RESUMEN
Neighborhood social ties matter crucially, especially during stressful life events like a global pandemic, for they represent vital sources of wellbeing and community capacity. Activities that enable community members to engage in incidental sociability and acts of "neighboring"-that is, authentic social interactions with their neighbors-warrant attention from sport and active living researchers because of their potential to bolster the social fabric of our neighborhoods and facilitate neighbors' access to important resources, such as information, material resources, and social support. Though perhaps dismissed as trivial, neighborhood walking represents a valuable and underappreciated everyday activity that fits this description, especially in an age characterized by an epidemic of social isolation and loneliness. Despite its vast potential to address the quasi-anonymity of urban life, neighborhood walking remains surprisingly underexamined as a facilitator for fostering social connectedness, the sense of connection and social bond people feel toward others. The goal of this manuscript, therefore, is to establish the conceptual grounding for how neighborhood walking strengthens social ties among neighbors to facilitate access to important coping resources. In doing so, it aims to advance a research agenda on walking that moves beyond the benefits of physical activity.
RESUMEN
Marine ice-cliff instability could accelerate ice loss from Antarctica, and according to some model predictions could potentially contribute >1 m of global mean sea level rise by 2100 at current emission rates. Regions with over-deepening basins >1 km in depth (e.g., the West Antarctic Ice Sheet) are particularly susceptible to this instability, as retreat could expose increasingly tall cliffs that could exceed ice stability thresholds. Here, we use a suite of high-fidelity glacier models to improve understanding of the modes through which ice cliffs can structurally fail and derive a conservative ice-cliff failure retreat rate parameterization for ice-sheet models. Our results highlight the respective roles of viscous deformation, shear-band formation, and brittle-tensile failure within marine ice-cliff instability. Calving rates increase non-linearly with cliff height, but runaway ice-cliff retreat can be inhibited by viscous flow and back force from iceberg mélange.
RESUMEN
In combination, the breakaway of icebergs (calving) and submarine melting at marine-terminating glaciers account for between one third and one half of the mass annually discharged from the Greenland Ice Sheet into the ocean. These ice losses are increasing due to glacier acceleration and retreat, largely in response to increased heat flux from the oceans. Behaviour of Greenland's marine-terminating ('tidewater') glaciers is strongly influenced by fjord bathymetry, particularly the presence of 'pinning points' (narrow or shallow parts of fjords that encourage stability) and over-deepened basins (that encourage rapid retreat). Despite the importance of calving and submarine melting and significant advances in monitoring and understanding key processes, it is not yet possible to predict the tidewater glacier response to climatic and oceanic forcing with any confidence. The simple calving laws required for ice-sheet models do not adequately represent the complexity of calving processes. New detailed process models, however, are increasing our understanding of the key processes and are guiding the design of improved calving laws. There is thus some prospect of reaching the elusive goal of accurately predicting future tidewater glacier behaviour and associated rates of sea-level rise.