Northwest Canada Research Articles

High Adherence to COVID-19 Public Health Preventive Measures in Indigenous Communities in the Canadian Northwest Territories.

The aim of this project is to explore perceptions towards and adherence to COVID-19 public health preventive measures in Indigenous communities within Northwest Territories, Canada. Utilizing a cross-sectional study design the project took place within ten Northwest Territories communities between 1st April and 30th November 2021. Convenience sampling methods were utilized and adhered to public health restrictions. Self-identifying Indigenous adults (≥ 18 years old) were invited to complete a semi-structured interviewer-administered questionnaire. Participants (n = 287; 33.1% men, 66.6% women) had a mean age of 41.6 years (SD ± 13.5). Preventive measures were practiced by 98.6% of participants. Most participants reported often or always practicing three measures: avoiding gatherings (67.2%), avoiding usual greetings (63.3%), and limiting contact with high-risk individuals (71.4%). Most participants reported rarely/never practicing self-isolation (67.5%) and self-quarantining (76.5%) measures. Significant associations existed between the August 2021 COVID-19 outbreak and self-quarantining (p = 0.0023), self-isolating (p = 0.0023), and going onto the land (p = 0.0001). Participants found masking and travel restrictions challenging. Sadness and loneliness resulted from limited access to Elders. Kinship and community safety were important to Indigenous community members and influenced COVID-19 preventive measure utilization. The findings can inform culturally specific COVID-19 public health policy development.

Spatial scale of stand-replacing forest disturbance influences the amplitude of snowshoe hare population fluctuations in boreal forests of northwest Canada

The natural disturbance model for ecosystem management of timber harvesting promotes the emulation of natural disturbance regimes in the patterns of tree removal. Wildfire is a prominent natural disturbance in boreal forests of western Canada, frequently removing most of the tree canopy from patches of 500–10,000 ha in stand-replacing events. However, fire suppression, coupled with a spatial pattern of timber harvesting dominated by small patch cuts of 10–160 ha, have changed the spatial scale of younger stands away from scales within which boreal organisms evolved. In two regions (Sub-Boreal Spruce biogeoclimatic zone of central British Columbia and Liard Basin of southeast Yukon), we tested the hypothesis that different spatial scales of stand-replacing forest disturbance (wildfire and timber harvesting) result in different amplitudes of change in abundance of snowshoe hare, a keystone boreal forest mammal for which mid-seral stand conditions provide optimal habitat. Landscapes with large patches (>2000 ha) of mid-seral forest following stand-replacing disturbance supported consistently and often significantly more hares, with wider amplitude in cyclic fluctuation, than small patches (20–200 ha) of mid-seral habitat and than mature forest landscapes. Densities of hares high enough to support reproduction by Canada lynx (a specialist hare predator) only occurred in landscapes disturbed at the scale of a moderate to large-sized wildfire (1000 – 10,000 ha). Landscapes unaffected by stand-replacing disturbance for at least 80 years (i.e. mature forests) supported very few hares and without cyclic fluctuations. We recommend that the recent pattern of cutting dominated by small patches (20–200 ha) be shifted to include many larger patches (2000–5000 ha). This can happen with incremental, contiguous patch cutting over a period of years short enough that the completed patch will supply high quality, mid-seral habitat for at least the period of one hare cycle (10 y). In designing relatively large patches, mature green tree retention would be desirable for various values, but would be best as small stands of mature forest dispersed within large patch cuts, similar to the legacy of fire. Silviculture (reforestation and stand tending) should create and sustain a mix of conifer and deciduous regeneration in the mid-seral stands. Emulating spatial patterns of stand-replacing natural disturbance appears necessary to sustain snowshoe hare cycles when most fires are suppressed in intensively managed western Canadian boreal forests.

Characterization of hydrocarbon degraders from Northwest Passage beach sediments and assessment of their ability for bioremediation.

Global warming-induced sea ice loss in the Canadian Northwest Passage (NWP) will result in more shipping traffic, increasing the risk of oil spills. Microorganisms inhabiting NWP beach sediments may degrade hydrocarbons, offering a potential bioremediation strategy. In this study, the characterization and genomic analyses of 22 hydrocarbon-biodegradative bacterial isolates revealed that they contained a diverse range of key alkane and aromatic hydrocarbon-degradative genes, as well as cold and salt tolerance genes indicating they are highly adapted to the extreme Arctic environment. Some isolates successfully degraded Ultra Low Sulfur Fuel Oil (ULSFO) at temperatures as low as -5°C and high salinities (3%-10%). Three isolates were grown in liquid medium containing ULSFO as sole carbon source over 3 months and variation of hydrocarbon concentration was measured at three time points to determine their rate of hydrocarbon biodegradation. Our results demonstrate that two isolates (Rhodococcus sp. R1B_2T and Pseudarthrobacter sp. R2D_1T) possess complete degradation pathways and can grow on alkane and aromatic components of ULSFO under Arctic conditions. Overall, these results demonstrate that diverse hydrocarbon-degrading microorganisms exist in the NWP beach sediments, offering a potential bioremediation strategy in the events of a marine fuel spill reaching the shores of the NWP.

The Pacific Northwest Heat Wave of 25–30 June 2021: Synoptic/Mesoscale Conditions and Climate Perspective

Abstract An unprecedented heat wave occurred over the Pacific Northwest and southwest Canada on 25–30 June 2021, resulting in all-time temperature records that greatly exceeded previous record maximum temperatures. The impacts were substantial, including several hundred deaths, thousands of hospitalizations, a major wildfire in Lytton, British Columbia, Canada, and severe damage to regional vegetation. Several factors came together to produce this extreme event: a record-breaking midtropospheric ridge over British Columbia in the optimal location, record-breaking midtropospheric temperatures, strong subsidence in the lower atmosphere, low-level easterly flow that produced downslope warming on regional terrain and the removal of cooler marine air, an approaching low-level trough that enhanced downslope flow, the occurrence at a time of maximum insolation, and drier-than-normal soil moisture. It is shown that all-time-record temperatures have not become more frequent and that annual high temperatures only increased at the rate of baseline global warming. Although anthropogenic warming may have contributed as much as 1°C to the event, there is little evidence of further amplification from increasing greenhouse gases. Weather forecasts were excellent for this event, with highly accurate predictions of the extreme temperatures. Significance Statement This paper describes the atmospheric evolution that produced an extreme heat wave over the Pacific Northwest during June 2021 and puts this event into historical perspective.

Post-fire soil carbon emission rates along boreal forest fire chronosequences in northwest Canada show significantly higher emission potentials from permafrost soils compared to non-permafrost soils

Boreal forests are one of the most important biomes storing carbon (C). Wildfires burn yearly on average more than 1% of the boreal forest, and it is expected that the fire return intervals will shorten due to climate change. Fire is one of the most influential factors affecting soil organic matter quantity and quality, soil C pools, and presumably also the time C resides in the soil (soil C turnover time in years). We compared the potential effects of forest fire through post-fire succession on soil carbon dioxide (CO2) emission rates and soil C turnover time in two fire chronosequences, one with underlying permafrost soil and the other without permafrost. We found that fire had a significant effect on potential soil C turnover times, but surprisingly there was no significant difference in soil C turnover times between the permafrost and non-permafrost areas, although the soil CO2 emissions rates in permafrost areas are approximately three times higher compared to non-permafrost areas. In recently burned areas the potential soil C turnover times were two times longer compared to control areas located in forests burned more than 100 years ago. The longest potential soil C turnover times were recorded in mineral soil layers (30 cm) of permafrost soils, and the shortest potential soil C turnover times were recorded in humus layers of non-permafrost areas.

The Western Arctic – Tariuq (Offshore) Accord: A Long Time Coming

On 10 August 2023, representatives of the Inuvialuit Regional Corporation and the governments of the Northwest Territories, Yukon, and Canada signed the Western Arctic–Tariuq (Offshore) Accord.1 The Accord establishes a system for the shared management and regulation of offshore petroleum resources north of the Arctic Circle, west of Nunavut to the limit of Canada’s jurisdiction in the Beaufort Sea and Arctic Ocean and the equitable sharing of benefits. Upon the consent of all Parties, implementing legislation will be introduced to establish the Accord and will, among other things, amend or replace relevant federal legislation. The Accord is a step towards Canada’s implementation of the United Nations Declaration on the Rights of Indigenous Peoples.2 It is also part of a quest for meaningful participation dating back to the initial activities concerning oil and gas in the region that fuelled negotiations leading to the Inuvialuit Final Agreement. This contribution situates the Accord in the context of these developments to illuminate its potential significance.

The Comparative Analysis of Carbon Pricing Policies on Canadian Northwest Territories’ Economy under Different Climate Change Scenarios

Policymakers in the Northwest Territories have introduced carbon pricing as a strategy to reduce fossil fuel consumption and CO2 emissions across various population segments and industries. This indirect approach, chosen for its acceptability, aims to influence behavior rather than directly limit carbon-intensive products. The main purpose of this study was to evaluate the economic and ecological impacts of this policy and its alignment with intended objectives. Using a CGE macroeconomic model incorporating economic structural and behavioral equations, we assessed the policy’s effects on NWT’s economy in general and on a subset of its key sectors. We also incorporated a few observed and simulated climate data for diverse climate change scenarios. The estimated results revealed that climate variables, especially precipitation, significantly influenced sectors like agriculture, construction, and manufacturing. The standardized precipitation evapotranspiration index (SPEI), which encompasses both temperature and precipitation, notably impacted the agriculture, oil, and gas sectors. However, temperature alone showed limited significance, except in the oil and gas sector. The simulation results indicated that, while carbon pricing reduced economic contributions of fossil fuel sector, household rebates could counteract these effects of the economic growth of NWT. Our findings offer valuable insights for shaping NWT’s environmental policies, aligning them with Canada’s goal of net-zero CO2 emissions by 2050.

Widespread Permafrost Degradation and Thaw Subsidence in Northwest Canada

AbstractLong‐term (1991–2018) thaw tube measurements highlight widespread permafrost thaw and ground surface (GS) subsidence over a large portion of northwest Canada. Statistically significant positive trends in thaw penetration (TP), measured with respect to a fixed datum, were observed at 18 of 28 sites with data that span three decades at a median rate of 0.8 cm a−1. This rate implies thawing of about 22 cm of permafrost over the study period. Similarly significant trends in GS subsidence occurred at 21 of 28 sites, at a median rate of 0.4 cm a−1. In contrast with TP and GS elevation, long‐term trends in active layer thickness (ALT) were less consistent, with 10 of 28 sites having statistically significant trends indicating increasing ALT (median rate: 0.6 cm a−1), and 7 sites having trends indicating decrease in ALT (median: 0.3 cm a−1). The ALT measurements underestimated the thawing of ice‐rich permafrost due to GS subsidence. Sites with high rates of thaw had relatively warm permafrost, deep snow cover, and poor drainage. Masking of ice‐rich permafrost degradation by ALT measurements has important implications for modeling permafrost thaw and climate change reporting. Accurate simulation of ice‐rich permafrost thaw is conceivable for sites where conditions are well‐defined. However, the prediction of subsidence and TP at regional or broader scales is only possible in general terms due to variation in surface conditions and ground ice content. Trends in TP and GS subsidence more accurately characterize ice‐rich permafrost degradation than trends in ALT.

No evidence of supracrustal recycling in Si-O isotopes of Earth's oldest rocks 4 Ga ago.

Identifying the oldest evidence for the recycling of hydrated crust into magma on Earth is important because it is most effectively achieved by subduction. However, given the sparse geological record of early Earth, the timing of first supracrustal recycling is controversial. Silicon and oxygen isotopes have been used as indicators of crustal evolution on Archean igneous rocks and minerals to trace supracrustal recycling but with variable results. We present Si-O isotopes of Earth's oldest rocks [4.0 billion years ago (Ga)] from the Acasta Gneiss Complex, northwest Canada, obtained using multiple techniques applied to zircon, quartz, and whole rock samples. Undisturbed zircon is considered the most reliable recorder of primary Si signatures. By combining reliable Si isotope data from the Acasta samples with filtered data from Archean rocks globally, we observe that widespread evidence for a heavy Si signature is recorded since 3.8 Ga, marking the earliest record of surface silicon recycling.

Quantification of wetland vegetation communities features with airborne AVIRIS-NG, UAVSAR, and UAV LiDAR data in Peace-Athabasca Delta

Arctic-boreal wetlands, important ecosystems for biodiversity and ecological services, are experiencing hydrological changes including permafrost thaw, earlier snowmelt, and increased wildfire susceptibility. These changes are affecting wetland productivity, species diversity, and biogeochemical cycles. However, given the diverse forms and structures of wetland vegetation communities, traditional wetland maps generated from lower spatial and spectral resolution satellite imagery lack community-level vegetation classification and miss spatially complex patterns. In this study, we built a cloud-based workflow to map wetland vegetation community of the Peace-Athabasca Delta (PAD), Canada, by leveraging high-resolution (5-m) airborne multi-sensor datasets, namely NASA's Airborne Visible/Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) and Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR), and a historical LiDAR archive. Validation of our classifications using ground references indicates that classifications derived from AVIRIS-NG have higher accuracies (≥87.9%) than either UAVSAR (65.6%) or LiDAR (75.9%) for mapping wetland vegetation communities. We also show improved classification accuracy when combining information from multiple sensors. In particular, incorporating AVIRIS-NG and UAVSAR datasets substantially reduced omission errors of wet graminoid and wet shrub classes from 29.6% to 20.5% and from 10.8% to 7.5%, respectively. Combining AVIRIS-NG and LiDAR datasets further improves overall accuracy (+2.2%) for most classifications, especially emergent vegetation, wet graminoid, and wet shrub. The best performing model, using features derived from all three sensors, achieved an overall accuracy of 93.5%. The framework established here can be used to leverage extensive airborne AVIRIS-NG and UAVSAR datasets collected across Alaska and northwest Canada to understand the spatial distribution of Arctic-Boreal wetland vegetation communities.

Batagay megaslump: A review of the permafrost deposits, Quaternary environmental history, and recent development

AbstractThe Batagay megaslump, in the Yana Uplands of northern Yakutia, Russia, is the largest known retrogressive thaw slump in the world. The slump exposes a remarkable sequence of Ice Age permafrost deposits that record the interaction of colluvial, eolian and periglacial processes on a hillslope episodically forested during the last 650 ka or more in response to climate variability on glacial–interglacial timescales. Numerous bones, teeth, and occasional carcasses of Pleistocene and Holocene mammals have been recovered from the permafrost. The megaslump developed over the course of several decades in three stages: (1) gullying, (2) thaw slumping, and (3) megaslumping. After disturbance to the taiga vegetation cover in the 1940s–1960s, a hillslope gully formed by the early 1960s. The gully initiated thaw slumping along its central part during the 1980s, with the slump enlarging to megaslump (>20 ha) proportions during the 1990s. By 2019, the area of the slump had reached about 80 ha and its headwall above the slump floor was up to about 55 m high. The main geomorphic processes of slump growth are headwall ablation and thermal erosion, producing a distinctive terrain of icy badlands on the slump floor. Though much of the megaslump is rapidly growing at present, it will probably stabilize eventually as an irregular terrain characterized by sandy ridges and sand‐filled elongate depressions formed by degradation of the badlands. Comparison of the Batagay megaslump with megaslumps from northwest Canada reveals several similarities and differences in terms of their geomorphology, permafrost deposits, and Quaternary history.

Performance of Climate Projections for Yukon and Adjacent Northwest Territories, 1991 – 2020

Permafrost foundation design recognizes the impact of climate change on soil bearing capacity, as described in Canadian guideline CSA PLUS 4011:19. There is, however, no guidance as to the climate scenarios most prudent to adopt for such design. We have compared climate change scenarios outlined in 2003 for the design of the proposed Mackenzie Gas Project (MGP) with climate data for 1991 – 2020 to determine the projections most representative of what did, in fact, occur. In Canada, the greatest change in climate during the last 50 years has been measured in the western Arctic, where fluctuations in annual air temperatures are regionally consistent. In this region, the rate of change in annual mean air temperature for 1971 – 2020 has ranged from 0.77 °C decade-1 at Inuvik, NT, to 0.30 °C decade-1 at Komakuk Beach, YT, with warming concentrated in winter. No statistically significant trends in total annual precipitation have been observed and these records are poorly correlated within the region. In 2003, 29 climate projections from seven global climate models were examined for the MGP and, in 2005, for research regarding forest fires in Yukon. The observed climate warming in Yukon and adjacent Northwest Territories during 1991 – 2020 was close to the upper projections for mean annual and winter air temperature. For example, at Inuvik the 2.3 °C increase observed in mean annual air temperature between 1961 – 90 and 1991 – 2020, exceeds the median projection for change by 2010 – 39 of +1.6 °C and approaches the upper value of +2.4 °C. No consistency between observed and projected precipitation has been determined. These results indicate that, when required, future projections of temperature in northwest Canada may prudently adopt higher or more extreme scenarios because they have been the most realistic to date. They imply that near-surface permafrost may soon become unsustainable in southern parts of the region and so site investi gations to locate thaw-stable soils will likely be cost effective for new projects.

Citizen science photographs indicate different timing and location use of migrating adult and juvenile Whimbrels

Abstract It is imperative to identify factors that influence population trends for declining species, but demographic parameters can be especially challenging to quantify for birds, such as Whimbrels (Numenius phaeopus), that breed in locations that are logistically difficult to access. At least two disjunct Whimbrel populations breed in remote and difficult to access northern latitudes but migrate through the heavily populated North American Atlantic Coast during autumn migration. Here, we capitalize on the Whimbrel migrations through the more populated coastal areas to age Whimbrels in photographs uploaded to the citizen science website, eBird, to identify the timing and location of juvenile Whimbrels staging for trans-Atlantic migratory flights. Mean photograph dates for adult migration were synchronous with reported dates for the Mackenzie Delta population that breeds along the northern coast of Northwest Territories, Canada, and stages in Atlantic Canada and for the Hudson Bay population that stages along the South Atlantic USA coast. However, the mean dates of juvenile photographs were 29–41 days later than adult dates, depending on the region. Space use by juveniles along the coast also differed from that reported for adults. Adults primarily depend on Atlantic Canada and the South Atlantic USA coast during fall migration. The percentage of juveniles was greater outside these two primary staging locations. Region-specific juvenile photograph dates suggest that juveniles may drift farther south than the majority of adults from their respective populations. The percentage of juvenile photos collected better predicted the percentage of adult photos 3 years later than 1 and 2 years later which is consistent with Whimbrel’s delayed reproductive strategy and provides validation for using photographs to obtain age ratios. As photograph uploads become more commonplace, this and similar analyses may be used to obtain information that would normally be logistically difficult with traditional field methods.

Subfossil Insect Collections From the Arctic of Northeast Asia and Northwest North America

Subfossil insects (mostly beetles) are common in the Late Cenozoic terrestrial loose deposits of the Arctic. The best-studied areas are those regions that remained ice-free during the Pleistocene — in Alaska and Yukon, northeast Siberia, and west Chukotka. Tertiary subfossil insects have been found in Alaska, Yukon, Canadian Northwest Territories, and Greenland. The northernmost sites (above 75°N) are Ellesmere and Meighen Islands in Canada, Kap Kobenhavn in Greenland, and Faddeyevsky and Navaya Sibir’ Islands in Siberia. Collections from North America and Russia are housed in research institutions such as The Geological Survey of Canada (GSC) in Ottawa, University of Alberta (UofA) in Edmonton, Paleontological Institute (PIN) in Moscow, and Institute of Plant and Animal Ecology in Yekaterinburg; collections from Greenland are housed in the Zoological Museum, University of Copenhagen. The collections are mainly used for research purposes, including reconstruction of past climate and environment, stratigraphy, origin of local faunas, and ecosystems of the past. A few extinct species have been described from the late Neogene and early Quaternary.

A New P‐Wave Tomographic Model (CAP22) for North America: Implications for the Subduction and Cratonic Metasomatic Modification History of Western Canada and Alaska

AbstractOur understanding of the present‐day state and evolution of the Canadian and Alaskan mantle is hindered by a lack of absolute P‐wavespeed constraints that provide complementary sensitivity to composition in conjunction with existing S‐wavespeed models. Consequently, cratonic modification, orogenic history of western North America and complexities within the Alaskan Proto‐Pacific subduction system remain enigmatic. One challenge concerns the difficulties in extracting absolute arrival‐time measurements from often‐noisy data recorded by temporary seismograph networks required to fill gaps in continental and global databases. Using the Absolute Arrival‐time Recovery Method (AARM), we extract >180,000 new absolute arrival‐time residuals from seismograph stations across Canada and Alaska and combine these data with USArray and global arrival‐time data from the contiguous US and Alaska. We develop a new absolute P‐wavespeed tomographic model, CAP22, spanning North America that significantly improves resolution in Canada and Alaska over previous models. Slow wavespeeds below the Canadian Cordillera sharply abut fast wavespeeds of the continental interior at the Rocky Mountain Trench in southwest Canada. Slow wavespeeds below the Mackenzie Mountains continue farther inland in northwest Canada, indicating Proterozoic‐Archean metasomatism of the Slave craton. Inherited tectonic lineaments colocated with this north‐south wavespeed boundary suggest that both the crust and mantle may control Cordilleran orogenic processes. In Alaska, fast upper mantle wavespeeds below the Wrangell Volcanic Field favor a conventional subduction related mechanism for volcanism. Finally, seismic evidence for the subducted Kula and Yukon slabs indicate tectonic reconstructions of western North America may require revision.

Cross‐disciplinary insights into the mechanisms of plant cold hardiness: From molecules to ecosystems

Cross‐disciplinary insights into the mechanisms of plant cold hardiness: From molecules to ecosystems

Ovipositor characteristics differ between two parasitoids (Hymenoptera, Figitidae) of Drosophila suzukii (Diptera, Drosophilidae) in an adventive landscape

Different ovipositor characteristics among parasitoid species that share similar niches are associated with different wasp life histories and selective pressures. The length of wasp ovipositors, for example, can determine the accessibility of hosts that feed at different depths within food substrates. Two parasitoids, Ganaspis brasiliensis and Leptopilina japonica (Hymenoptera, Figitidae), which attack Drosophila suzukii (Diptera, Drosophilidae) in their native range, have been investigated for their suitability for the global biological control of the small fruit pest. Despite their sympatry in microhabitat, the parasitoids have differing host ranges, and D. suzukii parasitism rates by each parasitoid species appear to depend on the fruit species occupied by the host species. Adventive populations of both parasitoids have been detected in the Pacific Northwest of Canada and the United States where they can be found parasitizing D. suzukii larvae in crop and non-crop fruits. We dissected and measured the ovipositors of parasitoids reared from three species of fresh fruits at three sites in southwestern British Columbia, Canada, and investigated the influence of parasitoid species, fruit type, and collection site on ovipositor characteristics. We found that ovipositor length differed markedly between the two parasitoid species and between sites while ovipositor width, and stoutness, differed only between the two parasitoid species, but did not vary among sites or fruit hosts. We discuss how ovipositor morphology traits could be associated with differences in life history and host ranges in the two parasitoid species.

Care through closure: mine transitions in the mixed economy of the Northwest Territories, Canada

This article, emerging from a community-university research partnership, examines community concerns around diamond mine closure in the Northwest Territories, Canada, and Dene visions of post-extractive futures. The Northwest Territories is a region of the sub-arctic characterized by a political economy that combines settler and Indigenous modes of governance, production, and social reproduction, with an outsized settler engagement in resource extraction. In this article, we turn our attention to the under-examined social processes of mine closure in this region. In taking a feminist political economy approach to mine closure, we attend to the multiple labours of the northern mixed economy. We aim to unsettle the settler preoccupation with the mine itself, and rather, to centre the social reproduction of mining affected communities. Responding to calls for greater attention to the social aspects of mine closure, this paper brings together feminist imaginaries of care and reproduction with place-based insights regarding the gender of settler colonialism and Indigenous women’s transgressive caring labours in northern Canada. It draws upon community-based interviews and talking circles, analyzing mine closure as both a site of ongoing settler colonial dispossession and as a space of resistance to ongoing colonialism through the assertion of Dene modes of life.

Climate change, species thermal emergence, and conservation design: a case study in the Canadian Northwest Atlantic

Marine Protected Areas (MPAs) are conservation tools that promote biodiversity by regulating human impacts. However, because MPAs are fixed in space and, by design, difficult to change, climate change may challenge their long-term effectiveness. It is therefore imperative to consider anticipated ecological changes in their design. We predict the time of emergence (ToE: year when temperatures will exceed a species’ tolerance) of 30 fish and invertebrate species in the Scotian Shelf-Bay of Fundy draft network of conservation areas based on climate projections under two contrasting emission scenarios (RCP 2.6 and RCP 8.5). We demonstrate a strong Southwest-to-Northeast gradient of change under both scenarios. Cold water-associated species had earlier ToEs, particularly in southwesterly areas. Under low emissions, 20.0% of habitat and 12.6% of species emerged from the network as a whole by 2100. Under high emissions, 51% of habitat and 42% of species emerged. These impacts are expected within the next 30–50 years in some southwestern areas. The magnitude and velocity of change will be tempered by reduced emissions. Our identification of high- and low-risk areas for species of direct and indirect conservation interest can support decisions regarding site and network design (and designation scheduling), promoting climate resilience.

The design and performance of the XL-Calibur anticoincidence shield

The XL-Calibur balloon-borne hard X-ray polarimetry mission comprises a Compton-scattering polarimeter placed at the focal point of an X-ray mirror. The polarimeter is housed within a BGO anticoincidence shield, which is needed to mitigate the considerable background radiation present at the observation altitude of ∼40 km. This paper details the design, construction and testing of the anticoincidence shield, as well as the performance measured during the week-long maiden flight from Esrange Space Centre to the Canadian Northwest Territories in July 2022. The in-flight performance of the shield followed design expectations, with a veto threshold <100 keV and a measured background rate of ∼0.5 Hz (20–40 keV). This is compatible with the scientific goals of the mission, where %-level minimum detectable polarisation is sought for a Hz-level source rate.