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

The Canadian Federation of Earth Sciences Scientific Statement on Climate Change – Its Impacts in Canada, and the Critical Role of Earth Scientists in Mitigation and Adaptation

The Canadian Federation of Earth Sciences (CFES) has issued this statement to summarize the science, effects, and implications of climate change. We highlight the role of Earth scientists in documenting and mitigating climate change, and in managing and adapting to its consequences in Canada. CFES is the coordinated voice of Canada’s Earth Sciences community with 14 member organizations representing some 15,000 geoscientists. Our members are drawn from academia, industry, education, and government. The mission of CFES is to ensure decision makers and the public understand the contributions of Earth Science to Canadian society and the economy.  Climate change has become a national and global priority for all levels of government. The geological record shows us that the global climate has changed throughout Earth’s history, but the current rates of change are almost unprecedented. Over the last 70 years, levels of common greenhouse gases (GHGs) in the atmosphere have steadily increased. Carbon dioxide (CO2) concentration is now 418 parts per million — its highest of the last three million years. The chemical (isotopic) composition of carbon in the atmosphere indicates the increase in GHGs is due to burning fossil fuels. GHGs absorb energy emitted from Earth’s surface and re-radiate it back, warming the lower levels of the atmosphere. Climatic adjustments that have recently occurred are, in practical terms, irreversible, but further change can be mitigated by lowering emissions of GHGs.  Climate change is amplified by three important Earth system processes and effects. First, as the climate warms evaporation increases, raising atmospheric concentrations of water vapour, itself a GHG — and adding to warming. Second, loss of ice cover from the polar ice sheets and glaciers exposes larger areas of land and open water — leading to greater absorption of heat from the sun. Third, thawing of near-surface permafrost releases additional GHGs (primarily CO2 and methane) during decay of organic matter previously preserved frozen in the ground. Some impacts of climate change are incremental and steadily occurring, such as melting of glaciers and ice sheets, with consequent sea level rise. Others are intermittent, such as extreme weather events, like hurricanes — but are becoming more frequent. Summer water shortages are increasingly common in western Canada as mountain snowpacks melt earlier and summer river flows decline. In northern Canada, warming and thawing of near-surface permafrost has led to deterioration of infrastructure and increased costs for buildings that now require chilled foundations. Other consequences of unchecked climate change include increased coastal erosion, increases in the number and size of wildfires, and reduction in winter road access to isolated northern communities. Reductions in net GHG emissions are urgently required to mitigate the many effects of further climate change. Industrial and public works development projects must now assess the effects of climate change in their planning, design, and management. Cities, municipalities, and rural communities need to plan new residential development carefully to avoid enhanced risk of flooding, coastal erosion, or wildfire.  Earth Science knowledge and expertise is integral to exploration and development of new metals and Earth materials required for a carbon-neutral future, and in the capture and storage of CO2 within the Earth. Earth Science is also central to society’s adaptation to new climatic regimes and reduction of risks. This includes anticipation, assessment, and management of extreme events, development of new standards and guidelines for geotechnical and engineering practice, and revision to regulations that consider climate change. Geoscientists also have an important role in the education of students and the public on the reasons for necessary action. Canada is uniquely positioned with its strong global geoscientific leadership, its vast landmass, and its northern terrain to effectively leverage research activities around climate change. Geoscience tools and geoscientists’ skills will be integral to Canada’s preparation for climate change.La Fédération canadienne des sciences de la Terre (FCST) a publié ce communiqué pour résumer la science, les effets et les implications des changements climatiques. Nous soulignons le rôle des scientifiques en science de la Terre dans la documentation et l'atténuation des changements climatiques, ainsi que dans la gestion de leurs conséquences et la création de mesures d'adaptation au Canada. La FCST est la voix coordonnée de la communauté canadienne des sciences de la Terre avec 14 organisations membres représentant environ 15 000 géoscientifiques. Nos membres sont issus du milieu universitaire, de l'industrie, de l'éducation et du gouvernement. La mission de la FCST est de s'assurer que les décideurs et le public comprennent les contributions des sciences de la Terre à la société canadienne et à l'économie.  Les changements climatiques sont devenus une priorité nationale et mondiale à tous les niveaux de gouvernement. Les archives géologiques nous montrent que le climat mondial a changé tout au long de l'histoire de la Terre, mais les taux de changement actuels sont presque sans précédent. Au cours des 70 dernières années, les niveaux de gaz à effet de serre (GES) communs dans l'atmosphère n'ont cessé d'augmenter. La concentration de dioxyde de carbone (CO2) est maintenant de 418 parties par million - son plus haut niveau des trois derniers millions d'années. La composition chimique (isotopique) du carbone dans l'atmosphère indique que l'augmentation des GES est due à la combustion de combustibles fossiles. Les GES absorbent l'énergie émise par la surface de la Terre et la réfléchissent, réchauffant les niveaux inférieurs de l'atmosphère. Les modifications climatiques qui se sont produits récemment sont, concrètement, irréversibles, mais les changements additionnels peuvent être atténués en réduisant les émissions de GES.  Les changements climatiques sont amplifiés par trois processus et effets importants du système terrestre. Premièrement, à mesure que le climat se réchauffe, l'évaporation augmente, ce qui augmente les concentrations atmosphériques de vapeur d'eau, elle-même un GES, et contribue au réchauffement. Deuxièmement, la perte de la couverture de glace des calottes glaciaires polaires et des glaciers expose de plus grandes superficies de terre et d'eau libre, ce qui entraîne une plus grande absorption de la chaleur du soleil. Troisièmement, le dégel du pergélisol proche de la surface libère des GES supplémentaires (principalement du CO2 et du méthane) lors de la décomposition de la matière organique jusqu’alors préservée gelée dans le sol. Certains impacts des changements climatiques sont progressifs et se produisent régulièrement, comme la fonte des glaciers et des calottes glaciaires, avec pour conséquence une élévation du niveau de la mer. D'autres sont intermittents, comme les événements météorologiques extrêmes, tels que les ouragans, mais deviennent de plus en plus fréquents. Les pénuries d'eau en été sont de plus en plus courantes dans l'ouest du Canada, car le manteau neigeux des montagnes fond plus tôt et le débit des rivières en été diminue. Dans le nord du Canada, le réchauffement et le dégel du pergélisol proche de la surface ont entraîné une détérioration des infrastructures et une augmentation des coûts des bâtiments qui nécessitent maintenant des fondations réfrigérées. Les autres conséquences des changements climatiques incontrôlés comprennent l'augmentation de l'érosion côtière, l'augmentation du nombre et de la taille des incendies de forêt et la réduction de l'accès aux routes d’hiver aux collectivités isolées du Nord. Des réductions des émissions nettes de GES sont nécessaires de toute urgence pour atténuer les nombreux effets de nouveaux changements climatiques. Les projets de développement industriel et de travaux publics doivent désormais évaluer les effets des changements climatiques dans leur planification, leur conception et leur gestion. Les villes, les municipalités et les communautés rurales doivent planifier soigneusement les nouveaux développements résidentiels pour éviter les risques accrus d'inondation, d'érosion côtière ou d'incendie de forêt.  Les connaissances et l'expertise en sciences de la Terre font partie intégrante de l'exploration et du développement de nouveaux métaux et matériaux terrestres requis pour un avenir neutre en carbone, ainsi que dans la capture et la séquestration du CO2 dans la Terre. Les sciences de la Terre sont également au cœur de l'adaptation de la société aux nouveaux régimes climatiques et de la réduction des risques. Cela comprend l'anticipation, l'évaluation et la gestion des événements extrêmes, l'élaboration de nouvelles normes et directives pour les pratiques géotechniques et d'ingénierie, et la révision des réglementations qui tient compte des changements climatiques. Les géoscientifiques ont également un rôle important dans l'éducation des étudiants et du public sur le fondement des mesures nécessaires. Le Canada occupe une position unique grâce à son solide leadership géoscientifique mondial, sa vaste étendue et son territoire nordique pour tirer efficacement parti des activités de recherche sur les changements climatiques. Les outils géoscientifiques et les compétences des géoscientifiques feront partie intégrante de la préparation du Canada aux changements climatiques

Variability and change in the Canadian cryosphere

Abstract During the International Polar Year (IPY), comprehensive observational research programs were undertaken to increase our understanding of the Canadian polar cryosphere response to a changing climate. Cryospheric components considered were snow, permafrost, sea ice, freshwater ice, glaciers and ice shelves. Enhancement of conventional observing systems and retrieval algorithms for satellite measurements facilitated development of a snapshot of current cryospheric conditions, providing a baseline against which future change can be assessed. Key findings include: 1. surface air temperatures across the Canadian Arctic exhibit a warming trend in all seasons over the past 40 years. A consistent pan-cryospheric response to these warming temperatures is evident through the analysis of multi-decadal datasets; 2. in recent years (including the IPY period) a higher rate of change was observed compared to previous decades including warming permafrost, reduction in snow cover extent and duration, reduction in summer sea ice extent, increased mass loss from glaciers, and thinning and break-up of the remaining Canadian ice shelves. These changes illustrate both a reduction in the spatial extent and mass of the cryosphere and an increase in the temporal persistence of melt related parameters. The observed changes in the cryosphere have important implications for human activity including the close ties of northerners to the land, access to northern regions for natural resource development, and the integrity of northern infrastructure

Dielectric constant engineering of organic semiconductors: effect of planarity and conjugation length

Bulk heterojunction organic solar cells continue to show steady photoconversion efficiency improvements. However, single component organic solar cells are a particularly attractive alternative due to the relative simplicity of device manufacture. It has been proposed that organic semiconductors with a high dielectric constant (≈10) could give rise to spontaneous free charge carrier generation upon photoexcitation. In this manuscript, factors are explored that affect the dielectric constant of organic semiconductors, particularly the optical-frequency dielectric constant. The properties of monomers, dimers and trimers of two isoelectronic families of materials that have acceptor units composed of one or two dicyanovinylbenzothiadiazole moieties and one to three donor units are compared. The donor components are composed of either fluorenyl or cyclopentadithiophene moieties with the same glycol-based solubilizing groups. It is found that chromophore planarity and orientation with respect to the substrate, and film density affect the optical and electronic properties of the materials, especially the high-frequency dielectric constant. The results also indicate that delocalization of the highest occupied and lowest unoccupied molecular orbitals is a critical factor. The dimer with two dicyanovinylbenzothiadiazole moieties and two dithienocyclopentadiene units is found to have the highest optical frequency dielectric constant and overall performance

Dielectric constant engineering of organic semiconductors: effect of planarity and conjugation length

Bulk heterojunction organic solar cells continue to show steady photoconversion efficiency improvements. However, single component organic solar cells are a particularly attractive alternative due to the relative simplicity of device manufacture. It has been proposed that organic semiconductors with a high dielectric constant (≈10) could give rise to spontaneous free charge carrier generation upon photoexcitation. In this manuscript, factors are explored that affect the dielectric constant of organic semiconductors, particularly the optical-frequency dielectric constant. The properties of monomers, dimers and trimers of two isoelectronic families of materials that have acceptor units composed of one or two dicyanovinylbenzothiadiazole moieties and one to three donor units are compared. The donor components are composed of either fluorenyl or cyclopentadithiophene moieties with the same glycol-based solubilizing groups. It is found that chromophore planarity and orientation with respect to the substrate, and film density affect the optical and electronic properties of the materials, especially the high-frequency dielectric constant. The results also indicate that delocalization of the highest occupied and lowest unoccupied molecular orbitals is a critical factor. The dimer with two dicyanovinylbenzothiadiazole moieties and two dithienocyclopentadiene units is found to have the highest optical frequency dielectric constant and overall performance

Limited release of previously-frozen C and increased new peat formation after thaw in permafrost peatlands

Permafrost stores globally significant amounts of carbon (C) which may start to decompose and be released to the atmosphere in form of carbon dioxide (CO 2 ) and methane (CH 4 ) as global warming promotes extensive thaw. This permafrost carbon feedback to climate is currently considered to be the most important carbon-cycle feedback missing from climate models. Predicting the magnitude of the feedback requires a better understanding of how differences in environmental conditions post-thaw, particularly hydrological conditions, control the rate at which C is released to the atmosphere. In the sporadic and discontinuous permafrost regions of north-west Canada, we measured the rates and sources of C released from relatively undisturbed ecosystems, and compared these with forests experiencing thaw following wildfire (well-drained, oxic conditions) and collapsing peat plateau sites (water-logged, anoxic conditions). Using radiocarbon analyses, we detected substantial contributions of deep soil layers and/or previously-frozen sources in our well-drained sites. In contrast, no loss of previously-frozen C as CO 2 was detected on average from collapsed peat plateaus regardless of time since thaw and despite the much larger stores of available C that were exposed. Furthermore, greater rates of new peat formation resulted in these soils becoming stronger C sinks and this greater rate of uptake appeared to compensate for a large proportion of the increase in CH 4 emissions from the collapse wetlands. We conclude that in the ecosystems we studied, changes in soil moisture and oxygen availability may be even more important than previously predicted in determining the effect of permafrost thaw on ecosystem C balance and, thus, it is essential to monitor, and simulate accurately, regional changes in surface wetness

Diagnosis Across the Spectrum of Progressive Supranuclear Palsy and Corticobasal Syndrome

IMPORTANCE: Patients with atypical parkinsonian syndromes (APS), including progressive supranuclear palsy (PSP), corticobasal syndrome (CBS) and multiple system atrophy (MSA), may be difficult to distinguish in early stages and are often misdiagnosed as Parkinson’s disease (PD). The diagnostic criteria for PSP have been updated to encompass a range of clinical subtypes, but have not been prospectively studied. OBJECTIVE: To define the distinguishing features of PSP and CBS, and to assess their usefulness in facilitating early diagnosis and separation from PD. DESIGN, SETTING, PARTICIPANTS: Cohort study which recruited APS and PD patients from movement disorder clinics across the UK from September 2015 to December 2018, and will follow up patients over 5 years. APS patients were stratified into PSP-Richardson syndrome, PSP-subcortical (including PSP-parkinsonism and PSP-progressive gait freezing cases), PSP-cortical (including PSP-frontal and PSP/CBS overlap cases), MSA-parkinsonism, MSA-cerebellar, CBS-Alzheimer’s and CBS-non-Alzheimer’s groups. MAIN OUTCOME MEASURES: Baseline group comparisons were conducted using: 1) Clinical trajectory; 2) Cognitive screening scales; 3) Serum neurofilament light chain (NF-L); 4) TRIM11, ApoE and MAPT genotypes; 5) Volumetric MRI. RESULTS: 222 APS cases (101 PSP, 55 MSA, 40 CBS and 26 indeterminate) were recruited (58% male; mean age at recruitment, 68.3 years). Age-matched controls (n=76) and PD cases (n=1967) were also included. Concordance between the ante-mortem clinical diagnosis and pathological diagnosis was achieved in 12/13 (92%) of PSP and CBS cases coming to post-mortem. Applying the MDS PSP diagnostic criteria almost doubled the number of patients diagnosed with PSP. 49/101 (49%) of reclassified PSP patients did not have classical PSP-Richardson syndrome. PSP-subcortical patients had a longer diagnostic latency and a more benign clinical trajectory than PSP-Richardson syndrome and PSP-cortical (p<0.05). PSP-subcortical was distinguished from PSP-cortical and PSP-Richardson syndrome by cortical volumetric MRI measures (AUC 0.84-0.89), cognitive profile (AUC 0.80-0.83), serum NF-L (AUC 0.75-0.83) and TRIM11 rs564309 genotype. Midbrain atrophy was a common feature of all PSP subtypes. 8/17 (47%) of CBS patients with CSF analysis were identified as having CBS-Alzheimer’s. CBS-Alzheimer’s patients had a longer diagnostic latency, relatively benign clinical trajectory, greater cognitive impairment and higher APOE-ε4 allele frequency than CBS-non-Alzheimer’s (p<0.05, AUC 0.80-0.87). Serum NF-L levels distinguished PD from PSP and CBS (p<0.05, AUC 0.80). CONCLUSIONS AND RELEVANCE: Clinical, therapeutic and epidemiological studies focusing on PSP-Richardson syndrome are likely to miss a large number of patients with underlying PSP-tau pathology. CSF analysis defines a distinct CBS-Alzheimer’s subgroup. PSP and CBS subtypes have distinct characteristics that may enhance their early diagnosis

Episodic Memory and Appetite Regulation in Humans

Psychological and neurobiological evidence implicates hippocampal-dependent memory processes in the control of hunger and food intake. In humans, these have been revealed in the hyperphagia that is associated with amnesia. However, it remains unclear whether 'memory for recent eating' plays a significant role in neurologically intact humans. In this study we isolated the extent to which memory for a recently consumed meal influences hunger and fullness over a three-hour period. Before lunch, half of our volunteers were shown 300 ml of soup and half were shown 500 ml. Orthogonal to this, half consumed 300 ml and half consumed 500 ml. This process yielded four separate groups (25 volunteers in each). Independent manipulation of the 'actual' and 'perceived' soup portion was achieved using a computer-controlled peristaltic pump. This was designed to either refill or draw soup from a soup bowl in a covert manner. Immediately after lunch, self-reported hunger was influenced by the actual and not the perceived amount of soup consumed. However, two and three hours after meal termination this pattern was reversed - hunger was predicted by the perceived amount and not the actual amount. Participants who thought they had consumed the larger 500-ml portion reported significantly less hunger. This was also associated with an increase in the 'expected satiation' of the soup 24-hours later. For the first time, this manipulation exposes the independent and important contribution of memory processes to satiety. Opportunities exist to capitalise on this finding to reduce energy intake in humans

Meta-analysis of pharmacogenetic interactions in amyotrophic lateral sclerosis clinical trials

OBJECTIVE: To assess whether genetic subgroups in recent amyotrophic lateral sclerosis (ALS) trials responded to treatment with lithium carbonate, but that the treatment effect was lost in a large cohort of nonresponders. METHODS: Individual participant data were obtained from 3 randomized trials investigating the efficacy of lithium carbonate. We matched clinical data with data regarding the UNC13A and C9orf72 genotype. Our primary outcome was survival at 12 months. On an exploratory basis, we assessed whether the effect of lithium depended on the genotype. RESULTS: Clinical data were available for 518 of the 606 participants. Overall, treatment with lithium carbonate did not improve 12-month survival (hazard ratio [HR] 1.0, 95% confidence interval [CI] 0.7-1.4; p = 0.96). Both the UNC13A and C9orf72 genotype were independent predictors of survival (HR 2.4, 95% CI 1.3-4.3; p = 0.006 and HR 2.5, 95% CI 1.1-5.2; p = 0.032, respectively). The effect of lithium was different for UNC13A carriers (p = 0.027), but not for C9orf72 carriers (p = 0.22). The 12-month survival probability for UNC13A carriers treated with lithium carbonate improved from 40.1% (95% CI 23.2-69.1) to 69.7% (95% CI 50.4-96.3). CONCLUSIONS: This study incorporated genetic data into past ALS trials to determine treatment effects in a genetic post hoc analysis. Our results suggest that we should reorient our strategies toward finding treatments for ALS, start focusing on genotype-targeted treatments, and standardize genotyping in order to optimize randomization and analysis for future clinical trials