• Energy Research

AbstractThere is growing awareness among governments, businesses, and the general public of risks arising from changes to our climate on time scales from months through to decades. Some climatic changes could be unprecedented in their harmful socioeconomic impacts, while others with adequate forewarning and planning could offer benefits. There is therefore a pressing need for decision-makers, including policy-makers, to have access to and to use high-quality, accessible, relevant, and credible climate information about the past, present, and future to help make better-informed decisions and policies. We refer to the provision and use of such information as climate services. Established programs of research and operational activities are improving observations and climate monitoring, our understanding of climate processes, climate variability and change, and predictions and projections of the future climate. Delivering climate information (including data and knowledge) in a way that is usable and useful for decision-makers has had less attention, and society has yet to optimally benefit from the available information. While weather services routinely help weather-sensitive decision-making, similar services for decisions on longer time scales are less well established. Many organizations are now actively developing climate services, and a growing number of decision-makers are keen to benefit from such services. This article describes progress made over the past decade developing, delivering, and using climate services, in particular from the worldwide effort galvanizing around the Global Framework for Climate Services under the coordination of UN agencies. The article highlights challenges in making further progress and proposes potential new directions to address such challenges.

AbstractThere is growing awareness among governments, businesses, and the general public of risks arising from changes to our climate on time scales from months through to decades. Some climatic changes could be unprecedented in their harmful socioeconomic impacts, while others with adequate forewarning and planning could offer benefits. There is therefore a pressing need for decision-makers, including policy-makers, to have access to and to use high-quality, accessible, relevant, and credible climate information about the past, present, and future to help make better-informed decisions and policies. We refer to the provision and use of such information as climate services. Established programs of research and operational activities are improving observations and climate monitoring, our understanding of climate processes, climate variability and change, and predictions and projections of the future climate. Delivering climate information (including data and knowledge) in a way that is usable and useful for decision-makers has had less attention, and society has yet to optimally benefit from the available information. While weather services routinely help weather-sensitive decision-making, similar services for decisions on longer time scales are less well established. Many organizations are now actively developing climate services, and a growing number of decision-makers are keen to benefit from such services. This article describes progress made over the past decade developing, delivering, and using climate services, in particular from the worldwide effort galvanizing around the Global Framework for Climate Services under the coordination of UN agencies. The article highlights challenges in making further progress and proposes potential new directions to address such challenges.

Abstract Background The savannah ecosystems of Sahel have experienced continuous and heavy grazing of livestock for centuries but still, their vegetation response to grazing pressure remains poorly understood. In this study, we analysed the herbaceous plant dynamics, measured by species diversity, composition, cover, and biomass in response to grazing pressure in the savannah ecosystems of Sahel. In Senegal, we selected four savannah sites represented with high, moderate, light and no grazing intensity levels. Transect survey methods were used for sampling the vegetation data within each of the sites. Species richness and composition were analysed using species accumulation curve and multivariate analyses. Furthermore, we used General Linear Models and a piecewise Structural Equation Model (pSEM) to examine the relationships between grazing intensity, vegetation cover, diversity and biomass. Results The herbaceous species diversity and composition varied significantly among the different grazing intensity levels (p <0.001). The plant species composition shifted from the dominance of grass cover to the dominance of forb cover with increasing grazing pressure. Moreover, the attributes of species diversity, herbaceous biomass, and ground cover were higher on sites with low grazing than sites with high and moderate grazing intensity. Across all sites, species diversity was positively related to total biomass. The pSEM explained 37% of the variance in total biomass and revealed that grazing intensity negatively influenced total biomass both directly and indirectly through its negative influence on species diversity. Conclusions Managing grazing intensity may lead to higher plant production and higher mixed forage establishment in the dryland savannah ecosystems. This information can be used to support land management strategies and promote sustainable grazing practices that balance the needs of livestock with the conservation of ecosystem health and biodiversity.

Abstract Background The savannah ecosystems of Sahel have experienced continuous and heavy grazing of livestock for centuries but still, their vegetation response to grazing pressure remains poorly understood. In this study, we analysed the herbaceous plant dynamics, measured by species diversity, composition, cover, and biomass in response to grazing pressure in the savannah ecosystems of Sahel. In Senegal, we selected four savannah sites represented with high, moderate, light and no grazing intensity levels. Transect survey methods were used for sampling the vegetation data within each of the sites. Species richness and composition were analysed using species accumulation curve and multivariate analyses. Furthermore, we used General Linear Models and a piecewise Structural Equation Model (pSEM) to examine the relationships between grazing intensity, vegetation cover, diversity and biomass. Results The herbaceous species diversity and composition varied significantly among the different grazing intensity levels (p <0.001). The plant species composition shifted from the dominance of grass cover to the dominance of forb cover with increasing grazing pressure. Moreover, the attributes of species diversity, herbaceous biomass, and ground cover were higher on sites with low grazing than sites with high and moderate grazing intensity. Across all sites, species diversity was positively related to total biomass. The pSEM explained 37% of the variance in total biomass and revealed that grazing intensity negatively influenced total biomass both directly and indirectly through its negative influence on species diversity. Conclusions Managing grazing intensity may lead to higher plant production and higher mixed forage establishment in the dryland savannah ecosystems. This information can be used to support land management strategies and promote sustainable grazing practices that balance the needs of livestock with the conservation of ecosystem health and biodiversity.

Proponemos una reinterpretación de la influencia oceánica en el clima del Sahel africano que sea consistente a través de las observaciones, las simulaciones del siglo XX y las proyecciones del siglo XXI, y que resuelva la incertidumbre en las proyecciones del cambio de precipitación en esta región: el calentamiento continuo de los océanos tropicales globales aumenta el umbral de convección, lo que podría secar las tierras tropicales, pero este "ante superior" se puede cumplir si se suministra suficiente humedad en el flujo monzónico. En este marco, la reversión al calentamiento del Atlántico Norte subtropical, que ahora está superando el calentamiento de los océanos tropicales globales, proporciona esa humedad y explica la recuperación parcial de las precipitaciones desde la persistente sequía en los años setenta y ochenta. Encontramos que esta recuperación es el resultado de aumentos en la intensidad de las precipitaciones diarias, en lugar de en la frecuencia, más evidentemente en Senegal, el más occidental de los tres países sahelianos analizados. La continuación de estas tendencias observadas es consistente con las proyecciones para un Sahel más húmedo en general, pero con precipitaciones más variables en todas las escalas de tiempo, desde intraestacionales hasta multidecadales. Nous proposons une réinterprétation de l'influence océanique sur le climat du Sahel africain qui est cohérente entre les observations, les simulations du XXe siècle et les projections du XXIe siècle, et qui résout l'incertitude dans les projections du changement des précipitations dans cette région : le réchauffement continu des océans tropicaux mondiaux augmente le seuil de convection, asséchant potentiellement les terres tropicales, mais cette « ante haute » peut être atteinte si suffisamment d'humidité est fournie dans le flux de mousson. Dans ce cadre, le renversement du réchauffement de l'Atlantique Nord subtropical, qui dépasse maintenant le réchauffement des océans tropicaux mondiaux, fournit cette humidité et explique la récupération partielle des précipitations depuis la sécheresse persistante des années 1970 et 1980. Nous constatons que cette reprise résulte de l'augmentation de l'intensité quotidienne des précipitations, plutôt que de leur fréquence, surtout au Sénégal, le plus occidental des trois pays sahéliens analysés. La poursuite de ces tendances observées est conforme aux projections pour un Sahel globalement plus humide, mais des précipitations plus variables à toutes les échelles de temps, de l'intra-saisonnier au multi-décennal. We propose a re-interpretation of the oceanic influence on the climate of the African Sahel that is consistent across observations, 20th century simulations and 21st century projections, and that resolves the uncertainty in projections of precipitation change in this region: continued warming of the global tropical oceans increases the threshold for convection, potentially drying tropical land, but this 'upped ante' can be met if sufficient moisture is supplied in monsoon flow. In this framework, the reversal to warming of the subtropical North Atlantic, which is now out-pacing warming of the global tropical oceans, provides that moisture, and explains the partial recovery in precipitation since persistent drought in the 1970s and 1980s. We find this recovery to result from increases in daily rainfall intensity, rather than in frequency, most evidently so in Senegal, the westernmost among the three Sahelian countries analyzed. Continuation of these observed trends is consistent with projections for an overall wetter Sahel, but more variable precipitation on all time scales, from intra-seasonal to multi-decadal. نقترح إعادة تفسير التأثير المحيطي على مناخ الساحل الأفريقي بشكل متسق عبر الملاحظات والمحاكاة في القرن العشرين وتوقعات القرن الحادي والعشرين، والذي يحل عدم اليقين في توقعات تغير هطول الأمطار في هذه المنطقة: يزيد الاحترار المستمر للمحيطات الاستوائية العالمية من عتبة الحمل الحراري، مما قد يؤدي إلى جفاف الأراضي الاستوائية، ولكن يمكن تلبية هذا "الرهان المرتفع" إذا تم توفير رطوبة كافية في تدفق الرياح الموسمية. في هذا الإطار، فإن الانعكاس إلى الاحترار في شمال المحيط الأطلسي شبه المداري، والذي يتجاوز الآن الاحترار في المحيطات المدارية العالمية، يوفر تلك الرطوبة، ويفسر الانتعاش الجزئي في هطول الأمطار منذ الجفاف المستمر في السبعينيات والثمانينيات. ونجد أن هذا الانتعاش ناتج عن الزيادات في كثافة هطول الأمطار اليومية، وليس في تواترها، كما هو واضح في السنغال، وهي الأكثر غربيًا بين بلدان الساحل الثلاثة التي تم تحليلها. ويتسق استمرار هذه الاتجاهات الملحوظة مع التوقعات الخاصة بمنطقة الساحل الأكثر رطوبة بشكل عام، ولكن هطول الأمطار أكثر تغيرًا على جميع النطاقات الزمنية، من داخل الموسم إلى متعدد العقود.

Proponemos una reinterpretación de la influencia oceánica en el clima del Sahel africano que sea consistente a través de las observaciones, las simulaciones del siglo XX y las proyecciones del siglo XXI, y que resuelva la incertidumbre en las proyecciones del cambio de precipitación en esta región: el calentamiento continuo de los océanos tropicales globales aumenta el umbral de convección, lo que podría secar las tierras tropicales, pero este "ante superior" se puede cumplir si se suministra suficiente humedad en el flujo monzónico. En este marco, la reversión al calentamiento del Atlántico Norte subtropical, que ahora está superando el calentamiento de los océanos tropicales globales, proporciona esa humedad y explica la recuperación parcial de las precipitaciones desde la persistente sequía en los años setenta y ochenta. Encontramos que esta recuperación es el resultado de aumentos en la intensidad de las precipitaciones diarias, en lugar de en la frecuencia, más evidentemente en Senegal, el más occidental de los tres países sahelianos analizados. La continuación de estas tendencias observadas es consistente con las proyecciones para un Sahel más húmedo en general, pero con precipitaciones más variables en todas las escalas de tiempo, desde intraestacionales hasta multidecadales. Nous proposons une réinterprétation de l'influence océanique sur le climat du Sahel africain qui est cohérente entre les observations, les simulations du XXe siècle et les projections du XXIe siècle, et qui résout l'incertitude dans les projections du changement des précipitations dans cette région : le réchauffement continu des océans tropicaux mondiaux augmente le seuil de convection, asséchant potentiellement les terres tropicales, mais cette « ante haute » peut être atteinte si suffisamment d'humidité est fournie dans le flux de mousson. Dans ce cadre, le renversement du réchauffement de l'Atlantique Nord subtropical, qui dépasse maintenant le réchauffement des océans tropicaux mondiaux, fournit cette humidité et explique la récupération partielle des précipitations depuis la sécheresse persistante des années 1970 et 1980. Nous constatons que cette reprise résulte de l'augmentation de l'intensité quotidienne des précipitations, plutôt que de leur fréquence, surtout au Sénégal, le plus occidental des trois pays sahéliens analysés. La poursuite de ces tendances observées est conforme aux projections pour un Sahel globalement plus humide, mais des précipitations plus variables à toutes les échelles de temps, de l'intra-saisonnier au multi-décennal. We propose a re-interpretation of the oceanic influence on the climate of the African Sahel that is consistent across observations, 20th century simulations and 21st century projections, and that resolves the uncertainty in projections of precipitation change in this region: continued warming of the global tropical oceans increases the threshold for convection, potentially drying tropical land, but this 'upped ante' can be met if sufficient moisture is supplied in monsoon flow. In this framework, the reversal to warming of the subtropical North Atlantic, which is now out-pacing warming of the global tropical oceans, provides that moisture, and explains the partial recovery in precipitation since persistent drought in the 1970s and 1980s. We find this recovery to result from increases in daily rainfall intensity, rather than in frequency, most evidently so in Senegal, the westernmost among the three Sahelian countries analyzed. Continuation of these observed trends is consistent with projections for an overall wetter Sahel, but more variable precipitation on all time scales, from intra-seasonal to multi-decadal. نقترح إعادة تفسير التأثير المحيطي على مناخ الساحل الأفريقي بشكل متسق عبر الملاحظات والمحاكاة في القرن العشرين وتوقعات القرن الحادي والعشرين، والذي يحل عدم اليقين في توقعات تغير هطول الأمطار في هذه المنطقة: يزيد الاحترار المستمر للمحيطات الاستوائية العالمية من عتبة الحمل الحراري، مما قد يؤدي إلى جفاف الأراضي الاستوائية، ولكن يمكن تلبية هذا "الرهان المرتفع" إذا تم توفير رطوبة كافية في تدفق الرياح الموسمية. في هذا الإطار، فإن الانعكاس إلى الاحترار في شمال المحيط الأطلسي شبه المداري، والذي يتجاوز الآن الاحترار في المحيطات المدارية العالمية، يوفر تلك الرطوبة، ويفسر الانتعاش الجزئي في هطول الأمطار منذ الجفاف المستمر في السبعينيات والثمانينيات. ونجد أن هذا الانتعاش ناتج عن الزيادات في كثافة هطول الأمطار اليومية، وليس في تواترها، كما هو واضح في السنغال، وهي الأكثر غربيًا بين بلدان الساحل الثلاثة التي تم تحليلها. ويتسق استمرار هذه الاتجاهات الملحوظة مع التوقعات الخاصة بمنطقة الساحل الأكثر رطوبة بشكل عام، ولكن هطول الأمطار أكثر تغيرًا على جميع النطاقات الزمنية، من داخل الموسم إلى متعدد العقود.