ALBERT

Description: Villarrica Volcano is an active ice-covered volcano in southern Chile (2847 m a.s.l., 39°25’12’’ S, 71°56’27’’W), with a current glacier extent of 23.6 km〈sup〉2〈/sup〉. To investigate meteorological conditions and the impact of ongoing climatic warming on glacier melt, an automatic weather station (AWS) was installed at 1900 m a.s.l. on a tephra-covered surface in the glacier ablation zone in December 2019, providing continuous measurements of meteorological variables and tephra temperatures. To give further insight into the turbulent fluxes of sensible and latent heat at the glacier surface, an eddy covariance system, consisting of a parallel-mounted 3D sonic anemometer and krypton hygrometer, was deployed over tephra and snow surfaces close to the AWS between 12-16 January 2023. During the summer, snow and ice are subject to intense insolation and positive air temperatures, with high melt rates further amplified by surface darkening from windblown low-albedo tephra. In contrast, ice beneath extensive areas of tephra cover in the lower ablation zone is effectively insulated, with much lower ablation rates. Both tephra and snow exhibit predominantly negative latent heat fluxes, indicating surface water evaporation, with notably high magnitude and variable fluxes at the tephra site during the afternoon when surface temperature exceeds 35°C. The snow site is predominantly a sink of atmospheric sensible heat, due to positive air temperatures, while the tephra site alternates between positive and negative sensible heat fluxes, determined by high daytime and low night-time surface temperature, respectively. These measurements will be used to inform approaches to modelling the turbulent fluxes.

Description: Our understanding of the climatic teleconnections that drove ice-age cycles has been limited by a paucity of well-dated tropical records of glaciation that span several glacial–interglacial intervals. Glacial deposits offer discrete snapshots of glacier extent but cannot provide the continuous records required for detailed interhemispheric comparisons. By contrast, lakes located within glaciated catchments can provide continuous archives of upstream glacial activity, but few such records extend beyond the last glacial cycle. Here a piston core from Lake Junín in the uppermost Amazon basin provides the first, to our knowledge, continuous, independently dated archive of tropical glaciation spanning 700,000 years. We find that tropical glaciers tracked changes in global ice volume and followed a clear approximately 100,000-year periodicity. An enhancement in the extent of tropical Andean glaciers relative to global ice volume occurred between 200,000 and 400,000 years ago, during sustained intervals of regionally elevated hydrologic balance that modified the regular approximately 23,000-year pacing of monsoon-driven precipitation. Millennial-scale variations in the extent of tropical Andean glaciers during the last glacial cycle were driven by variations in regional monsoon strength that were linked to temperature perturbations in Greenland ice cores1; these interhemispheric connections may have existed during previous glacial cycles.

Description: This paper presents major gaps and challenges for implementing the UN Decade of Ocean Science for Sustainable Development (2021-2030) in the Mediterranean region. The authors make recommendations on the scientific knowledge needs and co-design actions identified during two consultations, part of the Decade preparatory-phase, framing them in the Mediterranean Sea’s unique environmental and socio-economic perspectives. According to the ‘Mediterranean State of the Environment and Development Report 2020’ by the United Nations Environment Programme Mediterranean Action Plan and despite notable progress, the Mediterranean region is not on track to achieve and fully implement the Sustainable Development Goals of Agenda 2030. Key factors are the cumulative effect of multiple human-induced pressures that threaten the ecosystem resources and services in the global change scenario. The basin, identified as a climate change vulnerability hotspot, is exposed to pollution and rising impacts of climate change. This affects mainly the coastal zones, at increasing risk of extreme events and their negative effects of unsustainable management of key economic assets. Transitioning to a sustainable blue economy is the key for the marine environment’s health and the nourishment of future generations. This challenging context, offering the opportunity of enhancing the knowledge to define science-based measures as well as narrowing the gaps between the Northen and Southern shores, calls for a joint (re)action. The paper reviews the state of the art of Mediterranean Sea science knowledge, sets of trends, capacity development needs, specific challenges, and recommendations for each Decade’s societal outcome. In the conclusions, the proposal for a Mediterranean regional programme in the framework of the Ocean Decade is addressed. The core objective relies on integrating and improving the existing ocean-knowledge, Ocean Literacy, and ocean observing capacities building on international cooperation to reach the “Mediterranean Sea that we want