Drought triggers and sustains overnight fires in North America

Overnight fires are emerging in North America with previously unknown drivers and implications. This notable phenomenon challenges the traditional understanding of the 'active day, quiet night' model of the diurnal fire cycle1-3 and current fire management practices4,5. Here we demonstrate that drought conditions promote overnight burning, which is a key mechanism fostering large active fires. We examined the hourly diurnal cycle of 23,557 fires and identified 1,095 overnight burning events (OBEs, each defined as a night when a fire burned through the night) in North America during 2017-2020 using geostationary satellite data and terrestrial fire records. A total of 99% of OBEs were associated with large fires (>1,000 ha) and at least one OBE was identified in 20% of these large fires. OBEs were early onset after ignition and OBE frequency was positively correlated with fire size. Although warming is weakening the climatological barrier to night-time fires6, we found that the main driver of recent OBEs in large fires was the accumulated fuel dryness and availability (that is, drought conditions), which tended to lead to consecutive OBEs in a single wildfire for several days and even weeks. Critically, we show that daytime drought indicators can predict whether an OBE will occur the following night, which could facilitate early detection and management of night-time fires. We also observed increases in fire weather conditions conducive to OBEs over recent decades, suggesting an accelerated disruption of the diurnal fire cycle.

Critical transitions in the Amazon forest system

The possibility that the Amazon forest system could soon reach a tipping point, inducing large-scale collapse, has raised global concern1-3. For 65 million years, Amazonian forests remained relatively resilient to climatic variability. Now, the region is increasingly exposed to unprecedented stress from warming temperatures, extreme droughts, deforestation and fires, even in central and remote parts of the system1. Long existing feedbacks between the forest and environmental conditions are being replaced by novel feedbacks that modify ecosystem resilience, increasing the risk of critical transition. Here we analyse existing evidence for five major drivers of water stress on Amazonian forests, as well as potential critical thresholds of those drivers that, if crossed, could trigger local, regional or even biome-wide forest collapse. By combining spatial information on various disturbances, we estimate that by 2050, 10% to 47% of Amazonian forests will be exposed to compounding disturbances that may trigger unexpected ecosystem transitions and potentially exacerbate regional climate change. Using examples of disturbed forests across the Amazon, we identify the three most plausible ecosystem trajectories, involving different feedbacks and environmental conditions. We discuss how the inherent complexity of the Amazon adds uncertainty about future dynamics, but also reveals opportunities for action. Keeping the Amazon forest resilient in the Anthropocene will depend on a combination of local efforts to end deforestation and degradation and to expand restoration, with global efforts to stop greenhouse gas emissions.

Increased Amazon carbon emissions mainly from decline in law enforcement

The Amazon forest carbon sink is declining, mainly as a result of land-use and climate change1-4. Here we investigate how changes in law enforcement of environmental protection policies may have affected the Amazonian carbon balance between 2010 and 2018 compared with 2019 and 2020, based on atmospheric CO2 vertical profiles5,6, deforestation7 and fire data8, as well as infraction notices related to illegal deforestation9. We estimate that Amazonia carbon emissions increased from a mean of 0.24 ± 0.08 PgC year-1 in 2010-2018 to 0.44 ± 0.10 PgC year-1 in 2019 and 0.52 ± 0.10 PgC year-1 in 2020 (± uncertainty). The observed increases in deforestation were 82% and 77% (94% accuracy) and burned area were 14% and 42% in 2019 and 2020 compared with the 2010-2018 mean, respectively. We find that the numbers of notifications of infractions against flora decreased by 30% and 54% and fines paid by 74% and 89% in 2019 and 2020, respectively. Carbon losses during 2019-2020 were comparable with those of the record warm El Niño (2015-2016) without an extreme drought event. Statistical tests show that the observed differences between the 2010-2018 mean and 2019-2020 are unlikely to have arisen by chance. The changes in the carbon budget of Amazonia during 2019-2020 were mainly because of western Amazonia becoming a carbon source. Our results indicate that a decline in law enforcement led to increases in deforestation, biomass burning and forest degradation, which increased carbon emissions and enhanced drying and warming of the Amazon forests.

Climate warming increases extreme daily wildfire growth risk in California

California has experienced enhanced extreme wildfire behaviour in recent years1-3, leading to substantial loss of life and property4,5. Some portion of the change in wildfire behaviour is attributable to anthropogenic climate warming, but formally quantifying this contribution is difficult because of numerous confounding factors6,7 and because wildfires are below the grid scale of global climate models. Here we use machine learning to quantify empirical relationships between temperature (as well as the influence of temperature on aridity) and the risk of extreme daily wildfire growth (>10,000 acres) in California and find that the influence of temperature on the risk is primarily mediated through its influence on fuel moisture. We use the uncovered relationships to estimate the changes in extreme daily wildfire growth risk under anthropogenic warming by subjecting historical fires from 2003 to 2020 to differing background climatological temperatures and aridity conditions. We find that the influence of anthropogenic warming on the risk of extreme daily wildfire growth varies appreciably on a fire-by-fire and day-by-day basis, depending on whether or not climate warming pushes conditions over certain thresholds of aridity, such as 1.5 kPa of vapour-pressure deficit and 10% dead fuel moisture. So far, anthropogenic warming has enhanced the aggregate expected frequency of extreme daily wildfire growth by 25% (5-95 range of 14-36%), on average, relative to preindustrial conditions. But for some fires, there was approximately no change, and for other fires, the enhancement has been as much as 461%. When historical fires are subjected to a range of projected end-of-century conditions, the aggregate expected frequency of extreme daily wildfire growth events increases by 59% (5-95 range of 47-71%) under a low SSP1-2.6 emissions scenario compared with an increase of 172% (5-95 range of 156-188%) under a very high SSP5-8.5 emissions scenario, relative to preindustrial conditions.

Reversed Holocene temperature-moisture relationship in the Horn of Africa

Anthropogenic climate change is predicted to severely impact the global hydrological cycle1, particularly in tropical regions where agriculture-based economies depend on monsoon rainfall2. In the Horn of Africa, more frequent drought conditions in recent decades3,4 contrast with climate models projecting precipitation to increase with rising temperature5. Here we use organic geochemical climate-proxy data from the sediment record of Lake Chala (Kenya and Tanzania) to probe the stability of the link between hydroclimate and temperature over approximately the past 75,000 years, hence encompassing a sufficiently wide range of temperatures to test the 'dry gets drier, wet gets wetter' paradigm6 of anthropogenic climate change in the time domain. We show that the positive relationship between effective moisture and temperature in easternmost Africa during the cooler last glacial period shifted to negative around the onset of the Holocene 11,700 years ago, when the atmospheric carbon dioxide concentration exceeded 250 parts per million and mean annual temperature approached modern-day values. Thus, at that time, the budget between monsoonal precipitation and continental evaporation7 crossed a tipping point such that the positive influence of temperature on evaporation became greater than its positive influence on precipitation. Our results imply that under continued anthropogenic warming, the Horn of Africa will probably experience further drying, and they highlight the need for improved simulation of both dynamic and thermodynamic processes in the tropical hydrological cycle.

Comparison of hybrid machine learning models to predict short-term meteorological drought in Guanzhong region, China

Reliable drought prediction plays a significant role in drought management. Applying machine learning models in drought prediction is getting popular in recent years, but applying the stand-alone models to capture the feature information is not sufficient enough, even though the general performance is acceptable. Therefore, the scholars tried the signal decomposition algorithm as a data pre-processing tool, and coupled it with the stand-alone model to build 'decomposition-prediction' model to improve the performance. Considering the limitations of using the single decomposition algorithm, an 'integration-prediction' model construction method is proposed in this study, which deeply combines the results of multiple decomposition algorithms. The model tested three meteorological stations in Guanzhong, Shaanxi Province, China, where the short-term meteorological drought is predicted from 1960 to 2019. The meteorological drought index selects the Standardized Precipitation Index on a 12-month time scale (SPI-12). Compared with stand-alone models and 'decomposition-prediction' models, the 'integration-prediction' models present higher prediction accuracy, smaller prediction error and better stability in the results. This new 'integration-prediction' model provides attractive value for drought risk management in arid regions.

Re-examining the effects of drought on intimate-partner violence

Droughts are associated with several societal ills, especially in developing economies that rely on rainfed agriculture. Recently, researchers have begun to examine the effect of droughts on the risk of Intimate-Partner Violence (IPV), but so far this work has led to inconclusive results. For example, two large recent studies analyzed comparable data from multiple sub-Saharan African countries and drew opposite conclusions. We attempt to resolve this apparent paradox by replicating previous analyses with the largest data set yet assembled to study drought and IPV. Integrating the methods of previous studies and taking particular care to control for spatial autocorrelation, we find little association between drought and most forms of IPV, although we do find evidence of associations between drought and women's partners exhibiting controlling behaviors. Moreover, we do not find significant heterogeneous effects based on wealth, employment, household drinking water sources, or urban-rural locality.

Successive epidemic waves of cholera in South Sudan between 2014 and 2017: a descriptive epidemiological study

BACKGROUND

Between 2014 and 2017, successive cholera epidemics occurred in South Sudan within the context of civil war, population displacement, flooding, and drought. We aim to describe the spatiotemporal and molecular features of the three distinct epidemic waves and explore the role of vaccination campaigns, precipitation, and population movement in shaping cholera spread in this complex setting.

METHODS

In this descriptive epidemiological study, we analysed cholera linelist data to describe the spatiotemporal progression of the epidemics. We placed whole-genome sequence data from pandemic Vibrio cholerae collected throughout these epidemics into the global phylogenetic context. Using whole-genome sequence data in combination with other molecular attributes, we characterise the relatedness of strains circulating in each wave and the region. We investigated the association of rainfall and the instantaneous basic reproduction number using distributed lag non-linear models, compared county-level attack rates between those with early and late reactive vaccination campaigns, and explored the consistency of the spatial patterns of displacement and suspected cholera case reports.

FINDINGS

The 2014 (6389 cases) and 2015 (1818 cases) cholera epidemics in South Sudan remained spatially limited whereas the 2016-17 epidemic (20 438 cases) spread among settlements along the Nile river. Initial cases of each epidemic were reported in or around Juba soon after the start of the rainy season, but we found no evidence that rainfall modulated transmission during each epidemic. All isolates analysed had similar genotypic and phenotypic characteristics, closely related to sequences from Uganda and Democratic Republic of the Congo. Large-scale population movements between counties of South Sudan with cholera outbreaks were consistent with the spatial distribution of cases. 21 of 26 vaccination campaigns occurred during or after the county-level epidemic peak. Counties vaccinated on or after the peak incidence week had 2·2 times (95% CI 2·1-2·3) higher attack rates than those where vaccination occurred before the peak.

INTERPRETATION

Pandemic V cholerae of the same clonal origin was isolated throughout the study period despite interepidemic periods of no reported cases. Although the complex emergency in South Sudan probably shaped some of the observed spatial and temporal patterns of cases, the full scope of transmission determinants remains unclear. Timely and well targeted use of vaccines can reduce the burden of cholera; however, rapid vaccine deployment in complex emergencies remains challenging.

FUNDING

The Bill & Melinda Gates Foundation.

Pea Gβ subunit of G proteins has a role in nitric oxide-induced stomatal closure in response to heat and drought stress

Heterotrimeric G proteins consisting of Gα, Gβ and Gγ subunits act as downstream effectors to regulate multiple functions including abiotic stress tolerance. However, the mechanism of Gβ-mediated heat and drought tolerance is yet to be established. To explore the role of Pisum sativum Gβ subunit (PsGβ) in heat and drought stress, transgenic tobacco plants overexpressing (OEs) PsGβ were raised. Transgenic plants showing ectopic expression of PsGβ performed better under heat and drought stress in comparison with vector control plants. The seed germination, relative water content (RWC) and nitric oxide (NO) induction in the guard cells of transgenic plants were significantly higher in contrast to control plants. PsGβ promoter was isolated and several stress-responsive elements were identified. The change in Gβ expression in response to heat, methyl jasmonate (MeJA), abscisic acid (ABA), drought and salt confirms the presence of heat, low temperature and drought-responsive elements in the PsGβ promoter. Also, heat and drought stress caused the release of NO-induced stomatal closure in the leaves of transgenic tobacco plants OEs PsGβ. The better performance of transgenic plant OEs PsGβ is also attributed to the improved photosynthetic parameters as compared with control plants. These findings suggest a role of PsGβ in the signalling pathway leading to NO-induced stomatal closure during heat and drought stress.

Drought index prediction using advanced fuzzy logic model: Regional case study over Kumaon in India

A new version of the fuzzy logic model, called the co-active neuro fuzzy inference system (CANFIS), is introduced for predicting standardized precipitation index (SPI). Multiple scales of drought information at six meteorological stations located in Uttarakhand State, India, are used. Different lead times of SPI were computed for prediction, including 1, 3, 6, 9, 12, and 24 months, with inputs abstracted by autocorrelation function (ACF) and partial-ACF (PACF) analysis at 5% significance level. The proposed CANFIS model was validated against two models: classical artificial intelligence model (e.g., multilayer perceptron neural network (MLPNN)) and regression model (e.g., multiple linear regression (MLR)). Several performance evaluation metrices (root mean square error, Nash-Sutcliffe efficiency, coefficient of correlation, and Willmott index), and graphical visualizations (scatter plot and Taylor diagram) were computed for the evaluation of model performance. Results indicated that the CANFIS model predicted the SPI better than the other models and prediction results were different for different meteorological stations. The proposed model can build a reliable expert intelligent system for predicting meteorological drought at multi-time scales and decision making for remedial schemes to cope with meteorological drought at the study stations and can help to maintain sustainable water resources management.

Drought severity and all-cause mortality rates among adults in the United States: 1968-2014

BACKGROUND

Little is known about the effect of drought on all-cause mortality, especially in higher income countries such as the United States. As the frequency and severity of droughts are likely to increase, understanding the connections between drought and mortality becomes increasingly important.

METHODS

Our exposure variable was an annual cumulative drought severity score based on the 1-month, county-level Standardized Precipitation Evapotranspiration Index. The outcome variables of demographic subgroup-specific all-cause mortality count data per year were obtained from the National Vital Statistics System. Any counts below 10 deaths were censored in that demographic group per county. We modeled county-stratum-year mortality using interval-censored negative binomial regression with county-level random intercepts, for each combined age-race-sex stratum either with or without further stratification by climate regions. Fixed effects meta-regression was used to test the associations between age, race, sex, and region with the drought-mortality regression coefficients. Predictive margins were then calculated from the meta-regression model to estimate larger subgroup (e.g., 'race' or 'sex') associations of drought with mortality.

RESULTS

Most of the results were null for associations between drought severity and mortality, across joint strata of race, age, sex and region, but incidence rate ratios (IRRs) for 17 subgroups were significant after accounting for the multiple testing; ten were < 1 indicating a possible protective effect of drought on mortality for that particular subpopulation. The meta-regression indicated heterogeneity in the association of drought with mortality according to race, climate region, and age, but not by sex. Marginal means of the estimated log-incidence rate ratios differed significantly from zero for age groups 25-34, 35-44, 45-54 and 55-64; for the white race group; and for the South, West and Southwest regions, in the analysis that included wet county-years. The margin of the meta-regression model suggested a slightly negative, but not statistically significant, association of drought with same-year mortality in the overall population.

CONCLUSIONS

There were significant, heterogeneous-direction associations in subpopulation-stratified models, after controlling for multiple comparisons, suggesting that the impacts of drought on mortality may not be monolithic across the United States. Meta-regression identified systematic differences in the associations of drought severity with all-cause mortality according to climate region, race, and age. These findings suggest there may be important contextual differences in the effects of drought severity on mortality, motivating further work focused on local mechanisms. We speculate that some of the estimated negative associations of drought severity with same-year mortality could be consistent with either a protective effect of drought on total mortality in the same year, or with a delayed health effect of drought beyond the same year. Further research is needed to clarify associations of drought with more specific causes of death and with sublethal health outcomes, for specific subpopulations, and considering lagged effects occurring beyond the same year as the drought.

Spatio-Temporal Analysis of Drought Variability Using CWSI in the Koshi River Basin (KRB)

Drought is one of the most frequent meteorological disasters, and has exerted significant impacts on the livelihoods and economy of the Koshi River Basin (KRB). In this study, we assessed drought patterns using the Crop Water Shortage Index (CWSI) based on the MOD16 product for the period between 2000 and 2014. The results revealed that the CWSI based on the MOD16 product can be act as an indicator to monitor the characteristics of the drought. Significant spatial heterogeneity of drought was observed in the basin, with higher CWSI values downstream and upstream than in the midstream. The midstream of the KRB was dominated by light drought, moderate drought occurred in the upstream, and the downstream was characterized by severe drought. The monthly CWSI during one year in KRB showed the higher CWSI between March to May (pre-monsoon) and October to December (post-monsoon) rather than June to September (monsoon), and the highest was observed in the month of April, suggesting that precipitation plays the most important role in the mitigation of CWSI. Additionally, the downstream and midstream showed a higher variation of drought compared to the upstream in the basin. This research indicates that the downstream suffered severe drought due to seasonal water shortages, especially during the pre-monsoon, and water-related infrastructure should be implemented to mitigate losses caused by drought.

Assessing farmers' perspectives on climate change for effective farm-level adaptation measures in Khyber Pakhtunkhwa, Pakistan

Agriculture is considered as the backbone of the economy of Pakistan. However, current changes in climate have been adversely affecting agricultural productivity. In this paper, perceived impacts of climate change on agriculture and adaptation towards it have been studied in Charsadda district (lowlands) of Khyber Pakhtunkhwa province of Pakistan through extensive field surveys, involving 116 farm households. Results have revealed that climate change factors including fluctuating temperature, evidence of yearly long droughts, and a steady shift in rainfall patterns have pressured the agriculture sector and livelihoods of the local peasants. The staggering floods of 2010 and 2011 in Pakistan have evidenced severe climatic changes in Pakistan. These countrywide floods have washed fertile soil in the study area that has directly contributed to losses in agricultural yield and increased vector-borne diseases in crops. The local farmers have commonly deployed adaptive measure such as crops diversification, changing fertilizer, and planting shaded trees to minimize the impacts of changes in climate. However, these adjustments measures are perceived as not appropriate for improving farm yield. Therefore, the study suggests that improved understanding of the climate change impacts and knowledge on adapting adequately will lead to no-regret adaptation. It will also help protecting farmer's lives and livelihoods and will boost their resilience towards changing climatic conditions. Graphical abstract .

Understanding disaster resilience in communities affected by recurrent drought in Lesotho and Swaziland-A qualitative study

Background

Lesotho and Swaziland experience intense, recurring drought resulting in disaster situations. Despite the recurrence of drought, both its influence on rural subsistence communities’ support systems and the actions that enable structures of resilience remain poorly understood. Each incidence of drought stimulates a disaster resilience discussion that stalls without achievement of positive results until the next disaster. This study has examined the influence of recurring drought on communities’ inherent resilience and proposes an evidence-based framework to enhance community resilience.

Methods

Data were collected from 16 focus group discussions (N = 197) in the Highveld, Midveld and Lowveld agro-ecological regions of Swaziland and Lesotho. Themes and subthemes have been identified, defined, categorised and narrated using structuration theory as a guide.

Results

Resilience activities were found to be characterised by knowledgeability and changes in behaviour in adapting and applying appropriate actions, all of which were enhanced by institutional support. The effectiveness of institutional support hinged on harnessing communities’ knowledge, social groups, value systems, connectedness, participation, decision-making and collectivism.

Conclusion

Large-scale interventions to build and strengthen resilience are urgently needed in order to maintain cohesiveness and development gains, especially because rural subsistence farmers make up the majority of these two countries’ populations. Policies that integrate resilience with national development planning must be urgently developed and executed.

Association between severe drought and HIV prevention and care behaviors in Lesotho: A population-based survey 2016-2017

BACKGROUND

A previous analysis of the impact of drought in Africa on HIV demonstrated an 11% greater prevalence in HIV-endemic rural areas attributable to local rainfall shocks. The Lesotho Population-Based HIV Impact Assessment (LePHIA) was conducted after the severe drought of 2014-2016, allowing for reevaluation of this relationship in a setting of expanded antiretroviral coverage.

METHODS AND FINDINGS

LePHIA selected a nationally representative sample between November 2016 and May 2017. All adults aged 15-59 years in randomly selected households were invited to complete an interview and HIV testing, with one woman per household eligible to answer questions on their experience of sexual violence. Deviations in rainfall for May 2014-June 2016 were estimated using precipitation data from Climate Hazards Group InfraRed Precipitation with Station Data (CHIRPS), with drought defined as <15% of the average rainfall from 1981 to 2016. The association between drought and risk behaviors as well as HIV-related outcomes was assessed using logistic regression, incorporating complex survey weights. Analyses were stratified by age, sex, and geography (urban versus rural). All of Lesotho suffered from reduced rainfall, with regions receiving 1%-36% of their historical rainfall. Of the 12,887 interviewed participants, 93.5% (12,052) lived in areas that experienced drought, with the majority in rural areas (7,281 versus 4,771 in urban areas). Of the 835 adults living in areas without drought, 520 were in rural areas and 315 in urban. Among females 15-19 years old, living in a rural drought area was associated with early sexual debut (odds ratio [OR] 3.11, 95% confidence interval [CI] 1.43-6.74, p = 0.004), and higher HIV prevalence (OR 2.77, 95% CI 1.19-6.47, p = 0.02). It was also associated with lower educational attainment in rural females ages 15-24 years (OR 0.44, 95% CI 0.25-0.78, p = 0.005). Multivariable analysis adjusting for household wealth and sexual behavior showed that experiencing drought increased the odds of HIV infection among females 15-24 years old (adjusted OR [aOR] 1.80, 95% CI 0.96-3.39, p = 0.07), although this was not statistically significant. Migration was associated with 2-fold higher odds of HIV infection in young people (aOR 2.06, 95% CI 1.25-3.40, p = 0.006). The study was limited by the extensiveness of the drought and the small number of participants in the comparison group.

CONCLUSIONS

Drought in Lesotho was associated with higher HIV prevalence in girls 15-19 years old in rural areas and with lower educational attainment and riskier sexual behavior in rural females 15-24 years old. Policy-makers may consider adopting potential mechanisms to mitigate the impact of income shock from natural disasters on populations vulnerable to HIV transmission.

Beyond reasonable drought: hotspots reveal a link between the 'Big Dry' and cryptosporidiosis in Australia's Murray Darling Basin

There is little evidence on how the health impacts of drought vary spatially and temporally. With a focus on waterborne cryptosporidiosis, we identify spatio-temporal hotspots and by using interrupted time series analysis, examine the impact of Australia's Big Dry (2001-2009) in these disease clusters in the Murray Darling Drainage Basin. Analyses revealed a statistically significant hotspot in the north of the Australian Capital Territory (ACT) and a hotspot in the north-eastern end of the basin in Queensland. After controlling for long-term trend and seasonality in cryptosporidiosis, interrupted time series analysis of reported cases in these hotspots indicated a statistically significant link with the Big Dry. In both areas, the end of the Big Dry was associated with a lower risk of reported cryptosporidiosis; in the ACT, the estimated relative risk (RR) was 0.16 (95% confidence interval: 0.07; 0.33), and in Queensland the RR was 0.42 (95% confidence interval: 0.19; 0.42). Although these data do not establish a causal association, this research highlights the potential for drought-related health risks.

Biomass burning and carbon monoxide patterns in Brazil during the extreme drought years of 2005, 2010, and 2015

In the 21st century, severe droughts associated with climate change will increase biomass burning (BB) in Brazil caused by the human activities. Recent droughts, especially in 2005, 2010, and 2015, caused strong socioeconomic and environmental impacts. The 2015 drought considered the most severe since 1901, surpassed the 2005 and 2010 events in respect to area and duration. Herein, based on satellite data, the 2005, 2010 and 2015 drought impacts on wildfire episodes and carbon monoxide (CO) variability during the dry and the dry-to-wet transition seasons were examined. The BB occurrences in the dry season were fewer during 2015 than during 2005 (-44%) and 2010 (-47%). Contrasting, the BB events in the dry-to-wet transition season, were higher during 2015 than during 2005 (+192%) and 2010 (+332%). The BB outbreaks were concentrated in the southern and southwestern Amazon during 2005, in the Cerrado region during 2010, and mainly in the central and northern Amazon during 2015, an area normally with few fires. The CO concentration showed positive variations (up to +30%) occurred in the southern Amazon and central Brazil during the 2005 and 2010 dry seasons, and north of 20 °S during the 2015-2016 dry-to-wet transition season. The BB outbreaks and the CO emissions showed a considerable spatiotemporal variability among the droughts of 2005, 2010, and 2016, first of them driven by local conditions in the tropical North Atlantic (TNA), characterized by warm than normal sea surface waters and the other two by the El Niño occurrences.

Limitations of Water Resources Infrastructure for Reducing Community Vulnerabilities to Extremes and Uncertainty of Flood and Drought

Debate and deliberation surrounding climate change has shifted from mitigation toward adaptation, with much of the adaptation focus centered on adaptive practices, and infrastructure development. However, there is little research assessing expected impacts, potential benefits, and design challenges that exist for reducing vulnerability to expected climate impacts. The uncertainty of design requirements and associated government policies, and social structures that reflect observed and projected changes in the intensity, duration, and frequency of water-related climate events leaves communities vulnerable to the negative impacts of potential flood and drought. The results of international research into how agricultural infrastructure features in current and planned adaptive capacity of rural communities in Argentina, Canada, and Colombia indicate that extreme hydroclimatic events, as well as climate variability and unpredictability are important for understanding and responding to community vulnerability. The research outcomes clearly identify the need to deliberately plan, coordinate, and implement infrastructures that support community resiliency.

Drought analysis in the Eastern Nile basin using the standardized precipitation index

Drought is considered by many researchers to be the most complex but least understood of all natural hazards, affecting more people than any other hazard. Drought affects many aspects of community and environment, and any future increases in the water demand will be most critical in periods of severe drought. Geospatial analysis of the historical drought events and their causes can be used to mitigate drought impacts and to develop preparedness plans. This study aimed to identify the changes in drought frequency, magnitude, duration, and intensity in the Eastern Nile basin during the period 1965-2000, using the standardized precipitation index (SPI). An SPI program based on C sharp language was developed to monitor drought in the study area. Twenty-eight meteorological stations distributed on the Eastern Nile basin were chosen to collect monthly precipitation data. For drought analysis, SPI series of 3-, 6-, 9-, 12-, and 24-month timescales have been calculated. Results showed that the study area received several drought events during the long rainy season (June to September) and the short rainy season (March to May) as well. Annual analysis of SPI time series indicated that the study area received several drought events, and the most severity event was during the year 1984.

Monitoring of meteorological and hydrological droughts in the Vistula basin (Poland)

The article presents the course of meteorological droughts in Vistula subcatchments in years 1981-2010 and their influence on the occurrence of hydrological droughts. Using the Standardized Precipitation Index (SPI) as an indicator of meteorological drought on the one hand and the Standardized Water-level Index (SWI) and Standardized Runoff Index (SRI) as indicators of hydrological drought on the other, the mutual relationships between precipitation conditions and hydrological conditions were evaluated, as well as the relationships between the two drought types. Studies were conducted for three cumulative periods of these indices, of 12, 24, and 48 months. It was determined that meteorological droughts occurred earliest in the north-western and central part of the basin, and latest in areas lying above 300 m a.s.l. and in the south of Poland. Total duration, depending on the cumulative period, for SPI comprised from 38 to 41% of the analyzed period and for SWI (35-47%) and SRI (24-51%). The strongest relationships were identified in the central part of the Vistula (0.8 < r < 0.85), while the weakest relationships were recorded in the foothill region (r < 0.5). There were also indicated non-climate-related factors influencing those relationships (underground reservoirs, diverse Vistula water resource usage for municipal and industrial intake).

An integrated method for assessing drought prone areas - Water efficiency practices for a climate resilient Mediterranean agriculture

This paper presents a new integrated GIS modeling method to assess drought vulnerability using multi-criteria analysis. The proposed methodology is an improvement over previous methods since it incorporates both dynamic and static factors that may affect water dynamics and contribute to water scarcity. These factors are: a) precipitation, b) evapotranspiration, c) soil water content, d) soil depth, e) artificial drainage, f) depth to water table, g) runoff accumulation, and h) saltwater intrusion zones. The above factors and their corresponding maps were fuzzified and spatially overlayed in order to obtain the final drought vulnerability map. The map depicts the spatial distribution of drought vulnerability represented by five classes ranging from very low to very high vulnerability. The proposed methodology was applied to the Greek island of Crete located in the Southeast Mediterranean region. The island of Crete is one of the most drought-prone areas in the region, while at the same time the island's economy relies strongly on agriculture and tourism. The derived results show that drought vulnerability is more severe in the eastern part of the island and that the coastal zones of the entire island are drought-prone areas. Also, according to the results, 19% of the island's area is characterized as "very highly vulnerable to drought". This percentage varies significantly across the prefectures, with Rethymnon having the lowest vulnerability (2.8%), followed by the prefectures of Chania (6.3%), and Heraklion (17.3%), while the prefecture of Lassithi is the most vulnerable to drought (51.4%). The developed methodology was validated using historical data for drought affected areas in Crete, which is not always addressed in publications. Moreover, in this study, sustainable agricultural practices that ensure water efficiency especially in drought prone areas are proposed. These practices can be adopted by farmers to promote climate resilient agriculture in the Mediterranean region.

Integrated spatiotemporal trends using TRMM 3B42 data for the Upper São Francisco River basin, Brazil

Trend analysis is an important issue for the decision-making processes. Thus, trends of rainfall, consecutive dry days (CDD), and consecutive wet days (CWD) in the Upper São Francisco River basin, Brazil, using daily rainfall data from the Tropical Rainfall Measuring Mission (TRMM) for recent 18 years, were analyzed. Instead of analyzing the trend of one average time series for one specific confidence level, a spatiotemporal analysis over the entire area with 169 continuous time series is done by applying the nonparametric Mann-Kendall and Sen tests for simultaneously 13 confidence levels and a new integrated confidence classification is proposed. The results show that the rainfall has increased during the less rainy periods (from June to October) and has decreased in the rainy periods (from November to May), with the highest and lowest confidence levels, respectively. An analysis of CDD and CWD shows that the number of CDD has decreased, while the number of CWD has increased, which revealed that the dry periods are more frequently interrupted for the period studied.

Probabilistic assessment of phenophase-wise agricultural drought risk under different sowing windows: a case study with rainfed soybean

A new methodology for crop-growth stage-specific assessment of agricultural drought risk under a variable sowing window is proposed for the soybean crop. It encompasses three drought indices, which include Crop-Specific Drought Index (CSDI), Vegetation Condition Index (VCI), and Standardized Precipitation Evapotranspiration Index (SPEI). The unique features of crop-growth stage-specific nature and spatial and multi-scalar coverage provide a comprehensive assessment of agricultural drought risk. This study was conducted in 10 major soybean-growing districts of Madhya Pradesh state of India. These areas contribute about 60% of the total soybean production for the country. The phenophase most vulnerable to agricultural drought was identified (germination and flowering in our case) for each district across four sowing windows. The agricultural drought risk was quantified at various severity levels (moderate, severe, and very severe) for each growth stage and sowing window. Validation of the proposed new methodology also yielded results with a high correlation coefficient between percent probability of agricultural drought risk and yield risk (r = 0.92). Assessment by proximity matrix yielded a similar statistic. Expectations for the proposed methodology are better mitigation-oriented management and improved crop contingency plans for planners and decision makers.

Tolerance or avoidance: drought frequency determines the response of an N2 -fixing tree

Climate change is increasing drought frequency, which may affect symbiotic N₂ fixation (SNF), a process that facilitates ecosystem recovery from disturbance. Here, we assessed the effect of drought frequency on the ecophysiology and SNF rate of a common N₂ -fixing tree in eastern US forests. We grew Robinia pseudoacacia seedlings under the same mean soil moisture, but with different drought frequency caused by wet-dry cycles of varying periodicity. We found no effect of drought frequency on final biomass or mean SNF rate. However, seedlings responded differently to wet and dry phases depending on drought frequency. Under low-frequency droughts, plants fixed carbon (C) and nitrogen (N) at similar rates during wet and dry phases. Conversely, under high-frequency droughts, plants fixed C and N at low rates during dry phases and at high rates during wet phases. Our findings suggest that R. pseudoacacia growth is resistant to increased drought frequency because it employs two strategies - drought tolerance or drought avoidance, followed by compensation. SNF may play a role in both by supplying N to leaf tissues for acclimation and by facilitating compensatory growth following drought. Our findings point to SNF as a mechanism for plants and ecosystems to cope with drought.

Effects of drought on child health in Marsabit District, Northern Kenya

This study uses five years of panel data (2009-2013) for Northern Kenya's Marsabit district to analyze the levels and extent of malnutrition among children aged five and under in that area. We measure drought based on the standardized normalized difference vegetation index (NDVI) and assess its effect on child health using mid-upper arm circumference (MUAC). The results show that approximately 20 percent of the children in the study area are malnourished and a one standard deviation increase in NDVI z-score decreases the probability of child malnourishment by 12-16 percent. These findings suggest that remote sensing data can be usefully applied to develop and evaluate new interventions to reduce drought effects on child malnutrition, including better coping strategies and improved targeting of food aid.

Misfortunes never come singly: Structural change, multiple shocks and child malnutrition in rural Senegal

This study considers the two most pronounced shocks Senegalese subsistence farmers struggle with, namely increasing purchase prices and droughts. We assess the relationship of these self-reported shocks with child health in a multi-shock approach to account for concomitance of adverse events from the natural, biological, economic and health sphere. We employ a unique farming household panel dataset containing information on children living in poor, rural households in eight regions of Senegal in 2009 and 2011 and account for structural changes occurring between survey periods due to the large scale, national Nutrition Enhancement Program. By zooming in to the micro level we demonstrate that Senegal as a Sahelian country, mainly reliant on subsistence agriculture, is very vulnerable to climate variability and international price developments: According to our conservative estimates, the occurrence of a drought explains 25% of the pooled weight-for-age standard deviation, income losses 31%. Our multi-shock analysis reveals that the shocks are perceived as more severe in 2011 with droughts explaining up to 44% of the standard deviation of child health, increased prices up to 21%. Yet, the concomitance of droughts and increased prices after the structural change, i.e. the Nutrition Enhancement Program, indicates that the health of children experiencing both shocks in 2011 has improved. We argue that these results are driven by the increase in rural household income as theoretically outlined in the agricultural household model. Thus, adequate policy responses to shocks do not only depend on the nature but also on the concomitance of hazardous events.

Integrated water resources management for emergency situations: A case study of Macau

Integrated urban water management (IUWM) is a useful tool that can be used to alleviate water resource shortages in developing regions like Macau, where 98% of the raw water comes from mainland China. In Macau, scarce water resources deteriorate rapidly in emergency situations, such as accidental chemical spills upstream of the supply reservoir or salty tides. During these times, only the water from the two freshwater reservoirs in Macau can be used. In this study, we developed urban water management optimization models that integrated the raw water supply from the two reservoirs with various proposed governmental policies (wastewater reuse, rainwater collection, and water saving). We then determined how various water resource strategies would influence the urban water supply in Macau in emergency situations. Our results showed that, without imported raw water, the water supply from only the two Macau reservoirs would last for 7.95days. However, when all the government policies were included in the model, the supply could be extended to 13.79days. Out of the three non-conventional water resources, wastewater reuse is the most beneficial for increasing the Macau water supply, and rainwater collection also has great potential.

Water balance analysis of the Morava River floodplain in the Kostice-Lanžhot transect using the WBCM-7 model

The study area of the Morava River floodplain is situated between the rivers Morava and Kyjovka in the reach from Hodonín to Lanžhot. This experimental area was chosen because during the last 30 years, there has been a serious problem with the frequent occurrence of hydrological extremes, such as floods and droughts. Dry seasons have a very negative impact on the floodplain forest and have been caused mainly by regulation of the Morava River channel in the 1970s. Since flooding in the catastrophic year 1977, a part of this area has served as a polder for flood impact mitigation of the urbanised area of the town of Lanžhot. Management and farming practices have been heavily affected by the enormous economic and ecological damage due to long-term flooding of agricultural land. The purpose of this study is to assess the extent to which the precipitation in the growing season of the dry years 2003 and 2011 was deficient, in comparison with the normal year 2009, through a study of the actual evapotranspiration caused by the significant drought in the Morava floodplain. A similar but converse situation in the wet year 2010 was also analysed, with the aim to show the differences in the components of the water balance equation in the growing seasons of all the extreme years tested here. The daily data from the Kostice climatological station were processed using the WBCM-7 model, where the input parameters were calibrated by the fluctuation of the groundwater table in the control borehole.

The impact of drought and air pollution on metal profiles in peat cores

Peat cores have long been used to reconstruct atmospheric metal deposition; however, debate remains regarding how well historical depositional patterns are preserved in peat. This study examined peat cores sampled from 14 peatlands in the Sudbury region of Ontario, Canada, which has a well-documented history of acid and metal deposition. Copper (Cu) and lead (Pb) concentrations within individual peat cores were strongly correlated and were elevated in the upper 10 cm, especially in the sites closest to the main Copper Cliff smelter. In contrast, nickel (Ni) and cobalt (Co) concentrations were often elevated at depths greater than 10 cm, indicating much greater post-depositional movement of these metals compared with Cu and Pb. Post-depositional movement of metals is supported by the observation that Ni and Co concentrations in peat pore water increased by approximately 530 and 960% for Ni and Co, respectively between spring and summer due to drought-induced acidification, but there was much less change in Cu concentration. Sphagnum cover and (210)Pb activity measured at 10 cm at the 14 sites significantly increased with distance from Copper Cliff, and the surface peat von Post score decreased with distance from Copper Cliff, indicating the rate of peat formation increases with distance from Sudbury presumably as a result of improved Sphagnum survival. This study shows that the ability of peat to preserve deposition histories of some metals is strongly affected by drought-induced post-depositional movement and that loss of Sphagnum due to air pollution impairs the rate of peat formation, further affecting metal profiles in peatlands.

Influence of extreme weather disasters on global crop production

In recent years, several extreme weather disasters have partially or completely damaged regional crop production. While detailed regional accounts of the effects of extreme weather disasters exist, the global scale effects of droughts, floods and extreme temperature on crop production are yet to be quantified. Here we estimate for the first time, to our knowledge, national cereal production losses across the globe resulting from reported extreme weather disasters during 1964-2007. We show that droughts and extreme heat significantly reduced national cereal production by 9-10%, whereas our analysis could not identify an effect from floods and extreme cold in the national data. Analysing the underlying processes, we find that production losses due to droughts were associated with a reduction in both harvested area and yields, whereas extreme heat mainly decreased cereal yields. Furthermore, the results highlight ~7% greater production damage from more recent droughts and 8-11% more damage in developed countries than in developing ones. Our findings may help to guide agricultural priorities in international disaster risk reduction and adaptation efforts.

Climate adversity and resilience: the voice of rural Australia

INTRODUCTION

Over the past decade, Australia has experienced prolonged drought and extensive flooding. It is argued that such events impact more significantly on rural communities than urban. Although there is a body of research investigating the effects of drought on mental and physical health in rural Australia, little research has examined the effects of flood and drought on wellbeing. This article explores the influence of drought and flood on the wellbeing of rural residents in New South Wales (NSW), Australia.

METHODS

Forty-six individuals living in four rural communities in NSW were recruited and asked their experience of flood and drought using in-depth semi-structured face to face interviews or focus groups. The study used a grounded hermeneutic approach to contextualise participants' experiences within a rural social and cultural construct.

RESULTS

Weather was found to be at the core of rural life, with flood and drought contributing to decreased wellbeing from stress, anxiety, loss and fear. Social connectedness was found to promote resilience in rural communities buffering the effects of flood and drought.

CONCLUSIONS

Flood and drought have negative impacts on an individual's wellbeing. Although these negative effects were seen to be buffered by individual and community resilience, the long term emotional impact of flood and drought on rural communities needs to be further considered.

Climate, water and tourism: causes and effects of droughts associated with urban development and tourism in Benidorm (Spain)

In this paper, we analyse the relationship between climate, tourism and water in Benidorm (Spain), an international icon of Fordist tourism (mass tourism). In particular, we have studied the causes and effects of the water supply droughts Benidorm has suffered since becoming a major holiday destination. For this purpose, we consulted the local press in Benidorm over the period 1969-2003. Using qualitative and quantitative geographical techniques, we found that the water supply in the area has managed to keep up with rapidly increasing demand, with only occasional imbalances and periods of crisis. We focused in particular on the causes and effects of the water supply crisis of 1978, a moment of great uncertainty in the history of Benidorm as a holiday resort. We also examined the influence of atmospheric conditions on precipitation levels and how these precipitation levels affect the water supply. Our results highlight the importance of intense rainfall episodes associated with easterly winds, which provided large inputs for Benidorm's water supply system (Marina Baja Water Consortium). We also found that the water supply crisis of 1978 resulted in serious economic losses for Benidorm and damaged its image as a holiday destination and that the city is now less vulnerable to variations in the climate, as a result of its search for new water resources (both surface and ground water resources and from other nonconventional sources).

Research on the drought index of irrigation district with multi-time scales

The empirical mode decomposition method is applied to analyze fluctuating periods and local features of the annual drought index and the drought index in the irrigation and non-irrigation periods from 1956 to 2010 in the Yinchuan irrigation district. In order to understand the uncertainty between these variables, the set pair analysis method is used to present the identity, discrepancy, and contrary of the drought index with multi-time scales. The results reveal that the annual drought index and the drought index in the irrigation and non-irrigation periods have a complex relationship which may be related to El Niño, the air-sea intersection, and the long period of solar activity. The drought index in the irrigation and non-irrigation periods presents mainly the contrary and the discrepancy; the fluctuating shapes of the annual drought index and drought index in the irrigation period are the same on their different period levels. The original annual drought index and its intrinsic mode function components have a certain connection degree; they mainly present the discrepancy.

A 323-year long reconstruction of drought for SW Romania based on black pine (Pinus Nigra) tree-ring widths

Increase in temperature and decrease in precipitation pose a major future challenge for sustainable ecosystem management in Romania. To understand ecosystem response and the wider social consequences of environmental change, we constructed a 396-year long (1615-2010) drought sensitive tree-ring width chronology (TRW) of Pinus nigra var. banatica (Georg. et Ion.) growing on steep slopes and shallow organic soil. We established a statistical relationship between TRW and two meteorological parameters-monthly sum of precipitation (PP) and standardised precipitation index (SPI). PP and SPI correlate significantly with TRW (r = 0.54 and 0.58) and are stable in time. Rigorous statistical tests, which measure the accuracy and prediction ability of the model, were all significant. SPI was eventually reconstructed back to 1688, with extreme dry and wet years identified using the percentile method. By means of reconstruction, we identified two so far unknown extremely dry years in Romania--1725 and 1782. Those 2 years are almost as dry as 1946, which was known as the "year of great famine." Since no historical documents for these 2 years were available in local archives, we compared the results with those from neighbouring countries and discovered that both years were extremely dry in the wider region (Slovakia, Hungary, Anatolia, Syria, and Turkey). While the 1800-1900 period was relatively mild, with only two moderately extreme years as far as weather is concerned, the 1900-2009 period was highly salient owing to the very high number of wet and dry extremes--five extremely wet and three extremely dry events (one of them in 1946) were identified.

Hazard analysis of Arid and semi-Arid (ASAL) regions of Kenya

INTRODUCTION

This paper describes a situationanalysis on hazards in the Arid and semi-Arid lands of Kenya. The leading hazards affecting the Arid and semi-arid lands are mainly natural and include among others drought, floods, and landslides. Other hazards of importance were found to be war and conflict, HIV/AIDS and fires. Over 80% of these are weather related.

OBJECTIVES

The overall objective of this study was to prioritize hazards in the ASAL region. Specifically, the study identified the top ten hazards in the ASAL Districts of Kenya, determined Probability of occurrence; Analyzed the potential impact of the hazard and utilizing multiplier effect prioritized the Hazards using a hypothetical model.

METHODOLOGY

This was a descriptive study conducted in over half of the Kenya's ASAL Districts in four regions of Lower and Upper Eastern, North Eastern and part of the Coast region. Six Districts were purposively selected per region with six officers from each District all totaling one hundred and forty four. The sectors where respondents were sourced from were Agriculture, Health, local Government, and Provincial Administration, Environment and NGO. The members through a consensus process analyzed hazards in groups of their respective districts using a tool that had been developed and respondents trained on its use.

RESULTS

One hundred and forty four (144) officers from Twenty four Districts in the four regions were recruited. One hundred twenty seven (81%) were male and only 27 (19% ) were female The representation of participants per sector was Governance 25% followed by Civil society organizations 21%, Health 16%, Agriculture and arid lands 15%, Research and scientific institutions 13%. The top Priority Hazards identified using the mean score were Drought and famine (5.4) Epidemics and epizootics (3.8), HIV/AIDS (3.6), War and conflict (2.5), Floods (2.5) CONCLUSIONS: The exercise confirmed the priority hazards in the Arid and semi-arid regions of Kenya and described vulnerability factors that included water scarcity, poverty and low educational levels. The region suffers from a variety of hazards in particular Drought and famine, Epidemics including HIV/AIDS and War and conflict. Environmental degradation though given a low score may be more of a perception. There is need to undertake a comprehensive hazard and Vulnerability analysis at regional and country level to inform interventions and other developmental activities. Women should be targeted at the community and leadership level, and efforts to empower them should be stepped up.

Could drought conditions trigger Schmallenberg virus and other arboviruses circulation?

BACKGROUND

In 2011, a new orthobunyavirus, named the Schmallenberg virus (SBV), was discovered in Europe. Like the related Shamonda virus, SBV is an arbovirus (arthropod-borne virus). After its discovery, the virus was detected in a wide area in north-western Europe, an unexpected finding in a territory where climatic conditions would not seem ideal for arbovirus transmission. This sudden expansion suggests the effect of 2011 drought as a key factor that may have triggered SBV circulation. The possible influence of drought, recorded in north-western Europe in early 2011, on virus circulation was evaluated.

METHODS AND RESULTS

The locations of SBV detections in Europe until April 2012 were obtained, and area of virus circulation was evaluated by kernel density estimation. Precipitation data in SBV circulation area, summarized by the 3 month precipitation indexes of May, were compared with precipitation data outside that area, confirming driest conditions in that area.

CONCLUSIONS

The onset of drought conditions recorded in the SBV detection area in early 2011 may have promoted the circulation of this virus. A correlation between circulation of some arboviruses and drought has been reported elsewhere. This was mainly explained by an effect of water deficit on the environment, which altered the relationships between vectors and reservoirs, but this correlation might be also the result of unknown effects of drought on the vectors. The effect of drought conditions on arbovirus circulation is most likely underestimated and should be considered, since it could promote expansion of arboviruses into new areas in a global warming scenario.

Predicting the future impact of droughts on ungulate populations in arid and semi-arid environments

Droughts can have a severe impact on the dynamics of animal populations, particularly in semi-arid and arid environments where herbivore populations are strongly limited by resource availability. Increased drought intensity under projected climate change scenarios can be expected to reduce the viability of such populations, yet this impact has seldom been quantified. In this study, we aim to fill this gap and assess how the predicted worsening of droughts over the 21^st century is likely to impact the population dynamics of twelve ungulate species occurring in arid and semi-arid habitats. Our results provide support to the hypotheses that more sedentary, grazing and mixed feeding species will be put at high risk from future increases in drought intensity, suggesting that management intervention under these conditions should be targeted towards species possessing these traits. Predictive population models for all sedentary, grazing or mixed feeding species in our study show that their probability of extinction dramatically increases under future emissions scenarios, and that this extinction risk is greater for smaller populations than larger ones. Our study highlights the importance of quantifying the current and future impacts of increasing extreme natural events on populations and species in order to improve our ability to mitigate predicted biodiversity loss under climate change.

Soil acidification occurs under ambient conditions but is retarded by repeated drought: results of a field-scale climate manipulation experiment

Acid atmospheric emissions within Europe and North America have decreased strongly since 1985 and most recent acidification studies have focused on the changes occurring within ecosystems as a result of this decreased deposition. This current study documents a soil acidification trend under ambient N deposition conditions over a 13 year period, suggesting that acidification continues to be a process of concern at this Calluna vulgaris dominated heathland with an acidic sandy soil. The annual manipulation of climatic conditions on this heathland simulated the predicted summer rainfall reduction (drought) and resulted in a long term retardation of the soil acidification trend. The pH of the soil solution significantly decreased over the course of the trial for both treatments, however, in the final 2 years the decline continued only in the Control treatment. This retardation is primarily associated with the reduction in rainfall leading to lower drainage rates, reduced loss of cations and therefore reduced lowering of the soil acid neutralizing capacity (ANC). However, a change in the underlying mechanisms also indicated that N transformations became less important in the Drought treatment. This change corresponded to an increase in groundcover of an air-pollution tolerant moss species and it is hypothesized that this increasing moss cover filtered an increasing quantity of deposited N, thus reducing the N available for transformation. A soil acidification lag time is expected to increase between the two treatments due to the cumulative disparity in cation retention and rates of proton formation. To the authors' knowledge, this is the first study in which such acidification trends have been demonstrated in a field-scale climate manipulation experiment.

Modifying rainfall patterns in a Mediterranean shrubland: system design, plant responses, and experimental burning

Global warming is projected to increase the frequency and intensity of droughts in the Mediterranean region, as well as the occurrence of large fires. Understanding the interactions between drought, fire and plant responses is therefore important. In this study, we present an experiment in which rainfall patterns were modified to simulate various levels of drought in a Mediterranean shrubland of central Spain dominated by Cistus ladanifer, Erica arborea and Phillyrea angustifolia. A system composed of automatic rainout shelters with an irrigation facility was used. It was designed to be applied in vegetation 2 m tall, treat relatively large areas (36 m2), and be quickly dismantled to perform experimental burning and reassembled back again. Twenty plots were subjected to four rainfall treatments from early spring: natural rainfall, long-term average rainfall (2 months drought), moderate drought (25% reduction from long-term rainfall, 5 months drought) and severe drought (45% reduction, 7 months drought). The plots were burned in late summer, without interfering with rainfall manipulations. Results indicated that rainfall manipulations caused differences in soil moisture among treatments, leading to reduced water availability and growth of C. ladanifer and E. arborea in the drought treatments. However, P. angustifolia was not affected by the manipulations. Rainout shelters had a negligible impact on plot microenvironment. Experimental burns were of high fire intensity, without differences among treatments. Our system provides a tool to study the combined effects of drought and fire on vegetation, which is important to assess the threats posed by climate change in Mediterranean environments.

A temperature-precipitation based leafing model and its application in Northeast China

Plant phenology models, especially leafing models, play critical roles in evaluating the impact of climate change on the primary production of temperate plants. Existing models based on temperature alone could not accurately simulate plant leafing in arid and semi-arid regions. The objective of the present study was to test the suitability of the existing temperature-based leafing models in arid and semi-arid regions, and to develop a temperature-precipitation based leafing model (TP), based on the long-term (i.e., 12-27 years) ground leafing observation data and meteorological data in Northeast China. The better simulation of leafing for all the plant species in Northeast China was given by TP with the fixed starting date (TPn) than with the parameterized starting date (TPm), which gave the smallest average root mean square error (RMSE) of 4.21 days. Tree leafing models were validated with independent data, and the coefficient of determination (R(2)) was greater than 0.60 in 75% of the estimates by TP and the spring warming model (SW) with the fixed starting date. The average RMSE of herb leafing simulated by TPn was 5.03 days, much lower than other models (>9.51 days), while the average R(2) of TPn and TPm were 0.68 and 0.57, respectively, much higher than the other models (<0.22). It indicates that TPn is a universal model and more suitable for simulating leafing of trees and herbs than the prior models. Furthermore, water is an important factor determining herb leafing in arid and semi-arid temperate regions.

GIS-based probability assessment of natural hazards in forested landscapes of Central and South-Eastern Europe

We assessed the probability of three major natural hazards--windthrow, drought, and forest fire--for Central and South-Eastern European forests which are major threats for the provision of forest goods and ecosystem services. In addition, we analyzed spatial distribution and implications for a future oriented management of forested landscapes. For estimating the probability of windthrow, we used rooting depth and average wind speed. Probabilities of drought and fire were calculated from climatic and total water balance during growing season. As an approximation to climate change scenarios, we used a simplified approach with a general increase of pET by 20%. Monitoring data from the pan-European forests crown condition program and observed burnt areas and hot spots from the European Forest Fire Information System were used to test the plausibility of probability maps. Regions with high probabilities of natural hazard are identified and management strategies to minimize probability of natural hazards are discussed. We suggest future research should focus on (i) estimating probabilities using process based models (including sensitivity analysis), (ii) defining probability in terms of economic loss, (iii) including biotic hazards, (iv) using more detailed data sets on natural hazards, forest inventories and climate change scenarios, and (v) developing a framework of adaptive risk management.

Impact of drought-related vaccination on livestock mortality in pastoralist areas of Ethiopia

Under a national Livestock Policy Forum in Ethiopia the impact of livestock vaccination during drought was assessed in order to inform the development of a best-practice guideline. For each of the different types of vaccine used during drought years there was no significant difference in livestock mortality, for any species, in vaccinated compared with non-vaccinated herds. The limited impact of vaccination on livestock mortality was attributed to weaknesses in the design and implementation of vaccination programmes, including use of inappropriate vaccines, low vaccination coverage, problems with vaccine dosing, incorrect timing of vaccination and problems with vaccine storage. If these weaknesses could be overcome vaccination could be a useful means to protect livestock assets, with considerable benefit-cost ratios. Vaccination should be conducted as a standard preventive measure during normal years, and programme design should be informed by participatory epidemiological studies.