Recent trends in the Central and Western Sahel rainfall regime (1990–2007)

Lebel, Thierry; Ali, Abdou

doi:10.1016/j.jhydrol.2008.11.030

Cited by 471 publications

(353 citation statements)

References 31 publications

Supporting

Mentioning

301

Contrasting

Unclassified

Order By: Relevance

“…The perception of declining income from rainfed crops also corroborates the data. Climate data show that during the past 20 years there has been a recovery rather than a decline in total precipitation (Lebel and Ali 2009), but the decline in August rainfall is crucial for yields as it coincides with grain development.…”

Section: Discussionmentioning

confidence: 99%

“…Averaged over 30-year intervals, annual rainfall in this area fell by between 20 and 30% between the 1930s and the 1950s and the three decades following the 1960s, prompting Hulme (2001:20) to state that "the African Sahel therefore provides the most dramatic example worldwide of climatic variability that has been directly and quantitatively measured." It is repeatedly argued that this change in rainfall had major consequences for the populations of the Sudano-Sahelian zone, already under stress from difficult economic conditions (Roncoli et al 2001), even if a recovery of annual rainfall, particularly in the eastern part of the West African Sahel, has been observed during the past decade (Lebel and Ali 2009). …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Climate Factors Play a Limited Role for Past Adaptation Strategies in West Africa

Mertz¹,

Mbow²,

Nielsen³

et al. 2010

E&S

View full text Add to dashboard Cite

ABSTRACT. The Sudano-Sahelian zone of West Africa has experienced recurrent droughts since the mid-1970s and today there is considerable concern for how this region will be able to adapt to future climate change. To develop well targeted adaptation strategies, the relative importance of climate factors as drivers of land use and livelihood change need to be better understood. Based on the perceptions of 1249 households in five countries across an annual rainfall gradient of 400-900 mm, we provide an estimate of the relative weight of climate factors as drivers of changes in rural households during the past 20 years. Climate factors, mainly inadequate rainfall, are perceived by 30-50% of households to be a cause of decreasing rainfed crop production, whereas a wide range of other factors explains the remaining 50-70%. Climate factors are much less important for decreasing livestock production and pasture areas. Increases in pasture are also observed and caused by improved tenure in the driest zone. Adaptation strategies to declining crop production include 'prayer' and migration in the 400-500 mm zone; reforestation, migration, and government support in the 500-700 mm zone; and soil improvement in the 700-900 mm zone. Declining livestock holdings are countered by improved fodder resources and veterinary services. It is concluded that although rainfed crop production is mainly constrained by climate factors, livestock and pasture are less climate sensitive in all rainfall zones. This needs to be reflected in national adaptation strategies in the region.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Climate Factors Play a Limited Role for Past Adaptation Strategies in West Africa

Mertz¹,

Mbow²,

Nielsen³

et al. 2010

E&S

View full text Add to dashboard Cite

show abstract

“…The effect of this increase in rainfall was assessed by a long-term analysis of satellite observations, which shows a general re-greening of Sahel for the period 1982-2003 (Herrmann et al, 2005). On the other hand, Lebel and Ali (2009) concluded from an analysis of a longer time period ) that the initial 20-year wet period (1950)(1951)(1952)(1953)(1954)(1955)(1956)(1957)(1958)(1959)(1960)(1961)(1962)(1963)(1964)(1965)(1966)(1967)(1968)(1969) was followed by a 40-year dry period a tipping point in the rainfall regime observed by Lebel and Ali (2009), which may suggest the beginning of a longer wet period. Future rainfall scenarios, however, are rather uncertain in this region due to the complexity of the physical mechanisms responsible for Sahelian rainfall patterns (Christensen et al, 2007;Giannini et al, 2008).…”

Section: Rainfall Patternsmentioning

confidence: 99%

“…Barrios et al (2010) provide evidence that long-term trends in rainfall have affected economic growth rates in sub-Saharan Africa in the past. Recently, long-term drying trends were observed in several African regions, for example, in Nigeria (Odjugo, 2010), the western Sahel Lebel and Ali, 2009), tropical North Africa (Ting et al, 2009;Kawase et al, 2010;Misra, 2010) and in the eastern part of southern tropical Africa (Yin and Gruber, 2010). In contrast, a study by Capecchi et al (2008) demonstrated that an increase in rainfall in West Africa between 1986 and 2000 had a positive effect 3583 on crop production, particularly on the production of millet.…”

Section: Introductionmentioning

confidence: 99%

A conceptual model for assessing rainfall and vegetation trends in sub‐Saharan Africa from satellite data

Hościło

Balzter

Bartholomé³

et al. 2014

Int. J. Climatol

View full text Add to dashboard Cite

Policymakers, governments and aid agencies require operational environmental monitoring in support of evidence-based policy-making and resource deployment in crisis situations. For Africa, this is only feasible at sub-continental scale with a large network of automated meteorological stations, a large number of highly coordinated field observers or with satellite remote sensing. The challenge with satellite data lies in the derivation of meaningful environmental indicators. This article describes a conceptual framework for understanding satellite-derived indicators of rainfall and vegetation greenness trends over Africa. It attributes observed vegetation changes to climatic (i.e. rainfall linked) and non-climatic drivers. A decade of annual rainfall and vegetation data over sub-Saharan Africa was analysed using satellite-based rainfall estimates [Famine Early Warning System Rainfall Estimation 2.0 (FEWSNET RFE 2.0)] from National Oceanic and Atmospheric Administration's (NOAA's) Climate Prediction Centre and the Normalized Difference Vegetation Index (NDVI) obtained from the Satellite Pour l'Observation de la Terre Vegetation (SPOT-VGT) sensor. Rainfall and vegetation greenness trends were analysed for 759 administrative regions of sub-Saharan Africa to identify those regions that have experienced a negative, positive or stable rainfall/vegetation trend over the period [2001][2002][2003][2004][2005][2006][2007][2008][2009][2010]. The character of the relationship between the annual rainfall and max NDVI trends were examined to identify areas where the changes in greenness could be attributed to climatic (rainfall) and non-climatic (human land use or ecological disturbance) changes. Regions where increasing rainfall was associated with vegetation greening were found in West Africa, Central African Republic, West Cameroon and northeastern part of South Africa, whereas areas with evidence of 'climatic vegetation degradation' were located in Southern Madagascar, Nigeria, Kenya and the Garden Route region of South Africa.

show abstract

“…Although a slight recovery of precipitation amount has been observed during the last 10 years, rainfall totals are still under the level of the 1950s and 1960s (Nicholson, 2008;Lebel and Ali, 2009;Fink et al, 2010). However, in August and September 2007 media and aid organizations have brought a completely different meteorological phenomenon to the attention of the World's public: between Senegal and Kenya large parts of sub-Saharan Africa were hit by severe flooding caused by a sequence of anomously abundant rain events (e.g.…”

Section: Introductionmentioning

confidence: 99%

Meteorological characteristics and potential causes of the 2007 flood in sub‐Saharan Africa

Paeth

Fink

Pohle

et al. 2011

Intl Journal of Climatology

View full text Add to dashboard Cite

ABSTRACT:In August and September 2007 media and aid organizations reported on a severe flood in large parts of sub-Saharan Africa caused by a sequence of extreme rain events. However, the reporting was partly controversial and much was speculated about how unusual the flood event was. Here, we analyse various observational data sets in order to assess and to compare the spatio-temporal characteristics and intensity of the flood and the associated rain events. The return times are estimated from daily precipitation time series at fine spatial resolution, and the potential causes are disclosed in a global and regional context.Satellite data reveal that the flood was not large scale but confined to the main river basins in sub-Saharan West Africa. Nonetheless, abundant rainfall prevailed over large parts of Western Africa extending north into the Western Sahara, particularly during the second half of August and the beginning of September 2007. In detail, various precipitation data sets differ considerably in terms of the monthly anomalies, demonstrating the difficulty to delineate meteorological extreme events even at a sub-continental scale and during the most recent past. Return times typically range between 1 and 50 years with high spatial heterogeneity but amount to 1200 years in the regional mean over the Upper Volta Basin. Among the potential causes we identify a La Niña event in the tropical Pacific, anomalous heating in the tropical Atlantic coming along with a greater depth of the monsoonal westerlies, and enhanced activity of African easterly waves, both evident in 2-6 day zonal wind and outgoing longwave radiation variance anomalies.

show abstract

Recent trends in the Central and Western Sahel rainfall regime (1990–2007)

Cited by 471 publications

References 31 publications

Climate Factors Play a Limited Role for Past Adaptation Strategies in West Africa

Climate Factors Play a Limited Role for Past Adaptation Strategies in West Africa

A conceptual model for assessing rainfall and vegetation trends in sub‐Saharan Africa from satellite data

Meteorological characteristics and potential causes of the 2007 flood in sub‐Saharan Africa

Contact Info

Product

Resources

About