The basal thermal state of the Antarctic ice sheet (AIS)—whether the base is frozen or thawed—fundamentally underpins its flow and is an important factor in understanding its large-scale response to external forcings. Here, we present a first synthesis of the AIS basal thermal state combining two indirect and independent methods: (1) a compilation of nine three-dimensional thermomechanical simulations that calculate AIS basal temperature as part of the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) and (2) an estimate of the basal slip ratio, defined as the ratio of observed surface speed to deformational speed. This synthesis is evaluated against direct observations from deep boreholes and predicted flowpaths for water originating from subglacial lakes detected by altimetry and radar sounding. The synthesis predicts a thawed bed across most of West Antarctica and localized regions in East Antarctica. Most of the Antarctic Peninsula, the Transantarctic Mountains and several regions of East Antarctica are likely frozen at the bed. Overall, our synthesis suggests 46% of the AIS bed is likely thawed, 18% likely frozen and the remaining 36% is uncertain. Additional observations, particularly at the continental scale, are required to improve our understanding of Antarctica’s basal thermal state.

In 1988, meteorological measurements started at the Spanish research station Juan Carlos I (JCI) on Livingston Island. A second station - Gabriel de Castilla (GdC) - was installed in 2005 on Deception Island. These long-term measurements improved our climatological understanding of the western region of the South Shetland Islands (SSI), a region that has received less attention than the more station-populated King George Island in the central SSI. Here, we present a complete climatological analysis of these stations after undertaking a full quality control process of the data. This analysis covers temperature, wind, precipitation, radiation, relative humidity and pressure, as well as trends and variability. The results show: 1) the stations along the western SSI coastline, particularly JCI, are warmer than those on the central SSI, especially in summer, 2) at GdC, winters are colder due to stagnant cold air pooling within the Deception Island caldera, 3) the importance of island orography in shaping local climatology, especially regarding wind patterns, and 4) the critical need to correct precipitation measurements for undercatchment of solid precipitation by common pluviometers. This study provides a climatological framework to support further research conducted in the region.

Glaciers provide critical ecosystem services, including water resources, biodiversity, cultural value and climate signals. But what makes a glacier a glacier? And when is a glacier no longer a glacier? Different glacier definitions can conflict. While a common definition emphasizes ‘past or present flow’, practical applications involve criteria like observable ice flow, crevassing, minimum thickness, minimum area, surficial features related to hydrology and/or debris cover and/or relative size. Increasingly, glacier inventories apply multiple criteria, acknowledging the nuanced, continuous nature of glacier retreat rather than a binary status. In the context of increasingly melting, shrinking and vanishing glaciers, as glaciologists consider when to declare a glacier lost, disappeared or dead, it is important to explore glacier definitions and their application. Ultimately, the glacier definition applied depends on the specific context, purpose and audience. This also highlights the need for careful language choice, clear communication and localized expertise in considering glacier loss.

The Silurian of Podolia, Ukraine, is renowned for its arthropod fauna, including eurypterids and the synziphosurine Pasternakevia. Here, we describe one of several new arthropods recently discovered in the vicinity of the Smotrych River. Smotrychaspis kurtopleurae gen. et sp. nov. is a synziphosurine euchelicerate with semicircular carapace lacking eyes, an unfused opisthosoma with 11 visible segments, the posterior tergites wide and bearing falcate epimera and a relatively long and stout telson. Smotrychaspis resembles pseudoniscid and bunodid synziphosurines but cannot be placed in either of these families.

Negotiations by more than 180 States during the Intergovernmental Negotiating Committee (INC) session 5.2 to develop a legally binding instrument with the purpose to end plastic pollution have, once again, concluded without a treaty. This is especially disastrous for developing States and marginalized peoples (such as indigenous communities and waste pickers), who are disproportionately suffering from plastic pollution. In this article, we show that developing States were underrepresented at the INC-5.2 negotiations in Geneva: Their delegations were on average only half as large (~5 delegates) when compared to delegations from Western European States (~13 delegates) and those from States with a high and very high Human Development Index (~10 delegates). In addition, more than 230 industry representatives participated in INC-5.2, exerting influence in diverse ways, both during official negotiations and through side events, organized by lobbying organizations. Finally, we discuss the importance of how treaty negotiations were organized: Simultaneously occurring negotiation formats (such as contact groups and informal meetings) put smaller delegations at a disadvantage, causing procedural injustice, which falls under the responsibility of the INC Secretariat.

This short report provides the first observations of deep-sea corals belonging to the class Octocorallia and order Antipatharia surveyed during the KM24-03 Leg 2 cruise in the waters around Minamidaito and Kitadaito Islands in Okinawa, Japan between approximately 200 and 1,000 m. It also lists and illustrates the specimens that were collected. Based on field observations, deep-sea corals occupied the niches inside and around caves and crevices, as well as non-cave environments such as flat seabeds and slopes. Our morphological and phylogenetic analyses of the collected specimens revealed the presence of Callogorgia cf. korema, Pleurocorallium inutile, and Acanthopathes undulata. We provide the first documentation of deep-sea corals found in this area, as well as extend the known geographic distribution of these species. In particular, the black coral A. undulata, which until now has only been reported from the western and central Pacific Ocean, is reported for the first time in the northwestern Pacific. Our preliminary findings warrant further investigation and more stringent protection of the deep-sea species and habitats found in the waters around these karstic islands from anthropogenic impacts, perhaps with inclusion in regional Marine Protected Areas.

The Chalbi Desert, located in eastern Africa, is a significant but overlooked archive of the Pleistocene and Holocene periods that could add insight into investigations on human evolution. We revisited southeastern Chalbi Desert landforms between the towns of Kargi and Maikona to improve the chronostratigraphy and provide paleoenvironmental context. Direct U-series and electron spin resonance dating of various fossil teeth recovered from a deflated dune (Qzs) landform at the Farre locality return a mean age of ∼545 ka, which is compatible with biostratigraphic inferences. While this numerical age result should probably be regarded as mostly indicative given the existing uncertainty on the environmental dose rate evaluation, the data set available nevertheless strongly suggests a Middle Pleistocene age for at least some of the fauna. Sedimentology, luminescence, and 14C dating further suggest that this Qzs landform and its contents were modified by alluvial fan development and weathering during denudation in a proximal fan setting through the late Pleistocene into the Holocene. The Qzs landform currently experiences aeolian additions, erosion, and salt-affected soil development in an arid climate. Pedogenic carbonate isotope geochemistry suggests that deflated sand dunes were covered by woody grasslands during Marine Isotope Stage (MIS) 4 and 3 pluvials, consistent with nearby fan progradation constrained at >35 ka. The desert experienced increased hydrologic activity during late Pleistocene and African humid period pluvials, as evidenced by additional optically stimulated luminescence and 14C dating from fan, dune, and playa contexts. The last significant pluvial episode ended after 4.4 ± 0.3 cal ka BP, which coincides with the final regression of nearby Lake Turkana. This study extends the chronology of Quaternary sediments in the Chalbi Desert to the Middle Pleistocene and offers paleoenvironmental insights into the conditions experienced by Middle Stone Age tool users in the region.