INSULATE: How above- and belowground biotic traits shape insulation of permafrost in a warming Arctic

The Arctic is underlain by vast areas of permafrost, holding tremendous amounts of greenhouse gasses trapped in the soil beneath the active layer (the part of permafrost soils that thaw and refreeze over the summer season). In times of climate change and steadily rising temperatures, these gases will be released into the atmosphere. At the same time, plant growth and soil life are enhanced in a warmer Arctic with longer growing seasons. Could this layer of plants, mosses, organic soil and other life on the surface function as a “cooling blanket” and protect the permafrost from warm temperatures? We know that plants can insulate the frozen ground to a certain extent, but these studies have concentrated on aboveground plant parts, ignoring the belowground root system and enigmatic microbial world. For instance, there is a distinct increase of shrubs in the Arctic regions, referred to as ‘Arctic Greening’ but still it is unknown whether this may counteract the thawing of the Arctic permafrost. Most of our knowledge is based on the Low Arctic, while drivers between Low- and high Arctic sites, such as Svalbard, may well be different. INSULATE aims to study the effects of climate change, both biotic (vegetation, microbiota) and abiotic factors (e.g. temperature) on permafrost insulation on a year-round basis in the High Arctic. During this project we will monitor Arctic biota (for instance, plants, mosses and microbes) at established borehole infrastructures in the High Arctic tundra of Svalbard. These boreholes are drilled several meters deep, with known soil temperatures and sediment or bedrock composition. We will combine a range of new field and lab techniques and state-of-the-art chemical and DNA-based measurements in order to distinguish between contributions of aboveground and belowground life forms and climatic factors in insulating permafrost. The outcome will be to identify tipping points in ecological protection by Arctic biota, and predict future insulation by Arctic biota in a warming Arctic. As a first step, to identify drivers of active layer thaw, we have chosen 10 boreholes in Longyearbyen and two boreholes in Ny Ålesund on Svalbard. Boreholes were chosen based on accessibility encompassing a wide range of vegetation types. In Longyearbyen, we monitor the development of the “active layer” over the entire growing season, linking it to greening of the vegetation, soil moisture characteristics, and soil temperature. To include different bioclimatic zones, most measurements are done in both Longyearbyen and Ny-Ålesund. In 2024, Longyearbyen data collection occurred regularly all summer, while in Ny-Ålesund data were gathered for a shorter period from end of July to mid-August. When plants were fully developed, we measured both above- and belowground characteristics that can influence the thawing of permafrost, such as the presence and abundance of different plant species and the amount of roots and fungi in the soil. We took soil samples to determine the amount of organic material and microbes in the soil, as this can influence the stability and insulation of the soil under warmer temperatures. Apart from such biotic characteristics, we also measured physical properties of the soil, such as the stability of soil aggregates, the density of the soil and the grain sizes of the mineral soil particles, which could affect thawing of the permafrost below. These key characteristics will be linked to thaw of the “active layer” and belowground temperatures.

Permafrost is thawing at unprecedented rates with rising temperatures in the Arctic, releasing large amount of greenhouse gases into the atmosphere. Currently, there is a large knowledge gap on the insulative effects of Arctic biota on the frozen ground. There is also a great urgency to understand whether drivers of permafrost insulation differ between High and Low Arctic environments, and whether Arctic greening might counteract the thawing of the Arctic. INSULATE aims to study the interactive effects of climate change and (a)biotic factors on permafrost insulation in both warm and cold seasons in the High Arctic. We will monitor Arctic biota at established borehole infrastructures in the High Arctic tundra of Svalbard. Combining new field and lab techniques and state-of-the-art chemical and DNA-based measurements, INSULATE will (1) disentangle the contribution of above versus belowground components and climatic factors to insulation of permafrost. It will investigate how they affect (2) soil temperatures and active layer thickness, (3) by including Low Arctic sites, identify tipping points in ecological protection by Arctic biota, and (4) predict future insulation by Arctic biota in a warming Arctic. Our project faces challenges linked to the planned interdisciplinary studies, and the complexity of year-round field work in the Arctic. The success of the project is guaranteed by the involvement of an interdisciplinary team of world-leading Arctic researchers who are part of world-wide research networks, the excellence of the research facilities, field logistic and infrastructure available to the team, and the high quality of the project organization. INSULATE will significantly increase our understanding of insulation properties and buffering potential of thawing permafrost under the largest threats to High Arctic ecosystems. The results will be of a global importance and relevant to the scientific community, stakeholders and to the public.