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The U.S. Climate Reference Network (USCRN) was deployed between 2001 and 2008 for the purpose of yielding high-quality and temporally stable in situ climate observations in pristine environments over the twenty-first century. Given this mission, USCRN stations are engineered to operate largely autonomously with great reliability and accuracy. A triplicate approach is used to provide redundant measurements of temperature and precipitation at each location, allowing for observations at a specific time to be compared for quality control. This approach has proven to be robust in the most extreme environments, from extreme cold (−49°C) to extreme heat (++52°C), in areas of heavy precipitation (4700 mm yr−1), and in locations impacted by strong winds, freezing rain, and other hazards. In addition to a number of stations enduring extreme winter environments in Alaska and the northern United States, seven of the USCRN stations are located at elevations over 2000 m, including stations on Mauna Loa, Hawaii (3407 m) and on Niwot Ridge above Boulder, Colorado (2996 m). The USCRN temperature instruments and radiation shield have also been installed and run successfully at a station on the Quelccaya Ice Cap in Peru (5670 m). This paper reviews the performance of the USCRN station network during its brief lifetime and the potential utility of its triplicate temperature instrument configuration for measuring climate change at elevation. [ABSTRACT FROM AUTHOR]

The study of climate change has deep roots in the history of North American ecology. At the time of the Wall Street crash and the Depression of the 1930s, America's Great Plains were struck by the Dust Bowl, a phenomenon of catastrophic soil erosion that resulted from the combined effects of intensive farming practices and a particularly harsh drought. Contemporaneously, the ecologist Frederic Clements proposed a theory of plant succession that itself took the history of the Great Plains as its model, and drew on the notion of climatic cycles. This theory became established as the model for ecological expertise in the politics of conservation adopted by the Roosevelt administration. In this paper, I will show how climatology became inscribed in plant ecology not only for epistemological reasons, but also due to an ideology that promoted the ecologist as an expert in the optimization of resources, in an illustration of the tripartite relationship between ecology, politics, and climate change. [ABSTRACT FROM AUTHOR]

Aim: Climate affects the flowering time of many species. Little is known, however, about how climate influences the properties of regional floras, including the rate at which taxa flower sequentially throughout the flowering season. This study is the first to detect geographical variation in this rate across North America. In addition, we tested for the independent effects of intraspecific variation in flowering time and taxonomic composition on the rate of sequential flowering among regional floras distributed across a temperature gradient. Location: North America. Time period: This study examined >59,000 herbarium specimens that were collected in flower from 1901 to 2013. Major taxa studied: 2,803 angiosperm taxa. Methods: We identified 51 climatically homogeneous regions across the continental, mostly western states of the USA, in each of which ≥100 species were represented by herbarium specimens. We then examined the effects of mean annual temperature (MAT) on the rate of sequential flowering among species in each region. We also evaluated whether geographical variation in the rate of sequential flowering was attributable to intraspecific variation in the flowering time and/or the taxonomic composition of regional floras. Results: As MAT increased over space, the rate of sequential flowering (standardized by the absolute length of the flowering season in each region) increased among relatively early‐flowering taxa but decreased among the latest‐flowering taxa. Both intraspecific variation and shifts in taxonomic composition among floras contributed to this pattern. Main conclusions: Among floras throughout North America, the rate of sequential flowering among co‐occurring taxa changes with MAT. Intraspecific phenological variation primarily affects the rate of sequential flowering during the first half of the growing season, consistent with the inference that future warming will most strongly affect flowering synchrony among early‐flowering taxa. [ABSTRACT FROM AUTHOR]

Time series of historical annual average temperature, total precipitation, and extreme weather indices were constructed and analyzed for 103 (for temperature indices) and 115 (for precipitation indices) U.S. cities with climate records starting earlier than 1900. Mean rate of change and related 95% confidence bounds were calculated for each city using linear regression for the full periods of record. Box–Cox transformations of some time series of climate records were performed to address issues of non-normal distribution. Thirteen cities among the nine U.S. climate regions were selected and further evaluated with adequacy diagnoses and analyses for each month. The results show that many U.S. cities exhibit long-term historical increases in annual average temperature and precipitation, although there are spatial and temporal variations in the observed trends among the cities. Some cities in the Ohio Valley and Southeast regions exhibit decreasing or statistically nonsignificant increasing trends in temperatures. Many of the cities exhibiting statistically significant increases in precipitation are in the Northeast and Upper Midwest regions. The records for the cities are individually unique in both annual and monthly change, and cities within the same climate region sometimes exhibit substantially different changes. Within the full periods of record, discernible decade-long subtrends were observed for some cities; consequently, analysis of selected shorter periods can lead to inconclusive and biased results. These statistical analyses of constructed time series of city-specific long-term historical climate records provide detailed historical climate change information for cities across the United States. [ABSTRACT FROM AUTHOR]

The production of maple syrup is an important cultural and economic activity directly related to the climate of northeastern North America. As a result, there are signs that climate change could have negative impacts on maple syrup production in the next decades, particularly for regions located at the southern margins of the sugar maple (Acer saccharum Marsh.) range. The purpose of this survey study is to present the beliefs and opinions of maple syrup producers of Canada (N = 241) and the U.S. (N = 113) on climate change in general, its impacts on sugar maple health and maple syrup production, and potential adaptation measures. Using conditional inference classification trees, we examined how the socio-economic profile of respondents and the geographic location and size of respondents’ sugar bushes shaped the responses of survey participants. While a majority (75%) of respondents are confident that the average temperature on Earth is increasing, less than half (46%) believe that climate change will have negative impacts on maple syrup yield in the next 30 years. Political view was a significant predictor of these results, with respondents at the right right and center-right of the political spectrum being less likely to believe in climate change and less likely to anticipate negative effects of climate change on maple syrup production. In addition, 77% of the participants indicated an interest in adopting adaptation strategies if those could increase maple syrup production. This interest was greater for respondents using vacuum tubing for sap collection than other collection methods. However, for many respondents (particularly in Canada), lack of information was identified as a constraint limiting adaptation to climate change. [ABSTRACT FROM AUTHOR]

Abstract: In many forested ecosystems, it is increasingly recognized that the probability of burning is substantially reduced within the footprint of previously burned areas. This self‐limiting effect of wildland fire is considered a fundamental emergent property of ecosystems and is partly responsible for structuring landscape heterogeneity (i.e., mosaics of different age classes), thereby reducing the likelihood of uncharacteristically large fires in regions with active fire regimes. However, the strength and longevity of this self‐limiting phenomenon is not well understood in most fire‐prone ecosystems. In this study, we quantify the self‐limiting effect in terms of its strength and longevity for five fire‐prone study areas in western North America and investigate how each measure varies along a spatial climatic gradient and according to temporal (i.e., annual) climatic variation. Results indicate that the longevity (i.e., number of years) of the self‐limiting effect ranges between 15 yr in the warm and dry study area in the southwestern United States to 33 yr in the cold, northern study areas in located in northwestern Montana and the boreal forest of Canada. We also found that spatial climatic variation has a strong influence on wildland fire's self‐limiting capacity. Specifically, the self‐limiting effect within each study area was stronger and lasted longer in areas with low mean moisture deficit (i.e., wetter and cooler settings) compared to areas with high mean moisture deficit (warmer and drier settings). Last, our findings show that annual climatic variation influences wildland fire's self‐limiting effect: drought conditions weakened the strength and longevity of the self‐limiting effect in all study areas, albeit at varying magnitudes. Overall, our study provides support for the idea that wildland fire contributes to spatial heterogeneity in fuel ages that subsequently mediate future fire sizes and effects. However, our findings show that the strength and longevity of the self‐limiting effect varies considerably according to spatial and temporal climatic variation, providing land and fire managers relevant information for effective planning and management of fire and highlighting that fire itself is an important factor contributing to fire‐free intervals. [ABSTRACT FROM AUTHOR]

North and Central America has a combined total of 2.5 million km of wetlands, with 51 % in Canada, 46 % in the USA, and the remainder in subtropical and tropical Mexico and Central America. Loss rates are well known for the conterminous USA and for parts of Canada but poorly understood for Mexico and Central America. Wetlands of North America continue to be threatened due to drainage for agriculture and urban development, extreme coastal and river management, water pollution from upstream watersheds, peat mining, waterfowl management, and more recently climate change. Human use of wetlands in this region are many, including receiving ecosystem services such as water purification, flood regulation, climate regulation, and direct provisioning benefits for many cultures living in and among wetlands, especially in the Louisiana Delta and in Mexico and Central America. Climate change affects will cause wetland impacts on coastal wetlands due to sea level rise and on inland wetlands due to changes in precipitation, air temperature, and river discharges. Wetlands, in turn, have a major role in the storage of carbon in boreal regions of Canada and with carbon sequestration in temperate and tropical wetlands of the Americas. [ABSTRACT FROM AUTHOR]

Monthly snowfall totals from over 500 stations in California, some of which date back to 1878, are examined. Most data were accessed through the NOAA archive, but several thousand station months of data were separately keyed in from image files of original documents. Over 26 000 of these entries were new relative to the NOAA archive, generally providing data prior to 1920. The stations were then subdivided into 18 regions for the construction of representative time series of each area. There were problems with the basic data-the most difficult with which to deal was the increasing presence of 'zero' totals that should have been recorded as 'missing.' This and other issues reduce the confidence that the regional time series are representative of true variations and trends, especially for regions with few systematically reporting stations. Interpreting linear trends on time series with infrequent large anomalies of one sign (i.e., heavy snowfall years) and unresolved data issues should be done with caution. For those regions characterized by consistent monitoring and with the most robust statistical reproducibility, no statistically significant trends in their periods of record (up to 133 years) nor in the most recent 50 years are found. This result encompasses the main snowfall region of the western slope of the Sierra Nevada Mountains. [ABSTRACT FROM AUTHOR]

In examining intense precipitation over the central United States, the authors consider only days with precipitation when the daily total is above 12.7 mm and focus only on these days and multiday events constructed from such consecutive precipitation days. Analyses show that over the central United States, a statistically significant redistribution in the spectra of intense precipitation days/events during the past decades has occurred. Moderately heavy precipitation events (within a 12.7-25.4 mm day−1 range) became less frequent compared to days and events with precipitation totals above 25.4 mm. During the past 31 yr (compared to the 1948-78 period), significant increases occurred in the frequency of 'very heavy' (the daily rain events above 76.2 mm) and extreme precipitation events (defined as daily and multiday rain events with totals above 154.9 mm or 6 in.), with up to 40%% increases in the frequency of days and multiday extreme rain events. Tropical cyclones associated with extreme precipitation do not significantly contribute to the changes reported in this study. With time, the internal precipitation structure (e.g., mean and maximum hourly precipitation rates within each preselected range of daily or multiday event totals) did not noticeably change. Several possible causes of observed changes in intense precipitation over the central United States are discussed and/or tested. [ABSTRACT FROM AUTHOR]

Most spiders use venom to paralyze their prey and are commonly feared for their potential to cause injury to humans. In North America, one species in particular, Loxosceles reclusa (brown recluse spider, Sicariidae), causes the majority of necrotic wounds induced by the Araneae. However, its distributional limitations are poorly understood and, as a result, medical professionals routinely misdiagnose brown recluse bites outside endemic areas, confusing putative spider bites for other serious conditions. To address the issue of brown recluse distribution, we employ ecological niche modeling to investigate the present and future distributional potential of this species. We delineate range boundaries and demonstrate that under future climate change scenarios, the spider's distribution may expand northward, invading previously unaffected regions of the USA. At present, the spider's range is centered in the USA, from Kansas east to Kentucky and from southern Iowa south to Louisiana. Newly influenced areas may include parts of Nebraska, Minnesota, Wisconsin, Michigan, South Dakota, Ohio, and Pennsylvania. These results illustrate a potential negative consequence of climate change on humans and will aid medical professionals in proper bite identification/treatment, potentially reducing bite misdiagnoses. [ABSTRACT FROM AUTHOR]

Background: Climate change is increasingly being implicated in species' range shifts throughout the world, including those of important vector and reservoir species for infectious diseases. In North America (México, United States, and Canada), leishmaniasis is a vector-borne disease that is autochthonous in México and Texas and has begun to expand its range northward. Further expansion to the north may be facilitated by climate change as more habitat becomes suitable for vector and reservoir species for leishmaniasis. Methods and Findings: The analysis began with the construction of ecological niche models using a maximum entropy algorithm for the distribution of two sand fly vector species (Lutzomyia anthophora and L. diabolica), three confirmed rodent reservoir species (Neotoma albigula, N. floridana, and N. micropus), and one potential rodent reservoir species (N. mexicana) for leishmaniasis in northern México and the United States. As input, these models used species' occurrence records with topographic and climatic parameters as explanatory variables. Models were tested for their ability to predict correctly both a specified fraction of occurrence points set aside for this purpose and occurrence points from an independently derived data set. These models were refined to obtain predicted species' geographical distributions under increasingly strict assumptions about the ability of a species to disperse to suitable habitat and to persist in it, as modulated by its ecological suitability. Models successful at predictions were fitted to the extreme A2 and relatively conservative B2 projected climate scenarios for 2020, 2050, and 2080 using publicly available interpolated climate data from the Third Intergovernmental Panel on Climate Change Assessment Report. Further analyses included estimation of the projected human population that could potentially be exposed to leishmaniasis in 2020, 2050, and 2080 under the A2 and B2 scenarios. All confirmed vector and reservoir species will see an expansion of their potential range towards the north. Thus, leishmaniasis has the potential to expand northwards from México and the southern United States. In the eastern United States its spread is predicted to be limited by the range of L. diabolica; further west, L. anthophora may play the same role. In the east it may even reach the southern boundary of Canada. The risk of spread is greater for the A2 scenario than for the B2 scenario. Even in the latter case, with restrictive (contiguous) models for dispersal of vector and reservoir species, and limiting vector and reservoir species occupancy to only the top 10% of their potential suitable habitat, the expected number of human individuals exposed to leishmaniasis by 2080 will at least double its present value. Conclusions: These models predict that climate change will exacerbate the ecological risk of human exposure to leishmaniasis in areas outside its present range in the United States and, possibly, in parts of southern Canada. This prediction suggests the adoption of measures such as surveillance for leishmaniasis north of Texas as disease cases spread northwards. Potential vector and reservoir control strategies-besides direct intervention in disease cases-should also be further investigated. [ABSTRACT FROM AUTHOR]

An iterative chi-square method is applied to determine recent climate change of extremes of daily minimum temperature at two locations between an 18-year recent period and a 36-year prior period. The method determines for each of two locations in northwestern North America, Bozeman, Montana, USA and Coldstream, British Columbia, Canada, which values of the extreme daily weather elements are most significantly different between the prior years and the recent years and gives a measure of the weekly significance of that difference. Determination was made of the average percent of each recent year date (plotted weekly) that was impacted by extreme weather due to climate change as well as the percentage change in the frequency of the number of extreme days for each period of contiguous significant weeks. During the recent period at both locations, most weeks experienced a greater number of days of extreme high minimum temperature and a fewer number of days of extreme low minimum temperature. The weekly percentage changes indicate that extreme high minimum temperatures at both Bozeman and Coldstream are increasing at the rate of about 10% per decade, with a close corresponding decrease of extreme low minimum temperatures. The major changes in climate were very similar at both locations, with greatest warming occurring during the late winter and early spring and during the late July to August period. [ABSTRACT FROM AUTHOR]

Large-scale atmospheric variables have been statistically downscaled to derive winter (December–March) maximum daily precipitation at stations over North America using the generalized extreme value distribution (GEV). Here, the leading principal components of the sea level pressure field and local specific humidity are covariates of the distribution parameters. The GEV parameters are estimated using data from 1949 to 1999 and the r-largest method. This statistical downscaling procedure is found to yield skill over the southern and northern West Coast, central United States, and areas of western and eastern Canada when tested with independent data. The projected changes in covariates or predictors are obtained from transient climate change simulations conducted with the Canadian Centre for Climate Modelling and Analysis (CCCma) Coupled General Circulation Model, version 3.1 (CGCM3.1) forced by the Intergovernmental Panel on Climate Change (IPCC) A2 forcing scenario. They are then used to derive the GEV distribution parameters for the period 2050–99. The projected frequency of the current 20-yr return maximum daily precipitation for that period suggests that extreme precipitation risk will increase heavily over the south and central United States but decrease over the Canadian prairies. The difference between the statistical downscaling results and those estimated using GCM simulation is also discussed. [ABSTRACT FROM AUTHOR]

Aim The magnitude of predicted range shifts during climate change is likely to be different for species living in mountainous environments compared with those living in flatland environments. The southern edges of ranges in mountain species may not shift northwards during warming as populations instead migrate up available elevational gradients; overall latitudinal range appears therefore to expand. In contrast, flatland species should shift range centroids northwards but not expand or contract their latitudinal range extent. These hypotheses were tested utilizing Late Pleistocene and modern occurrence data. Location North America. Methods The location and elevation of modern and Late Pleistocene species occurrences were collected from data bases for 26 species living in mountain or flatland environments. Regressions of elevation change over latitude, and southern and northern range edges were calculated for each species for modern and fossil data sets. A combination of regressions andanovas were used to test whether flatland species shift range edges and latitudinal extents more than mountain species do. Results Flatland species had significantly larger northward shifts at southern range edges than did mountain-dwelling species from the Late Pleistocene to the present. There was also a significant negative correlation between the amount of change in the latitude of the southern edge of the range and the amount of elevational shifting from the Late Pleistocene to the present. Although significant, only c. 25% of the variance could be explained by this relationship. In addition, there was a weak indication that overall range expansion was less in flatland-dwelling than in mountain-dwelling species. Main conclusions The approach used here was to examine past species’ range responses to warming that occurred after the last ice ages as a means to better predict potential future responses to continued warming. The results confirm predictions of differential southern edge and overall range shifts for species occupying mountain and flatland regions in North America. The findings may be broadly applicable in other regions, thus allowing better modelling of future range and distribution related responses. [ABSTRACT FROM AUTHOR]

In 1997, during the late stages of production of NCEP-NCAR Global Reanalysis (GR), exploration of a regional reanalysis project was suggested by the GR project's Advisory Committee, “particularly if the RDAS [Regional Data Assimilation System] is significantly better than the global reanalysis at capturing the regional hydrological cycle, the diurnal cycle and other important features of weather and climate variability.” Following a 6-yr development and production effort, NCEP's North American Regional Reanalysis (NARR) project was completed in 2004, and data are now available to the scientific community. Along with the use of the NCEP Eta model and its Data Assimilation System (at 32-km-45-layer resolution with 3-hourly output), the hallmarks of the NARR are the incorporation of hourly assimilation of precipitation, which leverages leverages a comprehensive precipitation analysis effort, the use of a recent version of the Noah land surface model, and the use of numerous other datasets that are additional or improved compared to the GR. Following the practice applied to NCEP's GR, the 25-yr NARR retrospective production period (1979-2003) is augmented by the construction and daily execution of a system for near-real-time continuation of the NARR, known as the Regional Climate Data Assimilation System (R-CDAS). Highlights of the NARR results are presented: precipitation over the continental United States (CONUS), which is seen to be very near the ingested analyzed precipitation; fits of tropospheric temperatures and winds to rawinsonde observations; and fits of 2-m temperatures and 10-m winds to surface station observations. The aforementioned fits are compared to those of the NCEP-Department of Energy (DOE) Global Reanalysis (GR2). Not only have the expectations cited above been fully met, but very substantial improvements in the accuracy of temperatures and winds compared to that of GR2 are achieved throughout the troposphere. Finally, the numerous datasets produced are outlined and information is provided on the data archiving and present data availability. [ABSTRACT FROM AUTHOR]

A forested dunefield covers the Baraga Plains in western upper Michigan. The ages of five dunes, from across the dunefield, were determined by optically stimulated luminescence (OSL), employing the single-aliquot regenerative-dose (SAR) method on quartz grains. The results indicate that sand mobilization was restricted to the middle Holocene, at around 7 ka. Four environmental variables, rapid climatic oscillations, fire, strong winds and a dry climate are invoked as a combined cause of dune formation. This study provides further evidence for the wide extent of aeolian activity in the upper Midwest of North America during the middle Holocene. [ABSTRACT FROM AUTHOR]

The article discusses a retrospective research conducted on the climate changes in North America since 1980, and its relation to the increase of fire danger. The researchers computed the Energy Release Component fire danger index using the North American Regional Reanalysis (NARR) for daily temperature, relative humidity and precipitation data in 1980-2005. Results revealed that the period of 1999-2005 was drier than the earlier period, and that it led to an increase of one to two weeks in the number of days with fire danger in the U.S. Moreover, nighttime firefighting was hindered by low humidity, and climate models showed projections of continued drying in the twenty-first century. It is concluded that fires are caused not only by climate change, but also by people and land management.