Bioclimatic Models Research Articles

Spatially explicit climate change projections for the recovery planning of threatened species: The Bicknell's Thrush (Catharus Bicknelli) as a case study

With climate change, natural resource managers are faced with the challenging task of planning the conservation of habitat for threatened species. Classified as "threatened" under the Species at Risk Act in Canada, the Bicknell's Thrush (Catharus Bicknelli - BITH) is a migratory bird whose range is highly restricted. Bioclimatic models project more than 50% loss of suitable habitat - high elevation dense balsam fir (Abies balsamea) forests - in the northeastern USA by 2050 due to climate change. We used BITH as a case study to demonstrate the value of forest landscape models (e.g., LANDIS-II) to support decision-making on conservation of habitat of threatened species. We modeled the impacts of forest management and natural disturbances, as well as climate-induced changes, on forest stand and landscape structure. Under RCP climate forcing scenarios 2.6, 4.5 and 8.5, simulations projected significant changes in dominant tree species biomass, from coniferous to broadleaved deciduous, implying important losses of mature balsam fir forest. Climate change was projected to have severe effects with major changes projected to occur after 2080 and losses of more than half of BITH suitable habitat by 2100 for “worst-case” climate change scenarios. This contrasts with results from bioclimatic models which do not capture the expected lags in vegetation responses to changing climate. Our results also suggest that innovative forest management strategies could help maintain BITH habitat abundance under RCP 2.6 and RCP 4.5 climate forcing. Such results can provide guidance for considering effective long-term conservation of habitat for threatened species in a changing world.

Биоклиматическое моделирование распространения Avenella flexuosa (L.) Drejer в связи с ее возможным полемохорным происхождением на территории Центральной России

For the first time, the method of bioclimatic modeling was used to determine the boundaries of the range of occurrence of a potential polemochoral species Avenella flexuosa (L.) Drejer. The simulation was performed by the method of maximum entropy (MaxEnt). It is shown that the conditions for the growth of this species are initially suitable (the probability of finding 0.54 and higher) in the territory of Central Russia. For comparison, the same bioclimatic modeling approach was applied for the occurrence data of Carex brizoides L. species, the polemochoral origin of which is not in doubt. It is shown that its growing places are beyond the limits of the climatic optimum (the probability of finding 0.08) in the territory of Central Russia.

Bioclimatic and environmental suitability models for capercaillie (Tetrao urogallus) conservation: Identification of optimal and marginal areas in Rodopi Mountain-Range National Park (Northern Greece)

Capercaillie is a species of particular conservation importance for Europe due to the observed population decline in various parts of its distribution. In the current study, the environmental and habitat requirements of the species are investigated at the southernmost range of its European distribution (Rodopi Mountain-Range National Park, northern Greece) using a set of 95 observations of species presence and a maximum-entropy (MaxEnt) modeling approach. A bioclimatic dataset derived from the Bioclim open source database and a set of environmental variables, mainly forest land-cover types and topographical variables, were employed to explain the current distribution of the species and to delineate potentially suitable areas for its distribution. The best scale per environmental variable was chosen among three different spatial scales (10 ha, 100 ha and 500 ha), in order to build a multiscale environmental model. According to our results, the species demonstrated a very narrow niche which is determined primarily by bioclimatic factors while a number of habitat requirements within a strict bioclimatic zone where also identified. It requires wet areas with mean summer temperature not exceeding 10 °C, which are only found at the higher altitudes of the National Park. Α strong tendency was also found for capercaillies to inhabit forest stands of norway spruce (Picea abies) with a minimum cover of 10% at an intermediate scale of 100 ha, followed at a larger scale i.e. 500 ha by pure beech (Fagus spp.) forests or mixed with pines (Pinus spp.), where optimum tree density ranges from 50% to 80%. Bioclimatic and environmental presence-prediction maps were reclassified in four suitability classes (unsuitable, marginal, sub-optimal, optimal), based on three Maxent thresholds (Minimum Training Presence, Fixed Cumulative Value 5 and Value 10). Monitoring the marginal climatic zone for the species and ensuring suitable habitats within it is the key for the species conservation in its southernmost part of its distribution.

Bioclimatic modeling for determining the minimum area of natural ventilation in buildings for the wet processing of coffee

Este estudio tuvo como objetivo encontrar el área mínima de ventilación natural necesaria para instalaciones de beneficio húmedo de café con secado mecánico en su interior, con el fin de preservar la calidad de café a través de un ambiente bioclimático que propicie la inocuidad biológica, este estudio se realizó con ayuda de simulaciones computacionales en el programa EnergyPlusTM. Se encontró que a medida que se incrementa la capacidad de secado, y por ende la potencia de las máquinas de secado, la temperatura y la humedad relativa interna tienden a aumentar. Por otra parte, se encontró una correlación lineal inversa entre el área de ventilación natural y las variables temperatura y humedad relativa. Por último, se encontraron relaciones de área mínima de ventilación natural con la capacidad de secado, con el fin de obtener un ambiente bioclimático adecuado para la preservación del café pergamino.

Climatic niche of the Saker Falcon Falco cherrug: predicted new areas to direct population surveys in Central Asia

Accurate species distribution data across remote and extensive geographical areas are difficult to obtain. Here, we use bioclimatic envelope models to determine climatic constraints on the distribution of the migratory Saker Falcon Falco cherrug to identify areas in data‐deficient regions that may contain unidentified populations. Sakers live at low densities across large ranges in remote regions, making distribution status difficult to assess. Using presence‐background data and eight bioclimatic variables within a species distribution modelling framework, we applied MaxEnt to construct models for both breeding and wintering ranges. Occurrence data were spatially filtered and climatic variables tested for multicollinearity before selecting best fit models using the Akaike information criterion by tuning MaxEnt parameters. Model predictive performance tested using the continuous Boyce index (B) was high for both breeding (BTEST = 0.921) and wintering models (BTEST = 0.735), with low omission rates and minimal overfitting. The Saker climatic niche was defined by precipitation in the warmest quarter in the breeding range model, and mean temperature in the wettest quarter in the wintering range model. Our models accurately predicted areas of highest climate suitability and defined the climatic constraints on a wide‐ranging rare species, suggesting that climate is a key determinant of Saker distribution across macro‐scales. We recommend targeted population surveys for the Saker based on model predictions to areas of highest climatic suitability in key regions with distribution knowledge gaps, in particular the Qinghai‐Tibet plateau in western China. Further applications of our models could identify protected areas and reintroduction sites, inform development conflicts, and assess the impact of climate change on distributions.

Decreasing brown bear (Ursus arctos) habitat due to climate change in Central Asia and the Asian Highlands.

Around the world, climate change has impacted many species. In this study, we used bioclimatic variables and biophysical layers of Central Asia and the Asian Highlands combined with presence data of brown bear (Ursus arctos) to understand their current distribution and predict their future distribution under the current rate of climate change. Our bioclimatic model showed that the current suitable habitat of brown bear encompasses 3,430,493 km2 in the study area, the majority of which (>65%) located in China. Our analyses demonstrated that suitable habitat will be reduced by 11% (378,861.30 km2) across Central Asia and the Asian Highlands by 2,050 due to climate change, predominantly (>90%) due to the changes in temperature and precipitation. The spatially averaged mean annual temperature of brown bear habitat is currently −1.2°C and predicted to increase to 1.6°C by 2,050. Mean annual precipitation in brown bear habitats is predicted to increase by 13% (from 406 to 459 mm) by 2,050. Such changes in two critical climatic variables may significantly affect the brown bear distribution, ethological repertoires, and physiological processes, which may increase their risk of extirpation in some areas. Approximately 32% (1,124,330 km2) of the total suitable habitat falls within protected areas, which was predicted to reduce to 1,103,912 km2 (1.8% loss) by 2,050. Future loss of suitable habitats inside the protected areas may force brown bears to move outside the protected areas thereby increasing their risk of mortality. Therefore, more protected areas should be established in the suitable brown bear habitats in future to sustain populations in this region. Furthermore, development of corridors is needed to connect habitats between protected areas of different countries in Central Asia. Such practices will facilitate climate migration and connectivity among populations and movement between and within countries.

Use of simulation-based statistical models to complement bioclimatic models in predicting continental scale invasion risks

Invasive species represent one of the greatest risks to global biodiversity and economic productivity of agroecosystems. The development of certain novel crops—e.g., herbaceous perennial biomass crops—may create a risk of novel invasions by these crops. Therefore, potential benefits and risks need to be weighed in making decisions about their introduction and subsequent management. Ideally, such a weighing will be based on good estimates of invasion risks in realistic scenarios pertaining to actual landscapes of concern. Most previous large-scale analyses of invasion risk have used species distribution models and their established methods. Unfortunately, these approaches are unable to incorporate local scale biotic and spatial factors that influence invasion risk. Here we present a case study for how such factors can be efficiently incorporated in large-scale analyses of invasion risk, by extending simulation models with statistical modeling tools. By these means, we predict invasion risk at the scale of the entire United States for a major biomass crop, Miscanthus × giganteus. We then combine invasion risk predictions for this method with those from bioclimatic methods, producing a map of aggregated invasion risk that can offer more nuanced predictions of invasion risk than either approach alone. Lastly, we evaluate potential risks for invasive crops that differ in invasiveness traits, to examine how geographic patterns of invasion risk vary among invaders as a result of their particular constellation of traits.

Картографирование потенциальных ареалов видов растений на северном макросклоне хр. Хамар-Дабан (Южная Сибирь) с использованием метода биоклиматического моделирования

Bioclimatic modeling enables not only mapping the areas of certain plant or animals species on the basis of environmental characteristics, but also investigating the influence of environmental factors on the occurrence of these species. We simulated the possible habitats of three species of higher vascular plants on the northern macroslope of the Khamar-Daban ridge

Bioclimatic assessment of abiotic factors affecting relative abundance and distribution of wheat stem sawfly (Hymenoptera: Cephidae) in western Canada

AbstractWheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), indigenous to North America, quickly adapted from host native grasses to wheat crops (Triticum Linnaeus (Poaceae)) with expansion of agriculture on the Great Plains of North America. Bioclimatic simulation tools, such as Climex, predict the potential geographic distribution and establishment of insects in ecosystems, based on climate. The ecoclimatic index, a measure of ecological suitability, integrates potential population growth with stresses to produce estimates of relative abundance. This simulation software was used to develop a bioclimate model for C. cinctus in western Canada. Results fostered a better understanding of how C. cinctus responded to selected climate variables. Two general circulation models were then applied to assess the response of C. cinctus populations to future climate. Relative to current climate, predicted changes in C. cinctus distribution and relative abundance were greatest for 2030, with a small further increase for 2070. Across the Prairies and Boreal Plains Ecozones, changes in ecoclimatic index were greater than in geographic distribution. Both general circulation models indicated most of this area would be categorised as very favourable. This suggests that the potential for pest populations could expand into areas that do not currently experience economic losses associated with C. cinctus.

How can climate change affect the potential distribution of common genet Genetta genetta (Linnaeus 1758) in Europe?

The common genet Genetta genetta is a carnivore of African origin introduced in Europe at least 13 centuries ago. Its distribution, located in the southwest of the continent, is chiefly constrained by climatic factors. With this premise, and taking into account the existing climate change projections, our goal was to assess possible changes in climatic suitability for common genet in Europe in the future. The maximum entropy statistical method was used to evaluate the potential effects of two greenhouse gas scenarios-low and high emissions-of an average ensemble of six different global circulation models. Projections showed that a large increase in climatically suitable habitat for common genet in continental Europe is likely in the next decades. In this way, the species range may expand within Europe to the east and north. The fact that the common genet may be favoured in a scenario of temperature increase is compatible with the origin of the species associated with hotter climates in Africa. However, despite these results, bioclimatic models do not represent the complete biotic and ecological niche of the species (e.g. competition, predation or dispersal ability), and a full understanding of potential future expansions should include factors that also determine the presence of the species at finer local scales. Bearing this in mind, we have to interpret our results as a first step towards the potential for species distribution change in the near future, but further work should incorporate environmental variability beyond climate in future projection assessments.

Comparing future shifts in tree species distributions across Europe projected by statistical and dynamic process-based models

Many tree species are predicted to shift their geographic ranges with changing climate, but the extents, timing, and magnitude of these shifts remain uncertain. Comparing various modeling strategies is crucial for reducing uncertainty related to these responses and for guiding the interpretation of model results. Here, we compared outputs of a dynamic vegetation model (DVM) and an ensemble of statistical bioclimatic envelope models (BEMs) in predicting range shifts of 14 representative tree species in continental Europe. Expanding the number of species and geographic extent compared to previous model comparisons, we found that the DVM produced more conservative range shift estimates, even in long-term equilibrium simulations. The differences in range shift projections were greatest for Mediterranean species, whose expansion northwards was inhibited in the DVM by more competitive prevailing temperate species. In contrast to our expectation, competitive traits of the species studied did not consistently affect the differences. The agreement between BEM and DVM results was highest in boreal species, suggesting that BEMs are an efficient method for modeling species under strong control of abiotic factors. BEMs produced substantially larger range contractions at the southern edge of distribution, in contrary to the DVM, where contractions were more modest. Despite these differences, both approaches also yielded consistent northwards shifts of forest types, which may have substantial negative impacts on forest economy, and alter species composition in natural forest stands.

Witch's Broom Disease of Lime (Candidatus Phytoplasma aurantifolia): Identifying High-Risk Areas by Climatic Mapping.

Biological invasions of vectorborne diseases can be devastating. Bioclimatic modeling provides an opportunity to assess and predict areas at risk from complex multitrophic interactions of pathogens, highlighting areas in need of increased monitoring effort. Here, we model the distribution of an economically critical vectorborne plant pathogen 'Candidatus Phytoplasma aurantifolia', the etiological agent of Witches' Broom Disease of Lime. This disease is a significant limiting factor on acid lime production (Citrus aurantifolia, Swingle) in the Middle East and threatens its production globally. We found that temperature, humidity, and the vector populations significantly determine disease distribution. Following this, we used bioclimatic modeling to predict potential novel sites of infections. The model outputs identified potential novel sites of infection in the citrus producing regions of Brazil and China. We also used our model to explore sites in Oman where the pathogen may not be infectious, and suggest nurseries be established there. Recent major turbulence in the citrus agricultural economy has highlighted the importance of this work and the need for appropriate and targeted monitoring programs to safeguard lime production.

Sustainability of culturally important teepee poles on Mescalero Apache Tribal Lands: Characteristics and climate change effects

Integrating traditional ecological knowledge (TEK) with western science and modeling tools can enhance not only the delivery of culturally important species, but also community support and overall effectiveness of management. This paper presents a case study of co-producing usable science integrating TEK on a culturally important species with a modeling tool, Climate-Forest Vegetation Simulator (C-FVS). The Mescalero Apache tribe (southwestern USA) conduct a coming of age ceremony for young women who follow a traditional way of life. In order to conduct this ceremony, tall, thin teepee poles made from Douglas-fir trees are needed. Douglas-fir trees capable of producing teepee poles are a culturally important resource for the Mescalero Apache tribe. We interacted with medicine people, tribal members, and forest managers to gain insight on characteristics of teepee pole stands. We established thirty, 400 m2 circular plots with nested 100 m2 regeneration plots in teepee pole producing stands to characterize composition, structure, age, growth rates, and fuels. Teepee pole producing stands occupy an elevation range from 2012 to 2561 m, slopes of 3–43%, and aspects from NW to NE. The stands consist of dense, relatively old trees dominated by Douglas-fir, with other species of trees usually present as a minor component. Douglas-firs in teepee pole producing stands averaged 1255 ± 99 trees per ha (TPH), basal area 31.7 ± 1.5 m2/ha, and 18.5 ± 0.5 cm quadratic mean diameters (QMD). Douglas-fir trees in teepee pole producing stands were most commonly 75–100 years old with diameters at breast height (DBH) ranging from 5.1 to 25.4 cm. In order to assess future trajectories of teepee pole stands, we applied C-FVS which incorporates the effects of climate change scenarios over the next 100 years. We compared three standard scenarios ranging from moderate to severe climate change: Representative Concentration Pathways (RCP) 4.5, 6.0, and 8.5. Simulated future forests at the current plot locations even under the most mild climate change scenario (RCP 4.5) did not contain Douglas-fir after a century of modeling. Complete forest mortality was predicted under RCP 6.0 and RCP 8.5. Comparing bioclimatic niche modeling of Douglas-fir with downscaled future climate scenarios indicated that the species would have to be planted at least 305 m higher to maintain 21st century viability under RCP 4.5 and 6.0, or at least 610 m higher under RCP 8.0. The characterization of current teepee pole producing stands and simulations of future effects of climate change provide useful information to the Mescalero Apache Tribe to support management decisions on how they would like to preserve this cultural important resource.

Comparing model parameterizations of the biophysical impacts of ocean acidification to identify limitations and uncertainties

Ocean acidification (OA) driven by anthropogenic CO2 emissions affects marine ecosystems, fisheries and aquaculture. Assessing the impacts of OA using projection models facilitates the development of future scenarios and potential solutions. Here, we explored various ways to incorporate OA impacts into a multi-stressor dynamic bioclimatic envelope model to project biogeographic changes of ten commercially exploited invertebrate species. We examine three dimensions of uncertainties in modelling biophysical OA effects: model structure, parameterization, and scenario uncertainty. Our results show that projected OA impacts are most sensitive to the choice of structural relationship between OA and biological responses, followed by the choice of climate change emission scenarios and parameterizations of the size of OA effects. Species generally showed negative effects to OA but sensitivity to the various sources of uncertainty were not consistent across or within species. For example, some species showed higher sensitivity to structural uncertainty and very low sensitivity to parameter uncertainty, while others showed greatest sensitivity to parameter uncertainty. This variability is largely due to geographic variability and difference in life history traits used to parameterize model simulations. Our model highlights the variability across the sources of uncertainty and contributes to the development of integrating OA impacts in species distribution models. We further stress the importance of defining the limitations and assumptions, as well as exploring the range of uncertainties associated with modelling OA impacts.

Adverse climatic periods precede and amplify defoliator‐induced tree mortality in eastern boreal North America

AbstractAs major alterations are occurring in climate and pest ranges, it is imperative to evaluate their combined contribution to tree mortality in order to propose mitigation measures and limit losses in forest productivity. The objective of this study was to explore the association between declines in tree growth resulting from climatic and biotic (spruce budworm) disturbances, and their interactions on tree mortality of two dominant tree species,Abies balsameaandPicea mariana,of the eastern North‐American boreal forest.We disentangle the influences of abiotic and biotic components on growth through a combination of model‐data comparison techniques. First, we characterized the variability in tree growth and mortality in the study area using a network of tree‐ring width measurements collected from living and dead trees. Subsequently, a bioclimatic simulation model was used to estimate the past annual, nonlinear, responses of stand‐level net primary production (NPP) to climate variability (period 1902–2012). From these two data sources, we defined the biotic stress events as the variance in the tree‐ring data unexplained by the bioclimatic forest growth simulation.Throughout the 20th century, two periods of adverse climatic conditions preceded spruce budworm outbreaks episodes and induced tree mortality. Climatic stress events were associated with cold springs, warmer than average summers. We found that past stress history in interaction with tree characteristics and species predisposed trees to mortality. In addition, co‐occurring events (climatic and biotic) increased the severity of mortality episodes.Synthesis. Our study challenges the belief that spruce budworm outbreak is the primary driver of broad‐scale tree mortality in eastern boreal forest. Rather, tree mortality is the result of cumulative events that combine unfavourable conditions for growth, resulting in loss of tree vigour and subsequently, mortality. Co‐occurrence of stresses in the future may lead to more severe episodes of mortality, as extreme climatic events become more frequent.

The De Nadale Cave (Zovencedo, Berici Hills, northeastern Italy): A small-mammal fauna from near the onset of Marine Isotope Stage 4 and its palaeoclimatic implications

Marine Isotope Stage 4 (MIS 4; ca. 71–57 ka) is not well documented in European continental contexts and is characterized mainly by minimum summer insolation, producing a maximum extension of the polar ice caps during the Late Pleistocene together with a lowering of the sea level in the Northern Hemisphere. The De Nadale Cave site, located at an altitude of 130 m a.s.l. in the Berici Hills in northeastern Italy, contains a single archaeological layer (Unit 7) dated to MIS 4. In this paper, we present a palaeoenvironmental and palaeoclimatic reconstruction based on small-mammal (insectivore, bat and rodent) assemblages from this layer. Habitat weighting and bioclimatic model methods were used in order to reconstruct the palaeoenvironmental and palaeoclimatic conditions. The results identify a cold climatic period with a landscape dominated by open woodland formations and open-dry habitats, dating to near the beginning of MIS 4. The findings are consistent with studies of large mammals and previously reported pollen studies in terrestrial sequences of this age in Italy and in cores from the offshore Mediterranean basin. Given the scarcity of terrestrial data for MIS 4, the De Nadale Cave constitutes an important site for our knowledge of the environment and climate of this period.

Bioclimatic analyses of Trichomalus perfectus and Mesopolobus morys (Hymenoptera: Pteromalidae) distributions, two potential biological control agents of the cabbage seedpod weevil in North America

Climatic requirements of natural enemies have important implications for predicting the outcome of classical biological control programs. A five year study (2011–2015) investigated the ectoparasitoid community of the oilseed rape pest Ceutorhynchus obstrictus (Coleoptera: Curculionidae), in different climate zones across Europe to better understand the distribution, abundance, phenology and thermal requirements of Trichomalus perfectus and Mesopolobus morys (Hymenoptera: Pteromalidae). Data generated were then used to develop bioclimatic models to predict the suitability and potential distribution of each species if introduced into North America for biological control of C. obstrictus. Findings indicated that, although T. perfectus and M. morys occupy the same feeding niche and overlap temporally, there are clear geographic differences in abundance. Trichomalus perfectus appears to be a ‘northern’ maritime species, whereas M. morys is likely a ‘southern’, continental species. If introduced, it was predicted that both species would establish in canola growing regions of North America, although climatic conditions appear to be less favourable for T. perfectus than M. morys. This study showed that variation in regional distributions may occur and these are likely based on differing tolerance to climatic conditions. Understanding these tolerances can enhance precision of ecological niche models that predict potential distributions of parasitoids for introduction as candidate biological control agents. Furthermore, the work reported here provides a basis for future research to determine if climate change may favour species such as M. morys that are adapted to warmer summer conditions.

Correction: Predicted Shifts in Small Mammal Distributions and Biodiversity in the Altered Future Environment of Alaska: An Open Access Data and Machine Learning Perspective.

[This corrects the article DOI: 10.1371/journal.pone.0132054.].

Snub-nosed monkeys (Rhinopithecus): potential distribution and its implication for conservation

Many threatened species have undergone range retraction, and are confined to small fragmented populations. To increase their survival prospects, it is necessary to find suitable habitat outside their current range, to increase and interconnect populations. Species distribution models may be used to this purpose and can be an important part of the conservation strategies. One pitfall is that such mapping will typically assume that the current distribution represents the optimal habitat, which may not be the case for threatened species. Here, we use maximum entropy modelling (Maxent) and rectilinear bioclimatic envelope modelling with current and historical distribution data, together with the location of protected areas, and environmental and anthropogenic variables, to answer three key questions for the conservation of Rhinopithecus, a highly endangered genus of primates consisting of five species of which three are endemic to China, one is endemic to China and Myanmar and one is endemic to Vietnam; Which environmental variables best predict the distribution? To what extent is Rhinopithecus living in an anthropogenically truncated niche space? What is the genus’ potential distribution in the region? Mean temperature of coldest and warmest quarter together with annual precipitation and precipitation during the driest quarter were the variables that best explained Rhinopithecus’ distribution. The historical records were generally in warmer and wetter areas and in lower elevation than the current distribution, strongly suggesting that Rhinopithecus today survives in an anthropogenic truncated niche space. There is 305,800–319,325 km2 of climatic suitable area within protected areas in China, of which 96,525–100,275 km2 and 17,175–17,550 km2 have tree cover above 50 and 75%, respectively. The models also show that the area predicted as climatic suitable using Maxent was 72–89% larger when historical records were included. Our results emphasise the importance of considering historical records when assessing restoration potential and show that there is high potential for restoring Rhinopithecus to parts of its former range.

Potential Geographic Distribution of Palmer Amaranth under Current and Future Climates

Core Ideas CLIMEX model projections match known Palmer amaranth distribution. Sub‐Sahara Africa and Australia are at risk for Palmer amaranth establishment. Future climate scenarios indicate the potential for poleward range expansion. Herbicide‐resistant weeds are increasingly becoming a major challenge for agricultural production worldwide. Palmer amaranth [Amaranthus palmeri (S.) Wats.] is an invasive annual forb that has recently emerged as one of the most widespread and severe agronomic weeds in the United States, due in part to its facility for evolving herbicide resistance. It has invaded several parts of the world, including key agricultural production regions in South America. Climate change will likely exacerbate the challenges of managing this species. To assess this, we developed a process‐oriented bioclimatic niche model of Palmer amaranth to examine its potential global distribution under current conditions and future climate scenarios. The model agreed well with all credible current distribution data. Projected future increases in temperatures will expand potential Palmer amaranth range northward into portions of Canada and Europe. Model projections under current and future climates highlight several agricultural production regions of increasing and emerging risk from this weed.