Future Climate (future + climate)

Distribution by Scientific Domains
Distribution within Life Sciences

Terms modified by Future Climate

  • future climate change
  • future climate condition
  • future climate scenario

  • Selected Abstracts

    The geography of climate change: implications for conservation biogeography

    D. D. Ackerly
    Abstract Aim, Climate change poses significant threats to biodiversity, including impacts on species distributions, abundance and ecological interactions. At a landscape scale, these impacts, and biotic responses such as adaptation and migration, will be mediated by spatial heterogeneity in climate and climate change. We examine several aspects of the geography of climate change and their significance for biodiversity conservation. Location, California and Nevada, USA. Methods, Using current climate surfaces (PRISM) and two scenarios of future climate (A1b, 2070,2099, warmer-drier and warmer-wetter), we mapped disappearing, declining, expanding and novel climates, and the velocity and direction of climate change in California and Nevada. We also examined fine-scale spatial heterogeneity in protected areas of the San Francisco Bay Area in relation to reserve size, topographic complexity and distance from the ocean. Results, Under the two climate change scenarios, current climates across most of California and Nevada will shrink greatly in extent, and the climates of the highest peaks will disappear from this region. Expanding and novel climates are projected for the Central Valley. Current temperature isoclines are projected to move up to 4.9 km year,1 in flatter regions, but substantially slower in mountainous areas because of steep local topoclimate gradients. In the San Francisco Bay Area, climate diversity within currently protected areas increases with reserve size and proximity to the ocean (the latter because of strong coastal climate gradients). However, by 2100 of almost 500 protected areas (>100 ha), only eight of the largest are projected to experience temperatures within their currently observed range. Topoclimate variability will further increase the range of conditions experienced and needs to be incorporated in future analyses. Main Conclusions, Spatial heterogeneity in climate, from mesoclimate to topoclimate scales, represents an important spatial buffer in response to climate change, and merits increased attention in conservation planning. [source]

    Why is the choice of future climate scenarios for species distribution modelling important?

    ECOLOGY LETTERS, Issue 11 2008
    Linda J. Beaumont
    Abstract Species distribution models (SDMs) are common tools for assessing the potential impact of climate change on species ranges. Uncertainty in SDM output occurs due to differences among alternate models, species characteristics and scenarios of future climate. While considerable effort is being devoted to identifying and quantifying the first two sources of variation, a greater understanding of climate scenarios and how they affect SDM output is also needed. Climate models are complex tools: variability occurs among alternate simulations, and no single ,best' model exists. The selection of climate scenarios for impacts assessments should not be undertaken arbitrarily - strengths and weakness of different climate models should be considered. In this paper, we provide bioclimatic modellers with an overview of emissions scenarios and climate models, discuss uncertainty surrounding projections of future climate and suggest steps that can be taken to reduce and communicate climate scenario-related uncertainty in assessments of future species responses to climate change. [source]

    Towards a predictive understanding of belowground process responses to climate change: have we moved any closer?

    FUNCTIONAL ECOLOGY, Issue 6 2008
    Elise Pendall
    Summary 1Belowground processes, including root production and exudation, microbial activity and community dynamics, and biogeochemical cycling interact to help regulate climate change. Feedbacks associated with these processes, such as warming-enhanced decomposition rates, give rise to major uncertainties in predictions of future climate. 2Uncertainties associated with these processes are more likely to be reduced if two key challenges can be met: increasing interdisciplinarity among researchers, and measuring belowground ecosystem structure and function at relevant spatial and temporal scales. For instance, recognizing the relationship between belowground primary production and soil respiration enhances modelling of global-scale C cycle temperature responses. At the opposite end of the spectrum, applying genomic techniques at the scale of microns improves mechanistic understanding of root,microbe interactions. 3Progress has been made in understanding interactions of belowground processes with climate change, although challenges remain. We highlight some of these advances and provide directions for key research needs in this Special Feature of Functional Ecology, which results from a symposium that was convened at the Soil Science Society of America National Meeting in November, 2006. [source]

    Disentangling effects of an experimentally imposed extreme temperature event and naturally associated desiccation on Arctic tundra

    FUNCTIONAL ECOLOGY, Issue 6 2006
    Summary 1Climate projections suggest that extreme events will increase in frequency during this century. As tundra is recognized to be among the most vulnerable biomes, we exposed patches of arctic tundra vegetation to an experimental heatwave (by infrared irradiation), followed by a recovery period. The heating increased the surface temperature with an average of 76 C during 13 days, which slightly exceeded the longest climatic episode with such a temperature deviation since 1961. 2The heatwave decreased stomatal conductance (gs) and PSII maximum efficiency (Fv/Fm), although there were differences in response among the four target species. Salix arctica Pall. (shrub) was affected during the heatwave and could not recover. In Carex bigelowii Tor. ex Schwein (sedge) and Pyrola grandiflora Radius (forb), on the other hand, the effects on gs and Fv/Fm became clear, particularly in the aftermath of the heatwave, whereas Polygonum viviparum L. (forb) was never stressed. 3Effects of the heat on gs were mainly indirect, through increased desiccation, whereas effects on Fv/Fm were more related to leaf temperature (although not in all species). The observed changes can therefore probably be ascribed to a combination of heat and drought causing dysfunctions that ultimately led to senescence. 4Two conclusions of this study, species-specific responses and increased leaf mortality, indicate that more frequent extreme temperature events accompanied by desiccation might alter/endanger tundra communities in a future climate. Predictions of global change effects on arctic ecosystems should therefore take into account the impact of extremes. [source]

    Current and Future Trends of Climatic Extremes in Switzerland

    Martin Beniston
    This article provides an overview of extreme climatic events that are a feature of current and future climate that require full understanding if they are to be assessed in terms of social and economic costs. A review is made of the type of events that are important in mid-latitudes, with examples taken from the heat waves, floods and wind-storms that have affected Switzerland during the twentieth century. Regional climate model results are also presented for a scenario conducted over Europe. These simulations suggest that there may be significant shifts in the frequency and intensity of many forms of extremes as a warmer global climate progressively replaces current climate. In view of the potential losses in human, economic and environmental terms, extreme events and their future evolution need to carefully assessed in order to formulate appropriate adaptation strategies aimed at minimizing the negative impacts that extremes are capable of generating. [source]

    Implications of future climate and atmospheric CO2 content for regional biogeochemistry, biogeography and ecosystem services across East Africa

    Abstract We model future changes in land biogeochemistry and biogeography across East Africa. East Africa is one of few tropical regions where general circulation model (GCM) future climate projections exhibit a robust response of strong future warming and general annual-mean rainfall increases. Eighteen future climate projections from nine GCMs participating in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment were used as input to the LPJ dynamic global vegetation model (DGVM), which predicted vegetation patterns and carbon storage in agreement with satellite observations and forest inventory data under the present-day climate. All simulations showed future increases in tropical woody vegetation over the region at the expense of grasslands. Regional increases in net primary productivity (NPP) (18,36%) and total carbon storage (3,13%) by 2080,2099 compared with the present-day were common to all simulations. Despite decreases in soil carbon after 2050, seven out of nine simulations continued to show an annual net land carbon sink in the final decades of the 21st century because vegetation biomass continued to increase. The seasonal cycles of rainfall and soil moisture show future increases in wet season rainfall across the GCMs with generally little change in dry season rainfall. Based on the simulated present-day climate and its future trends, the GCMs can be grouped into four broad categories. Overall, our model results suggest that East Africa, a populous and economically poor region, is likely to experience some ecosystem service benefits through increased precipitation, river runoff and fresh water availability. Resulting enhancements in NPP may lead to improved crop yields in some areas. Our results stand in partial contradiction to other studies that suggest possible negative consequences for agriculture, biodiversity and other ecosystem services caused by temperature increases. [source]

    Will climate change be beneficial or detrimental to the invasive swede midge in North America?

    Contrasting predictions using climate projections from different general circulation models
    Abstract Climate change may dramatically affect the distribution and abundance of organisms. With the world's population size expected to increase significantly during the next 100 years, we need to know how climate change might impact our food production systems. In particular, we need estimates of how future climate might alter the distribution of agricultural pests. We used the climate projections from two general circulation models (GCMs) of global climate, the Canadian Centre for Climate Modelling and Analysis GCM (CGCM2) and the Hadley Centre model (HadCM3), for the A2 and B2 scenarios from the Special Report on Emissions Scenarios in conjunction with a previously published bioclimatic envelope model (BEM) to predict the potential changes in distribution and abundance of the swede midge, Contarinia nasturtii, in North America. The BEM in conjunction with either GCM predicted that C. nasturtii would spread from its current initial invasion in southern Ontario and northwestern New York State into the Canadian prairies, northern Canada, and midwestern United States, but the magnitude of risk depended strongly on the GCM and the scenario used. When the CGCM2 projections were used, the BEM predicted an extensive shift in the location of the midges' climatic envelope through most of Ontario, Quebec, and the maritime and prairie provinces by the 2080s. In the United States, C. nasturtii was predicted to spread to all the Great Lake states, into midwestern states as far south as Colorado, and west into Washington State. When the HadCM3 was applied, southern Ontario, Saskatchewan, and Washington State were not as favourable for C. nasturtii by the 2080s. Indeed, when used with the HadCM3 climate projections, the BEM predicted the virtual disappearance of ,very favourable' regions for C. nasturtii. The CGCM2 projections generally caused the BEM to predict a small increase in the mean number of midge generations throughout the course of the century, whereas, the HadCM3 projections resulted in roughly the same mean number of generations but decreased variance. Predictions of the likely potential of C. nasturtii spatial spread are thus strongly dependent on the source of climate projections. This study illustrates the importance of using multiple GCMs in combination with multiple scenarios when studying the potential for spatial spread of an organism in response to climate change. [source]

    Projected changes in the organic carbon stocks of cropland mineral soils of European Russia and the Ukraine, 1990,2070

    Abstract In this paper, we use the Rothamsted Carbon Model to estimate how cropland mineral soil carbon stocks are likely to change under future climate, and how agricultural management might influence these stocks in the future. The model was run for croplands occurring on mineral soils in European Russia and the Ukraine, representing 74 Mha of cropland in Russia and 31 Mha in the Ukraine. The model used climate data (1990,2070) from the HadCM3 climate model, forced by four Intergovernmental Panel on Climate Change (IPCC) emission scenarios representing various degrees of globalization and emphasis on economic vs. environmental considerations. Three land use scenarios were examined, business as usual (BAU) management, optimal management (OPT) to maximize profit, and soil sustainability (SUS) in which profit was maximized within the constraint that soil carbon must either remain stable or increase. Our findings suggest that soil organic carbon (SOC) will be lost under all climate scenarios, but less is lost under the climate scenarios where environmental considerations are placed higher than purely economic considerations (IPCC B1 and B2 scenarios) compared with the climate associated with emissions resulting from the global free market scenario (IPCC A1FI scenario). More SOC is lost towards the end of the study period. Optimal management is able to reduce this loss of SOC, by up to 44% compared with business as usual management. The soil sustainability scenario could be run only for a limited area, but in that area was shown to increase SOC stocks under three climate scenarios, compared with a loss of SOC under business as usual management in the same area. Improved agricultural soil management will have a significant role to play in the adaptation to, and mitigation of, climate change in this region. Further, our results suggest that this adaptation could be realized without damaging profitability for the farmers, a key criteria affecting whether optimal management can be achieved in reality. [source]

    Performance of High Arctic tundra plants improved during but deteriorated after exposure to a simulated extreme temperature event

    GLOBAL CHANGE BIOLOGY, Issue 12 2005
    Fleur L. Marchand
    Abstract Arctic ecosystems are known to be extremely vulnerable to climate change. As the Intergovernmental Panel on Climate Change scenarios project extreme climate events to increase in frequency and severity, we exposed High Arctic tundra plots during 8 days in summer to a temperature rise of approximately 9C, induced by infrared irradiation, followed by a recovery period. Increased plant growth rates during the heat wave, increased green cover at the end of the heat wave and higher chlorophyll concentrations of all four predominating species (Salix arctica Pall., Arctagrostis latifolia Griseb., Carex bigelowii Torr. ex Schwein and Polygonum viviparum L.) after the recovery period, indicated stimulation of vegetative growth. Improved plant performance during the heat wave was confirmed at plant level by higher leaf photochemical efficiency (Fv/Fm) and at ecosystem level by increased gross canopy photosynthesis. However, in the aftermath of the temperature extreme, the heated plants were more stressed than the unheated plants, probably because they acclimated to warmer conditions and experienced the return to (low) ambient as stressful. We also calculated the impact of the heat wave on the carbon balance of this tundra ecosystem. Below- and aboveground respiration were stimulated by the instantaneous warmer soil and canopy, respectively, outweighing the increased gross photosynthesis. As a result, during the heat wave, the heated plots were a smaller sink compared with their unheated counterparts, whereas afterwards the balance was not affected. If other High Arctic tundra ecosystems react similarly, more frequent extreme temperature events in a future climate may shift this biome towards a source. It is uncertain, however, whether these short-term effects will hold when C exchange rates acclimate to higher average temperatures. [source]

    Climate- and crop-responsive emission factors significantly alter estimates of current and future nitrous oxide emissions from fertilizer use

    Helen C. Flynn
    Abstract The current Intergovernmental Panel on Climate Change (IPCC) default methodology (tier 1) for calculating nitrous oxide (N2O) emissions from nitrogen applied to agricultural soils takes no account of either crop type or climatic conditions. As a result, the methodology omits factors that are crucial in determining current emissions, and has no mechanism to assess the potential impact of future climate and land-use change. Scotland is used as a case study to illustrate the development of a new methodology, which retains the simple structure of the IPCC tier 1 methodology, but incorporates crop- and climate-dependent emission factors (EFs). It also includes a factor to account for the effect of soil compaction because of trampling by grazing animals. These factors are based on recent field studies in Scotland and elsewhere in the UK. Under current conditions, the new methodology produces significantly higher estimates of annual N2O emissions than the IPCC default methodology, almost entirely because of the increased contribution of grazed pasture. Total emissions from applied fertilizer and N deposited by grazing animals are estimated at 10 662 t N2O-N yr,1 using the newly derived EFs, as opposed to 6 796 t N2O-N yr,1 using the IPCC default EFs. On a spatial basis, emission levels are closer to those calculated using field observations and detailed soil modelling than to estimates made using the IPCC default methodology. This can be illustrated by parts of the western Ayrshire basin, which have previously been calculated to emit 8,9 kg N2O-N ha,1 yr,1 and are estimated here as 6.25,8.75 kg N2O-N ha,1 yr,1, while the IPCC default methodology gives a maximum emission level of only 3.75 kg N2O-N ha,1 yr,1 for the whole area. The new methodology is also applied in conjunction with scenarios for future climate- and land-use patterns, to assess how these emissions may change in the future. The results suggest that by 2080, Scottish N2O emissions may increase by up to 14%, depending on the climate scenario, if fertilizer and land management practices remain unchanged. Reductions in agricultural land use, however, have the potential to mitigate these increases and, depending on the replacement land use, may even reduce emissions to below current levels. [source]

    Statistical downscaling of daily precipitation from observed and modelled atmospheric fields

    Stephen P. Charles
    Abstract Statistical downscaling techniques have been developed to address the spatial scale disparity between the horizontal computational grids of general circulation models (GCMs), typically 300,500 km, and point-scale meteorological observations. This has been driven, predominantly, by the need to determine how enhanced greenhouse projections of future climate may impact at regional and local scales. As point-scale precipitation is a common input to hydrological models, there is a need for techniques that reproduce the characteristics of multi-site, daily gauge precipitation. This paper investigates the ability of the extended nonhomogeneous hidden Markov model (extended-NHMM) to reproduce observed interannual and interdecadal precipitation variability when driven by observed and modelled atmospheric fields. Previous studies have shown that the extended-NHMM can successfully reproduce the at-site and intersite statistics of daily gauge precipitation, such as the frequency characteristics of wet days, dry- and wet-spell length distributions, amount distributions, and intersite correlations in occurrence and amounts. Here, the extended-NHMM, as fitted to 1978,92 observed ,winter' (May,October) daily precipitation and atmospheric data for 30 rain gauge sites in southwest Western Australia, is driven by atmospheric predictor sets extracted from National Centers for Environmental Prediction,National Center for Atmospheric Research reanalysis data for 1958,98 and an atmospheric GCM hindcast run forced by observed 1955,91 sea-surface temperatures (SSTs). Downscaling from the reanalysis-derived predictors reproduces the 1958,98 interannual and interdecadal variability of winter precipitation. Downscaling from the SST-forced GCM hindcast only reproduces the precipitation probabilities of the recent 1978,91 period, with poor performance for earlier periods attributed to inadequacies in the forcing SST data. Copyright 2004 John Wiley & Sons, Ltd. [source]

    Statistical downscaling of extremes of daily precipitation and temperature and construction of their future scenarios

    Yeshewatesfa Hundecha
    Abstract Two statistical downscaling methods have been tested in terms of their ability to construct indices of extremes of daily precipitation and temperatures from large-scale atmospheric variables with the aim of developing a tool for the construction of future scenarios of the extremes. One of the methods implements an approach for constructing seasonal indices of extremes of precipitation and temperature from seasonal measures of large-scale variables, while the other method implements a stochastic model for generating daily series of precipitation and temperature whose parameters are conditioned on large-scale circulation patterns. While both models generally tend to perform fairly well in reproducing indices of precipitation in winter, their performance for the summer season is not attractive. For indices of temperature, the performance of both models is better than the corresponding performance for indices of precipitation and the seasonal variation in performance is less prominent. The models were applied to construct scenarios of the extremes for the end of the 21st century using predictor sets simulated by the Hadley Centre GCM (HadAM3P) forced by two of the special report on emission scenarios (SRES) emission scenarios. Both models project an increase in both the mean daily minimum and mean daily maximum temperatures for future climate change scenarios in all seasons. The summer increase is accompanied by an increase in the inter-annual variability of the temperatures. On the other hand, they show consistency in the direction of the projected changes in indices of precipitation only in winter, where they projected an increase in both the magnitude and frequency of extremes as well as the mean precipitation. The disparity in the changes simulated by the two models revealed the existence of considerable inter-model uncertainty in predicting changes for future climate. Copyright 2007 Royal Meteorological Society [source]

    Europe's 2003 heat wave: a satellite view of impacts and land,atmosphere feedbacks

    Benjamin F. Zaitchik
    Abstract A combination of satellite imagery, meteorological station data, and the NCEP/NCAR reanalysis has been used to explore the spatial and temporal evolution of the 2003 heat wave in France, with focus on understanding the impacts and feedbacks at the land surface. Vegetation was severely affected across the study area, especially in a swath across central France that corresponds to the Western European Broadleaf (WEB) Forests ecological zone. The remotely sensed surface temperature anomaly was also greatest in this zone, peaking at +15.4 C in August. On a finer spatial scale, both the vegetation and surface temperature anomalies were greater for crops and pastures than for forested lands. The heat wave was also associated with an anomalous surface forcing of air temperature. Relative to other years in record, satellite-derived estimates of surface-sensible heat flux indicate an enhancement of 48,61% (24.0,30.5 W m,2) in WEB during the August heat wave maximum. Longwave radiative heating of the planetary boundary layer (PBL) was enhanced by 10.5 W m,2 in WEB for the same period. The magnitude and spatial structure of this local heating is consistent with models of the late twenty-first century climate in France, which predict a transitional climate zone that will become increasingly affected by summertime drought. Models of future climate also suggest that a soil-moisture feedback on the surface energy balance might exacerbate summertime drought, and these proposed feedback mechanisms were tested using satellite-derived heat budgets. Copyright 2006 Royal Meteorological Society. [source]

    Statistical downscaling relationships for precipitation in the Netherlands and North Germany

    Abstract The statistical linkage of daily precipitation to the National Centers for Environment Prediction (NCEP) reanalysis data is described for De Bilt and Maastricht (Netherlands), and for Hamburg, Hanover and Berlin (Germany), using daily data for the period 1968,97. Two separate models were used to describe the daily precipitation at a particular site: an additive logistic model for rainfall occurrence and a generalized additive model for wet-day rainfall. Several dynamical variables and atmospheric moisture were included as predictor variables. The relative humidity at 700 hPa was considered as the moisture variable for rainfall occurrence modelling. For rainfall amount modelling, two options were compared: (i) the use of the specific humidity at 700 hPa, and (ii) the use of both the relative humidity at 700 hPa and precipitable water. An application is given with data from a time-dependent greenhouse gas forcing experiment using the coupled ECHAM4/OPYC3 atmosphere,ocean general circulation model for the periods 1968,97 and 2070,99. The fitted statistical relationships were used to estimate the changes in the mean number of wet days and the mean rainfall amounts for the winter and summer halves of the year at De Bilt, Hanover and Berlin. A decrease in the mean number of wet days was found. Despite this decrease, an increase in the mean seasonal rainfall amounts is predicted if specific humidity is used in the model for wet-day rainfall. This is caused by the larger atmospheric water content in the future climate. The effect of the increased atmospheric moisture is smaller if the alternative wet-day rainfall amount model with precipitable water and relative humidity is applied. Except for an anomalous change in mean winter rainfall at Hanover, the estimated changes from the latter model correspond quite well with those from the ECHAM4/OPYC3 model. Despite the flexibility of generalized additive models, the rainfall amount model systematically overpredicts the mean rainfall amounts in situations where extreme rainfall could be expected. Interaction between predictor effects has to be incorporated to reduce this bias. Copyright 2002 Royal Meteorological Society [source]

    Model-based uncertainty in species range prediction

    Richard G. Pearson
    Abstract Aim, Many attempts to predict the potential range of species rely on environmental niche (or ,bioclimate envelope') modelling, yet the effects of using different niche-based methodologies require further investigation. Here we investigate the impact that the choice of model can have on predictions, identify key reasons why model output may differ and discuss the implications that model uncertainty has for policy-guiding applications. Location, The Western Cape of South Africa. Methods, We applied nine of the most widely used modelling techniques to model potential distributions under current and predicted future climate for four species (including two subspecies) of Proteaceae. Each model was built using an identical set of five input variables and distribution data for 3996 sampled sites. We compare model predictions by testing agreement between observed and simulated distributions for the present day (using the area under the receiver operating characteristic curve (AUC) and kappa statistics) and by assessing consistency in predictions of range size changes under future climate (using cluster analysis). Results, Our analyses show significant differences between predictions from different models, with predicted changes in range size by 2030 differing in both magnitude and direction (e.g. from 92% loss to 322% gain). We explain differences with reference to two characteristics of the modelling techniques: data input requirements (presence/absence vs. presence-only approaches) and assumptions made by each algorithm when extrapolating beyond the range of data used to build the model. The effects of these factors should be carefully considered when using this modelling approach to predict species ranges. Main conclusions, We highlight an important source of uncertainty in assessments of the impacts of climate change on biodiversity and emphasize that model predictions should be interpreted in policy-guiding applications along with a full appreciation of uncertainty. [source]

    Holocene bipolar climate seesaw: possible subtle evidence from the deep North East Atlantic Ocean?,

    Mark A. Maslin
    Abstract The occurrence of a millennial-scale bipolar climate seesaw has been documented in detail for the last glacial period and Termination. There is, however, debate whether it occurs during interglacials and if it does what influence it could have on future climate. We present here new evidence from a North East Atlantic Ocean deep-sea core which supports the hypothesis for a Holocene bipolar climate seesaw. BENGAL Site 13078#16, from the Porcupine Abyssal Plain, is 4844,m deep and situated at the North Atlantic Deep Water and Antarctic Bottom Water (AABW) interface. Planktic foraminiferal fragment accumulation rate data at this site is an indicator of coarse carbonate dissolution, which is highly sensitive to the incursion of under-saturated AABW. Five dissolution peaks have been identified, which seem to occur approximately 500 a after each of the North Atlantic 'Bond' ice rafting pulses, suggesting a subsequent subtle shallowing of AABW. This indicates a possible lagged climatic link between North East Atlantic surface water conditions and AABW production in the Southern Ocean during the Holocene. This provides the first tentative evidence that there was a Holocene bipolar climate seesaw and that the deep ocean was involved. This study also suggests that extremely sensitive locations need to be sought as the Holocene bipolar climate seesaw seems to be very subtle compared with its glacial counterparts. Copyright 2009 John Wiley & Sons, Ltd. [source]


    Christina Tague
    ABSTRACT: Distributed hydrologic models which link seasonal streamflow and soil moisture patterns with spatial patterns of vegetation are important tools for understanding the sensitivity of Mediterranean type ecosystems to future climate and land use change. RHESSys (Regional Hydro-Ecologic Simulation System) is a coupled spatially distributed hydroecological model that is designed to be able to represent these feedbacks between hydrologic and vegetation carbon and nutrient cycling processes. However, RHESSys has not previously been applied to semiarid shrubland watersheds. In this study, the hydrologic submodel of RHESSys is evaluated by comparing model predictions of monthly and annual streamflow to stream gage data and by comparing RHESSys behavior to that of another hydrologic model of similar complexity, MIKESHE, for a 34 km2 watershed near Santa Barbara, California. In model intercomparison, the differences in predictions of temporal patterns in streamflow, sensitivity of model predictions to calibration parameters and landscape representation, and differences in model estimates of soil moisture patterns are explored. Results from this study show that both models adequately predict seasonal patterns of streamflow response relative to observed data, but differ significantly in terms of estimates of soil moisture patterns and sensitivity of those patterns to the scale of landscape tessellation used to derive spatially distributed elements. This sensitivity has implications for implementing RHESSys as a tool to investigate interactions between hydrology and ecosystem processes. [source]


    Norman L. Miller
    ABSTRACT: Previous reports based on climate change scenarios have suggested that California will be subjected to increased wintertime and decreased summertime streamflow. Due to the uncertainty of projections in future climate, a new range of potential climatological future temperature shifts and precipitation ratios is applied to the Sacramento Soil Moisture Accounting Model and Anderson Snow Model in order to determine hydrologic sensitivities. Two general circulation models (GCMs) were used in this analysis: one that is warm and wet (HadCM2 run 1) and one that is cool and dry (PCM run B06.06), relative to the GCM projections for California that were part of the Third Assessment Report of the Intergovernmental Panel on Climate Change. A set of specified incremental temperature shifts from 1.5C to 5.0C and precipitation ratios from 0.70 to 1.30 were also used as input to the snow and soil moisture accounting models, providing for additional scenarios (e.g., warm/dry, cool/wet). Hydrologic calculations were performed for a set of California river basins that extend from the coastal mountains and Sierra Nevada northern region to the southern Sierra Nevada region; these were applied to a water allocation analysis in a companion paper. Results indicate that for all snow-producing cases, a larger proportion of the streamflow volume will occur earlier in the year. The amount and timing is dependent on the characteristics of each basin, particularly the elevation. Increased temperatures lead to a higher freezing line, therefore less snow accumulation and increased melting below the freezing height. The hydrologic response varies for each scenario, and the resulting solution set provides bounds to the range of possible change in streamflow, snowmelt, snow water equivalent, and the change in the magnitude of annual high flows. An important result that appears for all snowmelt driven runoff basins, is that late winter snow accumulation decreases by 50 percent toward the end of this century. [source]

    Effects of a Severe Frost on Riparian Rainforest Restoration in the Australian Wet Tropics: Foliage Retention by Species and the Role of Forest Shelter

    Timothy J. Curran
    Restoration of ecological communities that can withstand future climate and land use changes requires information on species responses to various natural disturbances. Frost is an important disturbance that regulates plant species distributions, and although rare in tropical rainforest, it can occur in upland areas, especially where deforestation has occurred. We report the impacts of a severe frost that occurred in June and July 2007 on the Atherton Tablelands, Queensland, Australia and caused extensive damage to riparian restoration plots of upland rainforest species. We estimated proportion foliage retention to (1) compare impacts across 45 species; (2) examine the influence of plant height on frost effects; and (3) determine if plantings under shelterbelts of mature trees received less damage. Species exhibited different levels of foliage retention. Species that were particularly frost resistant included those from riparian habitats and a conifer. Some heavily impacted species are deciduous and may survive frost by shedding leaves; this warrants further investigation. Plant canopy height above ground level was only weakly correlated to foliage retention. Sheltered plants were much less damaged than unsheltered conspecifics, suggesting a useful way to mitigate frost impacts. These principles should help guide the development of resilient ecological communities in frost-prone areas. [source]

    Modelling species distributions without using species distributions: the cane toad in Australia under current and future climates

    ECOGRAPHY, Issue 4 2008
    Michael Kearney
    Accurate predictions of the potential distribution of range-shifting species are required for effective management of invasive species, and for assessments of the impact of climate change on native species. Range-shifting species pose a challenge for traditional correlative approaches to range prediction, often requiring the extrapolation of complex statistical associations into novel environmental space. Here we take an alternative approach that does not use species occurrence data, but instead captures the fundamental niche of a species by mechanistically linking key organismal traits with spatial data using biophysical models. We demonstrate this approach with a major invasive species, the cane toad Bufo marinus in Australia, assessing the direct climatic constraints on its ability to move, survive, and reproduce. We show that the current range can be explained by thermal constraints on the locomotor potential of the adult stage together with limitations on the availability of water for the larval stage. Our analysis provides a framework for biologically grounded predictions of the potential for cane toads to expand their range under current and future climate scenarios. More generally, by quantifying spatial variation in physiological constraints on an organism, trait-based approaches can be used to investigate the range-limits of any species. Assessments of spatial variation in the physiological constraints on an organism may also provide a mechanistic basis for forecasting the rate of range expansion and for understanding a species' potential to evolve at range-edges. Mechanistic approaches thus have broad application to process-based ecological and evolutionary models of range-shift. [source]

    Bacterial metabolism in small temperate streams under contemporary and future climates

    FRESHWATER BIOLOGY, Issue 12 2007
    Summary 1. We examined the detailed temperature dependence (0,40 C) of bacterial metabolism associated with fine sediment particles from three Danish lowland streams to test if temperature dependence varied between sites, seasons and quality of organic matter and to evaluate possible consequences of global warming. 2. A modified Arrhenius model with reversible denaturation at high temperatures could account for the temperature dependence of bacterial metabolism and the beginning of saturation above 35 C and it was superior to the unmodified Arrhenius model. Both models overestimated respiration rates at very low temperatures (<5 C), whereas Ratkowsky's model , the square root of respiration , provided an excellent linear fit between 0 and 30 C. 3. There were no indications of differences in temperature dependence among samples dominated by slowly or easily degradable organic substrates. Optimum temperature, apparent minimum temperature, Q10 -values for 0,40 C and activation energies of bacterial respiration were independent of season, stream site and degradability of organic matter. 4. Q10 -values of bacterial respiration declined significantly with temperature (e.g. 3.31 for 5,15 C and 1.43 for 25,35 C) and were independent of site and season. Q10 -values of bacterial production behaved similarly, but were significantly lower than Q10 -values of respiration implying that bacterial growth efficiency declined with temperature. 5. A regional warming scenario for 2071,2100 (IPCC A2) predicted that mean annual temperatures will increase by 3.5 C in the air and 2.2,4.3 C in the streams compared with the control scenario for 1961,1990. Temperature is expected to rise more in cool groundwater-fed forest springs than in open, summer-warm streams. Mean annual bacterial respiration is estimated to increase by 26,63% and production by 18,41% among streams assuming that established metabolism,temperature relationships and organic substrate availability remain the same. To improve predictions of future ecosystem behaviour, we further require coupled models of temperature, hydrology, organic production and decomposition. [source]

    Climate change and cattle nutritional stress

    GLOBAL CHANGE BIOLOGY, Issue 10 2010
    Abstract Owing to the complex interactions among climate, plants, cattle grazing, and land management practices, the impacts of climate change on cattle have been hard to predict. Predicting future grassland ecosystem functioning relies on understanding how changes in climate alter the quantity of forage produced, but also forage quality. Plant protein, which is a function of plant nitrogen concentrations, and digestible energy limit the performance of herbivores when in short supply; moreover, deficiencies can be expensive to mitigate. To better understand how changes in temperature and precipitation would affect forage protein and energy availability, we analyzed over 21 000 measurements of cattle fecal chemistry acquired over 14 years in the continental US. Our analysis of patterns in forage quality among ecologically defined regions revealed that increasing temperature and declining precipitation decreased dietary crude protein and digestible organic matter for regions with continental climates. Within regions, quality also declined with increased temperature; however, the effects of precipitation were mixed. Any future increases in precipitation would be unlikely to compensate for the declines in forage quality that accompany projected temperature increases. As a result, cattle are likely to experience greater nutritional stress in the future. If these geographic patterns hold as a proxy for future climates, agriculture will require increased supplemental feeds or the consequence will be a decrease in livestock growth. [source]

    Genetic maladaptation of coastal Douglas-fir seedlings to future climates

    Abstract Climates are expected to warm considerably over the next century, resulting in expectations that plant populations will not be adapted to future climates. We estimated the risk of maladaptation of current populations of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) to future climates as the proportion of nonoverlap between two normal distributions where the means and genetic variances of current and future populations are determined from genecological models derived from seedling common garden studies. The risk of maladaptation was large for most traits when compared with the risk associated with current transfers within seed zones, particularly for the more drastic climate change scenario. For example, the proportion of nonoverlap for a composite trait representing bud set, emergence, growth, and root : shoot ratio was as high as 0.90. We recommend augmenting within-population variation by mixing local populations with some proportion of populations from lower elevations and further south. Populations expected to be adapted to climates a century from now come from locations as far down in elevation as 450,1130 m and as far south in latitude as 1.8,4.9. [source]

    Use of response functions in selecting lodgepole pine populations for future climates

    GLOBAL CHANGE BIOLOGY, Issue 12 2006
    T. WANG
    Abstract Although growth response functions have previously been developed for lodgepole pine (Pinus contorta Dougl. ex Loud.) populations in British Columbia, new analyses were conducted: (1) to demonstrate the merit of a new local climate model in genecological analysis; (2) to highlight new methods for deriving response functions; and (3) to evaluate the impacts of management options for existing geographically defined seed planning units (SPUs) for reforestation. Results of this study suggest that new methods for anchoring population response functions, and a multivariate approach for incorporating climate variables into a single model, considerably improve the reliability of these functions. These functions identified a small number of populations in central areas of the species distribution with greater growth potential over a wide range of mean annual temperature (MAT). Average productivity of lodgepole pine is predicted to increase (up to 7%) if moderate warming (,2C MAT) occurs in the next few decades as predicted, although productivity would substantially decline in some SPUs in southern BC. Severe global warming (>3C MAT) would result in either a drastic decline in productivity or local populations being extirpated in southern SPUs. New deployment strategies using the best seed sources for future reforestation may not only be able to mitigate the negative impact of global warming, but may even be able to increase productivity in some areas. [source]

    Effects of elevated temperature and carbon dioxide on seed-set and yield of kidney bean (Phaseolus vulgaris L.)

    P. V. Vara Prasad
    Abstract It is important to quantify and understand the consequences of elevated temperature and carbon dioxide (CO2) on reproductive processes and yield to develop suitable agronomic or genetic management for future climates. The objectives of this research work were (a) to quantify the effects of elevated temperature and CO2 on photosynthesis, pollen production, pollen viability, seed-set, seed number, seeds per pod, seed size, seed yield and dry matter production of kidney bean and (b) to determine if deleterious effects of high temperature on reproductive processes and yield could be compensated by enhanced photosynthesis at elevated CO2 levels. Red kidney bean cv. Montcalm was grown in controlled environments at day/night temperatures ranging from 28/18 to 40/30 C under ambient (350 mol mol,1) or elevated (700 mol mol,1) CO2 levels. There were strong negative relations between temperature over a range of 28/18,40/30 C and seed-set (slope, ,,6.5% C,1) and seed number per pod (, 0.34 C,1) under both ambient and elevated CO2 levels. Exposure to temperature >,28/18 C also reduced photosynthesis (, 0.3 and ,,0.9 mol m,2 s,1 C,1), seed number (, 2.3 and ,,3.3 C,1) and seed yield (, 1.1 and ,,1.5 g plant,1 C,1), at both the CO2 levels (ambient and elevated, respectively). Reduced seed-set and seed number at high temperatures was primarily owing to decreased pollen production and pollen viability. Elevated CO2 did not affect seed size but temperature >,31/21 C linearly reduced seed size by 0.07 g C,1. Elevated CO2 increased photosynthesis and seed yield by approximately 50 and 24%, respectively. There was no beneficial interaction of CO2 and temperature, and CO2 enrichment did not offset the negative effects of high temperatures on reproductive processes and yield. In conclusion, even with beneficial effects of CO2 enrichment, yield losses owing to high temperature (> 34/24 C) are likely to occur, particularly if high temperatures coincide with sensitive stages of reproductive development. [source]

    Climate change scenarios and models yield conflicting predictions about the future risk of an invasive species in North America

    Anna M. Mika
    1The pea leafminer Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae) is an invasive species in North America and a serious economic pest on a wide variety of crops. We developed a bioclimatic envelope model (BEM) for this species and examined the envelope's potential location in North America under various future climates. 2We compared the future bioclimatic envelopes for L. huidobrensis using either simple scenarios comprising uniform changes in temperature/precipitation or climate projections from general circulation models (GCMs). Our simple scenarios were: (i) an increase of 0.1C per degree in latitude with a 20% increase in summer precipitation and a 20% decrease in winter precipitation and (ii) an overall increase of 3C everywhere, also with the same changes in precipitation. For GCM-modelled climate change, we used the Canadian Centre for Climate Modelling and Analysis GCM (CGCM2) and the Hadley Centre climate model (HadCM3), each in combination with two scenarios from the Special Report on Emissions Scenarios (A2 and B2). 3The BEM results using the simple scenarios were more similar to each other than to the results obtained using GCM projections. The results were also qualitatively different (i.e. spatially different and divergent) depending on which GCM-scenario combination was used. 4This modelling exercise illustrates that: (i) results using first approximation simple climate change scenarios can give predictions very different from those that use GCM-modelled climate projections (comprising a result that has worrying implications for empirical impact research) and that (ii) different GCM-models using the same scenario can give very different results (implying strong model dependency in projected biological impacts). [source]

    Effects of genotype, elevated CO2 and elevated O3 on aspen phytochemistry and aspen leaf beetle Chrysomela crotchi performance

    Leanne M. Vigue
    1Trembling aspen Populus tremuloides Michaux is an important forest species in the Great Lakes region and displays tremendous genetic variation in foliar chemistry. Elevated carbon dioxide (CO2) and ozone (O3) may also influence phytochemistry and thereby alter the performance of insect herbivores such as the aspen leaf beetle Chrysomela crotchi Brown. 2The present study aimed to relate genetic- and atmospheric-based variation in aspen phytochemistry to C. crotchi performance (larval development time, adult mass, survivorship). The experiment was conducted at the Aspen Free-Air CO2 Enrichment (FACE) site in northern Wisconsin. Beetles were reared on three aspen genotypes under elevated CO2 and/or O3. Leaves were collected to determine chemical characteristics. 3The foliage exhibited significant variation in nitrogen, condensed tannins and phenolic glycosides among genotypes. CO2 and O3, however, had little effect on phytochemistry. Nonetheless, elevated CO2 decreased beetle performance on one aspen genotype and had inconsistent effects on beetles reared on two other genotypes. Elevated O3 decreased beetle performance, especially for beetles reared on an O3 -sensitive genotype. Regression analyses indicated that phenolic glycosides and nitrogen explain a substantial amount (27,45%) of the variation in herbivore performance. 4By contrast to the negative effects that are typically observed with generalist herbivores, aspen leaf beetles appear to benefit from phenolic glycosides, chemical components that are largely genetically-determined in aspen. The results obtained in the present study indicate that host genetic variation and atmospheric concentrations of greenhouse gases will be important factors in the performance of specialist herbivores, such as C. crotchi, in future climates. [source]

    Coping with variability and change: Floods and droughts

    Zbigniew W. Kundzewicz
    Floods and droughts are natural phenomena for which the risks of occurrence are likely to continue to grow. Increasing levels of exposure and insufficient adaptive capacity are among the factors responsible for the rising vulnerability. The former is conditioned by anthropopressure (e.g., economic development of flood,prone areas) and adverse effects of climate change; scenarios for future climates indicate the possibility of amplified water,related extremes. This article presents the current situation of coping with extreme hydrological events within the pressure,state,response framework. Among promising response strategies, the role of forecast and warning, and of watershed management are reviewed. Sample success stories and lessons learnt related to hydrological extremes are given and policy implications discussed. [source]

    Diurnal and seasonal variations in stomatal conductance of rice at elevated atmospheric CO2 under fully open-air conditions

    PLANT CELL & ENVIRONMENT, Issue 3 2010
    ABSTRACT Understanding of leaf stomatal responses to the atmospheric CO2 concentration, [CO2], is essential for accurate prediction of plant water use under future climates. However, limited information is available for the diurnal and seasonal changes in stomatal conductance (gs) under elevated [CO2]. We examined the factors responsible for variations in gs under elevated [CO2] with three rice cultivars grown in an open-field environment under flooded conditions during two growing seasons (a total of 2140 individual measurements). Conductance of all cultivars was generally higher in the morning and around noon than in the afternoon, and elevated [CO2] decreased gs by up to 64% over the 2 years (significantly on 26 out of 38 measurement days), with a mean gs decrease of 23%. We plotted the gs variations against three parameters from the Ball-Berry model and two revised versions of the model, and all parameters explained the gs variations well at each [CO2] in the morning and around noon (R2 > 0.68), but could not explain these variations in the afternoon (R2 < 0.33). The present results provide an important basis for modelling future water use in rice production. [source]

    Does It Make Sense to Restore Wildland Fire in Changing Climate?

    Peter Z. Ful
    Abstract Forest restoration guided by historical reference conditions of fire regime, forest structure, and composition has been increasingly and successfully applied in fire-adapted forests of western North America. But because climate change is expected to alter vegetation distributions and foster severe disturbances, does it make sense to restore the ecological role of wildland fire through management burning and related activities such as tree thinning? I suggest that some site- and date-specific historical conditions may be less relevant, but reference conditions in the broad sense are still useful. Reference conditions encompass not only the recent past but also evolutionary history, reflecting the role of fire as a selective force over millennia. Taking a long-term functional view of historical reference conditions as the result of evolutionary processes can provide insights into past forest adaptations and migrations under various climates. As future climates change, historical reference data from lower, southerly, and drier sites may be useful in places that are higher, northerly, and currently wetter. Almost all models suggest that the future will have substantial increases in wildfire occurrence, but prior to recent human-caused fire exclusion, fire-adapted pine forests of western North America were among the most frequently burned in the world. Restoration of patterns of burning and fuels/forest structure that reasonably emulate historical conditions prior to fire exclusion is consistent with reducing the susceptibility of these ecosystems to catastrophic loss. Priorities may include fire and thinning treatments of upper elevation ecotones to facilitate forest migration, whereas vulnerable low-elevation forests may merit less management investment. [source]