At the upper reaches of the Jutulstraumen Glacier in central Dronning Maud Land, East Antarctica, nunataks—exposed rock formations—are widely distributed. This image captures the summit of one such nunatak, named Nashornet. The exposed rock to the left consists of a mafic sill intruding into Proterozoic sedimentary sequences. Based on the surface exposure dating of bedrock and erratics on this nunatak, it is possible to reconstruct past changes in the elevation of the East Antarctic Ice Sheet. The author participated in the 57th Japanese Antarctic Research Expedition (2015-2016) and conducted extensive fieldwork based out of Norway's Troll Station. To reach the site, a helicopter was chartered from South Africa's SANAE Station. This image was taken while heading to the helicopter pickup point after completing glacial geomorphological surveys and collecting samples for surface exposure dating.

(Photograph & Explanation: Yusuke SUGANUMA)

 The East Antarctic Ice Sheet (EAIS) is the largest continental ice mass on Earth, hold a freshwater storage equivalent to approximately 52.2 m of global sea level. Consequently, even minor volume alterations in the ice sheet can have significant ramifications for global sea level and climate dynamics. The imperative to understand the EAIS's sensitivity to different forcing agents is heightened by this potential impact. Although recent advancements in satellite gravimetry and ice-sheet modeling have resulted in refined EAIS mass balance estimates and evaluation of its response to global climatic shifts, space-geodetic data on ice-sheet changes span only recent decades. To validate and refine models studying the ice-sheet's sensitivity to atmospheric and oceanic warming, circulation changes, and sea-level rise, well-constrained records of past ice-sheet changes are essential. These emphasize the need for long-term (millennial-scale) glacio-geological records from field-based studies. Historical efforts by Japanese researchers have employed glacial geomorphology and geology to reconstruct past changes in EAIS at Dronning Maud Land, East Antarctica. Building on these foundational efforts, recent research has delved into the mechanisms behind EAIS mass loss over longer time scales, integrating space geodetic measurements, oceanographic observations, and numerical modelings. Recently, key findings highlighted rapid thinning of EAIS during the Early to Middle Holocene, as evidenced by the deglacial chronology derived from in situ cosmogenic nuclide surface exposure dates and simulations encompassing ice sheet, oceanographic, and glacial isostatic adjustments. Additionally, innovative techniques, such as marine sediment coring aboard the icebreaker Shirase and the use of a newly developed portable percussion piston coring system, are poised to provide further insights into the transition from ice shelf breakup to potential EAIS collapse. It is emphasized that glacial geomorphological and geological studies hold great potential to provide essential insights into the mechanisms of large-scale ice mass loss in EAIS, insights that cannot be obtained from modern observations alone.

 We review the progress of research on permafrost and periglacial dynamics over the last two decades and explore future periglacial landscapes in Svalbard, High Arctic. This area has been subjected to rapid air and ground warming at a rate of 0.1-0.2°C yr⁻¹, as well as simultaneous thawing of the top layer of permafrost at a rate of about 1 cm yr⁻¹ over the last two decades. Periglacial features studied include ice-wedge polygons, mudboils, sorted patterned ground, pingos, solifluction lobes, active-layer detachment slides, and rock glaciers. These landforms are concentrated within narrow alluvial plains and valley-side slopes but separated by geomorphological specifics and ground materials. Decadal-scale monitoring highlights climatic control of the morphology and dynamics of three landforms—ice-wedge polygons, mudboils, and rock glaciers—and the impact of long-term warming on their dynamics. Despite the location close to the southern limit of continuous permafrost, multiple cold spells in mid-winter activate thermal contraction cracking, which permits the growth of ice wedges. If such cold spells continue under a warmer climate, ice wedge could still grow below the deepening active layer. In a mudboil-small polygon landscape, seasonal frost heaving (or thaw settlement) of the central mound is coupled with closing (or opening) of the marginal crack. This movement would be maintained under a warmer climate and at a deeper active layer if the active layer is kept very humid. Although the contemporary cold climate is generally unfavorable for the growth of well-developed rock glaciers in Svalbard, slow permafrost creep at a rate of a few centimeters per year produces basal bulging of the valley-side talus slopes. The warming trend in the last decade has led to a steady acceleration of the movement. Further warming in the near future is expected to develop longer valley-side rock glaciers.

 Mountain glaciers around the world have been retreating since the beginning of the 20th century. Glaciers in the tropical alpine zones of Africa are shrinking at a particularly fast rate. In the early 1900s, research in the tropical high mountains was exploratory, with observations of landforms, vegetation, and ecosystems, and the discovery of glaciers. During the 1950s to 1980s, the main research trend was to elucidate changes in the masses of glaciers. From the 1990s to the present, there have been many studies on the effects of climate change and shrinking glaciers on the surrounding environment and ecosystems. These studies were cumulatively greater than in other periods. This indicates that the tropical high mountains in Africa and their glaciers have attracted the interest of many researchers as icons at the forefront of the effects of climate change. Glaciers in the tropical African high mountains are expected to disappear within the next decade. In recent years, aridification and changes in the water environment have been reported not only in mountain bodies but also in foothill areas. Changes in the surrounding environment as glaciers shrink are summarized, in order to contribute to future environmental conservation.

 A thick mass of and unsorted debris is located in a valley-head cirque in the Tateyama area of the Northern Japanese Alps. The debris shows a characteristic deformation structure with jigsaw cracks, dike-like injections of fines, and shearing. Therefore it is judged to be composed of massive rock avalanche materials that are not of glacial or fluvial origin. Based on the cosmogenic nuclide exposure ages of granitic boulders, the debris is covered by late Pleistocene (18 to 12 ka) glacial, fluvioglacial, or debris flow deposits. The debris suggests that a massive rock slope failure occurred prior to glacial advance in the cirque during MIS2. Further investigations are required at other areas of the glaciated high mountains in central Japan.

 The denudation processes at the rockwall of Mt. Shakushi (Hakuba Mountains) were investigated by examining the recent retreat (1976-2023) of a slope linked to a rock slope failure in 2005, using multi-year 3D topography models created from SfM-MVS software together with aerial photographs and UAV images. The results show that denudation occurred frequently on rockwalls with high joint density. Two parallel cracks were observed in the head area of the rockwall before the collapse in 2005. The collapse occurred along one of the two cracks. The remaining crack expanded between 2019 and 2023, such that the rockwall is now in an unstable state. In addition to the observed denudation processes and their joint density dependence, crack expansion along one of the dominant joints was revealed, indicating that gravitational deformation plays an important role in denudation.

 On September 25-26, 2013, core drilling was conducted at the Sannomado Glacier, Mt. Tsurugi, in the northern Japanese Alps. The ice core obtained is 20 m in length. The ice core consists of a firn layer from the core top to the dirty layer laid down in 2012 (520-532 cm in depth), alternating layers of glacier ice and firn from the dirty layer laid down in 2012 to the dirty layer laid down in 2011 (660-670 cm in depth), and glacier ice from a depth of 660 cm to the core bottom. The glacier ice consists of bubble ice, clear ice, and interbedded dirty layer. Eight distinct dirty layers, estimated to be annual layer boundaries, are found in the core. The Sannomado Glacier is in an environment with extremely thick snow cover in winter and significant snow melt in summer. Analysis of grain size of ice core shows no growth of grain size with icing. Therefore, it is assumed that the glacier ice was formed by dentification of water-saturated firn within two years after snow deposition. Elongated bubbles are more pronounced below 1,278 cm in depth, and the dip of the elongated bubbles is roughly in line with the dip of the glacier flow. These are taken to be evidence that internal deformation is currently occurring in this glacier.

 At Hakuba Daisekkei, a perennial snow patch in the northern Japanese Alps, three accidents resulting in casualties due to snow-patch collapses have occurred since the 1960s. The locations of the snow-patch collapses and their precursor phenomena between 2016 and 2021 are investigated using GPR surveys, topographical analyses with UAV-DSMs, UAV-ortho images, and field observations. The research reveals that a tunnel forms at the bottom of the snow patch in the same location annually. Measurements taken at ten points in the exposed tunnel at the ends of snow melts in 2016, 2019, and 2020 show that the tunnel was 9-16 m high and 20-31 m wide. Snow-patch collapses since 2016 are found to have occurred in the ice tunnel, specifically at sites with unstable cantilever bridges and at confluence points of tributaries. Precursor phenomena of snow-patch collapse are identified as the formation and expansion of cracks and local depressions on the snow patch. There is a tendency for many crack formations and snow-patch collapses to occur in light snow years.

 An algific talus slope, which maintains a local subsurface low-temperature environment in a mountainous terrain, is called Fuketsu in Japanese, which translates as wind hole. Since the 19th century, storage stations have been built on algific talus slopes and used for storing silkworm eggs for sericulture. Tree seeds have also been stored for forestry plantations since the 20th century. The process for storing seeds by the Japanese Forest Office is examined. In addition, a list is compiled of existing seed storages at various locations.