34 results
Search Results
2. What climate? The different meaning of climate indicators in violent conflict studies.
- Author
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Dahm, Ruben, Meijer, Karen, Kuneman, Ernst, and van Schaik, Louise
- Subjects
- *
NATURAL disasters , *RAINFALL , *CLIMATE change , *OPERATIONAL definitions ,EL Nino - Abstract
This paper explores the operationalization of climate-related indicators in violent conflict research. The climate-conflict narrative gained traction in recent decades and climate change is often referred to as a 'threat multiplier' by both policy makers and scholars. Yet, the relationships between climate-related phenomena and violent conflict are complex and context-specific. However, limited attention has been given to the climatic indicators applied in climate-conflict research. This paper addresses that gap by analyzing 32 studies published from 2004 to 2020 on the operationalization of climatic indicators and their relationship with violent conflict. It first categorizes climate indicators operationalization into five clusters: natural disasters, basic climate variability, advanced climate variability, freshwater availability, and the ENSO. The study evaluates the climate indicators for each cluster and shows that at an aggregate level these clusters examine 68 different climate representations. When paired with their respective conflict types, it finds a total of 113 climate-conflict combinations. Most operationalizations represent various forms of climate-related phenomena and variability rather than climate change. Some indicators are advancements over time, for example moving from changes in average rainfall to standardized precipitation indices. However, other indicators refer to various natural processes, making it challenging to determine whether climatic variability impacts conflict. The paper then demonstrates a discrepancy between the pathways through which climate may affect violent conflict and the representation of these pathways in the selected climate indicators. It discusses how the selection and operationalization of climate indicators requires careful consideration, and the phenomena researched should be well-specified in research findings. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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3. Climate change attribution and the economic costs of extreme weather events: a study on damages from extreme rainfall and drought.
- Author
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Frame, David J., Rosier, Suzanne M., Noy, Ilan, Harrington, Luke J., Carey-Smith, Trevor, Sparrow, Sarah N., Stone, Dáithí A., and Dean, Samuel M.
- Subjects
ECONOMIC change ,CLIMATE change ,WEATHER ,DROUGHTS ,RAINFALL - Abstract
An important and under-quantified facet of the risks associated with human-induced climate change emerges through extreme weather. In this paper, we present an initial attempt to quantify recent costs related to extreme weather due to human interference in the climate system, focusing on economic costs arising from droughts and floods in New Zealand during the decade 2007–2017. We calculate these using previously collected information about the damages and losses associated with past floods and droughts, and estimates of the "fraction of attributable risk" that characterizes each event. The estimates we obtain are not comprehensive, and almost certainly represent an underestimate of the full economic costs of climate change, notably chronic costs associated with long-term trends. However, the paper shows the potential for developing a new stream of information that is relevant to a range of stakeholders and research communities, especially those with an interest in the aggregation of the costs of climate change or the identification of specific costs associated with potential liability. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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4. Successive volcanic eruptions (1809–1815) and two severe famines of Korea (1809–1810, 1814–1815) seen through historical records.
- Author
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Kim, Sungwoo
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NATURAL disasters ,VOLCANIC eruptions ,FAMINES ,CLIMATE extremes ,CHOSON dynasty, Korea, 1392-1910 ,RAINFALL - Abstract
Based on the government's historical records and personal documents of the pre-modern Chosŏn Dynasty, this paper examines the socio-economic impacts in Korea in response to climatic variability from 1809 until 1819 that may have been influenced to some degree by the eruption of the "unknown volcano" (1809) and the Tambora eruption (1815). In the early 1800s, when volcanic eruptions occurred successively, the Korean Peninsula experienced a temporal precipitation variation—drought, abundant rainfall, and normalcy—twice. The precipitation variation in this period had a heavy impact on the yields of rice, major crop on the peninsula. In the phase of drought in 1809 and extreme climatic anomalies in 1814, the country suffered record poor harvests, and in the abundant rainfall phase in 1810 and 1816–1817, it had bumper crops. For this reason, 1816–1817 were the halcyon years for Korea, unlike the case of Europe and the northeastern USA which suffered from extreme climatic anomalies in those years. This case of the Korean Peninsula indicates that the climate change and natural disasters of the 1810s were influenced by not only of the single event of the Tambora eruption but of the successive eruptions of volcanoes in the 7 years from 1809 to 1815, which also affected other areas on the globe for 11 years (1809–1819). [ABSTRACT FROM AUTHOR]
- Published
- 2023
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5. Assessment of projected agro-climatic indices over Awun river basin, Nigeria for the late twenty-first century.
- Author
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Gbangou, Talardia, Sylla, Mouhamadou Bamba, Jimoh, Onemayin David, and Okhimamhe, Appollonia Aimiosino
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RAINFALL ,ATMOSPHERIC models ,EVAPOTRANSPIRATION ,AGRICULTURAL climatology ,RAINFALL frequencies ,WATERSHEDS ,FARMERS' attitudes - Abstract
This paper examines changes in rainfall effectiveness indices of the Awun basin in Nigeria during the late twenty-first century for agricultural applications with outputs from high-resolution regional climate model (RCM) simulations. The RCM simulations are driven by two global climate models for a reference period (1985-2004) and a future period (2080-2099) and for RCP4.5 (a scenario with some mitigation) and RCP8.5 (a business as usual scenario) forcings. Simulations are provided for the control (1985-2004) and scenario (2080-2099) periods. Observations from synoptic station are used for bias-correction. Three indices being local onset date, seasonality index (SI), and hydrologic ratio (HR) are analyzed. Onset and HR are tested with two evapotranspiration (ET
p ) models. Farmers' perceptions are also collected to validate trends of rainfall indices for the present-day climate. We found that onset dates do not depend much on the ETp models used, and farmers' perceptions are consistent with predicted rainfall patterns. Present-day climate trend shows an early onset. However, onset is projected to be late in future and the delay will be magnified under the business as usual scenario. Indeed, average onset date is found on the 5th May for present-day while in the future, a delay about 4 and 8 weeks is projected under RCP4.5 and RCP8.5 scenarios respectively. SI is between 0.80 and 0.99, and HR is less than 0.75 for all scenarios, meaning respectively that (i) the rainy season will get shorter and (ii) the area will get drier in the future compared to the present-day. Local stakeholders are forewarned to prepare for potential response strategies. A continuous provision of forecast-based rainfall indices to support farmer's decision making is also recommended. [ABSTRACT FROM AUTHOR]- Published
- 2018
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6. Assessment of the Pacific decadal oscillation's contribution to the occurrence of local torrential rainfall in north China.
- Author
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Pei, Lin, Xia, Jiangjiang, Yan, Zhongwei, and Yang, Hui
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CLIMATE change ,PRECIPITATION (Chemistry) ,MONSOONS ,RAINFALL ,CITIES & towns & the environment - Abstract
On 21-22 July 2012, torrential rains hit North China, with the daily precipitation record at Beijing station reaching 160.6 mm; this event is named the Beijing 7-21 case. This paper assesses the likelihood of the occurrence of local torrential rains, such as the Beijing 7-21 case, from the perspective of climate variability. In particular, the influence of the Pacific Decadal Oscillation (PDO) is assessed. There were five extreme events, with daily precipitation records equal to or larger than 160.6 mm, at Beijing station during the period 1951-2012; all of these events happened during negative phases of the PDO. The present analysis indicates that precipitation events more extreme than the Beijing 7-21 case should happen more than once per decade during negative phases of the PDO, but only about once every four decades during positive PDO phases. The negative phase of the PDO is found to be associated with a much greater probability of daily records of southerly winds in North China during summer. Strong southerly summer monsoons are deemed favorable for increasing the occurrence of local extreme rainfall over North China. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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7. Practising historical climatology in West Africa: a climatic periodisation 1750-1800.
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Norrgård, Stefan
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RAINFALL ,WEST African monsoons ,FAMINES ,CLIMATOLOGY -- History ,RAINFALL periodicity ,COASTS - Abstract
This paper presents the first interdecadal and interannual periodisation of the climate in West Africa between 1750 and 1800. The climatic synthesis is founded on previously unexploited British documents written at Cape Coast Castle, Cape Coast, Ghana and travel journals, which are combined with previous research on the Sahel. By combining historical evidence with the most recently identified rainfall patterns in the Sahel and the Guinea coast, the climatic periodisation distinguishes between wetter and drier periods. The results show that there was great interannual and interdecadal variability in the West African rainfall regime in the 18th century. The historical evidence suggests that the climate in the Sahel and the Guinea coastal interior alternated between five wet and dry periods, whereas the coastal dry zone alternated between three wet and dry periods. The most pronounced changes in the climate are found in the 1780s and 1790s. The Guinea coastal interior and the Sahel experienced a wet period in the 1780s and a dry period in the 1790s, whereas the coastal dry zone was drier in the 1780s and wetter in the 1790s. The investigation shows that the secondary rainy season on the Gold coast was weak or non-existent. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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8. Temporal trends in extreme rainfall intensity and erosivity in the Mediterranean region: a case study in southern Tuscany, Italy.
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Vallebona, Chiara, Pellegrino, Elisa, Frumento, Paolo, and Bonari, Enrico
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CLIMATE change ,RAINFALL ,METEOROLOGICAL precipitation ,SOIL erosion ,DROUGHTS - Abstract
Worldwide climate is likely to become more variable or extreme with increases in intense precipitation. In Mediterranean areas, climate change will increase the risks of droughts, flash floods and soil erosion. Despite rainfall intensity being a key factor in erosive processes, in these areas information on extreme rainfall intensity and the associated erosivity, based on high-temporal resolution data, is either non homogeneous or scarce. These parameters thus need to be assessed in order to highlight suitable adaptation strategies. In this paper, an hourly rainfall intensity (RI) data series is analyzed together with the corresponding 1-min rainfall intensity maximum (RIm) of 23 rainfall gauges located in Tuscany, Italy, in an area highly vulnerable to erosion. The aim is to look for temporal trends (1989-2010) in extreme rainfall intensity and erosivity. Fixed effect logistic regression shows statistically significant temporal increases in the number of RI and RIm exceedances over the 95th percentile threshold. Winter is shown to be the season with the strongest increasing trend in coastal and inland rainfall gauge groups, followed by spring for the coastal group and autumn for the inland group. Linear regressions show that in the inland group there is a temporal increase in rainfall erosivity and on a seasonal basis, the highest increase is observed in autumn. By contrast, for the coastal group this increasing trend is only detectable for spring and winter. Such an increase in rainfall erosivity and its potential continuation could have a strong adverse effect on Mediterranean land conservation. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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9. Livelihood vulnerability assessment to climate variability and change using fuzzy cognitive mapping approach.
- Author
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Singh, Pramod and Nair, Abhishek
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FUZZY algorithms ,CLIMATE change ,SENSORY perception ,PRECIPITATION variability ,RAINFALL - Abstract
Existing studies in the context of assessing vulnerability to climate variability and change delineate, rather inadequately, interconnected interactions occurring within the climate-human-environment interaction space. Besides, studies documenting stakeholders' perceptions regarding climate change induced vulnerabilities are limited in terms of providing indicators for decision-making. This paper aims at constructing a livelihood vulnerability index for climate variability and change capturing interconnected interactions based on peoples' perceptions while providing indicators for evidence based decision-making. A semi-quantitative fuzzy cognitive mapping (FCM) approach has been deployed to capture peoples' perceptions of climate induced perturbations and adaptations. This approach helps quantify stakeholders' perspectives while capturing interconnected interactions in order to estimate livelihood vulnerability to climate variability and change of poor agro-pastoralists in the Bhilwara, a district in Western India. Combining the FCM approach with a sustainable livelihood framework warrants an understanding of assets sensitive to climate variability and change along with those serving as adaptive capacities. The findings of this study confirm that financial and natural assets are most susceptible to harm while organisational and financial assets provide resilience against climate variability and change. The results suggest that livelihood vulnerability of agro-pastoralists lie in the range of being 'vulnerable' to climate variability and change while varying across three seasons summer, winter, and rainfall. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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10. Public perceptions of rainfall change in India.
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Howe, Peter, Thaker, Jagadish, and Leiserowitz, Anthony
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RAINFALL ,METEOROLOGICAL precipitation ,FLOODS ,STORMS ,PUBLIC opinion - Abstract
People's perceptions of changes in local weather patterns are an important precursor to proactive adaptation to climate change. In this paper, we consider public perceptions of changes in average rainfall in India, analyzing the relationship between perceptions and the instrumental record. Using data from a national sample survey, we find that local instrumental records of precipitation are a strong predictor of perceived declines in rainfall. Perceptions of decreasing rainfall were also associated with perceptions of changes in extreme weather events, such as decreasing frequency of floods and severe storms, increasing frequency of droughts, and decreasing predictability of the monsoon. Higher social vulnerability-including low perceived adaptive capacity and greater food and livelihood dependence on local weather-was also associated with perceptions of decreasing rainfall. While both urban and rural respondents were likely to perceive local changes in precipitation, we show that rural respondents in general were more sensitive to actual changes in precipitation. Individual perceptions of changes in local climate may play an important role in shaping vulnerability to global climate change, adaptive behavior, and support for adaptation and mitigation policies. Awareness of local climate change is therefore particularly important in regions where much of the population is highly exposed and sensitive to the impacts of climate change. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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11. Dependence on agriculture and ecosystem services for livelihood in Northeast India and Bhutan: vulnerability to climate change in the Tropical River Basins of the Upper Brahmaputra.
- Author
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Amoako Johnson, Fiifi and Hutton, Craig
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NATURAL disasters ,ENVIRONMENTAL engineering ,FLOODS ,DROUGHTS ,RAINFALL ,WATERSHEDS - Abstract
The Upper Brahmaputra River Basin is prone to natural disasters and environmental stresses (floods, droughts and bank erosion, delayed rainfall, among others) creating an environment of uncertainty and setting the basin back in terms of socio-economic development. The climate change literature shows that agriculture and ecosystems and their services are highly climate sensitive, yet they are the main sources of livelihood that supports a large proportion of residents of the tributaries of the Brahmaputra River Basin. The continuous depletion of ecosystems and loss of agricultural outputs resulting from environmental stressors has a substantial impact on the socio-economic wellbeing of the basins residents, particularly the vulnerable rural poor. This paper uses spatially explicit data from Census, Household Surveys and Earth Observation to develop a transferable methodological approach which investigates the extent of dependence on agriculture and ecosystems as a source of livelihood in the contrasting sub-basins of the Brahmaputra River in the State of Assam, India and Bhutan, and the risk to these livelihood dependencies in these sub-basins due to potential environmental impacts of climate change. The results from this study constitute a case study in the development of a systematic and spatially explicit set of tools that inform and assist policy makers in the appropriate interventions to secure the livelihood benefits of sustainably managed agriculture in the face of environmental change. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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12. Attribution of the heavy rainfall events leading to severe flooding in Western Europe during July 2021.
- Author
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Tradowsky, Jordis S., Philip, Sjoukje Y., Kreienkamp, Frank, Kew, Sarah F., Lorenz, Philip, Arrighi, Julie, Bettmann, Thomas, Caluwaerts, Steven, Chan, Steven C., De Cruz, Lesley, de Vries, Hylke, Demuth, Norbert, Ferrone, Andrew, Fischer, Erich M., Fowler, Hayley J., Goergen, Klaus, Heinrich, Dorothy, Henrichs, Yvonne, Kaspar, Frank, and Lenderink, Geert
- Abstract
In July 2021 extreme rainfall across Western Europe caused severe flooding and substantial impacts, including over 200 fatalities and extensive infrastructure damage within Germany and the Benelux countries. After the event, a hydrological assessment and a probabilistic event attribution analysis of rainfall data were initiated and complemented by discussing the vulnerability and exposure context. The global mean surface temperature (GMST) served as a covariate in a generalised extreme value distribution fitted to observational and model data, exploiting the dependence on GMST to estimate how anthropogenic climate change affects the likelihood and severity of extreme events. Rainfall accumulations in Ahr/Erft and the Belgian Meuse catchment vastly exceeded previous observed records. In regions of that limited size the robust estimation of return values and the detection and attribution of rainfall trends are challenging. However, for the larger Western European region it was found that, under current climate conditions, on average one rainfall event of this magnitude can be expected every 400 years at any given location. Consequently, within the entire region, events of similar magnitude are expected to occur more frequently than once in 400 years. Anthropogenic climate change has already increased the intensity of the maximum 1-day rainfall event in the summer season by 3–19 %. The likelihood of such an event to occur today compared to a 1.2 ∘ C cooler climate has increased by a factor of 1.2–9. Models indicate that intensity and frequency of such events will further increase with future global warming. While attribution of small-scale events remains challenging, this study shows that there is a robust increase in the likelihood and severity of rainfall events such as the ones causing extreme impacts in July 2021 when considering a larger region. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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13. Author's response to the commentary by S.Fischer & A.Schumann on 'Multidecadal oscillatory behaviour of rainfall extremes in Europe (Climatic Change, 120(4), 931-944)'.
- Author
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Willems, Patrick
- Subjects
RAINFALL ,CLIMATE change research ,CLIMATE extremes ,ATMOSPHERIC circulation ,CLIMATOLOGY - Abstract
ᅟ [ABSTRACT FROM AUTHOR]
- Published
- 2015
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14. Topic modelling the mobility response to heat and drought.
- Author
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Zander, Kerstin K., Baggen, Hunter S., and Garnett, Stephen T.
- Abstract
We conducted a systematic literature review of peer-reviewed full text articles on the nexus between human mobility and drought or heat published between 2001 and 2021, inclusive. We identified 387 relevant articles, all of which were analysed descriptively using a dictionary-based approach and by using an unsupervised machine learning–based Latent Dirichlet Allocation (LDA) model. Most articles were in response to droughts (71%), but heat and extreme temperature became more prominent after 2015. The drought-related literature focuses geographically on African and Southern Asian countries, while heat-related research has mainly been conducted in developed countries (mostly in the USA and Australia). For both hazards, European countries are under-represented. The LDA model identified 46 topics which were clustered into five major themes. One cluster (14% of all articles) included literature on heat-related mobility, mostly data-driven models, including amenity migration. The other four clusters included literature on drought, primarily on farming societies and the agricultural sector with three of those clusters making up 63% of all articles, with the common overarching focus on climate migration and food security. One of the four drought clusters focused on social dysfunction in relation to droughts. A sentiment analysis showed articles focusing on voluntary mobility as part of adaptation to drought and heat were more positive than articles focusing on migration triggered by droughts and heat. Based on the topics and the article characterisation, we identified various research gaps, including migration in relation to urban droughts, heat in farming societies and in urban societies of developing countries, planned retreat from hot to cooler places, and the inability or barriers to doing so. More research is also needed to understand the compound effect of drought and heat, and the social and psychological processes that lead to a mobility decision. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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15. Vulnerability assessment of Northern Ghana to climate variability.
- Author
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Acheampong, Ernest, Ozor, Nicholas, and Owusu, Eric
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RAINFALL ,ATMOSPHERIC temperature ,RAINFALL anomalies ,MILLETS ,SORGHUM ,WATER in agriculture ,CROP yields - Abstract
The article discusses a study that focuses on the annual variability of climate parameters such as rainfall and temperature and examines the patterns of these parameters and their influence on millet and sorghum production in Northern Ghana. The study found that variability in rainfall and temperature creates uncertainty in available water for agriculture. Also the study concludes that millet and sorghum are sensitive to rainfall variability which may cause reduction in crop yield.
- Published
- 2014
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16. Assessing the spatiotemporal impact of climate change on event rainfall characteristics influencing landslide occurrences based on multiple GCM projections in China.
- Author
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Lin, Qigen, Wang, Ying, Glade, Thomas, Zhang, Jiahui, and Zhang, Yue
- Subjects
LANDSLIDE hazard analysis ,LANDSLIDES ,CLIMATE change ,GENERAL circulation model ,RAINFALL ,ATMOSPHERIC temperature ,SOIL moisture - Abstract
Landslides result in a significant number of casualties every year in China. The frequency and intensity of extreme precipitation are expected to increase due to climate change, leading to a change in landslide occurrence. This study focuses on climate change impacts on event rainfall characteristics that are commonly linked to landslide occurrence in China. A modelling framework was proposed to quantitatively assess the spatiotemporal change in event rainfall characteristics influencing landslide occurrences in China under future scenarios. First, an algorithm was used to extract the rainfall events from observed precipitation data and the 21 Global Circulation Models dataset. Then, the cumulative event rainfall-rainfall duration (E-D) threshold was identified and used as a proxy of landslide occurrence. Finally, the historical (1971–2000) and future (2031–2060 and 2066–2095) data of 21 GCMs were then applied to determine the E-D threshold in areas highly susceptible to landslides in China to assess the impact of climate change. Landslide occurrence is projected to increase potentially under all GCMs, by amounts ranging from 19.9% to 33.2% in the late 21st century compared to the historical period under the RCP4.5 and RCP85 scenarios, respectively. There are regional differences in the impact of climate change. Future landslide increases in the Northwest region and the Qinghai-Tibet region are the most significant, with consistency among multiple GCMs. However, there is only a slight increase in the South China region with high uncertainty. The monthly variations in landslides are bimodal, with the largest increases in spring and autumn. The results indicate that using a single GCM to assess climate change impacts may have biases, and consideration of median trends and variations among multiple GCMs is suggested. However, the study is a first hint on how climate change may affect landslide occurrence in the future, as the assessment of the effect of climate change on landslides is not straightforward based on only the precipitation-related proxy. The influence on air temperature and soil moisture and the selection of projection datasets and proxies should be carefully considered when applying the presented methods for climate change impacts on landslide studies. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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17. Potential impacts of climate change factors and agronomic adaptation strategies on wheat yields in central highlands of Ethiopia.
- Author
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Araya, A., Prasad, P. V. V., Gowda, P. H., Djanaguiraman, M., and Kassa, A. H.
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CLIMATE change ,WHEAT ,OCEAN acidification ,AGRICULTURAL productivity ,UPLANDS ,YIELD stress ,WHEAT farming - Abstract
The potential impacts of climate change on wheat were assessed for Kulmsa area in central highlands of Ethiopia using the Agricultural Production Systems sIMulator (APSIM)—wheat model. The objectives were to (i) evaluate the performance of wheat under increased temperatures with or without changes in rainfall and carbon dioxide (CO
2 ) levels and (ii) assess the response of different wheat cultivars to projected future climates under improved management practices (optimal nitrogen rate, planting date, and density) (IMPs). The model was first calibrated and used to identify ranges of IMPs. Then, the model was used to (i) conduct sensitivity analysis of wheat in response to assumed elevated temperature (T), with and without change in rainfall and CO2 level, and to (ii) evaluate average effect of future worst-case climate change scenarios as predicted by an ensemble of three global climate models (GCM) under highest Representative Concentration Pathways (RCP8.5) for three future time frames, NF (2010–2039), MC (2040–2069), and EC (2070–2099). The simulation was evaluated for three wheat cultivars ("early", "medium", and "late") relative to their corresponding baseline values under the selected IMPs. The baseline climate was represented by the long-term (1980–2009) dataset and CO2 of 360 μmol/mol. Results showed that increased temperature above 4 °C alone had strong negative impacts on yields under the IMPs when CO2 staying constant at the baseline level. In contrast, climate change simulations with GCM projections under IMPs and elevated CO2 effect showed that wheat yield remained unchanged (− 0.4 to + 9%) for all three genotypes. This suggests that the IMPs and elevated CO2 were able to reduce the negative effect of elevated T on wheat yield as T stress did not go beyond optimal T range for wheat. Overall, climate change may not reduce wheat production in the climate of the location of study in the near future, midcentury, or end century. [ABSTRACT FROM AUTHOR]- Published
- 2020
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18. Management of drought in sali rice under increasing rainfall variability in the North Bank Plains Zone of Assam, North East India.
- Author
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Neog, Prasanta, Sarma, Pallab K., Saikia, Debashis, Borah, Palakshi, Hazarika, Girindra Nath, Sarma, Manoj Kr, Sarma, Digambar, Chary, G. Ravindra, and Rao, Ch. Srinivasa
- Subjects
DROUGHT management ,RAINFALL anomalies ,RAINFALL ,RICE ,GROWING season - Abstract
The intermittent dry spells during growing season of winter or sali rice, cultivated in NBPZ of Assam located in the foothills of Eastern Himalayan region, is a major weather risk causing widespread damage to the crop. Herein, variability of rainfall in Lakhimpur district situated in NBPZ was studied. A significant decreasing trend of annual and seasonal rainfall was observed. Significant decrease in monsoon rainfall and increase in monthly rainfall variability clearly explains the recent rainfall fluctuations with increasing frequency of intermittent dry spells and flash floods. A participatory evaluation trial was conducted in Chamua village of Lakhimpur district having different land situations to identify climate resilient technologies to cope with seasonal drought in sali rice. High-yielding short-duration varieties, viz., Dishang, Luit, Lachit and Kolong, and medium-duration varieties, viz., Basundhara, Mohan, Mulagabhoru and TTB-404 performed consistently better than the long-duration HYV or the traditional varieties under upland and medium land situations, respectively. Though the effect of dry spells on long-duration varieties cultivated on low lands was least, yield of these varieties reduced up to 43.07% when sowing was delayed beyond 23rd of June. Performance of the delayed sown varieties was further declined, when exposed to dry spells at later growth stages. However, adverse impact of dry spells can be managed effectively by replacing farmers' varieties with short and medium-duration high-yielding varieties in upland and medium lands, respectively, and manipulating sowing time of long-duration varieties for low lands. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
19. Projected changes in the seasonal cycle of extreme rainfall events from CORDEX simulations over Central Africa.
- Author
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Fotso-Nguemo, Thierry C., Diallo, Ismaïla, Diakhaté, Moussa, Vondou, Derbetini A., Mbaye, Mamadou L., Haensler, Andreas, Gaye, Amadou T., and Tchawoua, Clément
- Subjects
RAINFALL ,EMERGENCY management ,FLOOD risk ,ATMOSPHERIC models ,TWENTY-first century ,GLOBAL warming ,CLIMATE change models - Abstract
This study explores the potential response of the seasonal cycle of extreme rainfall indices over Central Africa (CA) to the global warming for both the middle (2029–2058) and late twenty-first century (2069–2098), based on analysis of multi-model ensembles mean of fifteen regional climate models (RCMs) simulations. Although few dry/wet biases are still evident, for the present day climate, the RCMs ensemble mostly outperforms the driving global climate models, with a better representation of the seasonal cycle of various rainfall indices over two key sub-regions of CA chosen according to their particular rainfall patterns. Both middle and late twenty-first century project a non-significant decrease in total wet-day rainfall amount over the two analysed sub-regions, with peaks found during pre-monsoon months. We also found a significant decrease in wet-day frequency which was consistent with decreases in total wet-day rainfall amount, while wet-day intensity is projected to significantly increase. These results suggest that the decrease in total wet-day rainfall amount could be associated with less frequent events and not with their intensity. The results also have shown that dry (wet) spells are projected to significantly increase (decrease) over both sub-regions with shorter (longer) dry (wet) spells projected during pre-monsoon months. Consequently, countries within these two sub-regions could experience a more extended dry season, and therefore would be exposed to high drought risk in the future under global warming. However, changes in maximum 1-day rainfall amount, maximum 5-day rainfall amount, and 95th percentile are projected to significantly increase during monsoon months, with the maximum 1-day rainfall amount recording largest increases. Additionally, the total amount of rainfall events above the 95th percentile projects a significant increase of about 10–45 % during monsoon months, while the total number of occurrence of rainfall events above the 95th percentile projects a slight significant decrease of 4–8 % during pre-monsoon months but more pronounced for the late twenty-first century. This implies that in the future, extremes rainfall events could be more intense both in terms of rainfall amount and intensity during monsoon months. Such changes are likely to amplify the probability of flood risks during monsoon months over CA, particularly the two sub-regions. This study could therefore be an important input for disaster preparedness, adaptation planning, and mitigation strategies for Central African countries. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
20. Impacts of climate change on bovine livestock production in Argentina.
- Author
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Rolla, Alfredo L., Nuñez, Mario N., Ramayón, Jorge J., and Ramayón, Martín E.
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LIVESTOCK ,ATMOSPHERIC temperature ,RAINFALL ,CATTLE - Abstract
The study considers the most important livestock regions of Argentina and the correlation between livestock and climate units. The conceptual scheme designed to understand these effects of climate elements on cattle describes a basic direct action by the air temperature in the environment in which they develop, considering temperature as the limit for the distribution of breeds and other action through its effects on vegetation and forage resources that will be available. The work done here shows a shift of the livestock regions southward and eastward simultaneously in the region under consideration. This is a consequence of the displacement towards the south of the isotherm of 26 °C and towards the east of the humidity indices, co-incidentally with the displacement of the isohyets of 600 and 1200 mm. As a consequence of the climate change, according to the CCSM4 climate model, in the near and far future under two emission scenarios, the regions suitable for tropical livestock (breeds with high heat tolerance as the Bos indicus) will extend to the southeast, displacing and reducing the regions suitable for European breed cattle. The displacement of the higher rainfall area mainly to the east could benefit livestock production by increasing forage and reducing livestock feed requirements. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
21. Site-based adaptation reduces the negative effects of weather upon a southern range margin Welsh black grouse Tetrao tetrix population that is vulnerable to climate change.
- Author
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Douglas, David J.T., Pearce-Higgins, James W., Grant, Murray C., Johnstone, Ian G., Thorpe, Reg I., and Lindley, Patrick J.
- Subjects
CLIMATE change ,BLACK grouse ,EFFECT of climate on animal behavior ,BIODIVERSITY ,RAINFALL - Abstract
Climate change is an increasing threat to global biodiversity. Whilst there is growing evidence about the potential effectiveness of some aspects of climate change adaptation, the role for site-based management to increase the resilience of vulnerable populations to climate change has been little studied. Here, we test whether such management may reduce the negative effects of unfavourable weather upon a southern range margin Welsh black grouse Tetrao tetrix population that is vulnerable to climate change. The Welsh black grouse recovery programme funded a range of interventions that contributed to a 39% population increase over 10 years. One likely mechanism linking black grouse populations to climate change is the sensitivity of chicks to high June rainfall. We modelled the relationship between June rainfall and management interventions which aimed to increase breeding success (habitat management and lethal predator control) to test whether management could increase the resilience of black grouse populations to such unfavourable weather. Importantly, we found that the negative effect of June rainfall upon productivity was eliminated at sites where predator control occurred, and that productivity was maximised when predator and habitat management were combined. Active management therefore reduced the negative effects of June rainfall upon this vulnerable southern range margin black grouse population, although further work is required to quantify any limits to the success of such management. Active management should be considered as a tool for climate change adaptation in other vulnerable populations, particularly where there is limited potential for species to undergo climate-driven range changes. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
22. Perceptions of climate and ocean change impacting the resources and livelihood of small-scale fishers in the South Brazil Bight.
- Author
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Martins, Ivan Machado and Gasalla, Maria A.
- Subjects
CLIMATE change ,FISHERS ,OCEAN dynamics ,FISHING ,DROUGHTS ,RAINFALL - Abstract
Coastal fishing communities are closely linked to the biological and ecological characteristics of exploited resources and the physical conditions associated with climate and ocean dynamics. Thus, the human populations that depend on fisheries are inherently exposed to climate variability and uncertainty. This study applied an ethno-oceanographic framework to investigate the perceptions of fishers on climate and ocean change to better understand the impacts of climate change on the coastal fishing communities of the South Brazil Bight. Seven coastal fishing communities that cover the regional diversity of the area were selected. Fishers were interviewed using a semi-structured questionnaire. The results suggest that fishers have detected climate-related changes in their environment such as reduced rainfall, increased drought events, calmer sea conditions, increases in air and ocean temperatures, changes in wind patterns and shoreline erosion. The perceptions of the fishers were compared to the available scientific data, and correlations were found with rainfall, wind speed and air and ocean temperatures. New hypotheses were raised based on the perceptions of fishers about sea level, coastal currents and sea conditions such as the hypothesis that the sea has become calmer. These perceived changes have positive and negative effects on the yields and livelihoods of fishers. The present work is the first evaluation of the perceptions of fishers on climate and ocean change and brings new understandings of climate-fishery-human interactions as well as provides inputs for future adaptation plans. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
23. Discrete seasonal hydroclimate reconstructions over northern Vietnam for the past three and a half centuries.
- Author
-
Hansen, Kyle, Buckley, Brendan, Zottoli, Brian, D'Arrigo, Rosanne, Nam, Le, Van Truong, Vinh, Nguyen, Dung, and Nguyen, Hau
- Subjects
CLIMATE change ,RAINFALL ,PSEUDOTSUGA ,TREE-rings ,DROUGHTS ,SEASONAL temperature variations - Abstract
We present a 350-year hydroclimatic year (HY) index for northern Vietnam derived from three discrete seasonal reconstructions from tree rings: an index of autumn rainfall from the earlywood widths of Chinese Douglas fir ( Pseudotsuga sinensis), the first such record from this species, and two nearby published Palmer Drought Severity Index (PDSI) reconstructions from cypress ( Fokienia hodginsii) tree rings for spring and summer, respectively. Autumn rainfall over the study region constitutes only around 9% of the annual total, but its variability is strongly linked to the strength of the atmospheric gradient over Asia during the transition from the boreal summer to winter monsoons. Deficit or surplus of autumn rainfall enhances or mitigates, respectively, the impact of the annual winter dry season on trees growing on porous karst hillsides. The most protracted HY drought (dry across all seasons) occurred at the turn of the twentieth century at a time of relative quiet, but a mid-to-late eighteenth century multi-year HY drought coincided with a period of great societal turmoil across mainland Southeast Asia and the Tay Son Rebellion in northern Vietnam. A mid-nineteenth century uprising accompanied by a smallpox epidemic, crop failure and famine, occurred during the worst autumn drought of the past two and a half centuries but only moderate drought in spring and summer. The 'Great Vietnamese Famine' of the mid-twentieth century was dry only in autumn, with a wet spring and an average summer. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
24. Understanding climate as a driver of food insecurity in Ethiopia.
- Author
-
Lewis, Kirsty
- Subjects
CLIMATE change ,FOOD security ,RAINFALL ,DROUGHTS ,METEOROLOGICAL precipitation ,AGRICULTURAL productivity & the environment - Abstract
Despite large increases in national cereal production in recent decades, Ethiopia continues to experience regular acute food insecurity crises, often associated with drought events. However, the meteorology of these events is poorly defined and local populations frequently experience food insecurity crises in years when national rainfall and cereal production totals are high. Therefore, looking at national, or even to some extent sub-national, rainfall variability is a misappropriation of climate as a causal factor in food insecurity in Ethiopia. The distinction between 'drought' as catch-all driver of food insecurity and a more nuanced view of the relationship between rainfall variability and food security is necessary both for addressing food insecurity now and for interpreting long-term climate model projections. The on-going recurrence of acute food insecurity is a feature of the heterogeneity of climate and climate variability in Ethiopia, but only in the context of a food system dominated by smallholder farming and climate-sensitive livelihoods. Climate variability has the greatest adverse impact in the most marginal livelihood zones in the drier east of the country. Increasing the resilience of smallholder farmers and pastoralists to climate variability and improvements in early warning and disaster risk response could reduce the frequency and severity of food security crises. However, unless the food system in Ethiopia undergoes transformational adaptation, food insecurity crises will continue to occur, and the opportunity to achieve zero hunger by 2030 will be missed. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
25. Erratum to: Uncovering consistencies in Indian rainfall trends observed over the last half century.
- Author
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Lacombe, Guillaume and McCartney, Matthew
- Subjects
RAINFALL ,MONSOONS - Abstract
A correction to the article "Uncovering consistencies in Indian rainfall trends observed over the last half century" that was published online in the September 29, 2016 issue is presented.
- Published
- 2016
- Full Text
- View/download PDF
26. Effect of future climate change on the coupling between the tropical oceans and precipitation over Southeastern South America.
- Author
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Martín-Gómez, Verónica and Barreiro, Marcelo
- Subjects
CLIMATE change ,METEOROLOGICAL precipitation ,SYNCHRONIZATION ,ANTHROPOGENIC effects on nature ,GLOBAL warming ,RAINFALL - Abstract
El Niño, the Indian Ocean Dipole (IOD), and the Tropical North Atlantic variability (TNA) can influence southeastern South America (SESA) rainfall, particularly during springtime. A recent study has shown that during the last century, there were two synchronization periods (1930s and 1970s) in which different tropical oceans interacted among themselves and, in turn, induced precipitation anomalies over SESA. In this study, we evaluate how this collective influence of the tropical oceans on SESA precipitation observed during the twentieth century, can change in the next century as result of anthropogenic forcing. To do so, we use the output of seven different CMIP5 models and construct a network using as nodes the indices of the Niño3.4, the TNA, the IOD and rainfall over SESA. After evaluating their skill in representing the observed network statistics during the twentieth century, we study changes in the network under RCP4.5 and 8.5 global warming scenarios in the twenty-first century. Focusing on the grand CMIP5 ensemble mean, results suggest that an anthropogenic forcing would increase the number of synchronization periods per century, their time length, and the connectivity between nodes (with the exception of TNA and IOD in RCP8.5). The stronger connectivity of SESA precipitation with the tropical oceans in both scenarios suggest an increase of the oceanic influence on rainfall over SESA as a result of anthropogenic forcing, which would enhance its seasonal predictability. However, these results have to be taken with caution because there is a large disparity in model behavior and thus a large uncertainty in conclusions suggested from the grand ensemble mean. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
27. A 258-year reconstruction of precipitation for southern Northeast China and the northern Korean peninsula.
- Author
-
Chen, Zhenju, He, Xingyuan, Davi, Nicole, and Zhang, Xianliang
- Subjects
METEOROLOGICAL precipitation ,HUMIDITY ,MONSOONS ,PINUS koraiensis ,RAINFALL - Abstract
We present a well-verified precipitation reconstruction ( r = 0.612, p < 0.01), spanning 1741 to 1998, for a relatively humid monsoon region from southern Northeast China and the northern Korean peninsula, based on tree rings from Chinese pine and Korean pine. We then investigate the variability of the reconstruction, and identify the leading rainfall patterns and regional dryness and wetness modes during the latest 2.5 centuries. This reconstruction shows that three persistent dry decades occurred during the 1840s, 1910s and 1850s and the three wettest decades occurred during the 1770s, 1820s and 1930s. The five years with lowest rainfall were 1759, 1917, 1841, 1747 and 1839, and 1770, 1938, 1819, 1941 and 1822 were the five years with highest rainfall, respectively. As indicated by the spatial correlation patterns, the reconstruction also exhibits regional characteristics. The variation of reconstructed rainfall significantly corresponds to East Asian monsoon. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
28. Evaluation and projections of extreme precipitation over southern Africa from two CORDEX models.
- Author
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Pinto, Izidine, Lennard, Christopher, Tadross, Mark, Hewitson, Bruce, Dosio, Alessandro, Nikulin, Grigory, Panitz, Hans-Juergen, and Shongwe, Mxolisi
- Subjects
CLIMATE change ,METEOROLOGICAL precipitation ,ATMOSPHERIC models ,RAINFALL - Abstract
The study focuses on the analysis of extreme precipitation events of the present and future climate over southern Africa. Parametric and non-parametric approaches are used to identify and analyse these extreme events in data from the Coordinated Regional Climate Downscaling Experiment (CORDEX) models. The performance of the global climate model (GCM) forced regional climate model (RCM) simulations shows that the models are able to capture the observed climatological spatial patterns of the extreme precipitation. It is also shown that the downscaling of the present climate are able to add value to the performance of GCMs over some areas depending on the metric used. The added value over GCMs justifies the additional computational effort of RCM simulation for the generation of relevant climate information for regional application. In the climate projections for the end of twenty-first Century (2069-2098) relative to the reference period (1976-2005), annual total precipitation is projected to decrease while the maximum number of consecutive dry days increases. Maximum 5-day precipitation amounts and 95th percentile of precipitation are also projected to increase significantly in the tropical and sub-tropical regions of southern Africa and decrease in the extra-tropical region. There are indications that rainfall intensity is likely to increase. This does not equate to an increase in total rainfall, but suggests that when it does rain, the intensity is likely to be greater. These changes are magnified under the RCP8.5 when compared with the RCP4.5 and are consistent with previous studies based on GCMs over the region. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
29. Rainfall in Iberian transnational basins: a drier future for the Douro, Tagus and Guadiana?
- Author
-
Guerreiro, Selma B., Kilsby, Chris G., and Fowler, Hayley
- Subjects
WATERSHEDS ,RAINFALL ,CLIMATE change ,AGRICULTURE - Abstract
Water scarcity is critical in both Portugal and Spain; therefore, assessing future changes in rainfall for this region is vital. We analyse rainfall projections from climate models in the CMIP5 ensemble for the transnational basins of the Douro, Tagus and Guadiana with the aim of estimating future impacts on water resources. Two downscaling methods (change factor and a variation of empirical quantile mapping) and two ways of analysing future rainfall changes (differences between 30 years periods and trends in transient rainfall) are used. For the 2050s, most models project a reduction in rainfall for all months and for both methods, but there is significant spread between models. Almost all significant seasonal trends identified from 1961 to 2100 are negative. For annual rainfall, only 3 (2) models show no significant trends for the Douro/Tagus (Guadiana), while the rest show negative trends up to −6 % per decade. Reductions in rainfall are projected for spring and autumn by almost all models, both downscaling methods and both ways of analysing changes. This increases the confidence in the projection of the lengthening of the dry season which could have serious impacts for agriculture, water supply and forest fires in the region. A considerable part of the climate model disagreement in the projection of future rainfall changes for the 2050s is shown to be due to the use of 30 year intervals, leading to the conclusion that such intervals are too short to be used under conditions of high inter-annual variability as found in the Iberian Peninsula. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
30. Seasonal rainfall variability in southeast Africa during the nineteenth century reconstructed from documentary sources.
- Author
-
Nash, David, Pribyl, Kathleen, Klein, Jørgen, Neukom, Raphael, Endfield, Georgina, Adamson, George, and Kniveton, Dominic
- Subjects
RAINFALL ,METEOROLOGICAL precipitation ,DROUGHTS ,NINETEENTH century ,PALEOCLIMATOLOGY - Abstract
Analyses of historical patterns of rainfall variability are essential for understanding long-term changes in precipitation timing and distribution. Focussing on former Natal and Zululand (now KwaZulu-Natal, South Africa), this study presents the first combined annual and seasonal reconstruction of rainfall variability over southeast Africa for the 19th century. Analyses of documentary sources, including newspapers and colonial and missionary materials, indicate that the region was affected by severe or multi-year drought on eight occasions between 1836 and 1900 (the rainy seasons of 1836-38, 1861-63, 1865-66, 1868-70, 1876-79, 1883-85, 1886-90 and 1895-1900). Six severe or multi-year wet periods are also identified (1847-49, 1854-57, 1863-65, 1879-81, 1890-91 and 1892-94). The timing of these events agrees well with independent reconstructions of 19th century rainfall for other parts of the southern African summer rainfall zone (SRZ), suggesting subcontinental scale variability. Our results indicate that the relationship between El Niño and rainfall in southeast Africa was relatively stable, at least for the latter half of the 19th century. El Niño conditions appear to have had a more consistent modulating effect upon rainfall during the 19th century than La Niña. The rainfall chronology from this study is combined with other annually-resolved palaeoclimate records from mainland southern Africa and surrounding oceans as part of a multi-proxy rainfall reconstruction for the SRZ. This reconstruction confirms (i) the long-term importance of ENSO and Indian Ocean SSTs for modulating regional rainfall; and (ii) that summer precipitation has been declining progressively over the last 200 years. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
31. Adapting to climate change in shifting landscapes of belief.
- Author
-
Murphy, Conor, Tembo, Mavuto, Phiri, Adrian, Yerokun, Olusegun, and Grummell, Bernie
- Subjects
CLIMATE change ,LANDSCAPES ,BIOLOGICAL adaptation ,TRADITIONAL ecological knowledge ,FOOD production ,RURAL geography ,RAINFALL - Abstract
Religious beliefs, an important element of culture, influence adaptation to climate change. Less understood is how changing beliefs shape the adaptive capacity of communities responding to climate change. In the last century sub-Saharan Africa has experienced a transformation in beliefs. Since 1900 Christians have increased 70-fold while in rural areas Traditional Beliefs and associated Traditional Ecological Knowledge (TEK) continue to influence the lived practices of vulnerable rural communities. Using two case studies of rural communities in Malawi (Bolero) and Zambia (Monze) we explore how Christianity and Traditional beliefs (and associated TEK) co-exist and assess if, and how, holding multiple belief systems affects climate-sensitive livelihood practices of food production. In Bolero we observed a lack of tensions between belief systems with Traditional leaders and elders noting the flexibility of adhering to both belief systems. In Monze however, basing livelihood decisions on the practice of rain-rituals resulted in strong tensions. In both communities elders noted their concern of how changing beliefs affect adherence to TEK management practices. We find that culture and beliefs play an important role in adaptive capacity but are not static. In the context of changing beliefs, adaptive capacity will be influenced by how different belief systems co-exist and how epistemological and intergenerational frictions are negotiated. As climate services become the focus of research and government interventions in vulnerable regions, avoiding culturally and economically expensive mal-adaptation will require giving attention to the complexity and dynamism of changing religious landscapes. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
32. Use of very high resolution climate model data for hydrological modelling: baseline performance and future flood changes.
- Author
-
Kay, A., Rudd, A., Davies, H., Kendon, E., and Jones, R.
- Subjects
CLIMATE change research ,HYDROLOGICAL research ,FLOODS ,DROUGHTS ,BOUNDARY value problems ,STREAMFLOW ,RAINFALL - Abstract
Increasingly, data from Regional Climate Models (RCMs) are used to drive hydrological models, to investigate the potential water-related impacts of climate change, particularly for flood and droughts. Generally, some form of further downscaling of RCM data has been required, but recently the first decadal-length runs of very high resolution RCMs (with convection-permitting scales) have been performed. Here, a set of such runs for southern Britain has been used to drive a gridded hydrological model. Results using a 1.5 km RCM nested in a 12 km RCM driven by European-reanalysis boundary conditions show that the 1.5 km RCM generally performs worse than the 12 km RCM for simulating river flows in 32 example catchments. The clear spatial patterns of bias are consistent with bias patterns shown in the RCM precipitation data. Results using 1.5 and 12 km RCM runs for the current climate and a potential future climate (driven by GCM boundary conditions) show clear differences in projected changes in flood peaks. The 1.5 km RCM tends towards larger increases than the 12 km RCM, particularly in spring and winter. If robust, this could have important consequences for adaptation planning under climate change, but further research is required, particularly given the greater biases in the baseline flow simulations driven by 1.5 km RCM data, and the use of only a single short future climate projection. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
33. Rainfall patterns in the Southern Amazon: a chronological perspective (1971-2010).
- Author
-
S. Debortoli, Nathan, Dubreuil, Vincent, Funatsu, Beatriz, Delahaye, Florian, Oliveira, Carlos, Rodrigues-Filho, Saulo, Saito, Carlos, and Fetter, Raquel
- Subjects
RAINFALL ,EFFECT of environment on plants ,REGRESSION analysis ,RAIN gauges ,SEASONAL temperature variations ,OCEAN temperature - Abstract
The aim of this study is to characterize rainfall patterns in a vast transition zone between the Amazon and the Cerrado Biomes. The analysis is focused on annual and seasonal tendencies, mainly about the onset and offset of the rainy season, its length and shifts. More than 200 Rain Gauges (RGs) were analyzed in the study area using Pettitt's and Mann-Kendall's non-parametric tests allied to a Linear Regression Analysis over the period 1971-2010. The onset and offset dates of the rainy season and its duration are also identified for 89 RGs. Pettitt's test indicates ruptures in 16 % of the rainfall time series while Mann-Kendall's monthly test indicates that 45 % of the RGs had negative trends, mainly in the transition seasons (spring and austral autumn). Linear Regression Analysis indicates negative trends in 63 % of the time series concomitant to the rainy season onset and offset analysis, which confirmes a delay for the onset of the rainy season in 76 % of the RGs and a premature demise for 84 % of the RGs. Identification of the tendencies for rainy season duration indicates that the rainy season has become shorter at 88 % of the RGs. There were recurring patterns in the results displaying drier conditions in RGs localized in deforested areas opposed to forested locations. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
34. Impact of Atlantic SST and high frequency atmospheric variability on the 1993 and 2008 Midwest floods: Regional climate model simulations of extreme climate events.
- Author
-
Patricola, Christina, Chang, Ping, and Saravanan, R.
- Subjects
OCEAN temperature ,MISSISSIPPI & Missouri Rivers Floods, 1993 ,CLIMATOLOGY ,CLIMATE change mathematical models ,METEOROLOGICAL precipitation ,FLOODS ,RAINFALL - Abstract
The role of sea surface temperature anomalies (SSTAs) in the Atlantic and eastern Pacific and high-frequency atmospheric variability from the Pacific during the 1993 and 2008 Midwest floods is investigated with a regional climate model. The SSTAs insignificantly modulate Midwest rainfall during the 1993 flood, but enhance precipitation during the 2008 peak flood by strengthening the southern portion of the Great Plains low-level jet, enhancing moisture transport from the Gulf of Mexico into the Midwest. This work suggests that while North Atlantic SST strongly controls Midwest decadal drought and pluvial periods, it plays a minimal or secondary role in modulating extreme flood events lasting weeks to months. A negative Pacific/North American (PNA) teleconnection marked the peak of both floods, suggesting a link between extreme Midwest warm season rainfall and high-frequency PNA variations. Simulations that apply a 10-day low-pass filter to the western lateral boundary condition indicate that interactions between the eddy and time-mean flow played a significant, but counterintuitive role, during the 1993 flood. Although above normal Pacific cyclone activity was observed to trigger heavy Midwest precipitation, the synoptic eddies also indirectly influenced rainfall by modifying the time-mean circulation. Simulations show that eddies from the Pacific dampened the positive rainfall anomalies by weakening vertically integrated moisture transport and upper level divergence anomalies over the Midwest. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
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