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Among the largest uncertainties in current projections of future climate is the feedback between the terrestrial carbon cycle and climate (1). Northern peatlands contain one-third of the world's soil organic carbon, equivalent to more than half the amount of carbon in the atmosphere (2). Climate-warming-induced acceleration of carbon dioxide ([CO.sub.2]) emissions through enhanced respiration of thick peat deposits, centuries to millennia old, may form a strong positive carbon cycle-climate feedback. The long-term temperature sensitivity of carbon in peatlands, especially at depth, remains uncertain, however, because of the short duration or correlative nature of field studies (3-5) and the disturbance associated with respiration measurements below the surface in situ or during laboratory incubations (6,7). Here we combine non-disturbing in situ measurements of [CO.sub.2] respiration rates and isotopic ([[sup.13]C) composition of respired [CO.sub.2] in two whole-ecosystem climate-manipulation experiments in a subarctic peatland. We show that approximately 1°C warming accelerated total ecosystem respiration rates on average by 60% in spring and by 52% in summer and that this effect was sustained for at least eight years. While warming stimulated both short-term (plant-related) and longer-term (peat soil-related) carbon respiration processes, we find that at least 69% of the increase in respiration rate originated from carbon in peat towards the bottom (25-50 cm) of the active layer above the permafrost. Climate warming therefore accelerates respiration of the extensive, subsurface carbon reservoirs in peatlands to a much larger extent than was previously thought (6,7). Assuming that our data from a single site are indicative of the direct response to warming of northern peatland soils on a global scale, we estimate that climate warming of about 1°C over the next few decades could induce a global increase in heterotrophic respiration of 38-100 megatonnes of C per year. Our findings suggest a large, long-lasting, positive feedback of carbon stored in northern peatlands to the global climate system., The long-term effect of climate warming on soil carbon in terrestrial ecosystems has been debated for more than a decade (8-13). This controversy has focused primarily on upland mineral soils [...]

Environmental changes brought on by increased levels of carbon dioxide and ultraviolet-B radiation will impact several aspects of Arctic ecosystems. The nutrient level exhibited the greatest response to change, with temperature and water following. Other responses included community level changes in vegetation for both existing and invading species.

Biological diversity is the basis for, and an indicator of biosphere integrity. Together with climate change, its loss is one of the two most important planetary boundaries. A halt in biodiversity loss is one of the UN Sustainable Development Goals. Current changes in biodiversity in the vast landmass of Siberia are at an initial stage of inventory, even though the Siberian environment is experiencing rapid climate change, weather extremes and transformation of land use and management. Biodiversity changes affect traditional land use by Indigenous People and multiple ecosystem services with implications for local and national economies. Here we review and analyse a large number of scientific publications, which are little known outside Russia, and we provide insights into Siberian biodiversity issues for the wider international research community. Case studies are presented on biodiversity changes for insect pests, fish, amphibians and reptiles, birds, mammals and steppe vegetation, and we discuss their causes and consequences. [ABSTRACT FROM AUTHOR]

Changes in climate, land-use and pollution are having disproportionate impacts on ecosystems and biodiversity of arctic and mountain ecosystems. While these impacts are well-documented for many areas of the Arctic and alpine regions, some isolated and inaccessible mountain areas are poorly studied. Furthermore, even in well-studied regions, assessments of biodiversity and species responses to environmental change are biased towards vascular plants and cryptogams, particularly bryophytes are far less represented. This paper aims to document the environments of the remote and inaccessible Altai-Sayan mountain mires and particularly their bryofloras where threatened species exist and species new to the regional flora are still being found. As these mountain mires are relatively inaccessible, changes in drivers of change and their ecosystem and biodiversity impacts have not been monitored. However, the remoteness of the mires has so far protected them and their species. In this study, we describe the mires, their bryophyte species and the expected impacts of environmental stressors to bring attention to the urgency of documenting change and conserving these pristine ecosystems. [ABSTRACT FROM AUTHOR]

Theme: Climate change impacts Terry Callaghan was a lead author of the snow and permafrost chapters of the assessment and Margareta Johansson, a research assistant in the ACIA process, became a lead author too. The rise of the Arctic: Intergenerational personal perspectives: This article belongs to Ambio's 50th Anniversary Collection. Communicating scientific understanding globally Terry Callaghan was the lead author of various chapters in the ACIA report and, together with a small team, ensured that ACIA results were incorporated into the IPCC 2007 Polar Regions Chapter (Anisimov et al. [3]). [Extracted from the article]