Ground Thermal Regimes and Implications for Permafrost Distribution on Kilimanjaro, Tanzania

Tropical mountain permafrost has a unique thermal regime due to ground surface exposure to strong solar radiation. The intensity of the surface offset resulting from snow cover also strongly affects the absence or presence of permafrost. Latent heat transfer and reflected solar radiation (higher albedo) that occur during the snow-covered season contribute to a positive feedback that cools the ground. Eleven ground temperature monitoring sites were established on the mountain at 2,780 to 5,820 m.a.s.l. The geothermal heat flow is locally high in the caldera of this volcano, as shown by borehole temperature data. Permafrost is located near the only glacier entirely within the caldera (Furtwangler). These three-year continuous records of ground temperature data encompass years of high and low snow cover. Our results show that the current lower boundary of permafrost is slightly above summit altitude and relict permafrost is present due to the influence of saturated sand on latent heat transfer. Permafrost tends to be lost more rapidly during drought years. The remaining permafrost seems likely to disappear in the future. The presence of permafrost and its thermal resistance depends on the ice content of caldera sand and the duration of snow cover

Early Holocene climate signals from stable isotope composition of ice wedges in the Chara Basin, northern Transbaikalia, Russia

Stable isotope composition of syngenetic and epigenetic ice wedges, radiocarbon age, and pollen spectra of the surrounding deposits were studied during long term investigations at the “Belyi Klyuch” site on the first (6–8 m height) terrace of the Chara River (720 m.a.s.l.) in northern Transbaikalia to assess climatic conditions during ice-wedge formation. It was revealed that Holocene ice wedges had been formed from 10 to 7.5 ka 14C BP. The isotope composition (δ18О, δ2H) of relict ice wedges is the lightest and amounts −23‰ and −185‰, correspondingly. The isotopic compositions of ice lenses from sandy loam above ice wedges are −15.7‰ and −133‰; of small ice wedge in peat and sand are −15.3‰ and −117.9‰, accordingly. Interpretation of the ice wedge isotope composition has yielded that mean winter temperatures during cold stages of Holocene optimum were lower than today, during warm stages they were close to modern ones. During the coldest stages of Holocene optimum the total annual freezing index varied from −5100 to −5700 °C degree days, i.e. 300–600 °C degree days colder than during extremely severe modern winters. The total annual thawing index varied from 1300 to 1800 °C degree days, which was slightly higher than modern ones

Early Holocene climate signals from stable isotope composition of ice wedges in the Chara Basin, northern Transbaikalia, Russia

Stable isotope composition of syngenetic and epigenetic ice wedges, radiocarbon age, and pollen spectra of the surrounding deposits were studied during long term investigations at the "Belyi Klyuch" site on the first (6-8 m height) terrace of the Chara River (720 m.a.s.l.) in northern Transbaikalia to assess climatic conditions during ice-wedge formation. It was revealed that Holocene ice wedges had been formed from 10 to 7.5 ka 14C BP. The isotope composition (δ18О, δ²H) of relict ice wedges is the lightest and amounts −23‰ and −185‰, correspondingly. The isotopic compositions of ice lenses from sandy loam above ice wedges are −15.7‰ and −133‰; of small ice wedge in peat and sand are −15.3‰ and −117.9‰, accordingly. Interpretation of the ice wedge isotope composition has yielded that mean winter temperatures during cold stages of Holocene optimum were lower than today, during warm stages they were close to modern ones. During the coldest stages of Holocene optimum the total annual freezing index varied from −5100 to −5700 °C degree days, i.e. 300-600 °C degree days colder than during extremely severe modern winters. The total annual thawing index varied from 1300 to 1800 °C degree days, which was slightly higher than modern ones

Conceptual Models of Gas Accumulation in the Shallow Permafrost of Northern West Siberia and Conditions for Explosive Gas Emissions

Gas accumulation and pressurized unfrozen rocks under lakes (sublake taliks) subject to freezing in shallow permafrost may lead to explosive gas emissions and the formation of craters. Gas inputs into taliks may have several sources: microbially-mediated recycling of organic matter, dissociation of intrapermafrost gas hydrates, and migration of subpermafrost and deep gases through permeable zones in a deformed crust. The cryogenic concentration of gas increases the pore pressure in the freezing gas-saturated talik. The gradual pressure buildup within the confined talik causes creep (ductile) deformation of the overlying permafrost and produces a mound on the surface. As the pore pressure in the freezing talik surpasses the permafrost strength, the gas-water-soil mixture of the talik erupts explosively and a crater forms where the mound was. The critical pressure in the confined gas-saturated talik (2–2.5 MPa for methane) corresponds to the onset of gas hydrate formation. The conditions of gas accumulation and excess pressure in freezing closed taliks in shallow permafrost, which may be responsible for explosive gas emissions and the formation of craters, are described by several models

The Permafrost Young Researchers Network (PYRN): Integrating priorities for permafrost research over the next generation

The Permafrost Young Researchers Network (PYRN) is an international organization fostering innovative collaboration, seeking to recruit, retain and promote future generations of permafrost researchers. PYRN was founded in November 2005 at the International Conference on Arctic Research Planning (ICARP II) and is steadily growing, reaching around 1500 early career permafrost researchers and engineers, many of them from non-permafrost countries. It builds partnerships with large organizations such as the International Permafrost Association (IPA) and the Association of Polar Early Career Scientists (APECS). The IPY 2007/2008 has emphasized the importance of including the young generation of polar researchers in its activities. PYRN and APECS are a direct legacy of the IPY. Under a joint Memorandum of Understanding, PYRN together with the IPA and APECS work closely together on a bi-polar perspective bringing together natural and social scientist, engineers and humanities for a better understanding of cryospheric processes for society and the elaborate representation of these processes in climate models. PYRN is guided by an Executive Committee but run through its members that organize themselves in an international Council, national communities, thematic groups and several groups of interest. Over the past years, PYRN hosted workshops during the regional and international permafrost conferences. It is increasingly present with sessions and social network events on large conferences like the European and American Geophysical Union (EGU, AGU). During the EUCOP4, PYRN will host a workshop to maintain an active, dynamic and growing early career scientific network on permafrost. Organized together with APECS, PAGE21, and ADAPT, this workshop is kindly sponsored by the IPA, the Climate and Cryosphere (CliC) project and the International Arctic Science Committee (IASC). One major workshop focus is to elaborate the future avenues of permafrost research from a young researchers' perspective. One of the key outcomes will be a young researcher contribution to the IPA strategy for ICARP III issued as a “Permafrost Priority Sheet” summarizing the discussions from the forum. This document is envisioned to contribute to an assessment of research priorities from an early career researcher perspective. It will feed into the final ICARP III meeting in Japan 2015, together with contributions from other initiatives. The 11. International Conference on Permafrost in 2016 (Potsdam, Germany) will provide a forum for many young researchers getting involved in a plethora of activities. PYRN has been involved in the conference planning from the very beginning to effectively integrate PYRN members in the process of ICOP2016 organization as well as young researchers activities in the overall conference program (e.g. workshop, PYRN awards, social program). The conference logo has been found through an international competition organized by PYRN and will be presented in Evora

The Permafrost Young Researchers Network (PYRN) is getting older: The past, present, and future of our evolving community

International audienceA lasting legacy of the International Polar Year (IPY) 2007–2008 was the promotion of the Permafrost Young Researchers Network (PYRN), initially an IPY outreach and education activity by the International Permafrost Association (IPA). With the momentum of IPY, PYRN developed into a thriving network that still connects young permafrost scientists, engineers, and researchers from other disciplines. This research note summarises (1) PYRN’s development since 2005 and the IPY’s role, (2) the first 2015 PYRN census and survey results, and (3) PYRN’s future plans to improve international and interdisciplinary exchange between young researchers. The review concludes that PYRN is an established network within the polar research community that has continually developed since 2005. PYRN’s successful activities were largely fostered by IPY. With >200 of the 1200 registered members active and engaged, PYRN is capitalising on the availability of social media tools and rising to meet environmental challenges while maintaining its role as a successful network honouring the legacy of IPY