Climate Change and...
Effects of Climate Change
- Climate Variability
- Climate Models
Effects of Climate Change
ABSTRACT: We review the observed and potential effects of climate change on native fauna of forests in northeastern North America by focusing on mammals, birds, amphibians, and insects. Our assessment is placed in the context of recent regional-scale climate projections. Climate change, particularly in recent decades, has affected the distribution and abundance of numerous wildlife species. Warming temperatures, alterations to precipitation regimes, seasonality, and climatic extremes are projected to affect species directly or indirectly in each of the focal taxa. Greatest climate change will occur during winter, and the survival of winter-active species as well as the survival, distribution, and abundance of hibernating mammals, amphibians, resident birds, and diapausing insects may be altered. Even under low emissions scenarios, effects on native fauna may be profound, affecting iconic species, endangered species, and species that provide econommically valuable services, such as pollination and regulation of insect populations. However, much research that is essential to assessing the effects of climate change on the native fauna of northeastern forests remains to be done. Research that reveals causal mechanisms and relates these findings to population and community level processes will be most valuable.
ABSTRACT: The paleontological record of mammals offers many examples of evolutionary change, which are well documented at many levels of the biological hierarchy—at the level of species (and above), populations, morphology, and, in ideal cases, even genes. The evolutionary changes developed against a backdrop of climatic change that took place on different scales, from rapid shifts in climate state that took only a few decades, to those that occurred over a millennial scale, to regular glacial-interglacial transitions with cycles of roughly a hundred thousand years, to long-term warming or cooling trends over hundreds of thousands to millions of years. Are there certain scales of climatic change that accelerate evolution? And what will the current global warming event do to evolutionary rates? Here we use paleontology—the study of fossils—to illustrate the scientific method behind answering such complex questions, and to suggest that current rates of global warming are far too fast to influence evolution much and instead are likely to accelerate extinctions.
ABSTRACT: Global circulation models predict and numerous observations confirm that anthropogenic climate change has altered high-frequency climate variability. However, it is not yet well understood how changing patterns of environmental variation will affect wildlife population dynamics and other ecological processes. Theory predicts that a population's long-run growth rate is diminished and the chance of population extinction is increased as environmental variation increases. This results from the fact that population growth is a multiplicative process and that long-run population growth rate is the geometric mean of growth rates over time, which is always less than the arithmetic mean. However, when population growth rates for unstructured populations are related nonlinearly to environmental drivers, increasing environmental variation can increase a population's long-run growth rate. This suggests that patterns of environmental variation associated with different aspects of climate change may affect population dynamics in different ways. Specifically, increasing variation in rainfall might result in diminished long-run growth rates for many animal species while increasing variation in temperature might result in increased long-run growth rates. While the effect of rainfall is theoretically well understood and supported by data, the hypothesized effect of temperature is not. Here, I analyse two datasets to study the effect of fluctuating temperatures on growth rates of zooplankton. Results are consistent with the prediction that fluctuating temperatures should increase long-run growth rates and the frequency of extreme demographic events.
ABSTRACT: Limitations imposed on species ranges by the climatic, ecological, and physiological effects of elevation are important determinants of extinction risk. We modeled the effects of elevational limits on the extinction risk of landbirds, 87% of all bird species. Elevational limitation of range size explained 97% of the variation in the probability of being in a World Conservation Union category of extinction risk. Our model that combined elevational ranges, four Millennium Assessment habitat-loss scenarios, and an intermediate estimate of surface warming of 2.8° C, projected a best guess of 400–550 landbird extinctions, and that approximately 2150 additional species would be at risk of extinction by 2100. For Western Hemisphere landbirds, intermediate extinction estimates based on climate-induced changes in actual distributions ranged from 1.3% (1.1° C warming) to 30.0% (6.4° C warming) of these species. Worldwide, every degree of warming projected a nonlinear increase in bird extinctions of about 100–500 species. Only 21% of the species predicted to become extinct in our scenarios are currently considered threatened with extinction. Different habitat-loss and surface-warming scenarios predicted substantially different futures for landbird species. To improve the precision of climate-induced extinction estimates, there is an urgent need for high-resolution measurements of shifts in the elevational ranges of species. Given the accelerating influence of climate change on species distributions and conservation, using elevational limits in a tested, standardized, and robust manner can improve conservation assessments of terrestrial species and will help identify species that are most vulnerable to global climate change. Our climate-induced extinction estimates are broadly similar to those of bird species at risk from other factors, but these estimates largely involve different sets of species.
EXECUTIVE SUMMARY: The scientific literature contains numerous descriptions and predictions of the effects of climate change on wildlife populations and ecosystems. Recently, resource managers and planners have proposed “adaptation strategies” to help wildlife and ecosystems adjust to the effects of a changing climate. In this report, we review the scientific literature on climate change adaptation as it relates to biodiversity conservation and wildlife management. We also review a series of actual climate change adaptation plans that have been developed in the U.S.A., Canada, England, México, and South Africa. From these reviews, we identify eighteen general strategies that could be used to manage the effects of climate change on wildlife and biodiversity.
We recommend that any strategy for managing the effects of climate change on wildlife and ecosystems be deployed within an adaptive management framework, in order to enable managers to learn from previous management activities, and to respond quickly and creatively to the challenges posed by climate change. For each of the eighteen strategies, we provide a brief summary and discussion of its advantages and disadvantages (including availability of tools or techniques for implementation, as well as relative costs). We present a decision tree to help natural resource managers select the most appropriate set of strategies for use in particular management situations.
Strategies related to land protection and management include: increasing the amount of protected areas; improving representation and redundancy within natural area networks; improving the management of existing natural areas to maximize resilience; designing new natural areas and restoration sites to maximize resilience in the face of climate change; protecting predicted movement corridors, “stepping stones,” and refugia; focusing restoration and management efforts on the maintenance of ecosystem function rather than specific assemblages and components; increasing overall landscape permeability to species movements; and reducing nonclimate stressors on natural areas and ecosystems.
Strategies related to direct species management include: focusing conservation resources on species most likely to become extinct; translocation of select species; captive breeding of select species; and the reduction of non-climate stressors affecting individual species.
Strategies related to monitoring and planning include: reviewing existing monitoring programs to insure that the information needed for the adaptive management of climate change effects is being collected; incorporating information on potential climate change impacts into species and land management plans; developing dynamic landscape conservation plans; and insuring that wildlife and biodiversity are included in broader adaptation plans developed by local, regional, or national governments.
Strategies in the legislative and regulatory arena include: reviewing existing laws, regulations, and policies regarding wildlife and natural resource management, to insure that these instruments provide managers with the flexibility needed to address effects of climate change; and proposing new legislation and regulations as needed to give managers additional tools and approaches to facilitate responses to climate change.
C. D. Thomas, A. Cameron, R. E. Green, M. Bakkenes, L. J. Beaumont, Y. C. Collingham, B. F. N. Erasmus, M. F. de Siqueira,, A. Grainger, L. Hannah, L. Hughes, B. Huntley, A. S. van Jaarsveld,, G. F. Midgley, L. Miles, M. A. Ortega-Huerta, A. T. Peterson, O. L. Phillips, S. E. Williams (2004). Extinction risk from climate change. Nature 427 (6970): 145-
ABSTRACT: Climate change over the past 30 years has produced numerous shifts in the distributions and abundances of species1, 2 and has been implicated in one species-level extinction3 . Using projections of species' distributions for future climate scenarios, we assess extinction risks for sample regions that cover some 20% of the Earth's terrestrial surface. Exploring three approaches in which the estimated probability of extinction shows a power-law relationship with geographical range size, we predict, on the basis of mid-range climate-warming scenarios for 2050, that 15–37% of species in our sample of regions and taxa will be 'committed to extinction'. When the average of the three methods and two dispersal scenarios is taken, minimal climate-warming scenarios produce lower projections of species committed to extinction (18%) than mid-range (24%) and maximum-change (35%) scenarios. These estimates show the importance of rapid implementation of technologies to decrease greenhouse gas emissions and strategies for carbon sequestration.
R. Brereton, S. Bennett, I. Mansergh (1995). Enhanced greenhouse climate change and its potential effect on selected fauna of south-eastern Australia: A trend analysis. Biological Conservation 72 (3): 339-354
ABSTRACT: It has been predicted that enhanced greenhouse climate change will modify the global climate and consequently cause large-scale changes to the distribution of flora and fauna. This study examined the potential effect of enhanced greenhouse climate change on the distribution of 42 species of fauna of south-eastern Australia. The best available information regarding faunal distributions and predictive models for bioclimatic ranges was used in conjunction with the accepted enhanced greenhouse climate scenarios for 1990. More recent developments that refine the potential climatic changes are discussed in relation to the analysis.
The 42 species of fauna were selected from the major Victorian bioclimatic regions and ecosystems and from species considered most at risk from enhanced greenhouse climate change. Most were species with a threatened conservation status. The results indicate that 41 undergo a reduction in bioclimatic range in response to climatic warming, the most extreme response being the extinction of bioclimatic range. A broadscale subcontinental analysis of the potential effects on faunal distribution is presented.
ABSTRACT: Modelling strategies for predicting the potential impacts of climate change on the natural distribution of species have often focused on the characterization of a species’ bioclimate envelope. A number of recent critiques have questioned the validity of this approach by pointing to the many factors other than climate that play an important part in determining species distributions and the dynamics of distribution changes. Such factors include biotic interactions, evolutionary change and dispersal ability. This paper reviews and evaluates criticisms of bioclimate envelope models and discusses the implications of these criticisms for the different modelling strategies employed. It is proposed that, although the complexity of the natural system presents fundamental limits to predictive modelling, the bioclimate envelope approach can provide a useful first approximation as to the potentially dramatic impact of climate change on biodiversity. However, it is stressed that the spatial scale at which these models are applied is of fundamental importance, and that model results should not be interpreted without due consideration of the limitations involved. A hierarchical modelling framework is proposed through which some of these limitations can be addressed within a broader, scale-dependent context.
ABSTRACT: Causal attribution of recent biological trends to climate change is complicated because non-climatic influences dominate local, short-term biological changes. Any underlying signal from climate change is likely to be revealed by analyses that seek systematic trends across diverse species and geographic regions; however, debates within the Intergovernmental Panel on Climate Change (IPCC) reveal several definitions of a 'systematic trend'. Here, we explore these differences, apply diverse analyses to more than 1,700 species, and show that recent biological trends match climate change predictions. Global meta-analyses documented significant range shifts averaging 6.1 km per decade towards the poles (or metres per decade upward), and significant mean advancement of spring events by 2.3 days per decade. We define a diagnostic fingerprint of temporal and spatial 'sign-switching' responses uniquely predicted by twentieth century climate trends. Among appropriate long-term/large-scale/multi-species data sets, this diagnostic fingerprint was found for 279 species. This suite of analyses generates 'very high confidence' (as laid down by the IPCC) that climate change is already affecting living systems.
Mote, P. W., D. J. Canning, D. L. Fluharty, R.C. Francis, J. F. Franklin, A. F. Hamlet, M. Hershman, M. Holmberg, K. N. Ideker, W. S. Keeton, D. P. Lettenmaier, L. R. Leung, N. J. Mantua, E. L. Miles, B. Noble, H. Parandvash, D. W. Peterson, A. K. Snover, S. R. Willard (1999). Impacts of climate variability and change, Pacific Northwest. National Atmospheric and Oceanic Administration, Office of Global Programs, and JISAO/SMA Climate Impacts Group: 110 pp.
OVERVIEW: Experience of the recent past illustrates the impacts that the climate variations have on the Pacific Northwest, and illustrates that there are both winners and loser when the climate is different from the “average.” The mild winter and spring of 1997—98 saw an early snow melt, which strained regional water supplies during the summer and fall months. An especially warm and dry summer, coupled with the early melt, led to exceptionally low flows and high temperatures in many Northwest streams. These conditions in turn caused severe difficulties for salmon. However, 1997—98 also had benefits for the region, which avoided the damage and disruption caused by heavy snow fall and winter flooding during the previous two winters.
Climate is not a constant, and yet many aspects of human infrastructure and activities are planned with the assumption that it is constant. But what happens when climate produces a surprise? What if, furthermore, there are long-term changes in climate? Humans have altered the composition of Earth’s atmosphere to such an extent that climate itself appears to be changing. The consequences of a changing climate may be beneficial for some places and activities, and detrimental for others.
This report describes the possible impacts of human-induced climate change and of natural climate variability like El Niño, focusing on the water resources, salmon, forests, and coasts of the Pacific Northwest (PNW). It has been prepared largely by the Climate Impacts Group (CIG) at the University of Washington. The CIG, under the direction of Professor Edward L. Miles, is an interdisciplinary group of researchers from the physical, biological, and social sciences working together to understand the impacts of climate variability and change on the Northwest.
Looking at the recent past, much of the climate history of the PNW can be described by a few recurring patterns. The strongest pattern highlights the tendency for winter climate to be either relatively cool and wet or relatively warm and dry. Cool-wet winters are generally associated with increased risks of flooding and landslides, abundant summer water supply, more abundant salmon, reduced risk of forest fires, and improved tree growth (except at high elevation). Warm-dry winters are often followed by summer water shortages, less abundant salmon, and increased risk of forest fires. The occurrence of the cool-wet or warm-dry winter pattern is influenced by two main climate variations in the Pacific Basin: ENSO (El Niño-Southern Oscillation) primarily on year-to-year timescales and PDO (the Pacific Decadal oscillation) primarily on decade-to-decade timescales. ENSO and PDO cause variation sin snowpack and streamflow, and hence the ability to meet water resource objectives; with respect tot he region’s water resources, ENSO and PDO can reinforce or cancel each other. In contrast, the response of forests and salmon is correlated more strongly with the PDO than with ENSO. The magnitude of seasonal anomalies of temperature and precipitation leading to the above effects is strikingly small, but these past anomalies enable us to calibrate the possible responses to long-term climate change.
Looking to the future, computer models of climate generally agree that the PNW will become, over the next half century, gradually warmer and wetter, with most of the precipitation increase in winter. These trends mostly agree with observed changes over the past century. Wetter winters would likely mean more flooding of certain rivers, and landslides on steep coastal bluffs. The region’s warm, dry summers may see slight increases in rainfall, according to the models, but the gains in rainfall will be more than offset by losses due to increases in evaporation. Loss of moderate-elevation snowpack in response to warmer winter temperatures would have enormous and mostly negative impacts on the region’s water resources, forests, and salmon. Among these impacts are a diminished ability to store water in reservoirs for summer use, more drought-stressed tress leading to reductions in forested area, and spawning and rearing difficulties for salmon.
Knowing what changes might occur is only part of the challenge, however. This knowledge must make its way from the realm of research to the realm of decisions, and be used in decisions. Large practical and, in some cases, legal constraints prevent climate information from being fully utilized. Meeting the challenges posed by climate variations and climate change will require considerable revision of the policies and practices concerning how the region’s natural resources are managed. An indication of the scope of such revisions comes from considering how government agencies have handled climate-related stresses in the past, like droughts and coastal erosion. In many cases, agencies cannot even make use of a good seasonal forecast in making short-term planning decision: the operating assumption is often that climate is constant and extremes do not occur. There are wide variations among the four sectors considered here in how management presently makes use of climate information.
Myers, P., Lundrigan, B. L., Hoffman, S. M. G., Haraminac, A. P., Seto, S. H. (2009). Climate-induced changes in the small mammal communities of the Northern Great Lakes Region. Global Change Biology 15 (6): 1434-1454
ABSTRACT: We use museum and other collection records to document large and extraordinarily rapid changes in the ranges and relative abundance of nine species of mammals in the northern Great Lakes region (white-footed mice, woodland deer mice, southern red-backed voles, woodland jumping mice, eastern chipmunks, least chipmunks, southern flying squirrels, northern flying squirrels, common opossums). These species reach either the southern or the northern limit of their distributions in this region. Changes consistently reflect increases in species of primarily southern distribution (white-footed mice, eastern chipmunks, southern flying squirrels, common opossums) and declines by northern species (woodland deer mice, southern red-backed voles, woodland jumping mice, least chipmunks, northern flying squirrels). White-footed mice and southern flying squirrels have extended their ranges over 225 km since 1980, and at particularly well-studied sites in Michigan's Upper Peninsula, small mammal assemblages have shifted from numerical domination by northern species to domination by southern species. Repeated resampling at some sites suggests that southern species are replacing northern ones rather than simply being added to the fauna. Observed changes are consistent with predictions from climatic warming but not with predictions based on recovery from logging or changes in human populations. Because of the abundance of these focal species (the eight rodent species make up 96.5% of capture records of all forest-dwelling rodents in the region and 70% of capture records of all forest-dwelling small mammals) and the dominating ecological roles they play, these changes substantially affect the composition and structure of forest communities. They also provide an unusually clear example of change that is likely to be the result of climatic warming in communities that are experienced by large numbers of people.
ABSTRACT: I examined the potential influence of climate change on the dynamics of a previously studied hybrid zone between a pair of terrestrial salamanders at the Coweeta Hydrologic Laboratory, U.S. Forest Service, in the Nantahala Mountains of North Carolina, USA. A 16-year study led by Nelson G. Hairston, Sr. revealed thatPlethodon teyahalee andPlethodon shermani hybridized at intermediate elevations, forming a cline between 'pure' parentalP. teyahalee at lower elevations and 'pure' parentalP. shermani at higher elevations. From 1974 to 1990 the proportion of salamanders at the higher elevation scored as 'pure'P. shermani declined significantly, indicating that the hybrid zone was spreading upward. To date there have been no rigorous tests of hypotheses for the movement of this hybrid zone. Using temperature and precipitation data from Coweeta, I re-analyzed Hairston's data to examine whether the observed elevational shift was correlated with variation in either air temperature or precipitation from the same time period. For temperature, my analysis tracked the results of the original study: the proportion of 'pure'P. shermani at the higher elevation declined significantly with increasing mean annual temperature, whereas the proportion of 'pure'P. teyahalee at lower elevations did not. There was no discernable relationship between proportions of 'pure' individuals of either species with variation in precipitation. From 1974 to 1990, low-elevation air temperatures at the Coweeta Laboratory ranged from annual means of 11.8 to 14.2 °C, compared with a 55-year average (1936–1990) of 12.6 °C. My re-analyses indicate that the upward spread of the hybrid zone is correlated with increasing air temperatures, but not precipitation, and provide an empirical test of a hypothesis for one factor that may have influenced this movement. My results aid in understanding the potential impact that climate change may have on the ecology and evolution of terrestrial salamanders in montane regions.
Rodenhouse, N. L., Sillett, T. S., Iverson, L. R., Matthews, S. N., McFarland, K. P., Lambert, J. D., Holmes, R. T., Prasad, A. M., T. S. Sillett, R. T. Holmes (2008). Potential effects of climate change on birds of the Northeast. Mitigation and Adaptation Strategies for Global Change 13 (5-6): 517-540
ABSTRACT: We used three approaches to assess potential effects of climate change on birds of the Northeast. First, we created distribution and abundance models for common bird species using climate, elevation, and tree species variables and modeled how bird distributions might change as habitats shift. Second, we assessed potential effects on high-elevation birds, especially Bicknell’s thrush (Catharus bicknelli ), that may be particularly vulnerable to climate change, by using statistical associations between climate, spruce-fir forest vegetation and bird survey data. Last, we complemented these projections with an assessment of how habitat quality of a migratory songbird, the black-throated blue warbler (Dendroica caerulescens ) might be affected by climate change. Large changes in bird communities of the Northeast are likely to result from climate change, and these changes will be most dramatic under a scenario of continued high emissions. Indeed, high-elevation bird species may currently be at the threshold of critical change with as little as 1°C warming reducing suitable habitat by more than half. Species at mid elevations are likely to experience declines in habitat quality that could affect demography. Although not all species will be affected adversely, some of the Northeast’s iconic species, such as common loon and black-capped chickadee, and some of its most abundant species, including several neotropical migrants, are projected to decline significantly in abundance under all climate change scenarios. No clear mitigation strategies are apparent, as shifts in species’ abundances and ranges will occur across all habitat types and for species with widely differing ecologies.
Preston, K. L., Rotenberry, J. T., Redak, R. A., Allen, M. F. (2008). Habitat shifts of endangered species under altered climate conditions: importance of biotic interactions. Global Change Biology 14 (11): 2501-2515
ABSTRACT: Predicting changes in potential habitat for endangered species as a result of global warming requires considering more than future climate conditions; it is also necessary to evaluate biotic associations. Most distribution models predicting species responses to climate change include climate variables and occasionally topographic and edaphic parameters, rarely are biotic interactions included. Here, we incorporate biotic interactions into niche models to predict suitable habitat for species under altered climates. We constructed and evaluated niche models for an endangered butterfly and a threatened bird species, both are habitat specialists restricted to semiarid shrublands of southern California. To incorporate their dependency on shrubs, we first developed climate-based niche models for shrubland vegetation and individual shrub species. We also developed models for the butterfly's larval host plants. Outputs from these models were included in the environmental variable dataset used to create butterfly and bird niche models. For both animal species, abiotic–biotic models outperformed the climate-only model, with climate-only models over-predicting suitable habitat under current climate conditions. We used the climate-only and abiotic–biotic models to calculate amounts of suitable habitat under altered climates and to evaluate species' sensitivities to climate change. We varied temperature (+0.6, +1.7, and +2.8 °C) and precipitation (50%, 90%, 100%, 110%, and 150%) relative to current climate averages and within ranges predicted by global climate change models. Suitable habitat for each species was reduced at all levels of temperature increase. Both species were sensitive to precipitation changes, particularly increases. Under altered climates, including biotic variables reduced habitat by 68–100% relative to the climate-only model. To design reserve systems conserving sensitive species under global warming, it is important to consider biotic interactions, particularly for habitat specialists and species with strong dependencies on other species.
Maclean, I. M., Austin, G. E., Rehfisch, M. M., Blew, J., Crowe, O., Delany, S., Devos, K., Deceuninck, B., Gunther, K., Laursen, K., Van Roomen, M., Wahl, J. (2008). Climate change causes rapid changes in the distribution and site abundance of birds in winter. Global Change Biology 14 (11): 2489-2500
ABSTRACT: Detecting coherent signals of climate change is best achieved by conducting expansive, long-term studies. Here, using counts of waders (Charadrii) collected from ca. 3500 sites over 30 years and covering a major portion of western Europe, we present the largest-scale study to show that faunal abundance is influenced by climate in winter. We demonstrate that the 'weighted centroids' of populations of seven species of wader occurring in internationally important numbers have undergone substantial shifts of up to 115 km, generally in a northeasterly direction. To our knowledge, this shift is greater than that recorded in any other study, but closer to what would be expected as a result of the spatial distribution of ecological zones. We establish that year-to-year changes in site abundance have been positively correlated with concurrent changes in temperature, but that this relationship is most marked towards the colder extremities of the birds' range, suggesting that shifts have occurred as a result of range expansion and that responses to climate change are temperature dependent. Many attempts to model the future impacts of climate change on the distribution of organisms, assume uniform responses or shifts throughout a species' range or with temperature, but our results suggest that this may not be a valid approach. We propose that, with warming temperatures, hitherto unsuitable sites in northeastern Europe will host increasingly important wader numbers, but that this may not be matched by declines elsewhere within the study area. The need to establish that such changes are occurring is accentuated by the statutory importance of this taxon in the designation of protected areas.
ABSTRACT: Weather is of major importance for the population dynamics of birds, but the implications of climate change have only recently begun to be addressed. There is already compelling evidence that birds have been affected by recent climate changes. This review suggests that although there is a substantial body of evidence for changes in the phenology of birds, particularly of the timing of migration and of nesting, the consequences of these responses for a species' population dynamics is still an area requiring in-depth research. The potential for phenological miscuing (responding inappropriately to climate change, including a lack of response) and for phenological disjunction (in which a bird species becomes out of synchrony with its environment) are beginning to be demonstrated, and are also important areas for further research. The study of climatically induced distributional change is currently at a predictive modelling stage, and will need to develop methods for testing these predictions. Overall, there is a range of intrinsic and extrinsic factors that could potentially inhibit adaptation to climate change and these are a high priority for research.
SUMMARY: Climate change is the most significant and far-reaching environmental threat facing humanity today. Scientists, policy makers and governments from around the world are seeking to understand the nature of the changes that are likely to occur in the 21st Century and beyond, and the effects these could have on human populations and the socio-economic systems that underpin them. Mitigation measures are being developed to reduce the long-term impacts of human-produced greenhouse gases on the Earth’s climate, whilst a wide range of ‘sectors’ are considering how they might adapt to the inevitable effects of climate change in the shorter term.
There is already clear evidence to show that wildlife from the poles to the tropics is being affected by climate change. Species migrations, extinctions and changes in populations, range and seasonal and reproductive behaviour are among a plethora of responses that have been recorded, and these are likely to continue apace as climate continues to change in decades to come.
In recent years, natural scientists and nature conservationists have been acquiring knowledge of the current and future impacts of climate change on global wildlife. In an attempt to share this information and identify future research priorities, four UK-based nature conservation organisations convened ‘The Norwich Conference’ at the University of East Anglia, England, in September 1999. The conference brought together many of the world’s leading research scientists in the field; this book synthesises the main messages from their presentations in a way that is accessible to the non-specialist reader. Contact details for each contributor are given on pages 4–5 to enable readers to obtain further information on subjects of particular interest to them.
ABSTRACT: Climate change effects on biodiversity are already manifested, and yet no predictive knowledge characterizes the likely nature of these effects. Previous studies suggested an influence of topography on these effects, a possibility tested herein. Bird species with distributions restricted to montane (26 species) and Great Plains (19 species) regions of central and western North America were modeled, and climate change effects on their distributions compared: in general, plains species were more heavily influenced by climate change, with drastic area reductions (mode 35% of distributional area lost under assumption of no dispersal) and dramatic spatial movements (0–400 km shift of range centroid under assumption of no dispersal) of appropriate habitats. These results suggest an important generality regarding climate change effects on biodiversity, and provide useful guidelines for conservation planning.
ABSTRACT: Wildlife conservation faces new and extreme challenges in adapting to the accelerating dynamics of a world responding to global change. The Quaternary record shows that migration has been the usual response of organisms to environmental change. This record also reveals that forecast future climate changes are of a magnitude and in a direction unprecedented in recent earth history: the rate of these changes is likely also to surpass that of any comparable change during the last 2.4 million years.
The relationship between a species' geographical distribution and present climate may be modelled by a surface representing the probability of encountering that species under given combinations of climate conditions. This 'climate response surface' then may be used to simulate potential future distributions of the species in response to forecast climate scenarios. Such simulations reveal the magnitude of the impacts of these forecast climate changes. Although to date this approach has been applied in Europe only to plants, it promises to be valuable also for other groups of organisms, including birds. Some bird species, however, may respond more directly to either habitat structure or presence of specific food plants; such factors may be incorporated into the models when required.
The magnitude of likely vegetation changes necessitates a global approach to conservation if there is to be any hope of long-term success. Successful conservation of global biodiversity will depend upon conservation of the global environment and limitation of the human population much more than upon parochial efforts to conserve locally rare organisms or habitats.
ABSTRACT: Across North America, tree swallows have advanced their mean date of clutch initiation (lay date) by ≈9 days over the past 30 years, apparently in response to climate change. In a sample of 2,881 nest records collected by the lay public from 1959 to 1991, we examined whether clutch size has also responded to climate change. We found that clutch size is strongly related to lay date, both within and among years, and there has been no significant temporal variation in the slopes or intercepts of the clutch-size/lay-date regressions. As a consequence, we expected increases in clutch size with advancement in lay date; however, we detected no such trend over time. The distributions of egg-laying dates were more constricted in the warmest (and earliest) years, suggesting that changes in mean clutch size might be constrained by changes in the distribution of laying dates. If spring temperatures continue to increase, we predict further reductions of variance in laying dates and relatively small increases in clutch size. Such constraints on life-history variation probably are common and need to be considered when modeling the effects of climate change on reproduction in natural populations. Predicting the long-term effects of constraints and interpreting changes in life-history traits require a better understanding of both adaptive and demographic effects of climate change.
ABSTRACT: Climate change has led to shifts in phenology in many species distributed widely across taxonomic groups. It is, however, unclear how we should interpret these shifts without some sort of a yardstick: a measure that will reflect how much a species should be shifting to match the change in its environment caused by climate change. Here, we assume that the shift in the phenology of a species' food abundance is, by a first approximation, an appropriate yardstick. We review the few examples that are available, ranging from birds to marine plankton. In almost all of these examples, the phenology of the focal species shifts either too little (five out of 11) or too much (three out of 11) compared to the yardstick. Thus, many species are becoming mistimed due to climate change. We urge researchers with long-term datasets on phenology to link their data with those that may serve as a yardstick, because documentation of the incidence of climate change-induced mistiming is crucial in assessing the impact of global climate change on the natural world.
J. D. Forester, A. R. Ives, M. G. Turner, D. P. Anderson, D. Fortin, H. L. Beyer, D. W. Smith, M. S. Boyce (2007). State-space models link elk movement patterns to landscape characteristics in Yellowstone National Park. Ecological Monographs 77 (2): 285-299
ABSTRACT: Explaining and predicting animal movement in heterogeneous landscapes remains challenging. This is in part because movement paths often include a series of short, localized displacements separated by longer-distance forays. This multiphasic movement behavior reflects the complex response of an animal to present environmental conditions and to its internal behavioral state. This state is an autocorrelated process influenced by preceding behaviors and habitats visited. Movement patterns depending on the behavioral state of an animal represent the broad-scale response of that animal to the environment. Quantifying how animals respond both to local conditions and to their internal state reveals how animals respond to spatial heterogeneity at different spatial scales. We used a state–space statistical approach to model the internal behavioral state and the proximate movement response of elk (Cervus elaphus ) to available forage biomass, landscape composition, topography, and wolf (Canis lupus ) density during summer in Yellowstone National Park, USA. We analyzed movement paths of 16 female elk fitted with global positioning system (GPS) radio collars that recorded locations at 5-h intervals. Habitat variables were quantified within 175 m radii (one-half of the median 5-h displacement) centered on the beginning location of each interval. Stepwise model selection identified models that best explained the movement distances of each animal. The behavioral state changed very slowly for most animals (median autocorrelation r = 0.93), and all animals responded strongly to time of day (with more movement in the crepuscular hours). However, the spatial variables included in the best-fitting models varied substantially among individual elk. These results suggest that strong patterns of habitat selection observed in other studies may result from frequent visits to preferred areas rather than a reduction of movement in those areas.
INTRODUCTION: Climate change is likely to emerge as the greatest threat to natural communities in many, if not most, of the world’s ecosystems in coming decades, with mid-range climate change scenarios expected to produce greater extinction rates than habitat loss, currently deemed the top threat to biodiversity (Thomas et al., 2004; Malcolm et al., 2006).
More is known about birds’ response to climate change to date than for any other animal group, mostly as a result of many species- and location-specific analyses. Yet of the global or international-scale analyses of biodiversity and climate change, very few concentrate on birds in particular. This review seeks to provide a global survey of the climate threat to birds by compiling hundreds of individual studies to resolve the larger picture of impacts.
This analysis finds compelling evidence that, with 0.8°C (Hansen et al., 2005) of warming having occurred over the past century, strong negative impacts on birds are already taking place. Climate change is affecting birds’ behaviour, distribution and population dynamics, and is implicated in complete breeding failure in some populations. The majority of evidence indicates that continuing and expected changes to the climate of 1.4 to 5.8°C by 2100 (IPCC, 2001a; a projection expected to be revised to 2.0 to 4.5°C under a scenario of a doubling of CO2 in the United Nations’ upcoming Fourth Assessment Report [Giles, 2006]) will have very serious effects on birds, including huge shifts in distributions, major population declines and high levels of extinction.
ABSTRACT: The Botteri's Sparrow (Aimophila botterii ) is a bird of tall grasslands that temporarily disappeared from Arizona following heavy livestock grazing in the 1890s. Its return was noted first in sacaton (Sporobolus wrightii ), an uncommon native floodplain ...
ABSTRACT: Reports of malformed amphibians and global amphibian declines have led to public concern, particularly because amphibians are thought to be indicator species of overall environmental health. The topic also draws scientific attention because there is no obvious, simple answer to the question of what is causing amphibian declines? Complex interactions of several anthropogenic factors are probably at work, and understanding amphibian declines may thus serve as a model for understanding species declines in general. While we have fewer answers than we would like, there are six leading hypotheses that we sort into two classes. For class I hypotheses, alien species, over-exploitation and land use change, we have a good understanding of the ecological mechanisms underlying declines; these causes have affected amphibian populations negatively for more than a century. However, the question remains as to whether the magnitude of these negative effects increased in the 1980s, as scientists began to notice a global decline of amphibians. Further, remedies for these problems are not simple. For class II hypotheses, global change (including UV radiation and global climate change), contaminants and emerging infectious diseases we have a poor, but improving understanding of how each might cause declines. Class II factors involve complex and subtle mechanistic underpinnings, with probable interactions among multiple ecological and evolutionary variables. They may also interact with class I hypotheses. Suspected mechanisms associated with class II hypotheses are relatively recent, dating from at least the middle of the 20th century. Did these causes act independently or in concert with pre-existing negative forces of class I hypotheses to increase the rate of amphibian declines to a level that drew global attention? We need more studies that connect the suspected mechanisms underlying both classes of hypotheses with quantitative changes in amphibian population sizes and species numbers. An important step forward in this task is clarifying the hypotheses and conditions under which the various causes operate alone or together.
Jarema, S. I., Samson, J., McGill, B. J., Humphries, M. M. (2009). Variation in abundance across a species’ range predicts climate change responses in the range interior will exceed those at the edge: a case study with North American beaver. Global Change Biology 15 (2): 508-522
ABSTRACT: The absence of information about how abundance varies across species' ranges restricts most modeling and monitoring of climate change responses to the range edge. We examine spatial variation in abundance across the northeastern range of North American beaver (Castor canadensis ), evaluate the extent to which climate and nonclimate variables explain this variation, and use a species–climate envelope model that includes spatial variation in abundance to predict beaver abundance responses to projected climate change. The density of beaver colonies across Québec follows a roughly logistic pattern, with high but variable density across the southern portion of the province, a sharp decline in density at about 49°N, and a long tail of low density extending as far as 58°N. Several climate and nonclimate variables were strong predictors of variation in beaver density, but 97% of the variation explained by nonclimate variables could be accounted for by climate variables. Because of the peak and tail density pattern, beaver climate sensitivity (change in density per unit change in climate) was greatest in the interior and lowest at the edge of the range. Combining our best density–climate models with projections from general circulation models (GCM) predicts a relatively modest expansion of the species' northern range limit by 2055, but density increases in the range interior that far exceed those at the range edge. Thus, some of the most dramatic responses to climate change may be occurring in the core of species' ranges, far away from the edge-of-the-range focus of most current modeling and monitoring efforts.
Van Buskirk, J., Mulvihill, R. S., Leberman, R. C. (2009). Variable shifts in spring and autumn migration phenology in North American songbirds associated with climate change. Global Change Biology 15 (3): 760-771
ABSTRACT: Monitoring studies find that the timing of spring bird migration has advanced in recent decades, especially in Europe. Results for autumn migration have been mixed. Using data from Powdermill Nature Reserve, a banding station in western Pennsylvania, USA, we report an analysis of migratory timing in 78 songbird species from 1961 to 2006. Spring migration became significantly earlier over the 46-year period, and autumn migration showed no overall change. There was much variation among species in phenological change, especially in autumn. Change in timing was unrelated to summer range (local vs. northern breeders) or the number of broods per year, but autumn migration became earlier in neotropical migrants and later in short-distance migrants. The migratory period for many species lengthened because late phases of migration remained unchanged or grew later as early phases became earlier. There was a negative correlation between spring and autumn in long-term change, and this caused dramatic adjustments in the amount of time between migrations: the intermigratory periods of 10 species increased or decreased by > 15 days. Year-to-year changes in timing were correlated with local temperature (detrended) and, in autumn, with a regional climate index (detrended North Atlantic Oscillation). These results illustrate a complex and dynamic annual cycle in songbirds, with responses to climate change differing among species and migration seasons.