Modeling effects of climate change on Yakima River salmonid habitats

We evaluated the potential effects of two climate change scenarios on salmonid habitats in the Yakima River by linking the outputs from a watershed model, a river operations model, a two-dimensional (2D) hydrodynamic model, and a geographic information system (GIS). The watershed model produced a discharge time series (hydrograph) in two study reaches under three climate scenarios: a baseline (1981–2005), a 1-°C increase in mean air temperature (plus one scenario), and a 2-°C increase (plus two scenario). A river operations model modified the discharge time series with Yakima River operational rules, a 2D model provided spatially explicit depth and velocity grids for two floodplain reaches, while an expert panel provided habitat criteria for four life stages of coho and fall Chinook salmon. We generated discharge-habitat functions for each salmonid life stage (e.g., spawning, rearing) in main stem and side channels, and habitat time series for baseline, plus one (P1) and plus two (P2) scenarios. The spatial and temporal patterns in salmonid habitats differed by reach, life stage, and climate scenario. Seventy-five percent of the 28 discharge-habitat responses exhibited a decrease in habitat quantity, with the P2 scenario producing the largest changes, followed by P1. Fry and spring/summer rearing habitats were the most sensitive to warming and flow modification for both species. Side channels generally produced more habitat than main stem and were more responsive to flow changes, demonstrating the importance of lateral connectivity in the floodplain. A discharge-habitat sensitivity analysis revealed that proactive management of regulated surface waters (i.e., increasing or decreasing flows) might lessen the impacts of climate change on salmonid habitats.     

The effects of increased stream temperatures on juvenile steelhead growth in the Yakima River Basin based on projected climate change scenarios

Stakeholders within the Yakima River Basin expressed concern over impacts of climate change on mid-Columbia River steelhead (Oncorhynchus mykiss), listed under the Endangered Species Act. We used a bioenergetics model to assess the impacts of changing stream temperatures—resulting from different climate change scenarios—on growth of juvenile steelhead in the Yakima River Basin. We used diet and fish size data from fieldwork in a bioenergetics model and integrated baseline and projected stream temperatures from down-scaled air temperature climate modeling into our analysis. The stream temperature models predicted that daily mean temperatures of salmonid-rearing streams in the basin could increase by 1–2 °C and our bioenergetics simulations indicated that such increases could enhance the growth of steelhead in the spring, but reduce it during the summer. However, differences in growth rates of fish living under different climate change scenarios were minor, ranging from about 1–5 %. Because our analysis focused mostly on the growth responses of steelhead to changes in stream temperatures, further work is needed to fully understand the potential impacts of climate change. Studies should include evaluating changing stream flows on fish activity and energy budgets, responses of aquatic insects to climate change, and integration of bioenergetics, population dynamics, and habitat responses to climate change.     

A stakeholder project to model water temperature under future climate scenarios in the Satus and Toppenish watersheds of the Yakima River Basin in Washington,USA

The goal of this study was to support an assessment of the potential effects of climate change on select natural, social, and economic resources in the Yakima River Basin. A workshop with local stakeholders highlighted the usefulness of projecting climate change impacts on anadromous steelhead (Oncorhynchus mykiss), a fish species of importance to local tribes, fisherman, and conservationists. Stream temperature is an important environmental variable for the freshwater stages of steelhead. For this study, we developed water temperature models for the Satus and Toppenish watersheds, two of the key stronghold areas for steelhead in the Yakima River Basin. We constructed the models with the Stream Network Temperature Model (SNTEMP), a mechanistic approach to simulate water temperature in a stream network. The models were calibrated over the April 15, 2008 to September 30, 2008 period and validated over the April 15, 2009 to September 30, 2009 period using historic measurements of stream temperature and discharge provided by the Yakama Nation Fisheries Resource Management Program. Once validated, the models were run to simulate conditions during the spring and summer seasons over a baseline period (1981–2005) and two future climate scenarios with increased air temperature of 1 °C and 2 °C. The models simulated daily mean and maximum water temperatures at sites throughout the two watersheds under the baseline and future climate scenarios.     

Climate warming, water storage, and Chinook salmon in California’s Sacramento Valley

The Chinook salmon (Oncorhynchus tshawytscha) spawns and rears in the cold, freshwater rivers and tributaries of California’s Central Valley, with four separate seasonal runs including fall and late-fall runs, a winter run, and a spring run. Dams and reservoirs have blocked access to most of the Chinook’s ancestral spawning areas in the upper reaches and tributaries. Consequently, the fish rely on the mainstem of the Sacramento River for spawning habitat. Future climatic warming could lead to alterations of the river’s temperature regime, which could further reduce the already fragmented Chinook habitat. Specifically, increased water temperatures could result in spawning and rearing temperature exceedences, thereby jeopardizing productivity, particularly in drought years. Paradoxically, water management plays a key role in potential adaptation options by maintaining spawning and rearing habitat now and in the future, as reservoirs such as Shasta provide a cold water supply that will be increasingly needed to counter the effects of climate change. Results suggest that the available cold pool behind Shasta could be maintained throughout the summer assuming median projections of mid-21st century warming of 2°C, but the maintenance of the cold pool with warming on the order of 4°C could be very challenging. The winter and spring runs are shown to be most at risk because of the timing of their reproduction.     

Impacts of climate change on August stream discharge in the Central-Rocky Mountains

In the snowmelt dominated hydrology of arid western US landscapes, late summer low streamflow is the most vulnerable period for aquatic ecosystem habitats and trout populations. This study analyzes mean August discharge at 153 streams throughout the Central Rocky Mountains of North America (CRMs) for changes in discharge from 1950–2008. The purpose of this study was to determine if: (1) Mean August stream discharge values have decreased over the last half-century; (2) Low discharge values are occurring more frequently; (3) Climatic variables are influencing August discharge trends. Here we use a strict selection process to characterize gauging stations based on amount of anthropogenic impact in order to identify heavily impacted rivers and understand the relationship between climatic variables and discharge trends. Using historic United States Geologic Survey discharge data, we analyzed data for trends of 40–59 years. Combining of these records along with aerial photos and water rights records we selected gauging stations based on the length and continuity of discharge records and categorized each based on the amount of diversion. Variables that could potentially influence discharge such as change in vegetation and Pacific Decadal Oscillation (PDO) were examined, but we found that that both did not significantly influence August discharge patterns. Our analyses indicate that non-regulated watersheds are experiencing substantial declines in stream discharge and we have found that 89% of all non-regulated stations exhibit a declining slope. Additionally our results here indicate a significant (α?≤?0.10) decline in discharge from 1951–2008 for the CRMs. Correlations results at our pristine sites show a negative relationship between air temperatures and discharge and these results coupled with increasing air temperature trends pose serious concern for aquatic ecosystems in CRMs.     

The effect of climate change on glacier ablation and baseflow support in the Nooksack River basin and implications on Pacific salmonid species protection and recovery

The Nooksack Indian Tribe (Tribe) inhabits the area around Deming, Washington, in the northwest corner of the state. The Tribe is dependent on various species of Pacific salmonids that inhabit the Nooksack River for ceremonial, commercial, and subsistence purposes. Of particular importance to the Tribe are spring Chinook salmon. Since European arrival, the numbers of fish that return to spawn have greatly diminished because of substantial loss of habitat primarily due to human-caused alteration of the watershed. Although direct counts are not available, it is estimated that native salmonid runs are less than 8 % of the runs in the late 1800’s. In addition, climate change has caused and will continue to cause an increase in winter flows, earlier snowmelt, decrease in summer baseflows, and an increase in water temperatures that exceed the tolerance levels, and in some cases lethal levels, of several Pacific salmonid species. The headwaters of the Nooksack River originate from glaciers on Mount Baker that have experienced significant changes over the last century due to climate change. Melt from the glaciers is a major source of runoff during the low-flow critical summer season, and climate change will have a direct effect on the magnitude and timing of stream flow in the Nooksack River. Understanding these changes is necessary to protect the Pacific salmonid species from the harmful effects of climate change. All nine salmonid species that inhabit the Nooksack River will be adversely affected by reduced summer flows and increased temperatures. The most important task ahead is the planning for, and implementation of, habitat restoration prior to climate change becoming more threatening to the survival of these important fish species. The Tribe has been collaboratively working with government agencies and scientists on the effects of climate change on the hydrology of the Nooksack River. The extinction of salmonids from the Nooksack River is unacceptable to the Tribe since it is dependent on these species and the Tribe is place-based and cannot relocate to areas where salmon will survive.     

Modeling the impacts of climate change on nitrogen retention in a 4th order stream

Climate induced changes of temperature, discharge and nitrogen concentration may change natural denitrification processes in river systems. Until now seasonal variation of N-retention by denitrification under different climate scenarios and the impact of river morphology on denitrification have not been thoroughly investigated. In this study climate scenarios (dry, medium and wet) have been used to characterize changing climatic and flow conditions for the period 2050–2054 in the 4th order stream Weiße Elster, Germany. Present and future periods of nitrogen turnover were simulated with the WASP5 river water quality model. Results revealed that, for a dry climate scenario, the mean denitrification rate was 71% higher in summer (low flow period between 2050 and 2054) and 51% higher in winter (high flow period) compared to the reference period. For the medium and wet climate scenarios, denitrification was slightly higher in summer (3% and 4%) and lower in winter (9% and 3% for medium and wet scenarios, respectively). Additionally, the variability of denitrification rates was higher in summer compared to winter conditions. For a natural river section, denitrification was a factor of 1.22 higher than for a canalized river reach. Besides, weirs along the river decrease the denitrification rate by 16% in July for dry scenario conditions. In the 42 km study reach, N-retention through denitrification amounted to 5.1% of the upper boundary N load during summer low flow conditions in the reference period. For the future dry climate scenario this value increased up to 10.2% and for the medium climate scenario up to 5.4%. In our case study the investigated climate scenarios showed that future discharge changes may have a larger impact on denitrification rates than future temperature changes. Overall results of the study revealed the significance of climate change in regulating the magnitude, seasonal pattern and variability of nitrogen retention. The results provide guidance for managing nitrogen related environmental problems for present and future climate conditions.     

Potential spread of recently naturalised plants in New Zealand under climate change

Climate change and biological invasions are major causes of biodiversity loss and may also have synergistic effects, such as range shifts of invaders due to changing climate. Bioclimatic models provide an important tool to assess how the threat of invasive species may change with altered temperature and precipitation regimes. In this study, potential distributions of three recently naturalised plant species in New Zealand are modelled (Archontophoenix cunninghamiana, Psidium guajava and Schefflera actinophylla), using four different general circulation models (CCCMA-CGCM3, CSIRO-Mk3.0, GFDL-CM2.0 and UKMO-HADCM3) with two emission scenarios (A2 and B1) each. Based on a maximum entropy approach, models were trained on global data using a small set of uncorrelated predictors. The models were projected to the country of interest, using climate models that had been statistically downscaled to New Zealand, in order to obtain high resolution predictions. This study provides evidence of the potential range expansion of these species, with potentially suitable habitat increasing by as much as 169 % (A. cunninghamiana; with up to 115,805 km² of suitable habitat), 133 % (P. guajava; 164,450 km²) and 208 % (S. actinophylla; 31,257 km²) by the end of the century compared to the currently suitable habitat. The results show that while predictions vary depending on the chosen climate scenario, there is remarkable consistency amongst most climate models within the same emission scenario, with overlaps in areas of predicted presence ranging between 81 % and 99.5 % (excluding CSIRO-Mk3.0). By having a better understanding of how climate change will affect distribution of invasive plants, appropriate management measures can be taken.     

Synoptic drivers of 400 years of summer temperature and precipitation variability on Mt. Olympus,Greece

The Mediterranean region has been identified as a global warming hotspot, where future climate impacts are expected to have significant consequences on societal and ecosystem well-being. To put ongoing trends of summer climate into the context of past natural variability, we reconstructed climate from maximum latewood density (MXD) measurements of Pinus heldreichii (1521–2010) and latewood width (LWW) of Pinus nigra (1617–2010) on Mt. Olympus, Greece. Previous research in the northeastern Mediterranean has primarily focused on inter-annual variability, omitting any low-frequency trends. The present study utilizes methods capable of retaining climatically driven long-term behavior of tree growth. The LWW chronology corresponds closely to early summer moisture variability (May–July, r = 0.65, p < 0.001, 1950–2010), whereas the MXD-chronology relates mainly to late summer warmth (July–September, r = 0.64, p < 0.001; 1899–2010). The chronologies show opposing patterns of decadal variability over the twentieth century (r = ?0.68, p < 0.001) and confirm the importance of the summer North Atlantic Oscillation (sNAO) for summer climate in the northeastern Mediterranean, with positive sNAO phases inducing cold anomalies and enhanced cloudiness and precipitation. The combined reconstructions document the late twentieth—early twenty-first century warming and drying trend, but indicate generally drier early summer and cooler late summer conditions in the period ~1700–1900 CE. Our findings suggest a potential decoupling between twentieth century atmospheric circulation patterns and pre-industrial climate variability. Furthermore, the range of natural climate variability stretches beyond summer moisture availability observed in recent decades and thus lends credibility to the significant drying trends projected for this region in current Earth System Model simulations.     

IMPACT OF ENSO ON VARIABILITY OF SUMMER MONSOON OVER ASIA AND SUMMER RAINFALL IN CHINA

In this paper, the variability of the Asian summer monsoon circulation during the ENSO period is diagnostically analyzed. Evidence suggests that every member of the Asian summer monsoon system change in varying degrees, even, oppositely, during El Nino and La Nina events. Then, the basis of the summer rainfall in east China analyzed using EOF, both region and extent of impact of the eastern tropical Pacific SSTA on the summer rainfall in East China are analyzed. This impact is closely related with development phase of the ENSO cycle, being most notable in the middle and lower reaches of the Yangtze and south of China.     

Simulating the hydrological response to predicted climate change on a watershed in southern Alberta, Canada

The current body of research in western North America indicates that water resources in southern Alberta are vulnerable to climate change impacts. The objective of this research was to parameterize and verify the ACRU agro-hydrological modeling system for a small watershed in southern Alberta and subsequently simulate the change in future hydrological responses over 30-year simulation periods. The ACRU model successfully simulated monthly streamflow volumes (r ²?=?0.78), based on daily simulations over 27 years. The delta downscaling technique was used to perturb the 1961?C1990 baseline climate record from a range of global climate model (GCM) projections to provide the input for future hydrological simulations. Five future hydrological regimes were compared to the 1961?C1990 baseline conditions to determine the average net effect of change scenarios on the hydrological regime of the Beaver Creek watershed over three 30-year time periods (starting in 2010, 2040 and 2070). The annual projections of a warmer and mostly wetter climate in this region resulted in a shift of the seasonal streamflow distribution with an increase in winter and spring streamflow volumes and a reduction of summer and fall streamflow volumes over all time periods, relative to the baseline conditions (1961?C1990), for four of the five scenarios. Simulations of actual evapotranspiration and mean annual runoff showed a slight increase, which was attributed to warmer winters, resulting in more winter runoff and snowmelt events.     

Changes in the climate of the Alaskan North Slope and the ice concentration of the adjacent Beaufort Sea

A reliable data set of Arctic sea ice concentration based on satellite observations exists since 1972. Over this time period of 36 years western arctic temperatures have increased; the temperature rise varies significantly from one season to another and over multi-year time scales. In contrast to most of Alaska, however, on the North Slope the warming continued after 1976, when a circulation change occurred, as expressed in the PDO index. The mean temperature increase for Barrow over the 36-year period was 2.9°C, a very substantial change. Wind speeds increased by 18% over this time period, however, the increase were non-linear and showed a peak in the early 1990s. The sea ice extent of the Arctic Ocean has decreased strongly in recent years, and in September 2007 a new record in the amount of open water was recorded in the Western Arctic. We observed for the Southern Beaufort Sea a fairly steady increase in the mean annual amount of open water from 14% in 1972 to 39% in 2007, as deduced from the best linear fit. In late summer the decrease is much larger, and September has, on average, the least ice concentration (22%), followed by August (35%) and October (54%). The correlation coefficient between mean annual values of temperature and sea ice concentration was 0.84. On a monthly basis, the best correlation coefficient was found in October with 0.88. However, the relationship between winter temperatures and the sea ice break-up in summer was weak. While the temperature correlated well with the CO₂ concentration (r?=?0.86), the correlation coefficient between CO₂ and sea ice was lower (r?=??0.68). After comparing the ice concentration with 17 circulation indices, the best relation was found with the Pacific Circulation Index (r?=??0.59).     

Modeling of climate change effects on stream temperatures and fish habitats below dams and near groundwater inputs

A deterministic heat transport model was developed to calculate stream water temperatures downstream of reservoir outlets (tailwaters) and groundwater sources. The model calculates heat exchange between the atmosphere, the water and the sediments and is driven by climate and stream hydrologic parameters. Past and projected climate conditions were used as input to the stream water temperature model. To produce a projected future weather scenario, output from the Columbia University Goddard Institute for Space Studies (GISS) global circulation model (GCM) for a doubling of atmospheric CO₂ were used to adjust past (1955–1979) weather parameters. Stream reach lengths, within which water temperatures are suitable for survival or good growth of 28 fish species, were determined for four selected streams. Several alternative upstream inflow conditions were chosen: Discharges from surface (epilimnion) and bottom (hypolimnion) outlets of reservoirs, and two groundwater inflow scenarios. By applying water temperature criteria for fish survival and good growth (Stefanet al., 1993) to simulated stream temperatures, it was possible to estimate stream lengths with suitable habitat. When simulated suitable habitat was compared to actual fish observations, good agreement was found. For projected climate change, the simulations showed how much of the available stream habitat would be lost. In the examples presented the effect of cold hypolimnetic water release from a reservoir or groundwater discharges is felt as far as 48 km (30 miles) downstream from its source, especially in smaller shaded streams. The impact of climate change on stream temperatures below dams is more pronounced when the water release is from the epilimnion (reservoir surface) rather than the hypolimnion (deep water). Examples used for this study show elimination of coldwater habitat for rainbow trout when the upstream release is from the surface of a reservoir, but only reductions of coldwater habitat when the upstream release is from a reservoir hypolimnion.     

Characterization of precipitation δ 18O variation in Nagqu, central Tibetan Plateau and its climatic controls

The stable isotopic composition of precipitation in different regions reflects climatic factors such as temperature, precipitation, moisture sources, and transport process. However, the isotopic variation in the region is usually much complicated due to the combined influences of these factors. A good understanding of climatic controls on the isotopic composition of precipitation can contribute to the study on isotopic tracer for climate and hydrology. To investigate the isotopic variation of precipitation and its climatic controls in the middle of the Tibetan Plateau, a monitoring station for stable isotope in precipitation has been established in Nagqu region, central Tibetan Plateau. We obtained 79 daily samples at Nagqu Meteorological Station in 2000. The observed δ ¹⁸O in precipitation showed a distinctly seasonal pattern with higher values in spring and winter and lower values in summer, despite of individually low values in winter due to extremely low temperature. To further understand this pattern, we evaluated the influence of temperature, precipitation, moisture sources, and moisture transport process on precipitation δ ¹⁸O. A multiple linear regression model represents quantitatively the dependence of precipitation δ ¹⁸O on precipitation and temperature: δ ¹⁸O_ppt?=??0.30P???0.11T???14.8 (R ²?=?0.13, n?=?79, P?=?0.005), which indicates δ ¹⁸O values in precipitation are more dependent on precipitation amount than on temperature. In contrast, when the temperature is low enough (<2°C), δ ¹⁸O values in precipitation are mainly dependent on temperature: δ ¹⁸O_ppt?=?0.53T???10.2 (R ²?=?0.44, n?=?19, P?=?0.002). The variation of δ ¹⁸O in precipitation is also closely related to moisture origins and transport trajectories. A model is set up to trace the trajectories for air masses arriving in the observed region, and the results demonstrated that humid marine air masses from the Indian Ocean generally have significantly lower δ ¹⁸O values than dry continental air masses from the north or local re-evaporation. During monsoon precipitation, the distance and depth of moisture transport as well as convective precipitation all lead to the large variability of δ ¹⁸O in precipitation.     

Impact of intensive fish farming on methane emission in a tropical hydropower reservoir

Fisheries and aquaculture are important sources of food for hundreds of millions of people around the world. World fish production is projected to increase by 15% in the next 10 years, reaching around 200 million tonnes per year. The main driver of this increase will be based on fish farming management in developing countries. In Brazil, fish farming is increasing due to the climate conditions and large supply of water resources, with the production system based on Nile tilapia (Oreochromis niloticus) farming in reservoirs. Inland waters like reservoirs are a natural source of methane (CH₄) to the atmosphere. However, knowledge of the impact from intensive fish production in net cages on CH₄ fluxes is not well known. This paper presents in situ measurements of CH₄ fluxes and dissolved CH₄ (DM) in the Furnas Hydroelectric Reservoir in order to evaluate the impact of fish farming on methane emissions. Measurements were taken in a control area without fish production and three areas with fish farming. The overall mean of diffusive methane flux (DMF) (5.9?±?4.5 mg CH₄ m^?2 day^?1) was significantly lower when compared to the overall mean of bubble methane flux (BMF) (552.9?±?1003.9 mg CH₄ m^?2 day^?1). The DMF and DM were significantly higher in the two areas with fish farming, whereas the BMF was not significantly different. The DMF and DM were correlated to depth and chlorophyll-a. However, the low production of BMF did not allow the comparison with the limnological parameters measured. This case study shows that CH₄ emissions are influenced more by reservoir characteristics than fish production. Further investigation is necessary to assess the impact of fish farming on the greenhouse gas emissions.     

Influence of climate factors on spatial distribution of Texas cattle breeds

This paper investigates the spatial distribution of cattle breeders in Texas to quantify how climate factors influence cattle breed selection. A multivariate probit model is employed to examine the county-level binary choices of Bos taurus, Bos indicus and composite breeds derived from cattle breed association membership data. The estimation results suggest that summer heat stress is a significant factor for breed selection: positive for Bos indicus and negative for Bos taurus and composite breeds, with the average marginal effects on breed membership probability being 9.7 %, ?26.5 % and ?7.9 %, respectively. The intensity of the summer heat impacts can lead to noteworthy changes in spatial distributions of Texas cattle breeds in the event of climate change.     

An analysis of the spatial pattern of summer persistent moderate-to-heavy rainfall regime in Guizhou Province of Southwest China and the control factors

In this study, we investigated spatial and temporal variation patterns of persistent moderate-to-heavy rainfall events in Guizhou Province of southwest China during 1951–2004. We first performed conventional frequency analysis using the annual maximum daily series at 36 weather stations fit to log-normal distribution curves. Then, we examined the frequencies of moderate-to-heavy rainfall events (>?=?20 mm/day) and persistent rainfall events (10–day running sum >?=?100 mm) during the summer season (June through August). Using principal component analysis, we identified various spatial patterns of the rainfall regime and macroscale atmospheric conditions that influence these patterns. It was found that a minor mode of variation in the 500 hPa geopotential height anomaly field over East Asia (the third principal component) had a very good relationship to the dominant regional precipitation regime (Spearman’s correlation coefficient?=?–0.623). This mode of circulation represents the N–S variation of the upper-air pressure gradients over East Asia. During its positive phase, the pressure gradient south of 40°N is reduced and accompanied by a ridge over the East China coast, while the pressure gradient north of this latitude is enhanced. Correspondingly, the study region experiences fewer persistent moderate-to-heavy rainfall events. In its negative phase, the pattern in the 500 hPa geopotential height anomaly field is reversed and the study region experiences more persistent moderate-to-heavy rainfall events. This circulation mode is related to both East Asian and Indian summer monsoons. It is also associated with the northward intrusion of the West Pacific subtropical high, the size of the circumpolar vortex over the Pacific, and the impact of the Tibetan Plateau.     

Impact of climate change on human-wildlife-ecosystem interactions in the Trans-Himalaya region of Nepal

The Trans-Himalaya region boasts an immense biodiversity which includes several threatened species and supports the livelihood of local human populations. Our aim in this study was to evaluate the impact of recent climate change on the biodiversity and human inhabitants of the upper Mustang region of the Trans-Himalaya, Nepal. We found that the average annual temperature in the upper Mustang region has increased by 0.13 °C per year over the last 23 years; a higher annual temperature increase than experienced in other parts of Himalaya. A predictive model suggested that the mean annual temperature will double by 2161 to reach 20 °C in the upper Mustang region. The combined effects of increased temperature and diminished snowfall have resulted in a reduction in the area of land suitable for agriculture. Most seriously affected are Samjung village (at 4,100 m altitude) and Dhey village (at 3,800 m) in upper Mustang, where villagers have been forced to relocate to an area with better water availability. Concurrent with the recent change in climate, there have been substantial changes in vegetation communities. Between 1979 and 2009, grasslands and forests in the Mustang district have diminished by 11 and 42 %, respectively, with the tree line having shifted towards higher elevation. Further, grasses and many shrub species are no longer found in abundance at higher elevations and consequently blue sheep (Pseduois nayaur) move to forage at lower elevations where they encounter and raid human crops. The movement of blue sheep attracts snow leopard (Panthera uncia) from their higher-elevation habitats to lower sites, where they encounter and depredate livestock. Increased crop raiding by blue sheep and depredations of livestock by snow leopard have impacted adversely on the livelihoods of local people.     

Sea level rise and tigers: predicted impacts to Bangladesh’s Sundarbans mangroves

The Sundarbans mangrove ecosystem, shared by India and Bangladesh, is recognized as a global priority for biodiversity conservation. Sea level rise, due to climate change, threatens the long term persistence of the Sundarbans forests and its biodiversity. Among the forests’ biota is the only tiger (Panthera tigris) population in the world adapted for life in mangrove forests. Prior predictions on the impacts of sea level rise on the Sundarbans have been hampered by coarse elevation data in this low-lying region, where every centimeter counts. Using high resolution elevation data, we estimate that with a 28 cm rise above 2000 sea levels, remaining tiger habitat in Bangladesh’s Sundarbans would decline by 96% and the number of breeding individuals would be reduced to less than 20. Assuming current sea level rise predictions and local conditions do not change, a 28 cm sea level rise is likely to occur in the next 50–90 years. If actions to both limit green house gas emissions and increase resilience of the Sundarbans are not initiated soon, the tigers of the Sundarbans may join the Arctic’s polar bears (Ursus maritimus) as early victims of climate change-induced habitat loss.     

Spatiotemporal trends of aridity index in arid and semi-arid regions of Iran

The spatiotemporal trends of aridity index in the arid and semi-arid regions of Iran in 1966–2005 were investigated using the Mann–Kendall test and Theil–Sen’s slope estimator. The results of the analysis showed negative trends in annual aridity index at 55 % of the stations, while just one site had a statistically significant (α?=?0.1) negative trend. Furthermore, the positive trends in the annual aridity index series were significant at the 95 % confidence level at Bushehr and Isfahan stations. The significant negative trend in the annual aridity index was obtained over Mashhad at the rate of ?0.004. In the seasonal series, the negative trends in the spring and winter aridity index were larger compared with those in the other seasonal series. A noticeable decrease in the winter aridity index series was observed mostly in the southeast of the study area. In the summer and autumn aridity index, two significant positive trends were found.