Geoengineering Symposium : Science Fiction or Possible Element for a Sustainable Environmental and Climate Future?

Geoengineering represents a set of large-scale technological interventions aimed at mitigating climate change by modifying Earth's natural systems. This report summarizes discussions from the Geoengineering Symposium held in Luleå, Sweden, in collaboration with the Swedish Foundation for Strategic Research and other key institutions. The symposium explored two primary geoengineering approaches: solar radiation management (SRM) and carbon dioxide removal (CDR). Experts assessed the feasibility, potential benefits, and risks associated with these technologies, emphasizing the uncertainties related to regional climate effects, governance challenges, and ethical concerns. Key discussions also addressed the role of international governance, public perception, and the risk of moral hazard in geoengineering deployment. The symposium concluded that while geoengineering should not replace emissions reduction efforts, it may serve as an emergency measure or complement traditional mitigation strategies. Further scientific research, climate modeling, and inclusive policymaking are crucial to evaluating the future role of geoengineering in climate action

GEOEO North of Greenland 2024 : Expedition Report

This cruise report describes the background of the GEOEO – North of Greenland 2024 Expedition, logistical operations, data collection methods, and presents the acquired data

Genomic variation in montane bumblebees in Scandinavia : High levels of intraspecific diversity despite population vulnerability

Populations of many bumblebee species are declining, with distributions shifting northwards to track suitable climates. Climate change is considered a major contributing factor. Arctic species are particularly vulnerable as they cannot shift further north, making assessment of their population viability important. Analysis of levels of whole-genome variation is a powerful way to analyse population declines and fragmentation. Here, we use genome sequencing to analyse genetic variation in seven species of bumblebee from the Scandinavian mountains, including two classified as vulnerable. We sequenced 333 samples from across the ranges of these species in Sweden. Estimates of effective population size (NE) vary from ~55,000 for species with restricted high alpine distributions to 220,000 for more widespread species. Population fragmentation is generally very low or undetectable over large distances in the mountains, suggesting an absence of barriers to gene flow. The relatively high NE and low population structure indicate that none of the species are at immediate risk of negative genetic effects caused by high levels of genetic drift. However, reconstruction of historical fluctuations in NE indicates that the arctic specialist species Bombus hyperboreus has experienced population declines since the last ice age and we detected one highly inbred diploid male of this species close to the southern limit of its range, potentially indicating elevated genetic load. Although the levels of genetic variation in montane bumblebee populations are currently relatively high, their ranges are predicted to shrink drastically due to the effects of climate change and monitoring is essential to detect future population declines

Quantifying earthworm soil ingestion from changes in vertical bulk density profiles

Soil mixing by earthworms can have a large impact on the fate of nutrients and pollutants and on the soil's ability to sequester carbon. Nevertheless, methods to quantify earthworm ingestion and egestion under field conditions are largely lacking. Soils of the Fennoscandian tundra offer a special possibility for such quantifications, as these soils commonly lack burrowing macrofauna and exhibit a well-defined O horizon with low bulk density on top of a mineral soil with higher density. Since ingestion-egestion mixes the two soil layers, the temporal changes in the bulk density profile of such soils may be useful for estimating field ingestion rates. In this study, we applied a model for earthworm burrowing through soil ingestion to observed changes in soil densities occurring in a mesocosm experiment carried out in the arctic during four summers with intact soil. The earthworms present in the mesocosms were Aporrectodea trapezoides, Aporrectodea tuberculata, Aporrectodea rosea, Lumbricus rubellus and Lumbricus Terrestris (fourth season only). We show that changes in soil density profiles can indeed be used to infer earthworm ingestion rates that are realistic in comparison to literature values. Although uncertainties in parameter values were sometimes large, the results from this study suggest that soil turnover rates and endogeic earthworm soil ingestion rates in tundra heath and meadow soils may be as high as those reported for temperate conditions. Such large ingestion rates can explain observed large morphological changes in arctic soils where dispersing earthworms have resulted in complete inmixing of the organic layer into the mineral soil. Our approach is applicable to soil profiles with marked vertical differences in bulk density such as the soils of the Fennoscandian tundra where earthworms are currently dispersing into new areas and to layered repacked soil samples that are incubated in the field

Higher vascular plant abundance associated with decreased ecosystem respiration after 20 years of warming in the forest–tundra ecotone

The on-going climate warming is promoting shrub abundance in high latitudes, but the effect of this phenomenon on ecosystem functioning is expected to depend on whether deciduous or evergreen species increase in response to warming. To explore effects of long-term warming on shrubs and further on ecosystem functioning, we analysed vegetation and ecosystem CO2 exchange after 20 years of warming in the forest–tundra ecotone in subarctic Sweden. A previous study conducted 9 years earlier had found increased evergreen Empetrum nigrum ssp. hermaphroditum in the forest and increased deciduous Betula nana in the tundra. Following current understanding, we expected continued increase in shrub abundance that would be stronger in tundra than in forest. We expected warming to increase ecosystem respiration (Re) and gross primary productivity (GPP), with a greater increase in Re in tundra due to increased deciduous shrub abundance, leading to a less negative net ecosystem exchange and reduced ecosystem C sink strength. As predicted, vascular plant abundances were higher in the warmed plots with a stronger response in tundra than in forest. However, whereas B. nana had increased in abundance since the last survey, E. hermaphroditum abundance had declined due to several moth and rodent outbreaks during the past decade. In contrast to predictions, Re was significantly lower in the warmed plots irrespective of habitat, and GPP increased marginally only in the forest. The lower Re and a higher GPP under warming in the forest together led to increased net C sink. Re was negatively associated with the total vascular plant abundance. Our results highlight the importance of disturbance regimes for vegetation responses to warming. Climate warming may promote species with both a high capacity to grow under warmer conditions and a resilience towards herbivore outbreaks. Negative correlation between Re and total vascular plant abundance further indicate that the indirect impacts of increased plants on soil microclimate may become increasingly important for ecosystem CO2 exchange in the long run, which adds to the different mechanisms that link warming and CO2 fluxes in northern ecosystems. Read the free Plain Language Summary for this article on the Journal blog

Small molecules dominate organic phosphorus in NaOH-EDTA extracts of soils as determined by 31P NMR

Understanding the composition of organic phosphorus (P) in soils is relevant to various disciplines, from agricultural sciences to ecology. Despite past efforts, the precise nature of soil organic P remains an enigma, especially that of the orthophosphate monoesters, which dominate 31P NMR spectra of NaOH-EDTA extracts of soils worldwide. The monoester region often exhibits an unidentified, broad background believed to represent high molecular weight (MW) P. We investigated this monoester background using 1D 31P NMR and 2D 1H[sbnd]31P NMR, as well as 31P transverse relaxation (T2) measurements to calculate its intrinsic linewidth and relate it to MW. Analyzing seven soils from different ecosystems, we observed linewidths of 0.5 to 3 Hz for resolved monoester signals and the background, indicating that it consists of many, possibly >100, sharp signals associated with small (<1.5 kDa) organic P molecules. This result was further supported by 2D 1H[sbnd]31P NMR spectra revealing signals not resolved in the 1D spectra. Our findings align with 31P NMR studies detecting background signals in soil-free samples and modern evidence that alkali-soluble soil organic matter consists of self-assemblies of small organic compounds mimicking large molecules

Förslag till forskningsstrategi för Antarktis : en integrerad ansats för svensk vetenskap

Den 30 april 2024 levererade Polarforskningssekretariatet ett förslag på forskningsstrategi för Antarktis på uppdrag av utbildningsdepartementet. Förslaget är utarbetat av Polarforskningssekretariatet i samarbete med Center for the Arctic and Antarctic (CAA) vid Luleå tekniska universitet. Målsättningen är att forskningsstrategin ska höja Sveriges ambitionsnivå som aktiv forskningsnation i Antarktis och Södra ishavet, genom att stärka den pågående forskningen samt initiera nya samarbeten och aktiviteter

Lufttemperaturens, vindens och snödjupets inverkan på utveckling av laviner i Abisko/Riksgränsen under 2021

Det huvudsakliga syftet med denna studie är att studera möjligheten att koppla rapporterade väderdata till antalet rapporterade laviner inom samma område och undersöka i vilken utsträckning rapporterad temperatur, snödjup och vindhastighet påverkar utvecklingen av laviner. I arbetet studeras väderdata kopplat till lavinrapportering inom området Abisko/Riksgränsen. Studien fokuserar på spontant utlösta laviner, det vill säga laviner som utlösts av naturliga väderfenomen utan mänsklig påverkan.Studien bygger på väderdata från endast en väderstation, Katterjåkk, som således får representera hela lavinprognosområdet Abisko/Riksgränsen. Trots att vädret kan uppvisa lokala variationer inom det valda området, tyder resultaten på att det finns ett klart samband mellan å ena sidan väderförhållandena (förändringar i snödjup, vindstyrka och temperatur) och antalet spontant utlösta laviner.Studien visar att väderdata kan användas för att undersöka lavinutveckling i området, och att mer eller mindre ökande snödjup i kombination med vindhastighet verkar vara den huvudsakliga orsaken bakom lavinerna. Många laviner under senare vår verkar också kunna initieras av snabba temperaturförändringar

Kvicksilverkoncentration i humusjordar i olika arktiska och subarktiska vegetationstyper : Inklusive en metodjämförelse för metallanalys i humusjordar

Heavy metals, such as mercury (Hg), have a long residence time in the atmosphere and can be transported long distances and deposited in the Arctic via wet and dry deposition. Still, there are few studies on the complex mercury cycle and how different plant groups absorb Hg. In this study, I investigated if and/or how Hg concentrations differ between different humus soils in tundra vegetation types in Alaska and Abisko. I also investigated the potential changes in Hg deposition with increasing elevation in Abisko (500, 750, and 1000 m a.s.l). Further, a comparison between the analyzing methods XRF (X-ray fluorescence) and HF digestion was evaluated to investigate if XRF is a suitable method for analyzing heavy metals in the humus layer of soils. To achieve this, humus soil samples from four different vegetation types in Alaska and two from Abisko were analyzed with a Hg analyzer (DMA-80 Direct Mercury Analyzer) and a handheld XRF. The results show that Hg concentration was highest in heath vegetation for Alaska and Abisko. Meanwhile, increasing elevation had no impact on Hg concentration in general, nor was there a difference within the two vegetation types. The comparison between HF digestion and XRF resulted in a positive linear relationship for P, Fe, and Al. The results highlight that Hg concentration differs between humus soil due to different vegetation types, although there is no clear explanation to the distribution of Hg in aboveground vegetation. Litterfall and precipitation may influence Hg concentrations with elevation, and the XRF samples need to be replicated multiple times to avoid errors, as my study shows

Individual trait matching of bumblebees (Bombus) and flowers along an environmental gradient

Insect pollinators serve a critical role in maintaining plant biodiversity and are especially susceptible to changes within their environment. To study the possible effects of seasonal variation in temperature, as well as climatic temperature increase on the plant-pollinator community, the relationship between bumblebee and flowering plant traits along an elevational gradient, representing warming-induced changes in plant community, were examined. Two hypotheses were tested; 1) if plant traits can predict visiting bumblebee proboscis length, and 2) if the relationship between plant traits and proboscis length is influenced by elevation, and the progression of the growing season. The study took place along an elevational gradient on Mt. Nuolja in Abisko National Park, Sweden. During surveys bumblebees were caught and measured. Flowers visited by captured bumblebees were collected, categorized by restrictiveness (i.e., whether or not the flower require a certain proboscis length, in order to access the nectar and pollen rewards) and floral traits measured (e.g., petal length). The results revealed that petal length was a significant predictor of bumblebee proboscis length, when taking restrictiveness into account. Furthermore, the relationship became weaker with increasing elevation for restrictive flowers but stronger for unrestrictive flowers. These findings show that trait-matching between bumblebees and flowers is an influential factor for flower selection and is affected by climatic temperature. This highlights the importance of considering individual-level traits when studying plant preference and creates a framework for assessing plant-pollinator networks. Future studies should examine additional traits that could explain the apparent size matching between unrestrictive flowers and proboscis