Hokkaido University · Earth and Planetary Sciences
Professor Akane Tsushima's research lab specializes in paleoclimatology and environmental science, focusing on high-resolution ice core and tree-ring analyses to reconstruct past climate and environmental changes in high-altitude and high-latitude regions. The lab investigates atmospheric aerosols—particularly refractory black carbon—and stable isotopes in ice and tree rings to understand long-term climate variability, human impacts, and hydrological cycles in monsoonal and polar regions. Key research directions include developing advanced analytical techniques for ice core components and applying these to improve the accuracy of paleoclimatic reconstructions.
Figures are computed from collected data and may differ slightly.
Abstract. Oxygen isotope ratios (δ18O) of tree-ring cellulose are a novel proxy for summer hydroclimate in monsoonal Asia. In central Japan, we collected 67 conifer wood samples, mainly Chamaecyparis obtusa, with ages encompassing the past 2600 years. The samples were taken from living trees, archeological wood, architectural wood, and buried logs. We analyzed stable isotope ratios of oxygen (δ18O) and hydrogen (δ2H) in tree-ring cellulose in these samples (more than 15 000 rings in total) witho
Abstract We drilled an 81.2-m-long ice core in the accumulation area (5860 m a.s.l.) of Trambau Glacier in the Rolwaling region during October–November 2019. The drilling operation was conducted with a lightweight electro-mechanical drill system after two reconnaissance fieldworks in 2017 and 2018, during which two shallow firn cores were drilled with a hand auger. The drill system and ice core samples were transported by helicopters at a high elevation of 6000 m a.s.l. A further challenging iss
Abstract. The roles and impacts of refractory black carbon (rBC), an important aerosol species affecting Earth's radiation budget, are not well understood owing to a lack of accurate long-term observations. To study the temporal changes in rBC since the pre-industrial period, we analyzed rBC in an ice core drilled in northwestern Greenland. Using an improved technique for rBC measurement and a continuous flow analysis (CFA) system, we obtained accurate and high-temporal-resolution records of rBC
Abstract We analyzed the water‐soluble chemical composition of an 81.2‐m‐long ice core collected in 2019 from 6,000 m elevation on a south‐facing glacier in the Nepal Himalaya. The ice core chronology is based on variability in nitrate and calcium ions, which reveal an apparently seasonal periodicity (with winter maxima) throughout the core's length. Two annual boundaries are consistent with the tritium peak representing nuclear tests conducted in 1963 CE and with the spike in sulfate ions due t
Abstract. A 180.17 m ice core was drilled at Aurora Peak in the central part of the Alaska Range, Alaska, in 2008 to allow reconstruction of centennial-scale climate change in the northern North Pacific. The 10 m-depth temperature in the borehole was −2.2 °C, which corresponded to annual mean air temperature at the drilling site. In this ice core, there were many melt-refrozen layers due to high temperature and/or strong insolation during summer seasons. We analyzed stable hydrogen isotopes (δD)
<strong class="journal-contentHeaderColor">Abstract.</strong> Ice cores can provide long-term records of black carbon (BC), an important aerosol species closely linked to the climate and environment. However, previous studies of ice cores only analysed BC particles with diameter of <600–850 nm, which could have led to underestimation of BC mass concentrations. Information on the size distribution of BC particles is very limited, and there are no Arctic ice core records of the temporal v
Abstract. Ice cores can provide long-term records of black carbon (BC), an important aerosol species closely linked to the climate and environment. However, previous studies of ice cores only analysed BC particles with diameter of <600–850 nm, which could have led to underestimation of BC mass concentrations. Information on the size distribution of BC particles is very limited, and there are no Arctic ice core records of the temporal variation in BC size distribution. In this study, we applie
<strong class="journal-contentHeaderColor">Abstract.</strong> Ice cores can provide long-term records of black carbon (BC), an important aerosol species closely linked to the climate and environment. However, previous studies of ice cores only analysed BC particles with diameter of <600–850 nm, which could have led to underestimation of BC mass concentrations. Information on the size distribution of BC particles is very limited, and there are no Arctic ice core records of the temporal v
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