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Emission budgets are defined as the cumulative amount of anthropogenic CO₂ emission compatible with a global temperature-change target. The simplicity of the concept has made it attractive to policy-makers, yet it relies on a linear approximation of the global carbon-climate system's response to anthropogenic CO2 emissions. Here we investigate how emission budgets are impacted by the inclusion of CO₂ and CH₄ emissions caused by permafrost thaw, a non-linear and tipping process of the Earth system. We use the compact Earth system model OSCAR v2.2.1, in which parameterizations of permafrost thaw, soil organic matter decomposition and CO₂ and CH₄ emission were introduced based on four complex land surface models that specifically represent high-latitude processes. We found that permafrost carbon release makes emission budgets path dependent (that is, budgets also depend on the pathway followed to reach the target). The median remaining budget for the 2 °C target reduces by 8% (1-25%) if the target is avoided and net negative emissions prove feasible, by 13% (2-34%) if they do not prove feasible, by 16% (3-44%) if the target is overshot by 0.5 °C and by 25% (5-63%) if it is overshot by 1 °C. (Uncertainties are the minimum-to-maximum range across the permafrost models and scenarios.) For the 1.5 °C target, reductions in the median remaining budget range from ~10% to more than 100%. We conclude that the world is closer to exceeding the budget for the long-term target of the Paris Climate Agreement than previously thought.

A detailed process-based methane module for a global land surface scheme has been developed which is general enough to be applied in permafrost regions as well as wetlands outside permafrost areas. Methane production, oxidation and transport by ebullition, diffusion and plants are represented. In this model, oxygen has been explicitly incorporated into diffusion, transport by plants and two oxidation processes, of which one uses soil oxygen, while the other uses oxygen that is available via roots. Permafrost and wetland soils show special behaviour, such as variable soil pore space due to freezing and thawing or water table depths due to changing soil water content. This has been integrated directly into the methane-related processes. A detailed application at the Samoylov polygonal tundra site, Lena River Delta, Russia, is used for evaluation purposes. The application at Samoylov also shows differences in the importance of the several transport processes and in the methane dynamics under varying soil moisture, ice and temperature conditions during different seasons and on different microsites. These microsites are the elevated moist polygonal rim and the depressed wet polygonal centre. The evaluation shows sufficiently good agreement with field observations despite the fact that the module has not been specifically calibrated to these data. This methane module is designed such that the advanced land surface scheme is able to model recent and future methane fluxes from periglacial landscapes across scales. In addition, the methane contribution to carbon cycle–climate feedback mechanisms can be quantified when running coupled to an atmospheric model.

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.

Effects of the short-term temporal variability of meteorological variables on soil temperature in northern high-latitude regions have been investigated. For this, a process-oriented land surface model has been driven using an artificially manipulated climate dataset. Short-term climate variability mainly impacts snow depth, and the thermal diffusivity of lichens and bryophytes. These impacts of climate variability on insulating surface layers together substantially alter the heat exchange between atmosphere and soil. As a result, soil temperature is 0.1 to 0.8 ∘C higher when climate variability is reduced. Earth system models project warming of the Arctic region but also increasing variability of meteorological variables and more often extreme meteorological events. Therefore, our results show that projected future increases in permafrost temperature and active-layer thickness in response to climate change will be lower (i) when taking into account future changes in short-term variability of meteorological variables and (ii) when representing dynamic snow and lichen and bryophyte functions in land surface models.