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Featured Application: This work helps to realise improvements in the cultivation of corn and corn–nixtamalisation–dough–tortillas production, which could mean more environmentally friendly food production. The research on the environmental impacts of corn-derived products has been mainly on cultivation techniques and the production of biofuels, so there is limited information on the impacts produced by the transformation of corn for human consumption. The tortilla is a millennial product derived from corn of which consumption is increasing in North America. The aim of this study is to identify the environmental hotspots of the tortilla using a life cycle assessment (LCA) approach. The process studied included only the corn–nixtamalisation–dough–tortillas production. The functional unit is one kg of tortillas packed in kraft paper. The impacts of the tortilla production process were evaluated using SimaPro 8.5.0 software, considering ReCiPe Midpoint. The production has the greatest impact in 15 of the 18 impact categories. The normalisation reveals that the most significant impacts concentrate in the categories terrestrial acidification (TA), particulate matter formation (PMF), marine ecotoxicity (MET) and fossil fuel depletion (FD). Improvements in the cultivation could mean more environmentally friendly tortilla production. [ABSTRACT FROM AUTHOR]

To investigate the relative contributions of current vs. historical factors in explaining broad-scale diversity gradients using a combination of contemporary factors and a quantitative estimate of the temporal accessibility of areas for recolonization created by glacial retreat following the most recent Ice Age. The part of the Nearctic region of North America that was covered by ice sheets during the glacial maximum 20 000 BP. We used range maps to estimate the species richness of mammals and terrestrial birds in 48 400 km2 cells. Current conditions in each cell were quantified using seven climatic and topographical variables. Historical conditions were estimated using the number of years before present when an area became exposed as the ice sheets retreated during the post-Pleistocene climate warming. We attempted to tease apart contemporary and historical effects using multiple regression, partial regression and spatial autocorrelation analysis. A measure of current energy inputs, potential evapotranspiration, explained 76–82% of the variance in species richness, but time since deglaciation explained an additional 8–13% of the variance, primarily due to effects operating at large spatial scales. Because of spatial covariation between the historical climates influencing the melting of the ice sheet and current climates, it was not possible to partition their effects fully, but of the independent effects that could be identified, current climate explained two to seven times more variance in richness patterns than age. Factors acting in the present appear to have the strongest influence on the diversity gradient, but an historical signal persisting at least 13 000 years is still detectable. This has implications for modelling changes in diversity patterns in response to future global warming. [ABSTRACT FROM AUTHOR]

In the lead-up to the Cretaceous/Paleogene mass extinction, dinosaur diversity is argued to have been either in long-term decline, or thriving until their sudden demise. The latest Cretaceous (Campanian-Maastrichtian [83-66 Ma]) of North America provides the best record to address this debate, but even here diversity reconstructions are biased by uneven sampling. Here we combine fossil occurrences with climatic and environmental modelling to quantify latest Cretaceous North American dinosaur habitat. Ecological niche modelling shows a Campanian-to-Maastrichtian habitability decrease in areas with present-day rock-outcrop. However, a continent-wide projection demonstrates habitat stability, or even a Campanian-to-Maastrichtian increase, that is not preserved. This reduction of the spatial sampling window resulted from formation of the proto-Rocky Mountains and sea-level regression. We suggest that Maastrichtian North American dinosaur diversity is therefore likely to be underestimated, with the apparent decline a product of sampling bias, and not due to a climatically-driven decrease in habitability as previously hypothesised.

Locust swarms had periodically raged in both North American Plains (NAP) and East Asian Plains (EAP) before 1880 AD. After this period, the locust outbreaks almost never recurred in NAP but have continued to occur in EAP. Since large quantities of pesticides were used in the major agriculture regions of NAP in the late 1870s; this has been suggested as a possible major cause of the disappearing of locust outbreaks. Extensive applications of more effective chemical pesticides were also used in the granary regions of EAP in the 1950s in an effort to kill the pests at a much higher intensity. However, locust swarms came back again in many areas of China in the 1960s. Therefore, NAP locust extinction still remains a puzzle. Frequent locust outbreaks in EAP over the past 130 yr may offer clues to probe key control elements in the disappearing of locust outbreaks in NAP. This paper analyzes the climate extremes and monthly temperature-precipitation combines of NAP and EAP, and found the differences in their frequencies of these climate combines caused different locust fates in the two regions: restrained the locust outbreak in NAP but induced such events in EAP. Validation shows that severer EAP locust outbreak years were coincided with the climate extreme combines years. Thus we suggest that climate changes in frequency, extremes and trends can explain why the fate of the locust plague in EAP was different from that in NAP. The study also points out that, under the present global warming, cautions should be taken to make sure the pest hazard being nipped in the-bud. [ABSTRACT FROM AUTHOR]

The article reports that the balmier climate of recent years has helped the mountain pine beetle of western North America reach ever-higher latitudes and elevations, resulting in the largest recorded outbreak of this insect. An effort to catalogue and predict the effects of the outbreak reveals that the destruction of pine forests by growing beetle populations will contribute to climate change. Werner Kurz, a forest ecologist with the Canadian Forest Service in Victoria, British Columbia, believes that the only way to stop the beetle is to kill it and its host which means cutting down and burning infected trees.

Nitrous oxide (N2O) is a potent greenhouse gas which also contributes to the depletion of stratospheric ozone (O3). However, the magnitude and underlying mechanisms for the spatiotemporal variations in the terrestrial sources of N2O are still far from certain. Using a process-based ecosystem model (DLEM -- the Dynamic Land Ecosystem Model) driven by multiple global change factors, including climate variability, nitrogen (N) deposition, rising atmospheric CO2, trophospheric O3 pollution, N fertilizer application, and land conversion, the spatial and temporal variations in terrestrial N2O flux over North America were examined and attributed to various driving factors. From 1979 to 2010, the North America accumulatively emitted 55.1±0.8 Tg N2O-N (1 Tg= 1012 g), of which global change factors contributed 2.8±1.0 Tg N2O-N, and baseline emission contributed 52.3±0.6 Tg N2O-N. Climate variability, N deposition, O3 pollution, N fertilizer application, and land conversion increased N2O emission by 0.3±0.7 Tg N2ON, 0.5±0.1 Tg N2O-N, 0.11±0.02 Tg N2O-N, 1.2±0.1 Tg N2O-N, and 0.2±0.02 Tg N2O-N, respectively. The elevated atmospheric CO2 led to a decrease in terrestrial N2O emission by 0.5±0.07 Tg N2O-N. The interactive effect among multiple factors enhanced N2O emission by 0.9±0.3 Tg N2O-N over the 32 years. At country level, climate variability and elevated atmospheric CO2 decreased, while all other single factors and multiple-factor interaction enhanced N2O emission in the United States of America (USA) over the study period. During the same time period, elevated atmospheric CO2 and multiple-factor interaction decreased, while other factors enhanced N2O emission from Canada. Elevated atmospheric CO2 and land conversion decreased while other factors enhanced N2O emission from Mexico. The interactive effects among climate variables play a predominant role in controlling climate -induced changes in N2O emision at both continental and country levels. Central and southeastern parts of the North America -- including central Canada, central USA, southeastern USA, and all of Mexico -- experienced increases in N2O emission from 1979 to 2010. The effects of climate variability and multiple-factor interaction dominating the inter-annual variations in terrestrial N2O emission at both continental and country levels indicate that projected changes in the global climate system during this century may substantially alter the regime of N2O emission from terrestrial ecosystems. They also imply that the interactive effect among global change factors may significantly affect N2O flux, needing more investigations through field experiments. [ABSTRACT FROM AUTHOR]

In this study, we obtained the first leading mode and principal component 1 (PC1) of North Pacific sea surface temperature (SST). The PC1‐related SST anomalies, located relatively north/south, are referred to as North/South PC1 events. Model outputs, observations, reanalysis datasets and sensitivity experiments show that during the North PC1 events, an enhanced Aleutian low occurs and is located relatively north, favoring anomalous southerlies over western North America. The anomalous southerlies induce a strong warming anomaly over North America via warm advection of the anomalous southerlies and temperature advection of the climatological westerlies over North America. However, the Aleutian low anomaly and corresponding southerly anomaly associated with South PC1 events shift southward, favoring weakened effects of South PC1 events on atmospheric circulations and surface temperatures over North America. The meridional position of PC1 events deserves to be considered in the studies of the PC1 and its related climate changes. Plain Language Summary: Understanding of surface temperature variations is important since it largely affects human and society. This paper categorizes the North Pacific sea surface temperature anomaly events, which are associated with the first leading mode of North Pacific sea surface temperature, into North and South events according to their meridional positions. Using model outputs, observations, reanalysis datasets and sensitivity experiments, we found that the surface temperature anomalies over North America during the North events are quite different from those during the South events. During the North events, an enhanced Aleutian low occurs over high‐latitude North Pacific. The enhanced Aleutian low tends to induce anomalous southerlies over western North America. The anomalous southerlies favor warming anomalies over North America via the warm advection of anomalous southerlies and temperature advection of climatological westerly. However, the Aleutian low anomaly and meridional wind anomaly during the South events shift southward, leading to weakened effects of the South events on atmospheric circulations and surface temperatures over North America. Key Points: North American warming anomaly occurs during North Pacific sea surface temperature anomaly events located northThe warming anomaly is related to an enhanced Aleutian low anomaly located north and climatological westerlyDuring the events located south, North American surface temperature responses are weak due to a southward‐shift Aleutian low anomaly [ABSTRACT FROM AUTHOR]

Warming climate and precipitation changes induce notable shifts in climate zones. In this study, the latest generation of global climate models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) and the previous generation CMIP5 under high‐emission scenarios are used together with observations and applied to the Köppen‐Geiger climate classification. The aim is to shed light on how projected warming and changes in precipitation will influence future climate zones and their associated ecosystems while revealing differences between the two model generations. Compared to CMIP5 models, CMIP6 models exhibit slightly improved performance in replicating the observed Köppen‐Geiger map for the historical (1976–2005) period and similar inter‐model agreement for the future. The models show major changes in climate zones with a range of projections depending on which ensemble subset is used: 37.9%–48.1% of the global land area is projected to change climate zone by the end of the century, with the most pronounced changes expected over Europe (71.4%–88.6%) and North America (51.2%–65.8%). CMIP6 models project a higher rate of areal climate zone change (km2/year) throughout the 21st century, which is mainly driven by their greater global land warming rates. Using a likely equilibrium climate sensitivity subset of CMIP6 models that is consistent with the latest evidence constrains the climate zone shifts, and their projections better match the results of CMIP5 simulations. Although the high warming rates of some CMIP6 models are less credible, the risks associated with them are greater, and they heighten the need for urgent action to preserve terrestrial ecosystems. Plain Language Summary: Köppen‐Geiger climate classification is a tool to map regional climate zones based on a region's temperature and precipitation. In recent decades, increasing temperatures and changing precipitation trends have started to affect the distribution of those climate zones, and more extensive changes are expected throughout the 21st century. In this paper, we assess the observed and expected changes in the global distribution of Köppen‐Geiger climate zones using observations along with the latest and the previous generation of global climate model projections. We find that shifts in climate zones are more pronounced in the latest generation of models due to their questionable greater global warming rate projections. Depending on which subset of model projections is used, up to half of the Earth's land area faces the risk of shifting to a different climate zone by the end of the century, with the greatest changes expected in Europe and North America. The rate of change (affected area per year) is also projected to accelerate through the 21st century, suggesting that vulnerable species and agricultural practices might have less time to adapt to changes in climate zones than previously projected. Key Points: Coupled Model Intercomparison Project Phase 6 (CMIP6) exhibits slightly improved performance in simulating the globally observed historical Köppen‐Geiger climate zones compared to CMIP5By the end of the century, 38%–48% of the global land area is projected to be in a different climate zone than todayThe rate of climate zone change is projected to accelerate, with more pronounced rates in CMIP6 due to considerably higher warming rates [ABSTRACT FROM AUTHOR]

A 2020 metastudy by Knutson et al. gave distributions for possible changes in the frequency and intensity of tropical cyclones under climate change. The results form a great resource for those who model the impacts of tropical cyclones. However, a number of steps of processing may be required to use the results in practice. These include interpolation in time, distribution fitting, and reverse engineering of correlations. In this paper we study another processing step that may be required, which is adjusting the frequency change results so that they apply to landfalling frequencies. An adjustment is required because the metastudy results give frequency adjustments as a function of storm lifetime maximum intensity rather than landfall intensity. Increases in the frequency of category-4 and category-5 storms, by lifetime maximum intensity, then contribute to increases in the frequencies of storms of all intensities at landfall. We consider North Atlantic Ocean storms and use historical storm information to quantify this effect as a function of landfall intensity and region. Whereas the original metastudy results suggest that the mean frequency of category-3 storms will decrease, our analysis suggests that the mean frequency of landfalling category-3 storms will increase. Our results are highly uncertain, particularly because we assume that tracks and genesis locations of storms will not change, even though some recent climate model results suggest otherwise. However, making the adjustments we describe is likely to be a better way to model future landfall risk than applying the original metastudy frequency changes directly at landfall. Significance Statement: A recent metastudy gave distributions for possible changes in the frequency and intensity of tropical cyclones under climate change. For the North Atlantic Ocean, we show how to convert these results to changes at landfall. This conversion increases the changes in the frequencies of storms in intensity categories 0–3, and, in particular, the mean frequency change of storms in category 3 flips from decreasing to increasing in most regions. [ABSTRACT FROM AUTHOR]

This paper provides an updated analysis of observed changes in extreme precipitation using high-quality station data up to 2018. We examine changes in extreme precipitation represented by annual maxima of 1-day (Rx1day) and 5-day (Rx5day) precipitation accumulations at different spatial scales and attempt to address whether the signal in extreme precipitation has strengthened with several years of additional observations. Extreme precipitation has increased at about two-thirds of stations and the percentage of stations with significantly increasing trends is significantly larger than that can be expected by chance for the globe, continents including Asia, Europe, and North America, and regions including central North America, eastern North America, northern Central America, northern Europe, the Russian Far East, eastern central Asia, and East Asia. The percentage of stations with significantly decreasing trends is not different from that expected by chance. Fitting extreme precipitation to generalized extreme value distributions with global mean surface temperature (GMST) as a covariate reaffirms the statistically significant connections between extreme precipitation and temperature. The global median sensitivity, percentage change in extreme precipitation per 1 K increase in GMST is 6.6% (5.1% to 8.2%; 5%–95% confidence interval) for Rx1day and is slightly smaller at 5.7% (5.0% to 8.0%) for Rx5day. The comparison of results based on observations ending in 2018 with those from data ending in 2000–09 shows a consistent median rate of increase, but a larger percentage of stations with statistically significant increasing trends, indicating an increase in the detectability of extreme precipitation intensification, likely due to the use of longer records. [ABSTRACT FROM AUTHOR]

In spite of the many factors that are occurring and known for positively affecting the growth of forests, some boreal forests across North America have recently felt the adverse impacts of environmental changes. Knowledge of causes for productivity declines in North American boreal forests remains limited and this is owed to the large spatial and temporal scales involved, and the many plant processes affected. Here, the response of pristine eastern boreal North American (PEBNA) forests to ongoing climatic changes is examined using in situ data, community ecology statistics, and species-specific model simulations of carbon exchanges forced by contemporary cli matic data. To examine trends in forest growth, we used a recently acquired collection of tree-ring width data from 252 sample plots distributed in PEBNA forests dominated by black spruce (Picea mariana [Mill.] B.S.P.) and jack pine (Pinus banksiana Lamb.). Results of linear trend analysis on the tree growth data highlight a dominating forest growth decline in overmature forests (age > 120 yr) from 1950 to 2005. In contrast, improving growth conditions are seen in jack pine and mature (70-120 yr) black spruce stands. Multivariate analysis of climate and growth relationships suggests that responses of PEBNA forests to climate are dependent on demographic and species traits via their mediation of temperature and water stress constraints. In support of this hypothesis, the simulation experiment suggests that in old-growth black spruce stands the benefit to growth brought on by a longer growing season may have been low in comparison with the increasing moisture stress and respiration losses caused by warmer summer temperatures. Predicted increases in wildfire frequency in PEBNA forests will likely enhance the positive response of landscape-level forest growth to climate change by shifting the forest distribution to younger age classes while also enhancing the jack pine component. [ABSTRACT FROM AUTHOR]

Robust estimates of regional-scale terrestrial CO2 exchange are needed to support carbon management policies and to improve the predictive ability of models representing carbon-climate feedbacks. Large discrepancies remain, however, both among and between CO2 flux estimates from atmospheric inverse models and terrestrial biosphere models. Improved atmospheric inverse models that provide robust estimates at sufficiently fine spatial scales could prove especially useful for monitoring efforts, while also serving as a validation tool for process-based assumptions in terrestrial biosphere models. A growing network of continental sites collecting continuous CO2 measurements provides the information needed to drive such models. This study presents results from a regional geostatistical inversion over North America for 2004, taking advantage of continuous data from the nine sites operational in that year, as well as available flask and aircraft observations. The approach does not require explicit prior flux estimates, resolves fluxes at finer spatiotemporal scales than previous North American inversion studies, and uses a Lagrangian transport model coupled with high-resolution winds (i.e. WRF-STILT) to resolve near-field influences around measurement locations. The estimated fluxes are used in an inter-comparison with other inversion studies and a suite of terrestrial biosphere model estimates collected through the North American Carbon Program Regional and Continental Interim Synthesis. Differences among in- versions are found to be smallest in areas of the continent best-constrained by the atmospheric data, pointing to the value of an expanded measurement network. Aggregation errors in previous coarser-scale inversion studies are likely to explain a portion of the remaining spread. The spatial patterns from a geostatistical inversion that includes auxiliary environmental variables from the North American Regional Reanalysis were similar to those from the median of the biospheric model estimates during the growing season, but diverged more strongly in the dormant season. This could be due to a lack of sensitivity in the inversion during the dormant season, but may also point to a lack of skill in the biospheric models outside of the growing season, particularly in agricultural areas. For the annual continental budget, the boundary conditions used as an input into the inversions were seen to have a substantial impact on the estimated net flux, with a difference of ~0.8 PgCyr-1 associated with results using two different plausible sets of boundary conditions. [ABSTRACT FROM AUTHOR]

Inland surface waters are abundant in the tundra and boreal forests of North America, essential to environments and human societies but vulnerable to climate changes. These high-latitude water bodies differ greatly in their morphological and topological characteristics related to the formation, type, and vulnerability. In this paper, we present a water body dataset for the North American high latitudes (WBD-NAHL). Nearly 6.5 million water bodies were identified, with approximately 6 million (∼90 %) of them smaller than 0.1 km2. The dataset provides area and morphological attributes for every water body. During this study, we developed an automated approach for detecting surface water extent and identifying water bodies in the 10 m resolution Sentinel-2 multispectral satellite data to enhance the capability of delineating small water bodies and their morphological attributes. The approach was applied to the Sentinel-2 data acquired in 2019 to produce the water body dataset for the entire tundra and boreal forests in North America. The dataset provided a more complete representation of the region than existing regional datasets for North America, e.g., Permafrost Region Pond and Lake (PeRL). The total accuracy of the detected water extent by the WBD-NAHL dataset was 96.36 % through comparison to interpreted data for locations randomly sampled across the region. Compared to the 30 m or coarser-resolution water datasets, e.g., JRC GSW yearly water history, HydroLakes, and Global Lakes and Wetlands Database (GLWD), the WBD-NAHL provided an improved ability on delineating water bodies and reported higher accuracies in the size, number, and perimeter attributes of water body by comparing to PeRL and interpreted regional dataset. This dataset is available from the National Tibetan Plateau/Third Pole Environment Data Center (TPDC; http://data.tpdc.ac.cn , last access: 6 June 2022): 10.11888/Hydro.tpdc.271021 (Feng and Sui, 2020). [ABSTRACT FROM AUTHOR]

This article puts forward love, care, and reverence for all people and our nonhuman kin as the center of posthumanist education. Opening our spiritual eye and building intimate relationships with nature and with all elements of the universe is envisioned as part of a schooling or postschooling experience; our body, heart and spirit, along with our mind, is an essential part of learning. The article describes the experiences of students taking a graduate level course focusing on global climate change and education at a university in the United States. We use the course as an example to explore what posthumanist education entails. In this qualitative study, students taking the course, along with the faculty designing and teaching the course, describe the course curriculum and pedagogies and reflect on the course's impact on them. Data sources include the syllabus, students' reflection papers, nature contact journals, final projects, art works, and group conversations. Although situated in North America, the article is rich with international perspectives as student authors came from six different countries. The article posits that posthumanist education must be eco-centric and love-based, engaging students' whole being to feel for and love Mother Nature. [ABSTRACT FROM AUTHOR]

Forest landscapes across western North America (wNA) have experienced extensive changes over the last two centuries, while climatic warming has become a global reality over the last four decades. Resulting interactions between historical increases in forested area and density and recent rapid warming, increasing insect mortality, and wildfire burned areas, are now leading to substantial abrupt landscape alterations. These outcomes are forcing forest planners and managers to identify strategies that can modify future outcomes that are ecologically and/or socially undesirable. Past forest management, including widespread harvest of fire‐ and climate‐tolerant large old trees and old forests, fire exclusion (both Indigenous and lightning ignitions), and highly effective wildfire suppression have contributed to the current state of wNA forests. These practices were successful at meeting short‐term demands, but they match poorly to modern realities. Hagmann et al. review a century of observations and multi‐scale, multi‐proxy, research evidence that details widespread changes in forested landscapes and wildfire regimes since the influx of European colonists. Over the preceding 10 millennia, large areas of wNA were already settled and proactively managed with intentional burning by Indigenous tribes. Prichard et al. then review the research on management practices historically applied by Indigenous tribes and currently applied by some managers to intentionally manage forests for resilient conditions. They address 10 questions surrounding the application and relevance of these management practices. Here, we highlight the main findings of both papers and offer recommendations for management. We discuss progress paralysis that often occurs with strict adherence to the precautionary principle; offer insights for dealing with the common problem of irreducible uncertainty and suggestions for reframing management and policy direction; and identify key knowledge gaps and research needs. [ABSTRACT FROM AUTHOR]

Background: Climate change is a defining issue and grand challenge for the health sector in North America. Synthesizing evidence on climate change impacts, climate-health adaptation, and climate-health mitigation is crucial for health practitioners and decision-makers to effectively understand, prepare for, and respond to climate change impacts on human health. This protocol paper outlines our process to systematically conduct a literature review to investigate the climate-health evidence base in North America., Methods: A search string will be used to search CINAHL®, Web of Science™, Scopus®, Embase® via Ovid, and MEDLINE® via Ovid aggregator databases. Articles will be screened using inclusion/exclusion criteria by two independent reviewers. First, the inclusion/exclusion criteria will be applied to article titles and abstracts, and then to the full articles. Included articles will be analyzed using quantitative and qualitative methods., Discussion: This protocol describes review methods that will be used to systematically and transparently create a database of articles published in academic journals that examine climate-health in North America.

Sea surface temperature (SST) observations in the North Atlantic since 1870 reveal a region of enhanced warming off the northeastern coast of North America, and a region of cooling to the south of Greenland. It has been hypothesized that these adjacent SST trends are a result of long‐term changes in the buoyancy‐driven ocean circulation—a slowdown of the Atlantic Meridional Overturning Circulation. The impacts of these historical SST trends on the atmosphere are estimated using idealized atmospheric general circulation model experiments in which the global atmosphere is exposed to modern climatological forcing minus the aforementioned regional SST trends. The local response includes a negative North Atlantic Oscillation tendency and southward shift of the wind forcing for the subtropical gyre. Due to planetary wave propagation, the regional SST trends also induce a northward shift of the intertropical convergence zone over the Indian Ocean. Implications for climate feedbacks and projections are discussed. Plain Language Summary: The ocean surface is warming over most of the planet, with a couple of notable exceptions. One is over the North Atlantic Ocean, just south of Greenland, where the temperature of the ocean surface has actually been cooling by about 1°C since 1870. Nearby, extending off the northeastern coastline of North America is a region where the ocean surface has been warming much faster than the global ocean on average—by about 1.5°C since 1870. This side‐by‐side pair of accelerated warming and cooling trends is likely due to a slowdown of the ocean's overturning circulation, which carries large amounts of heat energy from the tropics toward the poles. This paper reveals the effects of those unusual ocean temperature trends in the North Atlantic on the atmospheric circulation using a computer model of the global atmosphere. The model simulations indicate that these ocean temperature trends are causing shifts in the jet stream, changing the way the winds propel the upper ocean currents, and even have impacts quite far away by moving the tropical rain belt northward in the Indian Ocean. Key Points: The impact of historical sea surface temperature trends in the North Atlantic since 1870 is simulated with a global atmospheric modelAdjacent warming and cooling trends in the North Atlantic Ocean induce a negative NAO‐like response and southward‐shifted gyre forcingPropagation of planetary waves away from the North Atlantic induces a northward‐shifted intertropical convergence zone in the Indian Ocean [ABSTRACT FROM AUTHOR]

The boreal forest is the world’s largest terrestrial biome, covering all continents in the northern hemisphere. Much research has focused on the effects of forest management and climate change on biodiversity and ecosystem level processes of the boreal forest. However, even though climate change and the increasing rate of resource exploitation are likely to intensify the arrival and establishment of exotic species with the potential to become invasive, the boreal forest continues to be viewed as inhospitable to incoming species and we have little understanding of its invasive species status. We reviewed the literature and compiled information on the current status of invasive species across all taxa present in the North American boreal forest. We found that an increasing number of exotic plants, insects, earthworms, slugs and pathogens are establishing in the boreal forest. Research is scarce and their ecological effects are poorly understood. However, given that some of the reported species represent a major driver of change in many ecosystems globally, we expect that this review will provide direction for invasive species research as well as preventative measures aimed at better understanding and conserving Earth’s largest terrestrial biome. [ABSTRACT FROM PUBLISHER]

The variations of large-scale climatic controls and surface responses through the annual cycle during strong positive (El Niño) and negative (La Niña) phase ENSO events are analyzed to assess the within-year and among-year variations of climate anomalies. Data from the NCEP–NCAR reanalysis project are presented as small-multiple maps to illustrate the spatial and temporal variability in North American climate associated with extreme phases of ENSO. Temperature, mean sea level pressure, 500-mb geopotential heights, and 850-mb specific humidity have composite-anomaly patterns that exhibit the greatest degree of spatial and temporal coherence. In general, the composite-anomaly patterns for El Niño and La Niña events are of opposite sign, with stronger, more spatially coherent anomalies occurring during El Niño events than during La Niña events. However, the strength and coherency of the precipitation anomaly patterns are reduced in the interior intermountain west during both positive and negative phase of ENSO. The variations in precipitation anomalies are compared to the 500-mb omega and 850-mb specific humidity composite-anomaly patterns, which provide information on the controls of precipitation by large-scale vertical motions and moisture availability thus providing information on the specific mechanisms associated with precipitation variability during ENSO events. [ABSTRACT FROM AUTHOR]

The assumption of a stationary global signal linked to El Niño–Southern Oscillation (ENSO) events is often used in paleo-ENSO proxy data interpretation. This paper attempts to investigate whether the assumption is valid during the last glacial maximum (LGM) over the region 60°S–90°N, 60°E−60°W. Using four models within phase 3 of the Paleoclimate Modeling Intercomparison Project framework that well reproduce ENSO-induced variabilities, differences from the preindustrial period to LGM in the ENSO-related sea surface temperature pattern and its impacts are investigated. Compared to the preindustrial period, the ENSO impacts are revealed to weaken and shift eastward during the LGM. According to multimodel medians, ENSO impacts on precipitation and near-surface air temperature are attenuated over most regions of concern, with percentage changes in both parameters averaging −21% for the whole region; the ENSO-induced Pacific–North America (PNA) teleconnection pattern is weakened, manifested by the 41% diminished center over the North Pacific and the almost vanished activity centers over the continent. Spatially, there is a zonal contraction of 13° for the sea surface warming of ENSO, as well as eastward migration over 10° for the ENSO-induced positive precipitation anomaly center over the tropical Pacific and the PNA teleconnection pattern outside the tropics. The aforementioned changes are linked to the altered climatic background during the LGM, which features a 16° eastward shift for the Pacific Walker circulation rising branch and a weakened waveguide in the midlatitudes. The results suggest that the hypothesis of stationary ENSO impacts should be applied cautiously to the past. [ABSTRACT FROM AUTHOR]

Vegetation gross primary productivity (GPP) is the single largest carbon flux of the terrestrial biosphere which, in turn, is responsible for sequestering 25%–30% of anthropogenic carbon dioxide emissions. The ability to model GPP is therefore critical for calculating carbon budgets as well as understanding climate feedbacks. Earth system models (ESMs) have the capability to simulate GPP but vary greatly in their individual estimates, resulting in large uncertainties. We describe a machine learning (ML) approach to investigate two key factors responsible for differences in simulated GPP quantities from ESMs: the relative importance of different atmospheric drivers and differences in the representation of land surface processes. We describe the different steps in the development of our interpretable ML framework including the choice of algorithms, parameter tuning, training and evaluation. Our results show that ESMs largely agree on the physical climate drivers responsible for GPP as seen in the literature, for instance drought variables in the Mediterranean region or radiation and temperature in the Arctic region. However differences do exist since models don't necessarily agree on which individual variable is most relevant for GPP. We also explore a distance measure to attribute GPP differences to climate influences versus process differences and provide examples for where our methods work (South Asia, Mediterranean) and where they are inconclusive (Eastern North America). Plain Language Summary: Gross primary productivity (GPP) is the rate at which plants remove carbon dioxide from the atmosphere during photosynthesis. Carbon dioxide is a greenhouse gas and excess in the atmosphere causes global warming and climate change. Changes in the amounts of atmospheric carbon dioxide will impact the entire Earth System. We therefore need the ability to accurately calculate GPP, especially for different possible carbon usage pathways in the future. Earth system models or ESMs allow us to simulate various processes happening in the earth's atmosphere and biosphere including photosynthesis and can help us estimate GPP changes for such different pathways. However, ESMs can vary significantly in their simulated GPP estimates making it difficult to have confidence in using these estimates. We describe a ML framework to better understand where ESMs differ in calculating GPP so that we can address knowledge gaps in models. This approach allows us to understand the processes involved without having to run computationally expensive simulations. With improved models, we can also improve our ability to predict climate change outcomes for the future. Key Points: A machine learning framework to advance our understanding of the terrestrial carbon cycle in earth system models or ESMs is proposedDifferences in the relative importance of atmospheric drivers of gross primary productivity highlights differences across modelsA method to attribute differences in productivity estimates from ESMs due to process representation versus atmospheric forcing is demonstrated [ABSTRACT FROM AUTHOR]

Aim: Previous analyses of remotely sensed data detected the multimodality of the tree‐cover distribution of the boreal forest, and identified areas with potentially alternative tree‐cover states. This paper aims at investigating the causes of multimodality and multistability of the boreal forest, their influence on the asymmetric tree species distribution between Eurasia and North America, and whether multistability could be associated with recent greening trends in leaf area index (LAI) and normalized difference vegetation index (NDVI). Location: Eurasian and North American boreal forests. Time period: 2000–2010. Major taxa studied: Boreal forest plant functional types. Methods: We employ a conceptual model based on tree species competition to simulate the sensitivity of tree cover to stochastic disturbances and to changes in environmental factors. We include different plant functional types based on survival adaptations, and force the model with remotely sensed environmental data. We analyse the model as a dynamical system. We use metrics from statistics and information theory to compare the detection of alternative tree‐cover states and greening trends in LAI and NDVI. Results: We find that multimodality and multistability can emerge through competition between different plant functional types. Additionally, our model is able to reproduce the asymmetry in tree species distribution between Eurasia and North America. Moreover, changes in permafrost distribution can be associated with phenomenological bifurcation points of the model. Finally, we find that the detection of multistable areas is not affected by recent vegetation trends, whereas shifts between alternative states could have affected the greening trends. Main conclusions: Tree‐cover multistability in the boreal region can emerge through competition between species subject to periodic disturbances. Changes in permafrost thaw and distribution could be responsible for the asymmetry in tree species distribution between North America and Eurasia. Climate change and permafrost degradation could cause shifts in tree‐cover states and dominant species. Recent vegetation greening trends in multistable areas could have been affected by shifts between alternative states. [ABSTRACT FROM AUTHOR]

Copyright of Therya is the property of Asociacion Mexicana de Mastozoologia, A. C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pastureland maintenance is seen as a land-based measure to reduce dependency on feed concentrates and mitigate greenhouse gas (GHG) emissions from livestock production in the EU, while providing other ecosystems services. This paper assesses potential market-mediated impacts, including global Land Use Change (LUC) and GHG emissions, from increased subsidies to pasture-based livestock production in the EU. A tax recycling strategy (TRS) is simulated against a baseline up to 2030 under the shared socioeconomic pathway 2 (SSP2). This implies a budget-neutral increase in the level of pasture subsidies in individual Member States, as land subsidies for other cropping activities decrease. We employ the computable general equilibrium (CGE) model GTAP in its recursive-dynamic version, GTAP-RDEM, extended with the Multi-Regional Input-Output (MRIO) database FABIO to disaggregate agri-food sectors from 21 to 31. This approach allows considering price- and income-dependent feedbacks when assessing long-run changes in the global economy, improving the sectoral resolution relative to GTAP v10. The policy increases pastureland areas and cattle production in almost all EU Member States, whereas cropland and crop production decrease, causing significant changes across EU agri-food markets. Crop prices increase, leading to the reduced output of intensive animal production sectors, mainly pig and poultry. Cropland areas decrease and most EU countries increase imports of grain, oilseeds, and cakes, essentially soybean cake from Brazil and North America. While GHG emissions decrease in those EU countries where pasturelands expand mainly at the cost of croplands, GHG emissions increase in those countries where pastureland expansion comes with forest loss. As a result, net GHG emissions increase in the EU-27 in 2030 (+2.49 Mt CO 2 -eq). Emissions from LUC in major non-EU grain- and oilseed-exporting countries increase, e.g., by 102.52 Mt CO 2 -eq in Brazil and by 129.17 Mt CO 2 -eq in North America. The simulated policy shows that promoting extensive livestock per se does not meet the objectives of the Common Agricultural Policy and the EU Green Deal. The TRS should be complemented with policies to foster crop diversification and promote the use of domestic feed sources (e.g., legumes) to effectively ensure feed self-sufficiency and that extensive cattle production in the EU does not lead to deforestation in carbon-rich countries. [ABSTRACT FROM AUTHOR]

This paper contributes to the ongoing debate on the extent to which climate and climatic change can have a negative impact on societies by triggering migration, or even contribute to conflict. It summarizes results from the transdisciplinary project "Climate of migration" (funded 2010-2014), whose innovative title was created by Franz Mauelshagen and Uwe Lübken. The overall goal of this project was to analyze the relation between climatic and socioeconomic parameters and major migration waves from southwest Germany to North America during the 19th century. The article assesses the extent to which climatic conditions triggered these migration waves. The century investigated was in general characterized by the Little Ice Age with three distinct cooling periods, causing major glacier advances in the alpine regions and numerous climatic extremes such as major floods, droughts and severe winter. Societal changes were tremendous, marked by the warfare during the Napoleonic era (until 1815), the abolition of serfdom (1817), the bourgeois revolution (1847/48), economic freedom (1862), the beginning of industrialization accompanied by large-scale rural-urban migration resulting in urban poverty, and finally by the foundation of the German Empire in 1871. The presented study is based on quantitative data and a qualitative, information-based discourse analysis. It considers climatic conditions as well as socioeconomic and political issues, leading to the hypothesis of a chain of effects ranging from unfavorable climatic conditions to a decrease in crop yields to rising cereal prices and finally to emigration. These circumstances were investigated extensively for the peak emigration years identified with each migration wave. Furthermore, the long-term relations between emigration and the prevailing climatic conditions, crop yields and cereal prices were statistically evaluated with a sequence of linear models which were significant with explanatory power between 22 and 38%. [ABSTRACT FROM AUTHOR]

Inland surface waters are abundant in the tundra and boreal forests in North America, essential to environments and human societies but vulnerable to climate changes. These high-latitude water bodies differ greatly in their morphological and topological characteristics related to the formation, type, and vulnerability. In this paper we present an inland surface water body inventory (SWBI) dataset for the tundra and boreal forests of North America. Nearly 6.7 million water bodies were identified, with approximately 6 million (~90 %) of them smaller than 0.1 km². The dataset provides geometry coverage and morphological attributes for every water body. During this study we developed an automated approach for detecting surface water extent and identifying water bodies in the 10 m resolution Sentinel-2 multispectral satellite data to enhance the capability for delineating small water bodies and their morphological attributes. The approach was applied to the Sentinel-2 data acquired in 2019 to produce the water body dataset for the entire tundra and boreal forests in North America, providing a more complete representation of the region than existing regional datasets, e.g., Permafrost Region Pond and Lake (PeRL). Total accuracy of the detected water extent by SWBI dataset was 96.36 % by comparing to interpreted data for locations randomly sampled across the region. Compared to the 30 m or coarser resolution water datasets, e.g., JRC GSW yearly water history, HydroLakes, and Global Lakes and Wetlands Database (GLWD), the SWBI provided an improved ability on delineating water bodies, and reported higher accuracies in the size, number, and perimeter attributes of water body by comparing to PeRL and interpreted regional dataset. This dataset is available on the National Tibetan Plateau/Third Pole Environment Data Center (TPDC, http://data.tpdc.ac.cn): DOI: 10.11888/Hydro.tpdc.271021 (Feng et al., 2020). [ABSTRACT FROM AUTHOR]

Aim: Species distribution models (SDMs) have emerged as essential tools in the equipment of many ecologists, useful to explore species distributions in space and time and answering an assortment of questions related to biogeography, climate change biology and conservation biology. Historically, most SDM research concentrated on well‐known organisms, especially vertebrates. In recent years, these tools are becoming increasingly important for predicting the distribution of understudied invertebrate taxa. Here, we reviewed the literature published on main terrestrial arthropod predators (ants, ground beetles and spiders) to explore some of the challenges and opportunities of species distribution modelling in mega‐diverse arthropod groups. Location: Global. Methods: Systematic mapping of the literature and bibliometric analysis. Results: Most SDM studies of animals to date have focused either on broad samples of vertebrates or on arthropod species that are charismatic (e.g. butterflies) or economically important (e.g. vectors of disease, crop pests and pollinators). We show that the use of SDMs to map the geography of terrestrial arthropod predators is a nascent phenomenon, with a near‐exponential growth in the number of studies over the past ten years and still limited collaborative networks among researchers. There is a bias in studies towards charismatic species and geographical areas that hold lower levels of diversity but greater availability of data, such as Europe and North America. Conclusions: Arthropods pose particular modelling challenges that add to the ones already present for vertebrates, but they should also offer opportunities for future SDM research as data and new methods are made available. To overcome data limitations, we illustrate the potential of modern data sources and new modelling approaches. We discuss areas of research where SDMs may be combined with dispersal models and increasingly available phylogenetic and functional data to understand evolutionary changes in ranges and range‐limiting traits over past and contemporary time‐scales. [ABSTRACT FROM AUTHOR]

Background: West Nile virus (WNV), the most widely distributed flavivirus causing encephalitis globally, is a vector-borne pathogen of global importance. The changing climate is poised to reshape the landscape of various infectious diseases, particularly vector-borne ones like WNV. Understanding the anticipated geographical and range shifts in disease transmission due to climate change, alongside effective adaptation strategies, is critical for mitigating future public health impacts. This scoping review aims to consolidate evidence on the impact of climate change on WNV and to identify a spectrum of applicable adaptation strategies. Main body: We systematically analyzed research articles from PubMed, Web of Science, Scopus, and EBSCOhost. Our criteria included English-language research articles published between 2007 and 2023, focusing on the impacts of climate change on WNV and related adaptation strategies. We extracted data concerning study objectives, populations, geographical focus, and specific findings. Literature was categorized into two primary themes: 1) climate-WNV associations, and 2) climate change impacts on WNV transmission, providing a clear understanding. Out of 2168 articles reviewed, 120 met our criteria. Most evidence originated from North America (59.2%) and Europe (28.3%), with a primary focus on human cases (31.7%). Studies on climate-WNV correlations (n = 83) highlighted temperature (67.5%) as a pivotal climate factor. In the analysis of climate change impacts on WNV (n = 37), most evidence suggested that climate change may affect the transmission and distribution of WNV, with the extent of the impact depending on local and regional conditions. Although few studies directly addressed the implementation of adaptation strategies for climate-induced disease transmission, the proposed strategies (n = 49) fell into six categories: 1) surveillance and monitoring (38.8%), 2) predictive modeling (18.4%), 3) cross-disciplinary collaboration (16.3%), 4) environmental management (12.2%), 5) public education (8.2%), and 6) health system readiness (6.1%). Additionally, we developed an accessible online platform to summarize the evidence on climate change impacts on WNV transmission (https://2xzl2o-neaop.shinyapps.io/WNVScopingReview/). Conclusions: This review reveals that climate change may affect the transmission and distribution of WNV, but the literature reflects only a small share of the global WNV dynamics. There is an urgent need for adaptive responses to anticipate and respond to the climate-driven spread of WNV. Nevertheless, studies focusing on these adaptation responses are sparse compared to those examining the impacts of climate change. Further research on the impacts of climate change and adaptation strategies for vector-borne diseases, along with more comprehensive evidence synthesis, is needed to inform effective policy responses tailored to local contexts. [ABSTRACT FROM AUTHOR]

Background: Physical inactivity is a major public health concern, exacerbated in countries with a (sub)tropical climate. The built environment can facilitate physical activity; however, current evidence is mainly from North American and European countries with activity-friendly climate conditions. This study explored associations between built environment features and physical activity in global tropical or subtropical dry or desert climate regions. Methods: A systematic review of four major databases (Web of Science, Scopus, PubMed, and SportDISCUS) was performed. To be included, studies had to investigate associations between perceived or objective built environment characteristics and adult's physical activity and had to be conducted in a location with (sub)tropical climate. Each investigated association was reported as one case and results were synthesized based upon perceived and objectively assessed environment characteristics as well as Western and non-Western countries. Study quality was evaluated using a tool designed for assessing studies on built environment and physical activity. Results: Eighty-four articles from 50 studies in 13 countries with a total of 2546 built environment-physical activity associations were included. Design (connectivity, walking/cycling infrastructure), desirability (aesthetics, safety), and destination accessibility were the built environment characteristics most frequently associated with physical activity across the domains active transport, recreational physical activity, total walking and cycling, and moderate-to-vigorous physical activity, particularly if multiple attributes were present at the same time. Very few studies assessed built environment attributes specifically relevant to physical activity in (sub)tropical climates. Most studies were conducted in Western countries, with results being largely comparable with non-Western countries. Findings were largely generalizable across gender and age groups. Results from natural experiments indicated that relocating to an activity-friendly neighborhood impacted sub-groups differently. Conclusions: Built environment attributes, including destination accessibility, connectivity, walking and cycling infrastructure, safety, and aesthetics, are positively associated with physical activity in locations with (sub)tropical climate. However, few studies focus on built environment attributes specifically relevant in a hot climate, such as shade or indoor recreation options. Further, there is limited evidence from non-Western countries, where most of the urban population lives in (sub)tropical climates. Policy makers should focus on implementing activity-friendly environment attributes to create sustainable and climate-resilient cities. [ABSTRACT FROM AUTHOR]

Anthropogenic climate change has already affected drought severity and risk across many regions, and climate models project additional increases in drought risk with future warming. Historically, droughts are typically caused by periods of below‐normal precipitation and terminated by average or above‐normal precipitation. In many regions, however, soil moisture is projected to decrease primarily through warming‐driven increases in evaporative demand, potentially affecting the ability of negative precipitation anomalies to cause drought and positive precipitation anomalies to terminate drought. Here, we use climate model simulations from Phase Six of the Coupled Model Intercomparison Project (CMIP6) to investigate how different levels of warming (1, 2, and 3°C) affect the influence of precipitation on soil moisture drought in the Mediterranean and Western North America regions. We demonstrate that the same monthly precipitation deficits (25th percentile relative to a preindustrial baseline) at a global warming level of 2°C increase the probability of both surface and rootzone soil moisture drought by 29% in the Mediterranean and 32% and 6% in Western North America compared to the preindustrial baseline. Furthermore, the probability of a dry (25th percentile relative to a preindustrial baseline) surface soil moisture month given a high (75th percentile relative to a preindustrial baseline) precipitation month is 6 (Mediterranean) and 3 (Western North America) times more likely in a 2°C world compared to the preindustrial baseline. For these regions, warming will likely increase the risk of soil moisture drought during low precipitation periods while simultaneously reducing the efficacy of high precipitation periods to terminate droughts. Plain Language Summary: Regional warming associated with climate change is already making droughts worse in many places. This trend is expected to continue as global temperatures increase in response to continued emissions of greenhouse gases. With increasing temperatures, soils are projected to lose water to the atmosphere as it draws more and more moisture from the land surface, increasing drought risk. At the same time, climate change is also projected to shift precipitation patterns. This means it is important to understand how changes in rainfall will cause and end droughts in the future. Using state‐of‐the‐art climate models, we investigate how future warming will impact the influence of precipitation on soil moisture in the Mediterranean and Western North America. Our results suggest that current levels of monthly precipitation will be insufficient to alleviate drought conditions in a warmer world. Key Points: Warming causes declines in soil moisture in the Mediterranean and Western North AmericaThe probability of a moderate soil moisture drought increases during both low and high precipitation anomalies, even at 1°C of warmingThe ability of large positive precipitation anomalies to terminate soil moisture droughts will be substantially reduced in a warmer world [ABSTRACT FROM AUTHOR]

Background: Climate is an important driver of ungulate life-histories, population dynamics, and migratory behaviors. Climate conditions can directly impact ungulates via changes in the costs of thermoregulation and locomotion, or indirectly, via changes in habitat and forage availability, predation, and species interactions. Many studies have documented the effects of climate variability and climate change on North America's ungulates, recording impacts to population demographics, physiology, foraging behavior, migratory patterns, and more. However, ungulate responses are not uniform and vary by species and geography. Here, we present a systematic map describing the abundance and distribution of evidence on the effects of climate variability and climate change on native ungulates in North America. Methods: We searched for all evidence documenting or projecting how climate variability and climate change affect the 15 ungulate species native to the U.S., Canada, Mexico, and Greenland. We searched Web of Science, Scopus, and the websites of 62 wildlife management agencies to identify relevant academic and grey literature. We screened English-language documents for inclusion at both the title and abstract and full-text levels. Data from all articles that passed full-text review were extracted and coded in a database. We identified knowledge clusters and gaps related to the species, locations, climate variables, and outcome variables measured in the literature. Review findings: We identified a total of 674 relevant articles published from 1947 until September 2020. Caribou (Rangifer tarandus), elk (Cervus canadensis), and white-tailed deer (Odocoileus virginianus) were the most frequently studied species. Geographically, more research has been conducted in the western U.S. and western Canada, though a notable concentration of research is also located in the Great Lakes region. Nearly 75% more articles examined the effects of precipitation on ungulates compared to temperature, with variables related to snow being the most commonly measured climate variables. Most studies examined the effects of climate on ungulate population demographics, habitat and forage, and physiology and condition, with far fewer examining the effects on disturbances, migratory behavior, and seasonal range and corridor habitat. Conclusions: The effects of climate change, and its interactions with stressors such as land-use change, predation, and disease, is of increasing concern to wildlife managers. With its broad scope, this systematic map can help ungulate managers identify relevant climate impacts and prepare for future changes to the populations they manage. Decisions regarding population control measures, supplemental feeding, translocation, and the application of habitat treatments are just some of the management decisions that can be informed by an improved understanding of climate impacts. This systematic map also identified several gaps in the literature that would benefit from additional research, including climate effects on ungulate migratory patterns, on species that are relatively understudied yet known to be sensitive to changes in climate, such as pronghorn (Antilocapra americana) and mountain goats (Oreamnos americanus), and on ungulates in the eastern U.S. and Mexico. [ABSTRACT FROM AUTHOR]

Engaging students in research is increasingly recognized as a valuable pedagogical tool that can augment student learning outcomes. Here, we present an original activity that utilizes research as pedagogy to teach upper-division college students about phenological responses to climate change. By studying phenological responses in multiple species, this activity emphasizes interspecific variability in responses to a changing climate (i.e., that not all species respond in the same way), while demonstrating the relationship between environmental and phenotypic variability. In this activity, students collect data from herbarium specimens of spring ephemerals native to North America and are tasked with formulating and testing hypotheses about how the day of year that a species' flowering occurs (i.e., flowering phenology) has been affected by climate change. To accomplish this, students perform linear regressions using the R programming language—including data exploration and ensuring the dependent variable follows a normal distribution—and subsequently present their results via oral presentation. We taught this activity as a three-unit lab in an upper-division ecology course and observed quantifiable improvement in student learning outcomes. While designed as a three-unit, upper-division lab, this activity can be modified for other educational levels, blocks of time, and/or as a flipped classroom activity. Through this activity, students are provided with the opportunity to learn about the scientific method, biological collections, linear regressions, the R programming language, and scientific communication. Changes to flowering time are one of the most conspicuous effects of climate change, thus presenting an ideal topic for engaging students in biological inquiry. [ABSTRACT FROM AUTHOR]

Aim: Description of the driving forces for genetic divergence is important for understanding spatial pattern of biodiversity and development of conservation plans. Paleo‐climate, geographical barriers and habitat heterogeneity are considered to be the main influential factors; however, an integrative study is still lacking to reveal their interactions. Location: Eastern North America. Methods: Here, we generated MIG‐seq SNPs of 403 Sanguinaria canadensis samples and seven plastome data. The methods of phylogeography and landscape genomics were applied to infer their genetic divergence, demography, species distribution modelling, ecological differentiation and local adaptation. Results: We identified three distinct genetic lineages corresponding to geographical distributions isolated by the Appalachian Mountains and the Mississippi River. Ecological niche modelling and population demographic inference demonstrated that the response of S. canadensis to Pleistocene climate changes was consistent with the pattern of southward contraction during the ice age and northward recolonization during the inter−/postglacial period. Isolation in multiple southern refugia was a key factor resulting in the genetic divergence, whereas secondary contact triggered by repeated range shifts allowed gene flow among different lineages. A greater effect of isolation‐by‐environment than isolation‐by‐distance was founded, which suggested heterogeneous environment was also a promotor of genetic differentiation. Candidate adaptive loci related to transposable elements were identified under the influence of divergent environmental selection. Ecological niche divergence also reflected adaptation to different environments. Main Conclusions: This study revealed that genetic divergence has occurred within S. canadensis populations under the combined effect of paleo‐climate, geographical barriers and habitat heterogeneity, and emphasized the necessity of establishing different conservation units in future biological conservation and management work. [ABSTRACT FROM AUTHOR]

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There is growing concern about the effects of large-scale oceanic atmospheric climate variability, such as the Pacific decadal oscillation (PDO), on regional hydrology and water resources. In this paper, the effects of PDO on temporal patterns of winter (January–March) flow in northwestern North America (NWNA), which is believed to be a PDO-sensitive region, is studied for the period 1943–2007 using daily streamflow data from a much larger set of 179 stations, compared to previous studies in which only smaller subsets of these stations were analyzed. Time series of winter flows were divided into two nonoverlapping blocks corresponding to change points detected in time series of December–March mean monthly PDO indices. Both parametric and nonparametric measures of correlation and average percentage differences and average standardized differences from the period-of-record mean were explored. Like some of the previous studies, it is found that, on average, winter flows tend to be higher (lower) during the warm (cold) phase of the PDO and that establishes the physical link between large-scale climate variability and basin response. It is shown that the serial structure of time series of PDO indices conforms to that of a stochastic process with long-term persistence (LTP). Based on this finding and the climate–streamflow physical link, it is plausible to investigate temporal variations in winter flows with the LTP hypothesis, in addition to assuming merely independence (IND) or short-term persistence (STP). The results of the analysis demonstrate that the LTP mechanism, in combination with the STP, is able to explain more than half of the significant trends noted, with the IND assumption suggesting that the significance of trends reported in previous studies in NWNA may have been overstated. This result has important implications for future planning of regional water resources. [ABSTRACT FROM AUTHOR]

An important goal of the Climate Variability and Predictability (CLIVAR) research on the American monsoon systems is to determine the sources and limits of predictability of warm season precipitation, with emphasis on weekly to interannual time scales. This paper reviews recent progress in the understanding of the American monsoon systems and identifies some of the future challenges that remain to improve warm season climate prediction. Much of the recent progress is derived from complementary international programs in North and South America, namely, the North American Monsoon Experiment (NAME) and the Monsoon Experiment South America (MESA), with the following common objectives: 1) to understand the key components of the American monsoon systems and their variability, 2) to determine the role of these systems in the global water cycle, 3) to improve observational datasets, and 4) to improve simulation and monthly-to-seasonal prediction of the monsoons and regional water resources. Among the recent observational advances highlighted in this paper are new insights into moisture transport processes, description of the structure and variability of the South American low-level jet, and resolution of the diurnal cycle of precipitation in the core monsoon regions. NAME and MESA are also driving major efforts in model development and hydrologic applications. Incorporated into the postfield phases of these projects are assessments of atmosphere–land surface interactions and model-based climate predictability experiments. As CLIVAR research on American monsoon systems evolves, a unified view of the climatic processes modulating continental warm season precipitation is beginning to emerge. [ABSTRACT FROM AUTHOR]

Intensification of extreme rainfall due to climate change means that federally published rainfall metrics such as the "100-yr storm" are outdated throughout much of the United States. Given their central role in a wide range of infrastructure designs and risk management decisions, updating these metrics to reflect recent and future changes is essential to protect communities. There have been considerable advances in recent years in data collection, statistical methods, and climate modeling that can now be brought to bear on the problem. Scientists must take a lead in this updating process, which should be open, inclusive, and leverage recent scientific advances. [ABSTRACT FROM AUTHOR]

Managing annual row crops on marginally productive croplands can be environmentally unsustainable and result in variable economic returns. Incorporating perennial bioenergy feedstocks into marginally productive cropland can engender ecosystem services and enhance climate resiliency while also diversifying farm incomes. We use one of the oldest bioenergy-specific field experiments in North America to evaluate economically and environmentally sustainable management practices for growing perennial grasses on marginal cropland. This long-term field trial called 9804 was established in 1998 in eastern Nebraska and compared the productivity and sustainability of corn (Zea mays L.) --both corn grain and corn stover--and switchgrass (Panicum virgatum L.) bioenergy systems under different harvest strategies and nitrogen (N) fertilizer rates. This experiment demonstrated that switchgrass, compared to corn, is a reliable and sustainable bioenergy feedstock. This experiment has been a catalyst for other bioenergy projects which have also expanded our understanding of growing and managing bioenergy feedstocks on marginal cropland. We (1) synthesize research from this long-term experiment and (2) provide perspective concerning both the knowledge gained from this experiment and knowledge gaps and how to fill them as well as the role switchgrass will play in the future of bioenergy. [ABSTRACT FROM AUTHOR]

Pan global Permian coal measures are unique in the evolution of the Earth, not matched in any period before or since. Middle and late Permian coal-bearing strata are widely distributed in Mongolia. In particular, a large concentration of transtensive coal-bearing sub-basins is located in southern Mongolia, some of which are well documented. However, the late Permian coal measures developed along the shores of the Mongol-Transbaikalian Seaway in central Mongolia, the focus of this contribution, has received very limited attention. This study focuses on the c. 420 m thick coal-bearing middle part of a c. 2,600 m thick Permo-Triassic succession in the Bayanjargalan district. The study draws on data from 38 drillholes, 3 km of trenches, mapping, petrological analysis of sandstone samples, analysis of macroflora, fauna and trace fossils, 82 coal quality samples as well as washability and ash XRD analysis from a 3t coal bulk sample. The unstable and wedge-shaped architecture of the coal seams strongly suggest a syntectonic influence on their development. Paleoclimatic indicators suggest the peat mire ecosystem developed during relatively cold - temperate climatic conditions. Peat-forming plants such as Cordaites, Rufloria and Koretrophyllites probably benefited from moist air currents along the seaway. Plant-arthropod interactions are reported from two sites, in particular DT228 and DT246 oviposition lesions, the latter being almost twice the size of a previous report from North America. Results from 82 proximate analyses returned consistent very high ash yields of 46.95% (db) and 43.45% (adb) from the 3t bulk sample, which are unusual for Permian coals in Mongolia. [ABSTRACT FROM AUTHOR]

Simple Summary: The iconic monarch butterfly has undergone a dramatic decline in western North America since the 1990s, but in recent years has shown a capacity for resilience. This review identifies and investigates the likely drivers of this decline and resilience, and discusses their relative importance from a holistic viewpoint. Pesticides (particularly neonicotinoid insecticides), climate change, and habitat loss are likely to be the prime drivers of contemporary decline and instability in monarch population dynamics. Natural enemies (predators, parasites, and pathogens) are less likely to be a major contributor to contemporary population fluctuations, except on a local scale. Adaptation to changing environmental conditions will be an important component of the ongoing ability of western monarchs to show resilience. Human involvement with monarchs is a good and necessary thing for sustainable conservation, helping to prevent the 'extinction of experience', and the loss of human-nature contact, which has major adverse implications for nature conservation generally. Monarch butterfly populations in western North America suffered a substantial decline, from millions of butterflies overwintering in California in the 1980s to less than 400,000 at the beginning of the 21st century. The introduction of neonicotinoid insecticides in the mid–1990s and their subsequent widespread use appears to be the most likely major factor behind this sudden decline. Habitat loss and unfavorable climates (high temperatures, aridity, and winter storms) have also played important and ongoing roles. These factors kept overwintering populations stable but below 300,000 during 2001–2017. Late winter storm mortality and consequent poor spring reproduction drove winter populations to less than 30,000 butterflies during 2018–2019. Record high temperatures in California during the fall of 2020 appeared to prematurely terminate monarch migration, resulting in the lowest overwintering population (1899) ever recorded. Many migrants formed winter-breeding populations in urban areas. Normal seasonal temperatures in the autumns of 2021 and 2022 enabled overwintering populations to return to around the 300,000 level, characteristic of the previous two decades. Natural enemies (predators, parasitoids, parasites, and pathogens) may be important regional or local drivers at times but they are a consistent and fundamental part of monarch ecology. Human interference (capture, rearing) likely has the least impact on monarch populations. The rearing of monarch caterpillars, particularly by children, is an important human link to nature that has positive ramifications for insect conservation beyond monarch butterflies and should be encouraged. [ABSTRACT FROM AUTHOR]

Northern boreal forests are characterized by accumulation of accumulation of peat (e.g., known as paludification). The functioning of northern boreal forest species and their capacity to adapt to environmental changes appear to depend on soil conditions. Climate warming is expected to have particularly pronounced effects on paludified boreal ecosystems and can alter current forest species composition and adaptation by changing soil conditions such as moisture, temperature regimes, and soil respiration. In this paper, we review and synthesize results from various reported studies (i.e., 88 research articles cited hereafter) to assess the effects of climatic warming on soil conditions of paludified forests in North America. Predictions that global warming may increase the decomposition rate must be considered in combination with its impact on soil moisture, which appears to be a limiting factor. Local adaptation or acclimation to current climatic conditions is occurring in boreal forests, which is likely to be important for continued ecosystem stability in the context of climate change. The most commonly cited response of boreal forest species to global warming is a northward migration that tracks the climate and soil conditions (e.g., temperature and moisture) to which they are adapted. Yet, some constraints may influence this kind of adaptation, such as water availability, changes in fire regimes, decomposer adaptations, and the dynamic of peat accumulation. In this paper, as a study case, we examined an example of potential effects of climatic warming on future paludification changes in the eastern lowland region of Canada through three different combined hypothetical scenarios based on temperature and precipitation (e.g., unchanged, increase, or decrease). An increase scenario in precipitation will likely favor peat accumulation in boreal forest stands prone to paludification and facilitate forested peatland expansion into upland forest, while decreased or unchanged precipitation combined with an increase in temperature will probably favor succession of forested peatlands to upland boreal forests. Each of the three scenarios were discussed in this study, and consequent silvicultural treatment options were suggested for each scenario to cope with anticipated soil and species changes in the boreal forests. We concluded that, despite the fact boreal soils will not constrain adaptation of boreal forests, some consequences of climatic warming may reduce the ability of certain species to respond to natural disturbances such as pest and disease outbreaks, and extreme weather events. [ABSTRACT FROM AUTHOR]

Global climate change is having profound impacts on the natural world. However, climate influence on faunal dynamics at macroevolutionary scales remains poorly understood. In this paper we investigate the influence of climate over deep time on the diversity patterns of Cenozoic North American mammals. We use factor analysis to identify temporally correlated assemblages of taxa, or major evolutionary faunas that we can then study in relation to climatic change over the past 65 million years. These taxa can be grouped into six consecutive faunal associations that show some correspondence with the qualitative mammalian chronofaunas of previous workers. We also show that the diversity pattern of most of these chronofaunas can be correlated with the stacked deep-sea benthic foraminiferal oxygen isotope (δ(18)O) curve, which strongly suggests climatic forcing of faunal dynamics over a large macroevolutionary timescale. This study demonstrates the profound influence of climate on the diversity patterns of North American terrestrial mammals over the Cenozoic.

The grasslands of North America are threatened by woody encroachment. Restoring historical fire regimes has been used to manage brush encroachment. However, fire management may be insufficient due to the nonlinear and hysteretic responses of vegetation recovery following encroachment and the social–political constraints affecting fire management. We synthesized the fire thresholds required to control woody encroachment by typical encroaching species in North America, especially the Great Plains region, and identified the social–political constraints facing fire management in selected grassland national parks. Our synthesis revealed the resistance, hysteresis, and irreversibility of encroached grasslands using fire and emphasized the need for a combination of brush management methods if the impacts of climate change are to be addressed. Frequent fires alone may maintain grassland states, reflecting resistance. However, high-intensity fires exceeding fire-mortality thresholds are required to exclude non-resprouting shrubs and trees, indicating hysteresis. Fire alone may be insufficient to reverse encroachment by resprouting species, exhibiting reversibility. In practice, appropriate fire management may restore resistant grassland states. However, social–political constraints have restricted the use of frequent and high-intensity fires, thereby reducing the effectiveness of management actions to control woody encroachment of grasslands in national parks. This research proposes a resilience-based framework to manage woody encroachment in grassland national parks and similar protected areas. [ABSTRACT FROM AUTHOR]

Understanding seed characteristics, germination, and seedling establishment patterns is essential for formulating effective management strategies to control invasive species. Glossy buckthorn (Frangula alnus) is a shrub or small tree from Eurasia that has become invasive in North America, and which has negative impacts on plant communities and ecosystems. In this study, we analyzed the germination response of glossy buckthorn seeds to different temperatures (12, 14, 16, 18, 20, 24, and 28 °C), various stratification lengths (4 to 20 weeks), and scarification conditions to measure the impact on breaking seed dormancy, and the effect of light in triggering germination. Analysis using distinct time-to-event approaches, including the Kaplan–Meier estimator and Cox proportional hazard model, was employed to interpret germination data. Glossy buckthorn seeds exhibited physiological dormancy and required cold stratification to germinate. At 12 °C, only 14% of the seeds could germinate. At warmer temperatures, germination rates increased, reaching a peak of 70% at 20 °C. At 24 °C and 28 °C, germination declined, and seeds were probably induced into secondary dormancy. Scarified seeds had a higher probability of germination than non-scarified ones, even at the lowest temperatures. Darkness had a negative impact on germination at all tested temperatures. This study significantly advances our understanding of how temperature, light, stratification, and scarification impact glossy buckthorn seeds, elucidating the species' seasonal germination patterns in North America. The results emphasize that glossy buckthorn utilizes seed banks as a primary strategy for invading and establishing in new habitats. The ungerminated seeds form persistent seed banks, ensuring F. alnus' survival and bolstering its chances of successful establishment and invasion. As climate change drives temperature increases, it may affect seeds in the soil, altering stratification periods and consequently shifting the timing of germination. [ABSTRACT FROM AUTHOR]

SNOwpack TELemetry observations and model simulations both demonstrate that the fractional contribution of October through December (early season) snowfall to peak snow accumulation in North America increases with latitude due to both colder temperatures and Pacific storm tracks focusing further north earlier in the season. Early season snowfall also makes up greater than 60 percent of peak accumulation in interior low‐precipitation locations leeward of mountains, particularly those that are subject to strong, warm winds and midwinter snow loss. Early season snow observations show promise in predicting peak snow water equivalent in locations where large‐scale ocean‐atmosphere patterns similarly influence fall and winter conditions, and in northern maritime locations where winter temperatures are warm enough that rain on snow and midwinter melt occur. Because climate change is likely to increase the extent of midwinter melt, the latter relationship is expected to become important over more locations in the future. Plain Language Summary: Across North America, snow accumulates from October until the following spring. Early season snow, defined as the snow that accumulates by the end of December, is a greater fraction of total snow accumulation at higher latitudes and at colder locations. Early season snow accumulation can be used to predict peak snow accumulation. Predictions are more skillful at locations where fall precipitation is correlated with winter precipitation because more snow at the end of December indicates that weather patterns are favorable for greater than average snowfall to continue. Predictions also have skill at warmer northern locations where more snow on the ground early season increases the likelihood that mixed rain‐snow events add water to the snowpack rather than melting the snow. Predictions at warm southern locations do not have skill because winter and spring snowfall is highly variable, and frequently little to no snow has accumulated by the end of December. Key Points: Fall snow contributes more to peak snow at colder and more northerly locationsFall snow can be used to predict peak snow where large scale ocean and atmosphere patterns influence annual snowfall variationsFall snow regulates cold content, which in warm regions may tip a snowpack between lasting or ablating midwinter, influencing peak snow [ABSTRACT FROM AUTHOR]

Armillaria altimontana is a fungus (Basidiomycota, Agaricomycetes, Agaricales, and Physalacriaceae) that is generally considered as a weak/opportunistic pathogen or saprophyte on many tree hosts. It widely occurs across the northwestern USA to southern British Columbia, Canada, but relatively little is known about its ecological role in the diverse forest ecosystems where it occurs. This review summarizes the biology and ecology of A. altimontana, including its identification, life cycle, distribution, host associations, and bioclimatic models under climate change. [ABSTRACT FROM AUTHOR]

The North American Regional Climate Change Assessment Program (NARCCAP) is an international effort designed to investigate the uncertainties in regional-scale projections of future climate and produce high-resolution climate change scenarios using multiple regional climate models (RCMs) nested within atmosphere-ocean general circulation models (AOGCMs) forced with the Special Report on Emission Scenarios (SRES) A2 scenario, with a common domain covering the conterminous United States, northern Mexico, and most of Canada. The program also includes an evaluation component (phase I) wherein the participating RCMs, with a grid spacing of 50 km, are nested within 25 years of National Centers for Environmental Prediction-Department of Energy (NCEP-DOE) Reanalysis II. This paper provides an overview of evaluations of the phase I domain-wide simulations focusing on monthly and seasonal temperature and precipitation, as well as more detailed investigation of four subregions. The overall quality of the simulations is determined, comparing the model performances with each other as well as with other regional model evaluations over North America. The metrics used herein do differentiate among the models but, as found in previous studies, it is not possible to determine a "best" model among them. The ensemble average of the six models does not perform best for all measures, as has been reported in a number of global climate model studies. The subset ensemble of the two models using spectral nudging is more often successful for domain-wide root-mean-square error (RMSE), especially for temperature. This evaluation phase of NARCCAP will inform later program elements concerning differentially weighting the models for use in producing robust regional probabilities of future climate change. [ABSTRACT FROM AUTHOR]

The topics of climate change and renewable energy are often linked in policy discussions and scientific analysis, but public opinion on these topics exhibits both overlap and divergence. Although renewable energy has potentially broader acceptance than anthropogenic climate change, it can also face differently-based opposition. Analyses of US and regional surveys, including time series of repeated surveys in New Hampshire (2010–2018) and northeast Oregon (2011–2018), explore the social bases and trends of public views on both issues. Political divisions are prominent, although somewhat greater regarding climate change due to substantive differences and more partisan opposition. Regarding climate change and to a lesser extent renewable energy, political divisions tends to widen with education. There also are robust age and temporal effects: younger adults more often prioritize renewable energy development, and agree with scientists on the reality of anthropogenic climate change (ACC). Across all age groups and both regional series, support for renewable energy and recognition of ACC have been gradually rising. Contrary to widespread speculation, these trends have not visibly responded to events such as the US hurricanes of 2012, 2017 or 2018. Together with age-cohort replacement and the potential for changes in age-group voting participation, however, the gradual trends suggest that public pressure for action on these issues could grow. [ABSTRACT FROM AUTHOR]

Methane has been rising rapidly in the atmosphere over the past decade, contributing to global climate change. Unlike the late 20th Century when the rise in atmospheric methane was accompanied by an enrichment in the heavier carbon stable isotope (13C) of methane, methane in recent years has become more depleted in 13C. This depletion has been widely interpreted to indicate a primarily biogenic source for the increased methane. Here we show that the change may instead be associated with emissions from shale gas and shale oil development. While methane in conventional natural gas is enriched in 13C relative to the atmospheric mean, shale gas is depleted in 13C relative to this atmospheric level. Correcting for this difference, we conclude that emissions from shale gas production in North America over the past decade may well be the leading cause of the increased flux of methane to the atmosphere. Increased fluxes from biogenic sources such as animal agriculture and wetlands are far less important than indicated by some other recent papers using 13C data. [ABSTRACT FROM AUTHOR]