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PubMed2001

Climate extremes and adaptive management on the Colorado River: lessons from the 1997-1998 ENSO event.

The Colorado River system exhibits the characteristics of a heavily over-allocated or 'closing water system'. In such systems, development of mechanisms to allow resource users to acknowledge interdependence and to engage in negotiations and agreements becomes necessary. Recently, after a decade of deliberations and environmental assessments, the Glen Canyon Dam Adaptive Management Program (GCDAMP) was established to monitor and analyze the effects of dam operations on the Grand Canyon ecosystem and recommend adjustments intended to preserve and enhance downstream physical, cultural and environmental values. The Glen Canyon Dam effectively separates the Colorado into its lower and upper basins. Dam operations and adaptive management decisions are strongly influenced by variations in regional climate. This paper focuses on the management of extreme climatic events within the Glen and Grand Canyon Region of the Colorado River. It illustrates how past events (both societal and physical) condition management flexibility and receptivity to new information. The types of climatic information and their appropriate entry points in the annual cycle of information gathering and decision-making (the 'hydro-climatic decision calendar') for dam operations and the adaptive management program are identified. The study then describes how the recently implemented program, lessons from past events, and new climate information on the Colorado River Basin, facilitated responses during the major El Niño-Southern Oscillation (ENSO) event of 1997-1998. Recommendations are made for engaging researchers and practitioners in the effective use of climatic information in similar settings where the decision stakes are complex and the system uncertainty is large.

Climate↗
PubMed1991

Sensible climates in monsoon Asia.

This study identifies characteristics of the geographical distribution of sensible climates and their diurnal and annual variations, and presents a classification of bioclimates in monsoon Asia by using Kawamura's discomfort index formula. During the hottest month, tropical areas and areas in central and South China are uncomfortable for humans throughout the day and night, and temperate zones in lowlands are uncomfortable during the daytime. Tropical zones are uncomfortable all year long and temperate zones in lowlands are uncomfortable during summer. Four climatic types were distinguished in monsoon Asia. Climatic type I, hyperthermal throughout the year, occurs in the tropics south of latitude 20 degrees N. Climatic type II, hyperthermal in the hottest month and comfortable in the coldest month, extends over latitudes from 20 degrees to 30 degrees N except in the highlands. Climatic type III, hyperthermal in the hottest month and hypothermal in the coldest month, encompasses temperate zones of East Asia and subtropical arid areas of northwestern India. Climatic type V, comfortable in the hottest month and hypothermal in coldest month, occurs near the southeast coast of the Soviet Union and in the highlands of the Himalayas.

Asia↗
PubMed2006

Is body size of the water frog Rana esculenta complex responding to climate change?

Recent studies on climate responses in ectothermic (cold-blooded) vertebrates have been few in number and focussed on phenology rather than morphology. According to Bergmann's rule, endothermic (warm-blooded) vertebrates from cooler climates tend to be larger than congeners from warmer regions. Although amphibians are ectothermic vertebrates, weather and climatic conditions may also impact on their morphology, and thereby affect their survival rates and population dynamics. In this paper, we show, in a unique long-term study during the period 1963-2003 in an agricultural landscape in western Poland, that the body length of two water frog parental species (males of both Rana ridibunda and R. lessonae) increased significantly. However, their hybridogenetic hybrid R. esculenta did not show similar changes. A significant relationship with a large-scale climatic factor, the winter North Atlantic Oscillation index, was found positive for R. ridibunda males and R. lessonae females, and negative for R. esculenta females. Our findings, the first for amphibians, are consistent with other studies reporting that recent climate change has affected the morphology of animals. However, we also show that changes in amphibian phenotype linked to climate may vary independently between (even very similar) species.

Animals↗
PubMed2001

Application of a progressive-difference method to identify climatic factors causing variation in the rice yield in the Yangtze Delta, China.

Time series of rice yields consist of a technology-driven trend and variations caused by climate fluctuations. To explore the relationship between yields and climate, the trend and temporal variation often have to be separated. In this study, a progressive-difference method was applied to eliminate the trend in time series. By differentiating yields and climatic factors in 2 successive years, the relationship between variations in yield and climatic factors was determined with multiple-regression analysis. The number of hours of sunshine, the temperature and the precipitation were each defined for different intervals during the growing season and used as different regression variables. Rice yields and climate data for the Yangtze Delta of China from 1961 to 1990 were used as a case study. The number of hours of sunshine during the tillering stage and the heading to milk stage particularly affected the yield. In both periods radiation was low. In the first period, the vegetative organs of the rice crop were formed while in the second period solar radiation was important for grain filling. The average temperature during the tillering to jointing stage reached its maximum, which affected rice yields negatively. Precipitation was generally low during the jointing and booting stages, which had a positive correlation with yield, while high precipitation had a negative effect during the milk stage. The results indicate that the climatic factors should be expressed as 20- to 30-day averages in the Yangtze Delta; a shorter or longer period, e.g. 10 or 40 days, is less appropriate.

China↗
PubMed2001

An investigation of relationships between climate and dengue using a water budgeting technique.

Climatic water budget indicators were used to assess intra- and interannual variations in dengue incidence for San Juan, Puerto Rico. Multivariate stochastic relationships between dengue and the water budget were developed to (1) determine and quantify the particular climatic measures and their associated lag periods related to dengue variations, and (2) assess their use for dengue prediction and initiation of emergency response procedures. Such a predictive model would be advantageous because it is based on reliable, easily obtained, and low-cost weather observations. Daily running averages of water budget variables over an 8-week period were related to daily running averages of unconfirmed dengue totals (1988-1993). Resultant models show that a variety of water budget and traditional climate measures over the full 8-week period are associated with dengue. The mean seasonal variation in dengue is highly related (R2=88.1%) to the mean seasonal climate variation, with those thermal and energy variables immediately preceding the dengue response showing the strongest relationships. However, moisture variables, predominantly in the form of surplus, are more influential many weeks in advance. For the interannual model (R2=44.1%), energy change, thermal change, and moisture variables are significant across the 8-week period, with moisture variables playing a stronger role than in the intraannual model. Standardisation substantially changes the importance and timing of the variables, and suggests that dengue during this period is more associated with the mean annual variation of climate than deviations from mean conditions. A dengue early-warning model (based on 5 weeks of climate data) was also developed to predict dengue incidence 3 weeks later. While this predictive model is not reliable as a sole predictor of dengue in San Juan, it may be useful as part of a multifaceted watch/warning system.

Animals↗
PubMed2006

Climate change, flow regulation and land-use effects on the hydrology of the Peace-Athabasca-Slave System; findings from the Northern Rivers Ecosystem Initiative.

The Northern Rivers Ecosystem Initiative (NREI) was established in the late 1990s to address important science questions resulting from previous studies undertaken by the Northern Rivers Basin Study (NRBS). This manuscript summarizes the results from a number of reports on hydrologic research conducted on the Peace-Athabasca-Slave river and lake systems. Specific concerns expressed by the NRBS and subsequent NREI focused on how these systems were being affected by climate change, flow regulation and land-use changes. Issues addressed in this report include: the fate of aquatic perched basins within the Peace-Athabasca Delta under historical and future climate trends; the sources of major floods that replenish these basins and how the frequency, magnitude and source areas of such events have changed over time; the synoptic weather patterns and atmospheric teleconnections that are responsible for the generation of major snowmelt runoff that drive major floods; the potential effect that climate and land-use changes might have on basin runoff and delta lake levels; the specific hydro-climatic conditions required to produce major ice-jam floods on the Peace River and how these may be altered by climate change; remote-sensing methods to document delta flooding and vegetation change; and the dual effect of climate and flow regulation on the water levels of Great Slave Lake and how these may affect other nearshore processes, particularly wind seiches, that influence flooding of the Slave River Delta. A review of the major findings and recommendations for future research concludes the report.

Canada↗
PubMed2005

Climate change and the potential for range expansion of the Lyme disease vector Ixodes scapularis in Canada.

We used an Ixodes scapularis population model to investigate potential northward spread of the tick associated with climate change. Annual degree-days >0 degrees C limits for I. scapularis establishment, obtained from tick population model simulations, were mapped using temperatures projected for the 2020s, 2050s and 2080s by two Global Climate Models (the Canadian CGCM2 and the UK HadCM3) for two greenhouse gas emission scenario enforcings 'A2'and 'B2' of the Intergovernmental Panel on Climate Change. Under scenario 'A2' using either climate model, the theoretical range for I. scapularis establishment moved northwards by approximately 200 km by the 2020s and 1000 km by the 2080s. Reductions in emissions (scenario 'B2') had little effect on projected range expansion up to the 2050s, but the range expansion projected to occur between the 2050s and 2080s was less than that under scenario 'A2'. When the tick population model was driven by projected annual temperature cycles (obtained using CGCM2 under scenario 'A2'), tick abundance almost doubled by the 2020s at the current northern limit of I. scapularis, suggesting that the threshold numbers of immigrating ticks needed to establish new populations will fall during the coming decades. The projected degrees of theoretical range expansion and increased tick survival by the 2020s, suggest that actual range expansion of I. scapularis may be detectable within the next two decades. Seasonal tick activity under climate change scenarios was consistent with maintenance of endemic cycles of the Lyme disease agent in newly established tick populations. The geographic range of I. scapularis-borne zoonoses may, therefore, expand significantly northwards as a consequence of climate change this century.

Animals↗
PubMed2005

Simulating effects of fire disturbance and climate change on boreal forest productivity and evapotranspiration.

We used a terrestrial ecosystem process model, BIOME-BGC, to investigate historical climate change and fire disturbance effects on regional carbon and water budgets within a 357,500 km(2) portion of the Canadian boreal forest. Historical patterns of increasing atmospheric CO2, climate change, and regional fire activity were used as model drivers to evaluate the relative effects of these impacts to spatial patterns and temporal trends in forest net primary production (NPP) and evapotranspiration (ET). Historical trends of increasing atmospheric CO2 resulted in overall 13% and 5% increases in annual NPP and ET from 1994 to 1996, respectively. NPP was found to be relatively sensitive to changes in air temperature (T(a)), while ET was more sensitive to precipitation (P) change within the ranges of observed climate variability (e.g., +/-2 degrees C for T(a) and +/-20% for P). In addition, the potential effect of climate change related warming on NPP is exacerbated or offset depending on whether these changes are accompanied by respective decreases or increases in precipitation. Historical fire activity generally resulted in reductions of both NPP and ET, which consumed an average of approximately 6% of annual NPP from 1959 to 1996. Areas currently occupied by dry conifer forests were found to be subject to more frequent fire activity, which consumed approximately 8% of annual NPP. The results of this study show that the North American boreal ecosystem is sensitive to historical patterns of increasing atmospheric CO2, climate change and regional fire activity. The relative impacts of these disturbances on NPP and ET interact in complex ways and are spatially variable depending on regional land cover and climate gradients.

Canada↗
PubMed2003

Climate, Hydrochemistry and Economics of Surface-water Systems (CHESS): adding a European dimension to the catchment modelling experience developed under LOIS.

One achievement of the UK Land-Ocean Interaction Study (LOIS) was to link dynamic biogeochemical models of different domains, e.g. rivers, estuaries and coastal waters, and to use the linked model to investigate possible changes from the current status that might occur in the future, for example as the result of climate change. The Climate, Hydrochemistry and Economics of Surface-water Systems (CHESS) project has taken the LOIS methodology forward by exploring possible impacts of climate change on the water quality of European rivers, with the purpose of informing future catchment management. This was achieved by the application of a standard modelling framework to a set of five European catchments located in Finland (River Vantaa), United Kingdom (Yorkshire Ouse), Belgium (Dender), Italy (Enza) and Greece (Pinios). Baseline conditions were simulated using existing meteorological data from the period 1961-1990, and in all cases the modelling framework was able to reproduce key features of the flow and water quality regimes of the study catchments. The modelling framework comprised two models. The Soil Water Assessment Tool (SWAT) was used to simulate water and chemical fluxes, primarily nutrients and sediment, generated from diffuse areas and thereby provide sub-catchment inputs to an in-stream water quality model, the Quality Evaluation and Simulation Tool for River Systems (QUESTOR). QUESTOR integrated the diffuse runoff along the channel network, together with point source discharges from industry and sewage treatment works, and water abstractions for public supply, industry and agriculture. The modelling framework has been used for the baseline conditions, along with a set of six climate scenarios. These comprised four scenarios derived from different general circulation models (GCMs) representing the 2050s, and three scenarios from the same GCM representing the 2020s, 2050s and 2080s, with one scenario in both groups. Results have been explored using a range of measures to reflect the different stakeholder interests within and beyond the catchment. The results reflect the variability in present day conditions (e.g. climate, soils, agriculture and industry), and the variability in the climate scenarios, both between-catchment and between-scenario. Specific examples are: the loss of the spring snowmelt causing high flows on the Vantaa; a decrease in the already very low summer flows on the Pinios; and significant seasonal changes in nutrient losses, even though the annual change is small.

Agriculture↗
PubMed1998

The influence of climate on suicidal behaviour in Italy.

A growing number of studies report an asymmetry in the seasonal distribution of suicides, with a peak in the late spring months for both sexes. The aim of this study is to verify if the climate, apart from its seasonal change, exerts a direct influence on suicidal behaviour. To this end, deaths by suicide in 17 Italian towns which all have a meteorologic station have been analyzed, taking into account some climatic indicators. Results of analyses show an unequal distribution of suicides with respect to latitude, with a peak in the North. The distribution of deaths by suicide shows a negative relationship with mean yearly temperature values, max and min, and with sun exposure indicators, and a positive, but less significant relationship with rainfall values. As far as climatic variables considered as a whole are concerned, stepwise regression identifies three relevant factors with significant relationships to suicide rates: humidity grade, rainfall mean, and sunlight exposure. These three climatic indicators explain up to 63% (Adj R2) of the variance in the distribution of suicide rates for both genders, with sunlight exposure offering the most significant contribution, when regressed on suicide rates via a multiple regression model. Higher suicide rates, therefore, correspond to dry places which are less exposed to the sun. However, the variable which shows the most significant correlation with suicide rates for both sexes is not a climatic one, but the percentage of the population aged 65 and over. The distribution of people at greater biological risk for possible disruption of brain neurochemistry (i.e. older people), therefore, predicts the distribution of suicide rates. Climate contributes to this biological risk by modifying both the responsiveness of the circuits that control mood and behaviour, and also the frequency and intensity of social interaction.

Climate↗
PubMed2000

[Impact of the climatic scenario of global warming on the growth of trees].

The climatic impact on tree radial growth resulting from an atmospheric CO2 doubling was studied for 24 populations of five tree species in the French Alps and the French Mediterranean area. The Arpege AGCM, which predicts a 3 degrees C increase in mean temperature and a light increase of precipitation, is used to estimate the climatic perturbation. The method is based on the integration of estimated climate in an empirical tree-ring to climate model, involving artificial neural networks. Only a few populations are sensitive to the climatic change; all are located on the boundaries of their ecological area and can be divided in two groups. The first one is composed of high altitude populations which show a growth increase induced by the warmer climate during the growing season. The second one, composed of a single Mediterranean Scots pine population, reacts with a severe growth reduction induced by the stronger water stress in summer.

Altitude↗
PubMedDate not supplied

Using temporal coherence to determine the response to climate change in Boreal Shield lakes.

Climate change is expected to have important impacts on aquatic ecosystems. On the Boreal Shield, mean annual air temperatures are expected to increase 2 to 4 degrees C over the next 50 years. An important challenge is to predict how changes in climate and climate variability will impact natural systems so that sustainable management policies can be implemented. To predict responses to complex ecosystem changes associated with climate change, we used long-term biotic databases to evaluate how important elements of the biota in Boreal Shield lakes have responded to past fluctuations in climate. Our long-term records span a two decade period where there have been unusually cold years and unusually warm years. We used coherence analyses to test for regionally operating controls on climate, water temperature, pH, and plankton richness and abundance in three regions across Ontario: the Experimental Lakes Area, Sudbury, and Dorset. Inter-annual variation in air temperature was similar among regions, but there was a weak relationship among regions for precipitation. While air temperature was closely related to lake surface temperatures in each of the regions, there were weak relationships between lake surface temperature and richness or abundance of the plankton. However, inter-annual changes in lake chemistry (i.e., pH) were correlated with some biotic variables. In some lakes in Sudbury and Dorset, pH was dependent on extreme events. For example, El Nino related droughts resulted in acidification pulses in some lakes that influenced phytoplankton and zooplankton richness. These results suggest that there can be strong heterogeneity in lake ecosystem responses within and across regions.

Animals↗
PubMed2002

Synchronization of animal population dynamics by large-scale climate.

The hypothesis that animal population dynamics may be synchronized by climate is highly relevant in the context of climate change because it suggests that several populations might respond simultaneously to climatic trends if their dynamics are entrained by environmental correlation. The dynamics of many species throughout the Northern Hemisphere are influenced by a single large-scale climate system, the North Atlantic Oscillation (NAO), which exerts highly correlated regional effects on local weather. But efforts to attribute synchronous fluctuations of contiguous populations to large-scale climate are confounded by the synchronizing influences of dispersal or trophic interactions. Here we report that the dynamics of caribou and musk oxen on opposite coasts of Greenland show spatial synchrony among populations of both species that correlates with the NAO index. Our analysis shows that the NAO has an influence in the high degree of cross-species synchrony between pairs of caribou and musk oxen populations separated by a minimum of 1,000 km of inland ice. The vast distances, and complete physical and ecological separation of these species, rule out spatial coupling by dispersal or interaction. These results indicate that animal populations of different species may respond synchronously to global climate change over large regions.

Animals↗
PubMed2006

Malaria early warnings based on seasonal climate forecasts from multi-model ensembles.

The control of epidemic malaria is a priority for the international health community and specific targets for the early detection and effective control of epidemics have been agreed. Interannual climate variability is an important determinant of epidemics in parts of Africa where climate drives both mosquito vector dynamics and parasite development rates. Hence, skilful seasonal climate forecasts may provide early warning of changes of risk in epidemic-prone regions. Here we discuss the development of a system to forecast probabilities of anomalously high and low malaria incidence with dynamically based, seasonal-timescale, multi-model ensemble predictions of climate, using leading global coupled ocean-atmosphere climate models developed in Europe. This forecast system is successfully applied to the prediction of malaria risk in Botswana, where links between malaria and climate variability are well established, adding up to four months lead time over malaria warnings issued with observed precipitation and having a comparably high level of probabilistic prediction skill. In years in which the forecast probability distribution is different from that of climatology, malaria decision-makers can use this information for improved resource allocation.

Animals↗
PubMed2002

The impact of climate and traffic-related NO2 on the prevalence of asthma and allergic rhinitis in Italy.

BACKGROUND: Environmental factors are likely to be involved in explaining the wide geographical variation in asthma and atopic diseases that has been documented in many recent epidemiological studies. AIM: To evaluate to what extent climate and outdoor NO2 pollution can explain the geographical variation in the prevalence of asthma and allergic rhinitis, and to estimate the relative risk for exposure to different levels of these two factors. METHODS: The impact of climate and long-term exposure to nitrogen dioxide (NO2) pollution on asthma and allergic rhinitis was assessed in a cross-sectional study, carried out during 1998 to 2000 on young adults aged 20 to 44 years (n = 18 873), living in 13 areas from two different Italian climatic regions (subcontinental and Mediterranean). RESULTS: Mediterranean areas had a significantly higher prevalence of asthma-like symptoms (P < 0.001), higher annual mean temperature (16.2 degrees C vs. 12.9 degrees C), lower temperature range (16.0 C degrees vs. 22.1 degrees C) and lower NO2 levels (31.46 microg/m3 vs. 57.99 microg/m3) than subcontinental ones. Mediterranean climate was associated with an increased risk of wheeze (OR = 1.23; 95% CI 1.13 to 1.35), tightness in the chest (OR = 1.21; 95% CI 1.11 to 1.33), shortness of breath (OR = 1.21; 95% CI 1.08 to 1.36) and asthma attacks (OR = 1.19; 95% CI 1.07 to 1.31). After adjusting for climate, an increase of 18.3 microg/m3 in NO2 levels moderately increased the risk of asthma attacks (OR = 1.13; 95% CI 0.98 to 1.32), tightness in the chest (OR = 1.11; 95% CI 0.98 to 1.26) and wheeze (OR = 1.11; 95% CI 0.96 to 1.28). When the levels of outdoor NO2 exposure rose, the prevalence of allergic rhinitis increased significantly in the Mediterranean region (OR = 1.38; 95% CI 1.12 to 1.69), but not in the subcontinental one (OR = 1.03; 95% CI 0.83 to 1.28). CONCLUSION: Our results show that the prevalence of asthma increases when annual mean temperature increases and temperature range decreases. Furthermore, climate interacts with NO2 outdoor exposure, increasing the risk for allergic rhinitis in people exposed to high stable temperatures. A long-term role for the effect of traffic pollution on asthma is also suggested.

Adult↗
PubMed2005

Modeled regional climate change and California endemic oak ranges.

In the coming century, anthropogenic climate change will threaten the persistence of restricted endemic species, complicating conservation planning. Although most efforts to quantify potential shifts in species' ranges use global climate model (GCM) output, regional climate model (RCM) output may be better suited to predicting shifts by restricted species, particularly in regions with complex topography or other regionally important climate-forcing factors. Using a RCM-based future climate scenario, we found that potential ranges of two California endemic oaks, Quercus douglasii and Quercus lobata, shrink considerably (to 59% and 54% of modern potential range sizes, respectively) and shift northward. This result is markedly different from that obtained by using a comparable GCM-based scenario, under which these species retain 81% and 73% of their modern potential range sizes, respectively. The difference between RCM- and GCM-based scenarios is due to greater warming and larger precipitation decreases during the growing season predicted by the RCM in these species' potential ranges. Based on the modeled regional climate change, <50% of protected land area currently containing these species is expected to contain them under a future midrange "business-as-usual" path of greenhouse gas emissions.

California↗
PubMed2005

Scientific issues in the design of metrics for inclusion of oxides of nitrogen in global climate agreements.

The Kyoto Protocol seeks to limit emissions of various greenhouse gases but excludes short-lived species and their precursors even though they cause a significant climate forcing. We explore the difficulties that are faced when designing metrics to compare the climate impact of emissions of oxides of nitrogen (NO(x)) with other emissions. There are two dimensions to this difficulty. The first concerns the definition of a metric that satisfactorily accounts for its climate impact. NO(x) emissions increase tropospheric ozone, but this increase and the resulting climate forcing depend strongly on the location of the emissions, with low-latitude emissions having a larger impact. NO(x) emissions also decrease methane concentrations, causing a global-mean radiative forcing similar in size but opposite in sign to the ozone forcing. The second dimension of difficulty concerns the intermodel differences in the values of computed metrics. We explore the use of indicators that could lead to metrics that, instead of using global-mean inputs, are computed locally and then averaged globally. These local metrics may depend less on cancellation in the global mean; the possibilities presented here seem more robust to model uncertainty, although their applicability depends on the poorly known relationship between local climate change and its societal/ecological impact. If it becomes a political imperative to include NO(x) emissions in future climate agreements, policy makers will be faced with difficult choices in selecting an appropriate metric.

Climate↗
PubMed2002

Climate change hastens population extinctions.

Climate change is expected to alter the distribution and abundance of many species. Predictions of climate-induced population extinctions are supported by geographic range shifts that correspond to climatic warming, but few extinctions have been linked mechanistically to climate change. Here we show that extinctions of two populations of a checkerspot butterfly were hastened by increasing variability in precipitation, a phenomenon predicted by global climate models. We model checkerspot populations to show that changes in precipitation amplified population fluctuations, leading to rapid extinctions. As populations of checkerspots and other species become further isolated by habitat loss, climate change is likely to cause more extinctions, threatening both species diversity and critical ecosystem services.

Animals↗