• Energy Research

Abstract The study investigates how the rising global temperature will affect the spatial pattern of rainfall and consequently drought in West Africa. The precipitation and potential evapotranspiration variables that are obtained from the Rossby Centre regional atmospheric model (RCA4) and driven by ten (10) global climate models under the RCP8.5 scenario were used. The model data were obtained from the Coordinated Regional Climate Downscaling Experiment (CORDEX) and analyzed at four specific global warming levels (GWLs) (i.e., 1.5 °C, 2.0 °C, 2.5 °C, and 3.0 °C) above the pre-industrial level. This study utilized four (4) indices: the standardized precipitation index, the precipitation concentration index, the precipitation concentration degree, and the precipitation concentration period over West Africa to explore the spatiotemporal variations in the characteristics of precipitation concentrations. Additionally, studying the impact of the four GWLs on consecutive dry days, consecutive wet days, and frequency of the intense rainfall events led to a better understanding of the spatiotemporal pattern of extreme precipitation. The results show that, at each GWL studied, the onset of rainfall comes 1 month earlier in the Gulf of Guinea compared to the historical period (1971–2000) with increasing rainfall intensity in the whole study domain, and the northeastern part of the study area becomes wetter. The rainfall concentration is uniformly distributed over the Gulf of Guinea and the Savanna zone for both the historical period and RCP8.5 scenario, while the Sahel zone which has shown an irregular concentration of rainfall for the historical period shows a uniform concentration of rainfall under all four GWLs.

Pour réduire les risques du changement climatique, les gouvernements ont convenu dans l'Accord de Paris de limiter l'augmentation de la température mondiale à moins de 2,0 °C par rapport aux niveaux préindustriels, avec l'ambition de maintenir le réchauffement à 1,5 °C. La cartographie des réponses d'atténuation appropriées nécessite des informations sur les coûts d'atténuation par rapport aux dommages associés pour les deux niveaux de réchauffement. Dans cette évaluation, une considération critique est l'impact sur les rendements des cultures et la variabilité des rendements dans les régions actuellement confrontées à l'insécurité alimentaire. La présente étude a évalué les impacts de 1,5 °C par rapport à 2,0 °C sur les rendements du maïs, du millet perlé et du sorgho dans la savane soudanaise d'Afrique de l'Ouest en utilisant deux modèles de culture qui ont été calibrés avec des variétés communes issues d'expériences dans la région, la gestion reflétant une gamme de fenêtres de semis typiques. Comme l'intensification durable est encouragée dans la région pour améliorer la sécurité alimentaire, des simulations ont été menées à la fois pour l'utilisation actuelle d'engrais et pour un cas d'intensification (fertilité non limitative). Avec l'utilisation actuelle d'engrais, les résultats ont indiqué des pertes plus élevées de 2 % pour le maïs et le sorgho avec 2,0 °C par rapport au réchauffement de 1,5 °C, sans changement dans les rendements en mil pour aucun des scénarios. Dans le cas de l'intensification, les pertes de rendement dues au changement climatique étaient plus importantes qu'avec les niveaux actuels d'engrais. Cependant, malgré les pertes plus importantes, les rendements ont toujours été deux à trois fois plus élevés avec l'intensification, quel que soit le scénario de réchauffement. Bien que la variabilité du rendement ait augmenté avec l'intensification, il n'y avait aucune interaction avec le scénario de réchauffement. Une analyse des risques et du marché est nécessaire pour étendre ces résultats afin de comprendre les implications pour la sécurité alimentaire. Para reducir los riesgos del cambio climático, los gobiernos acordaron en el Acuerdo de París limitar el aumento de la temperatura global a menos de 2,0 °C por encima de los niveles preindustriales, con la ambición de mantener el calentamiento a 1,5 °C. El trazado de las respuestas de mitigación apropiadas requiere información sobre los costos de la mitigación frente a los daños asociados para los dos niveles de calentamiento. En esta evaluación, una consideración crítica es el impacto en los rendimientos de los cultivos y la variabilidad del rendimiento en las regiones actualmente desafiadas por la inseguridad alimentaria. El estudio actual evaluó los impactos de 1,5 °C frente a 2,0 °C en los rendimientos de maíz, mijo perla y sorgo en la sabana de Sudán de África Occidental utilizando dos modelos de cultivo que se calibraron con variedades comunes de experimentos en la región con un manejo que refleja una gama de ventanas de siembra típicas. A medida que se promueve la intensificación sostenible en la región para mejorar la seguridad alimentaria, se realizaron simulaciones tanto para el uso actual de fertilizantes como para un caso de intensificación (fertilidad no limitante). Con el uso actual de fertilizantes, los resultados indicaron pérdidas un 2% mayores para el maíz y el sorgo con 2,0 °C en comparación con el calentamiento de 1,5 °C, sin cambios en los rendimientos de mijo para ninguno de los dos escenarios. En el caso de la intensificación, las pérdidas de rendimiento debido al cambio climático fueron mayores que con los niveles actuales de fertilizantes. Sin embargo, a pesar de las mayores pérdidas, los rendimientos siempre fueron de dos a tres veces más altos con la intensificación, independientemente del escenario de calentamiento. Aunque la variabilidad del rendimiento aumentó con la intensificación, no hubo interacción con el escenario de calentamiento. Se necesitan análisis de riesgos y de mercado para ampliar estos resultados y comprender las implicaciones para la seguridad alimentaria. To reduce the risks of climate change, governments agreed in the Paris Agreement to limit global temperature rise to less than 2.0 °C above pre-industrial levels, with the ambition to keep warming to 1.5 °C. Charting appropriate mitigation responses requires information on the costs of mitigating versus associated damages for the two levels of warming. In this assessment, a critical consideration is the impact on crop yields and yield variability in regions currently challenged by food insecurity. The current study assessed impacts of 1.5 °C versus 2.0 °C on yields of maize, pearl millet and sorghum in the West African Sudan Savanna using two crop models that were calibrated with common varieties from experiments in the region with management reflecting a range of typical sowing windows. As sustainable intensification is promoted in the region for improving food security, simulations were conducted for both current fertilizer use and for an intensification case (fertility not limiting). With current fertilizer use, results indicated 2% units higher losses for maize and sorghum with 2.0 °C compared to 1.5 °C warming, with no change in millet yields for either scenario. In the intensification case, yield losses due to climate change were larger than with current fertilizer levels. However, despite the larger losses, yields were always two to three times higher with intensification, irrespective of the warming scenario. Though yield variability increased with intensification, there was no interaction with warming scenario. Risk and market analysis are needed to extend these results to understand implications for food security. للحد من مخاطر تغير المناخ، اتفقت الحكومات في اتفاقية باريس على الحد من ارتفاع درجة الحرارة العالمية إلى أقل من 2.0 درجة مئوية فوق مستويات ما قبل الصناعة، مع طموح للحفاظ على ارتفاع درجة الحرارة إلى 1.5 درجة مئوية. يتطلب رسم استجابات التخفيف المناسبة معلومات عن تكاليف التخفيف مقابل الأضرار المرتبطة بمستويي الاحترار. في هذا التقييم، يتمثل أحد الاعتبارات الهامة في التأثير على غلة المحاصيل وتقلب الغلة في المناطق التي تواجه حاليًا انعدام الأمن الغذائي. قيمت الدراسة الحالية تأثيرات 1.5 درجة مئوية مقابل 2.0 درجة مئوية على غلة الذرة والدخن اللؤلؤي والذرة الرفيعة في سافانا غرب إفريقيا باستخدام نموذجين للمحاصيل تمت معايرتهما بأصناف شائعة من التجارب في المنطقة مع الإدارة التي تعكس مجموعة من نوافذ البذر النموذجية. ومع تعزيز التكثيف المستدام في المنطقة لتحسين الأمن الغذائي، أجريت عمليات محاكاة لكل من الاستخدام الحالي للأسمدة وحالة التكثيف (الخصوبة غير محدودة). مع استخدام الأسمدة الحالي، أشارت النتائج إلى خسائر أعلى بنسبة 2 ٪ للذرة والذرة الرفيعة مع 2.0 درجة مئوية مقارنة بالاحترار 1.5 درجة مئوية، مع عدم وجود تغيير في غلة الدخن لأي من السيناريوهين. في حالة التكثيف، كانت خسائر الغلة بسبب تغير المناخ أكبر من مستويات الأسمدة الحالية. ومع ذلك، على الرغم من الخسائر الأكبر، كانت الغلة دائمًا أعلى مرتين إلى ثلاث مرات مع التكثيف، بغض النظر عن سيناريو الاحترار. على الرغم من زيادة تقلب المحصول مع التكثيف، لم يكن هناك تفاعل مع سيناريو الاحترار. هناك حاجة إلى تحليل المخاطر والسوق لتوسيع نطاق هذه النتائج لفهم الآثار المترتبة على الأمن الغذائي.

To investigate the ability of dynamical seasonal climate predictions for Vietnam, the RegCM4.2 is employed to perform seasonal prediction of 2 m mean (T2m), maximum (Tx), and minimum (Tn) air temperature for the period from January 2012 to November 2013 by downscaling the NCEP Climate Forecast System (CFS) data. For model bias correction, the model and observed climatology is constructed using the CFS reanalysis and observed temperatures over Vietnam for the period 1980–2010, respectively. The RegCM4.2 forecast is run four times per month from the current month up to the next six months. A model ensemble prediction initialized from the current month is computed from the mean of the four runs within the month. The results showed that, without any bias correction (CTL), the RegCM4.2 forecast has very little or no skill in both tercile and value predictions. With bias correction (BAS), model predictions show improved skill. The experiment in which the results from the BAS experiment are further successively adjusted (SUC) with model bias at one-month lead time of the previous run showed further improvement compared to CTL and BAS. Skill scores of the tercile probability forecasts were found to exceed 0.3 for most of the target months.

This study investigates trends of climate extreme indices in the Komadugu-Yobe Basin (KYB) based on observed data of the period 1971–2017 as well as regional climate model (RCM) simulations for the historical period (1979–2005), the near future (2020–2050), and the far future (2060–2090). In order to correct change points in the time historical series, the Adapted Caussinus Mestre Algorithm for homogenising Networks of Temperature series homogeneity test is used. The magnitude of the linear trends is estimated using the Sen's slope estimator and Mann-Kendall's test is performed to check the statistical significance of the trends. Future trends are assessed using the ensemble mean of eight regional climate model data under two emission scenarios, provided by the Coordinated Regional Climate Downscaling Experiment (CORDEX). Therefore, the projected rainfall and temperature have been corrected for biases by using empirical Quantile Mapping. In the observations, warm spell duration, warm day-, and warm night frequencies exhibit statistically significant positive trends. Although there is a positive trend in the annual total rainfall, the number of consecutive wet (dry) days decreases (increases). The future climate also shows a continuing positive trend in the temperature extreme indices as well as more frequent extreme rainfall events. Therefore, it is pertinent for decision-makers to develop suitable adaptation and mitigating measures to combat climate change in the Basin.

AbstractObservational evidence suggests that forests in the Northern Alps are changing at an increasing rate as a consequence of climate change. Yet, it remains unclear whether the acceleration of forest change will continue in the future, or whether downregulating feedbacks will eventually decouple forest dynamics from climate change. Here we studied future forest dynamics at Berchtesgaden National Park, Germany by means of a process‐based forest landscape model, simulating an ensemble of 22 climate projections until the end of the 21st century. Our objectives were (i) to assess whether the observed acceleration of forest dynamics will continue in the future, (ii) to analyze how uncertainty in future climate translates to variation in future forest disturbance, structure, and composition, and (iii) to determine the main drivers of future forest dynamics. We found that forest dynamics continue to accelerate in the coming decades, with a trend towards denser, structurally more complex and more species rich forests. However, changes in forest structure leveled off in the second half of the 21st century regardless of climate scenario. In contrast, climate scenarios caused trajectories of tree species change to diverge in the second half of the 21st century, with stabilization under RCP 2.6 and RCP 4.5 scenarios and accelerated loss of conifers under RCP 8.5. Disturbance projections were 3 to 20 times more variable than future climate, whereas projected future forest structure and composition varied considerably less than climate. Indirect effects of climate change via alterations of the disturbance regime had a stronger impact on future forest dynamics than direct effects. Our findings suggest that dampening feedbacks within forest dynamics will decelerate forest change in the second half of the 21st century. However, warming beyond the levels projected under RCP 4.5 might profoundly alter future forest disturbance and composition, challenging conservation efforts and ecosystem service supply.