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A catastrophic flood occurred on 7 February 2021 around 10:30 AM (local time) in the Rishiganga River, which has been attributed to a rockslide in the upper reach of the Raunthi River. The Resourcesat 2 LISS IV (8 February 2021) and CNES Airbus satellite imagery (9 February 2021) clearly show the location of displaced materials. The solar radiation observed was higher than normal by 10% and 25% on 6 and 7 February 2021, respectively, however, the temperature shows up to 34% changes. These conditions are responsible for the sudden change in instability in glacier blocks causing deadly rock-ice slides that led to the collapse of the hanging glacier as a wedge failure. The displaced materials mixed with ice, snow, and debris caused catastrophic floods downstream within no time that destroyed critical infrastructure and killed human lives. The hydrodynamic modelling (HEC-RAS software) shows mean flow velocity up to 22.4 ± 8.6 m/s with an average depth of 16.3 ± 6.5 m that caused deadly devastation in the source region and along the rivers due to the flow of water in the valley.

Southern Africa is a water-scarce region with an inherent climatic variability and uneven distribution of perennial rivers, which limits the economic growth potential of the region and makes water ...

Crop breeding for improved varieties, able to withstand climatic variability, pests and diseases, as well as to meet food and market demands, has the potential to greatly improve the livelihoods of...

Background: Despite extensive efforts to understand how biotic interactions and community dynamics respond to changes in environmental conditions many knowledge gaps remain. Assessing biotic interactions involving little studied organisms, such as the biological soil crust (BSC), can widen our understanding of ecosystem functioning. Aims: (1) to quantify the effects of two pioneer communities, one of shrubs and the other of BSC, on the survival and early growth of Nothofagus pumilio tree seedlings on land exposed after glacier retreat, and (2) evaluate how these biotic effects changed according to variations in environmental conditions. Methods: We conducted seedling transplants, at four glacier forelands in the Patagonian Andes across a precipitation gradient in three microsite types: bare soil, soil-covered BSC, low-stature vegetation cover by the creeping dwarf-shrub Empetrum rubrum (ER). Results: N. pumilio seedling survival was related to inter-annual climatic variations, with higher survival in cool-wet years. These effects depended on microsite conditions, with a tendency towards highest survival in BSC. Conversely, microsite type was the dominant factor affecting seedling leaf area, with a trend towards bigger leaves in bare soil. Conclusions: At regional scales, inter-annual climatic variability modulates N. pumilio colonisation. However, microenvironmental differences imposed by cover type introduce important variations. Accounting for interactions between climate and pre-existing communities is essential for predicting climate change impacts on plant community development.

This paper examines the gendered perceptions of climatic variability, its impacts on agriculture and food security, and adaptation practices in the Far-Western Terai region of Nepal. Buildi...

Parameterizing human-induced evapotranspiration (ET) process in models (e.g. hydrological or land surface models (LSMs)) has been a long-term challenge. As most LSMs can only simulate ET variations...

Snowmelt makes an essential component of the hydrological system of Kashmir Himalayas. The present study was carried out to examine the status of Snow Cover Area (SCA) using Moderate Resolution Ima...

Oscillations of the Caspian Sea level is the result of interrelated hydrometeorological processes and climate change not only in the catchment area of the sea but also far beyond it. The change in ...

The trends in annual maximum rainfall (AMR) intensity data in New South Wales, Australia, were examined. Data from 60 stations were used covering three study periods, 1955–2010, 1965–2010 and 1978–2010. Mann-Kendall (MK) and Spearman’s rho (SR) tests were applied to assess trends at local stations. Pre-whitening (PW), trend-free pre-whitening (TFPW) and the variance correction (VC) tests were used to assess the effects of serial correlation on trend results. For regional trend analysis, the regional MK test was employed. The impacts of climatic variability modes on the observed trends in AMR intensity and seasonal maximum rainfall data were investigated. It was found that positive trends were more frequent than the negative ones. The PW, TFPW and VC tests resulted in a slight reduction in the count of stations exhibiting significant positive trends. The number of stations exhibiting significant trends decreased when the impact of climate variability modes was considered.

Since humans and ecosystems require adequate, reliable water supplies, hydro-climatic variability and extremes pose serious threats to society and the environment. Western Canada, including the Athabasca River Basin (ARB), is prone to considerable hydro-climatic variability including periodic extreme droughts and excessive moisture conditions. The main causes of these extremes are persistent, mid-tropospheric circulation patterns that disrupt expected precipitation and temperature. However, no investigation has specifically focused on the occurrence and causes of both past and future hydro-climatologic variability within the ARB. Assessment of the Standardized Precipitation Evapotranspiration Index (SPEI) reveals substantial inter-annual and decadal-scale variability over the entire ARB and its individual reaches, with no discernible trends during the last ~100 years. Evaluation of the 500-hPa circulation patterns associated with identified hydro-climatic extremes shows that major droughts are related to ...

Members of the Engraulidae (anchovies) fuel large fisheries around the globe, helping to fulfil demands for food. On the other hand, unpredictable catches that are a very common occurrence with respect to this family can have drastic consequences on economies of different countries. Like many other fisheries, the Black Sea anchovy fishery is a very good example of a fishery greatly affected by abrupt peaks and troughs in landings. In this work, the existing knowledge on the species' overwintering behavior and exploitation patterns along the south coast of the Black Sea is re-evaluated with respect to recent observations. The strong seasonality and very short fishing season are noted as the main characteristics regulating development of the fishery over time. Climatic variability may sometimes generate favorable overwintering conditions outside areas where anchovy aggregations are usually expected, resulting in a temporal shift in overwintering grounds. As most fishing activity takes place on these...

Climatic variability and its effects have been experienced in the high-altitude regions of Nepal for some considerable time. Most of the studies on local people’s perception available so far in Nepal on climate include with respect to weather changes, and almost none have been verified with satellite imagery. This study thus attempts to combine meteorological and satellite imagery for comparing local people’s perception so that a more robust validation can be established. Both qualitative (transect walk, key informant interview, focus group discussion and institutional visit) and quantitative (meteorological and satellite image) data and techniques were employed. Local people from Rara and Langtang in Nepal shared their observations and perceptions on the changing climate for the last three decades and the effects on them and their local microclimate. Apart from temperature, rainfall and snowfall anomalies, locals observed changes in the water sources and increasing drought along with alteration i...

The present investigation was conducted to analyse the trends in hydrometeorological data to addresses how these trends impacted on the water extent of Wular Lake, Kashmir. Temporal changes in the lake surface area have been analysed, using the Landsat satellite data. The nonparametric Mann–Kendall and Sen’s methods were used to determine trends in hydrometeorological data. In addition, trends in extreme indices of frost days (FD), summer days, days with rainfall > 10 mm (R10), days with rainfall > 20 mm (R20) and dry spell for temperature and precipitation were also analysed. The results suggest an overall decrease in extreme rainfall events, R10 and R20, and annual precipitation pattern with increase in maximum and minimum annual average temperatures. Furthermore, the analysis of extreme temperature events suggests warming trend with increased number of warm days and decreased number of FD. With regard to water extent of the lake, an intense decreasing trend was observed.

Bhaga Basin has complex mountainous terrain; little study has been done on the spatial and temporal characteristics of snow cover in the region. The Moderate Resolution Imaging Spectroradiometer (MODIS) 8-day snow cover products between 2001 and 2012 for winter period (November–April) have been used to study the variation in snow cover area (SCA). The statistical analysis based on non-parametric Mann Kendall and Sen’s slope methods have been used for detecting and estimating trends for climatic variables (temperature and snowfall) and SCA for winter period. Results of statistical analysis indicate rise in minimum temperature (0.02 °C year−1) and fall in maximum temperature (0.17 °C year−1). It also shows decrease in mean seasonal snowfall (0.07 cm year−1). The seasonal SCA was found to decrease at the rate of 0.002% year−1. This study indicates that the climate change is probably one of the major causes for depleting SCA.

This study explores the temporal and spatial variability and change in rainfall across southeastern Mexico and the mechanisms by which smallholder farmers adapt to this variability, especially droughts. Members of 150 households in 10 communities were interviewed to investigate adaptation strategies among swidden maize smallholders, linked to their perceptions of climate changes. Precipitation data from seven weather stations were analyzed for the 1973–2012 period. Precipitation anomalies were estimated to evaluate the annual and seasonal stability, deficit, or surplus; and linear regressions were used to evaluate trends. Then, these anomalies were linked to variation in reported agricultural practices. Weather station data show a considerable decline in precipitation in most of the study area, coupled with increased drought frequency and an increase in negative anomalies in recent years. Surveys revealed several mechanisms of adaptation, including adjustment of the agricultural calendar (e.g. delaying pl...

International audience; Improvements in our understandings of the timing and nature of millennial-scale climatic variability combined with improved dating methods and more accurate calibration curves have allowed researchers to better place archaeological cultures within their paleoenvironmental contexts. Since all human cultures operate within an environmental framework, these developments allow researchers to investigate if and how cultural variability is related to temporal shifts in culture-environment relationships. Studying such relationships, however, is dependent on our ability to construct robust chronologies, and this need has been by incorporating Bayesian modeling methods into archaeological investigations. This paper reviews the assumptions and methods behind this practice and argues that while site-specific age models are useful, we should also employ methods with which chronological models for broad archaeological cultures can be constructed. Such a combination approach allows one to thoroughly incorporate available chronological data and build reliable chronologies that are critical to investigations aimed at examining culture-environment relationships.

The present study constitutes a climatic approach of aridity trend analysis in the south-eastern part of Romania (Dobrogea region), over the past five decades. The analysis is based on a series of investigations on the temporal trends of certain climatic parameters that play a key role in a territory's climatic variability, such as temperature, precipitation, and potential evapotranspiration. In this respect, a series of aridity index trends (De Martonne Index, UNEP Index, and Water Deficit Index), recorded between 1961 and 2009, was analyzed, using climatic parameters provided by eight weather stations in the Dobrogea region. While the results showed that the last five decades were generally characterized by an upward climatic aridity trend (increasing temperatures and potential evapotranspiration in all considered instances), there are certain regional differences due to precipitation regime variations (higher rainfall values were recorded at four weather stations). In terms of maximum aridity condition...

We review some recent work regarding climatic changes in selected mountain regions, with particular attention to the tropics and the American Cordillera. Key aspects of climatic variability and trends in these regions are the amplification of surface warming trends with height, and the strong modulation of temperature trends by tropical sea surface temperature, largely controlled by changes in El Nino–Southern Oscillation on multiple time scales. Corollary aspects of these climate trends include the increase in a critical plant growth temperature threshold, a rise in the freezing level surface, and the possibility of enhanced subtropical drying. Anthropogenic global warming projections indicate a strong likelihood for enhancement of these observed changes.

Semi-arid areas show climatic variability on a spatio-temporal scale. There are few studies on the long-term trends and intensity of this variability from East Africa. We used National Ocean and Atmospheric Administration re-analysis climate data (1979–2009) in this study. Rainfall exhibited a non-significant long-term trend. The climate of the area is variable (coefficient of variation-CV >35.0%) with spatio-temporal oddities in rainfall and temperature. A rise in minimum (0.9 °C), maximum (1.6 °C) and mean (1.3 °C) temperature occurred between 1979 and 2009. There were more months with climate variability indices below the threshold ( 2.6) were experienced between 2004 and 2009 than between 1984 and 2003. We consider that the use of spatio-temporal climatic informati...

This paper investigates what drives household coping strategies in rural Uganda under different climatic hazards. Rural households in sub-Saharan Africa draw on various coping strategies to reduce the impact of climatic hazards on their livelihoods. Research to date provides only limited understanding of how the coping strategy portfolio of households changes depending on the climatic stress. Using empirical data from Uganda, this research contributes to this gap by (1) exploring how household coping strategy relates to household characteristics and livelihood activity and (2) how these coping strategies vary depending on the hazard. Coping strategy is found to be hazard specific for households that lack market-orientated activities, whereas those with market access rely on economic activities regardless of hazard. To maintain and improve the livelihoods and coping strategies of those most vulnerable to climatic variability and change, policies that advocate diversification away from a sole reliance on cu...

The knowledge of exact amount of water required by different crops in a given set of climatological condition of a region is vital in planning and effective management of irrigation scheme, irrigation scheduling and so on. This paper proposes the effect of different climatological variables on reference evapotranspiration (ETo) and water uses in agriculture in the Seonath basin located in Chhattisgarh State. The study area has 24 meteorological stations. Results of analysis of annual temperature time series showed a rise of 0.9702 °C over a period of 51 years (1960–2010). The increasing trends in ETo were more pronounced. Annual analysis of the ETo series indicated an increasing trend in almost all the districts except Bilaspur district. The percentage change in annual ETo was maximum for Raipur (1.72%) and minimum for Bilaspur (–1.41%). The analysis of the impacts of meteorological variables on the trends of ETo revealed that the main driving force associated with the increasing trend of ETo in the Seona...

Strong climatic fluctuations have been documented in the Arctic in recent years. To detect possible impacts of the climatic variability on the pelagic ecosystem we investigated mesozooplankton communities collected in the summer of 2009. Oithona similis dominated in terms of total abundance while Calanus species contributed a major part of the total biomass. The total mesozooplankton abundance ranged from 143 to 6145 individuals m−3. The highest average mesozooplankton biomasses were found in the frontal zone of Atlantic waters (AW) located south of the Svalbard archipelago and in Arctic waters (ArW), while the minimum was registered in Murmansk coastal waters (MCW). The spatial distributions of the mesozooplankton communities were strongly related to latitude and hydrological conditions. A possible impact of the recent cooling registered in the Barents Sea since 2007 was detected as a decrease in the total mesozooplankton biomass within MCW in the summer of 2009.

Opportunistic sightings and strandings of Caperea marginata (n=196) from the vicinity of Australia and New Zealand (1884 to early 2007) were used to relate geographic and temporal patterns to oceanographic and broad-scale climatic variability. Records were not uniformly distributed along the coast and more (69%) were from Australia than New Zealand. Seven coastal whale ‘hotspots’ were identified which accounted for 61% of records with locality data. Half of the hotspot records were from southeast (37) and northwest (20) Tasmania—others each had 9–15 events. Upwelling and/or high zooplankton abundance has been documented near all whale hotspots. Records of C. marginata occurred in all months, with 75% in spring and summer. Inter-annual variability showed broad agreement between increased whale records (usually in spring/summer) and strongly positive ‘Nino 3.4’ during 1980–1995 but not thereafter. Coastal upwelling and productivity increase during climatic phenomena such as El Nino and are likely t...

Local mountain meteorology of the landscape around Longyearbyen in central Svalbard is analyzed through the decade from 2000 to 2011. Standard meteorological stations from close to sea level and up to 464 m a.s.l. located on different periglacial landforms, have been used. During winters with little sea ice, strong temperature inversions do not develop, and then there is a distinct cooling with height, as opposed to when sea ice is present. Airflow is accelerated due to topography and direction deflected in the confined valleys, whereas open plateaus have on average 1 m/s lower wind speeds with a regional SE direction. The permafrost thermal state is largely controlled by meteorology, with permafrost in the valley bottoms as cold as on the mountain plateaus. The periglacial landform most exposed to climatic variability is ice-wedges, which seem to crack mainly during shorter cooling periods. Such activity is also linked to temperature inversions, and thus also occur mainly when sea ice is present...

Cambium-peeled trees are relatively common in ponderosa pine forests of the Intermountain West. Found from British Columbia to southern New Mexico, cambium-peeled trees have been interpreted as (a) a response to famine conditions related to climatic variations, (b) a response to conflict-related food shortages and scheduling issues, (c) a sweet or delicacy, and (d) a medicinal product used to treat various internal and external ailments. This paper uses dendrochronology, and ethnohistory to examine three spatially discrete groups of peeled trees in the Zuni Mountains of New Mexico in terms of their relationships to climatic variability, conflict and cultural practices.

Landscape learning provides a model for examining how colonists in Australia came to terms with the landscape, positioning the environment at the centre of investigations into settler activity. The successful management of water was crucial in the colonising process, and settlers rapidly developed a sharp awareness of climate, soils and topography in their manipulation of environmental resources. Upon learning about climatic variability they built dams, races, reservoirs and other features to capture, store and divert water, which have left extensive archaeological traces. This paper explores the archaeological remains associated with water use on the goldfields of Victoria's central highlands, and the ways in which settlers learned the possibilities and limitations of natural landscapes.

In recent decades European silage maize production has extended northwards, into Scandinavia, and the importance of maize in fodder production has increased substantially. For the northward expansion of maize production it is of interest to evaluate both the role of climate change that has occurred already, and scenarios for possible future climate change. The aim of this study was to assess for Swedish climatic conditions, the annual variation in silage maize yield and quality (dry weight and starch contents) of cultivars currently grown in Germany. The MAISPROQ simulation model currently used in German maize production was applied to evaluate the effects of (i) cultivar differences (four cultivars; four sites; 2003–2009), (ii) intra-regional variation among ten sites representing three regions (two cultivars; 2003–2009), and (iii) climatic variability among two historical periods during 1961–2009 and three future periods during 2011–2100 using A2-emission climate scenarios and the Delta-method ...

An increasing body of research shows that climate change takes expression in local processes such as increased climatic variability; climatic risk is managed in relation to other risks in agricultural households; and adaptation is an everyday social process as much as a question of new crop varieties. Understanding how farming households experience the interactions of climatic variability, multifaceted risk, adaptation, and everyday social processes is crucial to informed policy development. A study of New South Wales wheat farming households during the failed harvest seasons of 2006–2007 and 2007–2008 provided a unique opportunity to examine how they approached unprecedented drought in relation to both past and future changes. We analyzed their experience of the hybrid assemblage comprising risk, climate change, and a deregulated policy environment in their everyday lives and individual bodies. These farmers are not adapting to future conditions but are in continuous interplay among multiple temporalitie...

This article presents a statistical investigation of the spatial and temporal changes of extreme sea surges in response to climate variability in coastal British Columbia. The study was based on an investigation of in situ hourly tide gauge data spanning the interval from 1950 to 2007 at eleven tide gauges in the region. The characteristics of the recorded extreme sea surges were parametrically modeled by the generalized extreme value distribution while accounting for trends and dependence via climate covariate coefficients. The study confirms that decadal to interdecadal climatic variability is a fundamental element in explaining the changing frequency and intensity of sea surges in coastal British Columbia. For instance, the sea-surge response to climate variability impacts on sites along the British Columbia coast were found to be fairly synchronous with an increase (decrease) in the magnitude of extreme sea surges in response to warm (cold) El Nino/La Nina-Southern Oscillation (ENSO) conditions. These...

The distinctive tool called 'tula' is an endemic adaptation, which was adopted by Aboriginal people across central and western Australia, encompassing some two-thirds of the continent. The tula is a hafted tool used for working hardwoods as well as other tasks including butchery and plant-processing. The geographic spread of tulas appears to have been rapid and no antecedent form has been identified. The sudden appearance of tulas was coincident with the onset of El Nino Southern Oscillation (ENSO) conditions. While we do not yet have the data to establish an unequivocal causal link, in this paper we hypothesise that the appearance of this new and specialised tool at c.3700 BP was very likely a human response to the intensification of ENSO. This intensification resulted in increased aridity and climatic variability lasting almost 2000 years. We posit that this technological adaptation, an element of a risk minimisation toolkit, was part of a wider economic and social strategy adopted by Aboriginal people to cope with increasing climatic uncertainty. This possibility has implications for the diversity of innovation processes operating in Australia during the Holocene, which is further explored in this paper with concluding suggestions for future research. We offer this discussion as a platform for these future, and what we believe, are very necessary critical studies.

An increased understanding of regional surface water quality and the key factors which differentiate regional from local differences is necessary for monitoring impacts such as mountain pine beetle infestation and related land management practices. This study develops a framework to identify water quality indicators which differentiate parameters influenced by rock type, by relatively short term anthropogenic activities, and those resulting from longer term climatic variability. Rock type was an overriding factor related to stream water chemistry in this British Columbia case study; with differences between watersheds differentiated by Ca, EC, Al and Fe. Grouping watersheds by their dominant rock type permitted the investigation of water quality with other watershed characteristics. The % forest cover, % pine cover, and dominant runoff processes demonstrated significant relationships with soluble cations, metals, turbidity and total organic carbon. Turbidity levels showed low variability, and relationship...

Resume L'analyse de la variabilite spatio-temporelle de totaux pluviometriques, de debits et de coefficients d'ecoulements, aux pas de temps mensuels, saisonniers et annuels dans le sud equatorial du Cameroun, revele que les pluies et les debits annuels ont diminue lors des annees tres seches (1972–1973 et 1983–1984). Le changement climatique le plus significatif reside dans la modification des regimes de pluie des saisons seches, modifiant le cycle hydrologique annuel. La diminution de la pluviometrie de la saison seche de Decembre a Fevrier entraine une baisse des coefficients d'ecoulement durant la petite saison des pluies qui suit (Mars—Juin). Inversement, alors que la pluviometrie a peu varie au cours de la saison des pluies de Septembre—Novembre, les ecoulements augmentent, probablement du fait que les pluies de la petite saison seche (Juillet et Aout) sont plus elevees depuis quelques decennies. Ceci indique une evolution du climat dans le sudouest du Cameroun, visible egalement au Gabon et au Cong...

Moraine ridges are commonly used to identify past glacier ice margins and so infer glacier mass balance changes in response to climatic variability. However, differences in the form of past ice mar...

Statistical analysis of a multi‐centennial dendrochronological proxy dataset of regional climate, constructed across the latitudinal gradient of 1000 km, was performed. It was shown that centennial...

8 páginas, 3 figuras., To infer future changes in the distribution of tree species in response to climatic variability, we need an understanding of the recruitment dynamics and their climatic controls at the species' distribution limit. We studied the recruitment processes in an isolated population of Pinus uncinata Ram. located at the southwestern limit of the species' distribution in Europe (Iberian System, NE Spain). We assessed (1) the temporal patterns of pine recruitment, and (2) how climate influenced recruitment. To reconstruct the recent recruitment episodes and to assess the climatic influence on recruitment and radial growth we employed dendrochronological methods. We mapped, measured the size, and estimated the age of all P. uncinata individuals located within a 50 m × 40 m plot. Additional age data were obtained from individuals located in four nearby 20 m × 20 m plots. The main episodes of tree establishment (early 1960s, late 1980s) coincided with low radial growth during a period with reduced grazing pressure. Grazing pressure and tree recruitment were not related at the spatiotemporal scale of this study. High May, August, and September minimum temperatures and high April precipitation were positively associated with recruitment, whereas high maximum April and June temperatures were negatively associated with recruitment. The studied population was in equilibrium with climate until the late 1990s, one of the warmest decades in the 20th century, when recruitment decreased despite the availability of suitable sites for establishment and the presence of reproductive individuals. We suggest that late-summer temperatures might have a non-linear negative threshold effect on recruitment rather than a linear effect. Despite increasing evidence of climate-induced recruitment episodes in isolated cold mountain forests, threshold effects of temperature on recruitment may imply limited range shifts of these populations in response to climate warming., CICyT (AMB95-0160) and EU (ForMAT, Contrat ENV4-CT97-0641) projects funded this work. Camarero acknowledges with gratitude the support of a postdoctoral INIADGA contract.

Tree-ring records of fires were used to examine the effects of inter-annual climatic variability on fire occurrence in forests dominated by the fire-adapted Araucaria araucana in the Andes of south-central Chile. Instrumental as well as tree-ring proxy records of climate indicate that low moisture availability is the main factor influencing fire occurrence. Years of widespread fire are strongly associated with warmer and drier summers. Years of extensive fire also tend to be favoured by one or two preceding years of dry climatic conditions. The El Nino–Southern Oscillation (ENSO) and its strong influence over large-scale climatic features is an important factor promoting fire activity. Years of high fire activity coincide with warm and dry summers following El Nino events. Fire in the Araucarian region is strongly related to inter-annual climatic variation associated primarily with the coupled effect of ENSO events and variations in the intensity and latitudinal position of the southeast Pacific ...

(2005). Persistence of coherence of ice-off dates for inland lakes across the Laurentian Great Lakes region. SIL Proceedings, 1922-2010: Vol. 29, No. 1, pp. 521-527.

Climatic simulations suggest that only slight changes in climatic variability are likely to be induced owing to greenhouse warming, and that these changes will project onto existing modes of climatic variability. A lesser studied aspect of the interaction of climatic variability with climatic change is how such a mutual interaction manifests itself as interannual climatic fluctuations. A number of examples are examined in this paper using simulations made with the Commonwealth Scientific and Industrial Research Organization (CSIRO) Mark 2 coupled climatic model. The simulations included an ensemble based on four Special Report on Emission Scenarios (SRES) cases, as well as individual ensembles for two selected SRES cases. In general, the intra‐ensemble variability for a given SRES case was quite similar to the inter‐ensemble variability of the four individual SRES cases. Time series of selected climatic variability and probability density function displays are used to illustrate the character of ...

Abstract Climatic variability in West and Central Africa has been detected using statistical tests for non-homogeneity in annual series of hydrological variables. This climatic variability is generally related to a shortage in water resources. This paper aims at looking for a statistical model for daily rainfall in the Sahelian area. This model should have a very low number of parameters, and be as flexible as possible to be able to adapt to the change introduced by the climatic variability. Raingauge stations have been selected where series of daily rainfall are long enough to reflect the climatic variability; these are situated in the upper part of the Senegal River basin, mainly in the countries of Mali and Senegal. One parameter exponential distribution truncated in frequency has been selected a priori and fitted graphically to each of these daily rainfall series. From the resulting plots, it appears that a two-component exponential distribution with four parameters is better for the fit. An ...

In climatology, spatial representativeness can be measured as the degree to which an instrumental temperature record resolves the climatic variability across an area. Some station records may disproportionately resolve characteristics of their immediate surroundings and, therefore, have less utility in representing climate (or weather) over larger spatial scales. To evaluate spatial representativeness of historical air-temperature records, a modified geostatistical procedure was developed. The procedure measures the spatial representativeness of a station based on variogram parameter estimates—in this case the nugget. This application is novel for two reasons: (1) variogram models are fit to station-specific or "point-centered" semivariance and (2) variogram models are fit to semivariance computed at intervals in a time series. Fitting variograms to point-centered semivariance may be used to create time series of nuggets for each station in a network. Nugget time series may show subsets of a time series t...

This contribution to the debate on the revision of rainfall and streamflow normals concerns three countries of West Africa: Burkina Faso, Ivory Coast and Mali. The rainfall deficit (15–20% on average in the study area) and the river flow deficit (about 30–50% and sometimes more) observed over the past 30 years in West and Central Africa raise the problem of the reference period that must be considered in estimates of hydrological characteristics. The hypothesis of the concept of “normal” supporting these estimates is a stability of the climate. However, the effect of taking or not taking into account the data of recent years on the estimates of these characteristics can lead to very different results. This would have serious consequences for the development and management of water resources systems, as seen in two examples of dams.

The letters, personal papers, and journals written by British missionaries based at mission stations within and around the Kalahari region of central southern Africa in the nineteenth century provide an invaluable insight into time- and place-specific interactions with local cultures and environments. This article employs a range of unpublished and published missionary correspondence and travelogues to examine two key aspects regarding the conceptualization of and responses to climatic variability in the region. First, we explore the way in which missionaries positioned climate variability within a moral economic framework and illustrate their attitude towards local drought myths and rainmaking superstitions. This reveals a degree of conflict in the respective environmental ideologies of missionaries and the local populations. Moreover, while missionaries appear to have linked drought to moral degradation, local populations had their own "environmental religion" or climatic philosophy that located the arrival of the European within a framework of climatic change. Second, we examine the introduction of irrigation technology to the region by the missionaries. The actual construction of irrigation projects provided a forum for cultural interaction, but findings also indicate that irrigation was considered to be not only a practical response to climatic conditions in the region and a means by which the missionaries could assert some ideological control over this environment, but also a route towards moral redemption of the local populations and environments.

The recent trend to explain socio-economic change throughout the world by new forms of environmental catastrophism has its counterpart in the history and prehistory of the British Isles. In particular, the paradigm that large parts of upland and northern Britain have been periodically vulnerable to climatic fluctuations has been highly influential. The evidence for climate-driven land abandonment in the past is, however, ambiguous at best. This article initially shows that climate change within the 'little ice age' from 1350 to 1750 is an unsatisfactory explanation for the 'marginalisation' of upland landscapes in parts of southern Scotland. It then ranges more widely across northern Britain in collating palaeo-ecological data with a view to exploring whether climate deterioration drove regional abandonment of upland areas in later prehistory, and concludes that no clear evidence exists. Rather than emphasise vulnerability in human occupation of the uplands, we should recognise the robustness and...

Climatic factors such as precipitation and temperature place primary controls on vegetation growth and development. The relationships between these factors and vegetation dynamics, as monitored using satellite remote sensing data, have been demonstrated on continental, regional and subregional scales. Most local studies have primarily focused on small areas immediately surrounding weather stations. Here, the effects of climatic “factors over intermediate‐scale sites of relatively homogenous vegetative land cover are examined. Two areas of Kansas are selected for study: the shortgrass Sandsage Prairie in the southwest and the Tallgrass Prairie National Preserve in the east‐central Flint Hills region. Within year and between year variation in vegetation in the context of climatic variability is examined on these sites using NOAA AVHRR data. Large increases in the strength of association between vegetative response (NDVI) and one‐month lagged precipitation as compared to same month correlations are ...

Previous attempts to map land cover at broad scales were based on single year time series and usually on the Normalized Difference Vegetation Index ( NDVI) Single years of data lack statistical representativity and the NDVI is partially driven by short-term climatic characteristics. We investigate two approaches to produce land-cover classifications that are not excessively influenced by short-term climatic variability: (i) averaging a climate-driven variable over several years, and (ii) measuring a more climate-independent variable. We test, compare and combine these two approaches for the African continent using 8 years of AVHRR Global Area Coverage (GAC) data. Our results demonstrate that times series of the ratio between surface temperature and NDVI are less influenced by interannual variations in climatic conditions than NDVI time series and thus produce more stable land-cover classifications. This finding is consistent with the biophysical interpretations of these two variables. When data a...

SUMMARY Micromammalian remains are relatively readily preserved in closed archaeological and palaeontological sites, as well as in modern barn-owl pellets, which act as controls. The animals themselves tend to have fairly precise habitat requirements and to respond quickly to environmental change. Long sequences of samples from the past can provide unique information on the nature and extent of climate change, as well as on conditions before human activities became a major agent of environmental change. So far, the evidence indicates that warm periods during the last 125 000 years in South Africa have not all been characterized by the same conditions. The evidence further indicates that during the last millennium the effects of natural climatic variability have only outweighed the depredations of humans in the presently more arid parts of South Africa. Several general conclusions arising from these facts could have a bearing on future planning. 1) Each investigation must be undertaken at the correct tempo...

As part of a study on the effects of climatic variability and change on the sustainability of agriculture in Alberto, the modelling performance of the second‐generation Canadian Climate Centre GCM (general circulation model) is examined. For the region in general, the simulation of 1 × CO2 mean temperature is generally better than that for mean precipitation, and summer is the season best modelled for each variable. At the scale of individual grid squares, DJF (December, January, February) (temperature) and JJA (June, July, August) (precipitation) are the seasons best modelled. The GCM‐simulated increases in mean annual temperature resulting from a doubling of CO2 are of the order of 5 to 6°C in the Prairie region, with much of this increase resulting from substantial warming in the winter and spring. Increases in mean annual precipitation are of the order of 50 to 150 mm (changes of +5 to +15%), with the greatest changes again occurring in winter and spring. As far as the limited GCM run duratio...

This study examines spatial and temporal characteristics of temperatures exceeding 38° C (100° F) in the south-central United States. Events are concentrated in three distinct zones in Texas with minimum frequencies along the coast. Although temporal analysis identifies no apparent region-wide linear trends in event frequencies, the seasonality of these events is found to vary widely across the study area. Explanations for the observed spatial and temporal patterns are offered. Although the relationship between mean and extreme temperatures is known to be strong, precipitation and rain days also were significantly correlated with extreme temperature events. Hence, the precipitation climatology may be important to understand in the assessment of the future of extreme 38° C events in the south-central United States. [Key words: extreme temperature events, spatial climatic variability, south-central United States.]