to the 10% of the initial galaxy mass, a fraction in interesting agreement with observational data. The effectiveness of this mechanism is due to the fact that the galaxy oscillation periods near equilibrium configurations in the CTF are comparable to stellar orbital times in the external galaxy regions. Here we extend our previous study to more realistic galaxy density profiles, in particular by adopting a triaxial Hernquist model.Comment: 6 pages, 2 figures. To appear on "Lecture Notes in Physics", proceedings of the Workshop on "Galaxies and Chaos. Theory and Observations", Athens (September 16-19, 2002), G. Contopoulos and N. Voglis, ed

Cosmological Neutrino Entanglement and Quantum Pressure

Context: The widespread view that cosmological neutrinos, even if massive, are well described since the decoupling redshift z~10^10 down to the present epoch by an almost perfectly collisionless fluid of classical point particles is re-examined. Aims: In view of the likely sub-eV rest mass of neutrinos, the main effects due to their fermionic nature are studied. Methods: By numerical means we calculate the accurate entropy, fugacity and pressure of cosmological neutrinos in the Universe expansion. By solving the Schroedinger equation we derive how and how fast semi-degenerate identical free fermions become entangled. Results: We find that for sub-eV neutrinos the exchange degeneracy has significantly increased during the relativistic to non-relativistic transition epoch at z~10^4-10^5. At all times neutrinos become entangled in less than 10^-6 s, much faster than any plausible decoherence time. The total pressure is increased by quantum effect from 5% at high redshifts to 68% at low redshifts with respect to a collisionless classical fluid. Conclusions: The quantum overpressure has no dynamical consequences in the homogeneous regime at high redshifts, but must be significant for neutrino clustering during the non-linear structure formation epoch at low redshifts.Comment: 11 pages, 7 figures, accepted version to Astronomy & Astrophysics (no change, correct wrong TeX rendering

A new dynamic framework is required to assess adaptation limits

Anthropogenic climate change is already causing dangerous and widespread disruptions in global ecological and social systems and affects the lives of billions of people around the world. Even with scaled-up risk management and adaptation, the limits of adaptation will often be reached. Currently, very little is known about the degree to which societies can adapt to climate change, and where and when limits to adaptation will be reached. In this paper, we conceptualize adaptation limits through a novel methodological framework, assess adaptation limits along adaptation pathways, and propose a research strategy for empirical and model-based limits assessments based on biophysical and socio-economic data. Assessing limits is central to national and international adaptation policymaking. More efficient adaptation can also help climate mitigation efforts

Loss and Damage in the mountain cryosphere

The mountain cryosphere, which includes glaciers, permafrost, and snow, is one of the Earth’s systems most strongly affected by climate change. In recent decades, changes in the cryosphere have been well documented in many high-mountain regions. While there are some benefits from snow and ice loss, the negative impacts, including from glacier lake outburst floods and variations in glacier runoff, are generally considered to far outweigh the positive impacts, particularly if cultural impacts are considered. In international climate policy, there has been growing momentum to address the negative impacts of climate change, or ‘Loss and Damage’ (L&D) from climate change. It is not clear exactly what can and should be done to tackle L&D, but researchers and practitioners are beginning to engage with policy discussions and develop potential frameworks and supporting information. Despite the strong impact of climate change on the mountain cryosphere, there has been limited interaction between cryosphere researchers and L&D. Therefore, little work has been done to consider how L&D in the mountain cryosphere might be conceptualized, categorized, and assessed. Here, we make a first attempt to analyze L&D in the mountain cryosphere by conducting a systematic literature review to extract L&D impacts and examples from existing literature. We find that L&D is a global phenomenon in the mountain cryosphere and has been more frequently documented in the developing world, both in relation with slow and sudden onset processes. We develop a categorization of L&D, making distinctions between physical and societal impacts, primary and secondary impacts, and identifying seven types of L&D (including L&D to culture, livelihoods, revenue, natural resources, life, and security). We hope this conceptual approach will support future work to understand and address L&D in the mountain cryosphere

Trends in climate adaptation solutions for mountain regions

This study addresses the critical need for documented adaptation progress in mountain regions by reviewing recently implemented or ongoing adaptation solutions collected from the Adaptation at Altitude Solutions Portal (A@A Solution Portal). Using a data driven approach, the research explores the characteristics, feasibility, and transformative potential of these solutions. Findings reveal a predominant focus on addressing droughts and floods, aligning with the IPCC’s emphasis on water-related impacts in mountains. Notably, watershed management practices emerge as popular solutions, showcasing their capacity to address multiple concerns beyond climate impacts. Education and awareness, along with land use practices, dominate the types of solutions, reflecting their positive impact on project acceptability and low associated risk of maladaptation. Agricultural land and forests are the main ecosystems where solutions are reported, with an evident association with education and awareness and land use change solutions. Most SDGs and Sendai targets are found to be addressed by the solutions emphasising the importance of documenting project experiences as way to bridge previously reported gaps between policy frameworks and on-the-ground implementation. Despite community involvement being high in many of the solutions, challenges such as gender inequality persists. While solutions often demonstrate local relevance and depth of change, upscaling remains challenging, with limited evidence of mainstreaming and replication. Sustainability criteria are moderately met, incorporating inclusive decision-making but with uncertainty regarding long-term plans. Furthermore, findings underscore the significance of co-developing and maintaining adaptation solution portals, illustrating how this approach enriches our understanding of adaptation progress in mountains. Moreover, this research contributes to broadening the scope of systematic adaptation assessments by providing a nuanced perspective that integrates local needs and diverse knowledge systems. In essence, this study makes a valuable contribution to the evolving landscape of adaptation research, emphasizing the importance of practical insights and collaborative efforts to address the complex challenges posed by climate-related impacts and corresponding adaptation efforts

Europe (Chapter 13)

Our current 1.1°C warmer world is already affecting natural and human systems in Europe (very high confidence1). Since AR5, there has been a substantial increase in detected or attributed impacts of climate change in Europe, including extreme events (high confidence). Impacts of compound hazards of warming and precipitation have become more frequent (medium confidence). Climate change has resulted in losses of, and damages to, people, ecosystems, food systems, infrastructure, energy and water availability, public health and the economy (very high confidence)

Knowledge priorities on climate change and water in the Upper Indus Basin: a horizon scanning exercise to identify the top 100 research questions in social and natural sciences

River systems originating from the Upper Indus Basin (UIB) are dominated by runoff from snow and glacier melt and summer monsoonal rainfall. These water resources are highly stressed as huge populations of people living in this region depend on them, including for agriculture, domestic use, and energy production. Projections suggest that the UIB region will be affected by considerable (yet poorly quantified) changes to the seasonality and composition of runoff in the future, which are likely to have considerable impacts on these supplies. Given how directly and indirectly communities and ecosystems are dependent on these resources and the growing pressure on them due to ever-increasing demands, the impacts of climate change pose considerable adaptation challenges. The strong linkages between hydroclimate, cryosphere, water resources, and human activities within the UIB suggest that a multi- and inter-disciplinary research approach integrating the social and natural/environmental sciences is critical for successful adaptation to ongoing and future hydrological and climate change. Here we use a horizon scanning technique to identify the Top 100 questions related to the most pressing knowledge gaps and research priorities in social and natural sciences on climate change and water in the UIB. These questions are on the margins of current thinking and investigation and are clustered into 14 themes, covering three overarching topics of ‘governance, policy, and sustainable solutions’, ‘socioeconomic processes and livelihoods’, and ‘integrated Earth System processes’. Raising awareness of these cutting-edge knowledge gaps and opportunities will hopefully encourage researchers, funding bodies, practitioners, and policy makers to address them