Cenário RCP de alta resolução para o século 21 na região Noroeste do Marrocos, projeções futuras para 2041-2060, 2061-2080 e 2081-2100

Climate model simulations of future climate are the basis for adaptation decisions, which the effectiveness will depend on the quality of the models. A set of climate models developed under the CMIP6 project and generated by the spatial bias correction disaggregation method (BCSD) using a statistical downscaling algorithm have been used. These models are used to evaluate the future changes in thermal extremes projected by the climate models over the different time horizons with comparison to the 1981-2000 reference period. These projections are made under the scenario RCP 4.5 (optimistic). The examination of future climate change projections could confirm the result of warming over the entire North West region of Morocco. The increase in temperature could reached an average of 1.8 °C to 2.5 °C just in 2060. In the same sense of warming, the number of hot days and hot nights could increase year by year while a decrease could be noticed in the number of cold days and cold nights. The simulations for the 2080 and 2100 horizons revealed a situation that worsens year by year. The temperature anomaly could reached about 3 °C and more. Thus, a climatic warming may be predicted in the future and generalized over the entire North West region.Las simulaciones de modelos climáticos del clima futuro son la base para las decisiones de adaptación, cuya efectividad dependerá de la calidad de los modelos. Se utilizó un conjunto de modelos climáticos desarrollados en el marco del proyecto CMIP6 y generados por el método de desagregación de corrección de sesgo espacial (BCSD) utilizando un algoritmo estadístico de reducción de escala. Estos modelos se utilizan para evaluar los cambios futuros en los extremos térmicos proyectados por los modelos climáticos en diferentes horizontes temporales en comparación con el período de referencia 1981-2000. Estas proyecciones se realizan bajo el escenario RCP 4.5 (optimista). Examinar las proyecciones del cambio climático futuro puede confirmar el resultado del calentamiento en toda la región noroeste de Marruecos. El aumento de temperatura podría alcanzar un promedio de 1,8 °C a 2,5 °C solo en 2060. En la misma dirección del calentamiento, el número de días y noches calurosos podría aumentar año tras año, mientras que se puede observar una disminución en el número de días y noches fríos. noches frías Las simulaciones para los horizontes 2080 y 2100 revelaron una situación que se agrava año tras año. La anomalía de temperatura puede alcanzar alrededor de 3 °C y más. Por lo tanto, el calentamiento climático puede predecirse en el futuro y generalizarse en toda la región del Noroeste.Simulações de modelos climáticos do clima futuro são a base para decisões de adaptação, cuja eficácia dependerá da qualidade dos modelos. Foi utilizado um conjunto de modelos climáticos desenvolvidos no âmbito do projeto CMIP6 e gerados pelo método de desagregação de correção de viés espacial (BCSD) usando um algoritmo estatístico de redução de escala. Esses modelos são usados para avaliar as mudanças futuras nos extremos térmicos projetados pelos modelos climáticos ao longo dos diferentes horizontes temporais em comparação com o período de referência 1981-2000. Essas projeções são feitas sob o cenário RCP 4.5 (otimista). O exame das projeções de mudanças climáticas futuras pode confirmar o resultado do aquecimento em toda a região Noroeste do Marrocos. O aumento da temperatura pode atingir uma média de 1,8 °C a 2,5 °C apenas em 2060. No mesmo sentido do aquecimento, o número de dias e noites quentes pode aumentar ano a ano enquanto uma diminuição pode ser observada no número de dias frios e noites frias. As simulações para os horizontes 2080 e 2100 revelaram uma situação que se agrava ano a ano. A anomalia de temperatura pode atingir cerca de 3 °C e mais. Assim, um aquecimento climático pode ser previsto no futuro e generalizado em toda a região Noroeste

Stable carbon isotope analysis of Cedrus atlantica pollen as an indicator of moisture availability

Stable carbon isotope analysis of pollen provides potential for reconstruction of past moisture availability in the environment on longer time-scales compared to isotope analysis of plant tissue. Here we show that the carbon isotopic compositions (δ13C) of pollen, sporopollenin, leaf and stem tissues of Cedrus atlantica are strongly related. Untreated pollen δ13C has a significant linear relationship with sporopollenin δ13C (r2 = 0.97, p < 0.0001) which is relatively depleted in 13C by an average 1.5‰. Carbon isotope discrimination (Δ13C) by sporopollenin (derived from pollen δ13C values) is related to mean annual (r2 = 0.54, p < 0.001) and summer precipitation (r2 = 0.63, p < 0.0001). A 100 mm increase in mean annual precipitation results in sporopollenin Δ13C increasing by 0.52‰, or by 1.4‰ per 100 mm summer precipitation. There is a stronger relationship between sporopollenin Δ13C and long-term annual scPDSI (r2 = 0.86, p < 0.0001) and summer scPDSI (r2 = 0.86, p < 0.001) aridity indexes, with reduced Δ13C as aridity increases. These relationships suggest that stable carbon isotope analysis of C. atlantica fossil pollen could be used as a quantitative proxy for the reconstruction of summer moisture availability in Northwest Africa

IMPACT DU CHANGEMENT CLIMATIQUE SUR LES EXTRÊMES DE TEMPÉRATURES AU MAROC

International audienceL'augmentation de l'évolution de certains types d'événements extrêmes a le potentiel de produire des impacts et des dégâts sur les secteurs socio-économiques. Une augmentation de la température minimale et maximale, se manifestant par de forts épisodes de canicule et des vagues de froid se renforcent bel et bien en terme d'intensité, de fréquence et leur durée. Notre étude vise à évaluer les changements climatiques observés en étudiant les tendances observées des indices de la température ainsi que leur significativité. Les résultats montrent que le Maroc a connu une augmentation des extrêmes chauds et une diminution des extrêmes froids sur notre pays à l'exception de quelques points d'observations où la tendance apparaît non significative. Mots-Clés : extrêmes chauds, réchauffement climatique, tendances observées

IMPACT DU CHANGEMENT CLIMATIQUE SUR LES EXTRÊMES DE TEMPÉRATURES AU MAROC

International audienceL'augmentation de l'évolution de certains types d'événements extrêmes a le potentiel de produire des impacts et des dégâts sur les secteurs socio-économiques. Une augmentation de la température minimale et maximale, se manifestant par de forts épisodes de canicule et des vagues de froid se renforcent bel et bien en terme d'intensité, de fréquence et leur durée. Notre étude vise à évaluer les changements climatiques observés en étudiant les tendances observées des indices de la température ainsi que leur significativité. Les résultats montrent que le Maroc a connu une augmentation des extrêmes chauds et une diminution des extrêmes froids sur notre pays à l'exception de quelques points d'observations où la tendance apparaît non significative. Mots-Clés : extrêmes chauds, réchauffement climatique, tendances observées

Cedrus atlantica pollen morphology and investigation of grain size variability using laser diffraction granulometry

The morphology and size variability of pollen grains of Cedrus atlantica were investigated using a novel approach employing laser diffraction granulometry. We provide new insights into size variability and present high-quality light microscopy (LM) and scanning electron microscopy (SEM) imagery of Cedrus atlantica pollen. Grains have an average size of 59.1 ± 4.0 µm, measured on millions of grains from 91 samples. Analysis showed there is high variability of grain size within individual samples, although variability between samples is not significant. We found no significant relationships between grain size and climate (including temperature, precipitation and aridity), and suggest that grain size of fossil Cedrus pollen would not be a good proxy for climate reconstruction. Grain size may be influenced by a number of complex factors such as genome size or adaptations to support wind pollination, while variability within individual samples may result from the irregular development of pollen. The laser diffraction method produced repeatable, robust measurements on millions of pollen grains which are highly correlated with measurements taken using LM (r = 0.91, p = 0.002). Where grain size information is crucial for pollen identification, for developing isolation techniques for geochemical analysis, for investigating climatic and environmental influence, or for investigating links between genomes and grain size, particle size analysis by laser diffraction provides a reproducible and robust method for quickly determining pollen grain size on many samples

UV-B absorbing compounds in modern Cedrus atlantica pollen: The potential for a summer UV-B proxy for Northwest Africa

Sporopollenin is a complex biopolymer which is the main component of the pollen grain exine and is partly composed of the aromatic compounds para-coumaric acid ( pCA) and ferulic acid (FA). These compounds absorb ultraviolet-B radiation (UV-B, 280–315 nm), and their abundance in pollen and spores has been shown to increase in response to increased UV-B flux. Here, we show that the relative abundance of UV-B-absorbing compounds (UACs) measured using Fourier Transform Infrared Spectrometry (FTIR) in modern pollen of autumn-pollinating Cedrus atlantica trees increases in response to summer UV-B flux. This relationship was observed in native Moroccan samples ( r2 = 0.84, p &lt; 0.0001), but not across a larger environmental gradient including non-Moroccan samples ( r2 = 0.00, p = 0.99). For non-Moroccan samples of known provenance, the abundance of UACs is similar to the abundance of UACs found in samples from their place of origin. The FTIR spectra of these samples also closely resemble the FTIR spectra of samples from their place of origin. This unexpected finding suggests there could be a heritable component to UAC production possibly associated with epigenetic memory, an important adaptive mechanism in conifers. Our results indicate that the relative abundance of UACs in Cedrus atlantica pollen could be used as a proxy to reconstruct historic summer UV-B flux in Northwest Africa during at least the Holocene and Late Glacial period while also highlighting how UV-B proxies should be established using pollen samples from specimens growing in their native range or environment. </jats:p

UV-B-absorbing compounds in modern <i>Cedrus atlantica</i> pollen: The potential for a summer UV-B proxy for Northwest Africa

Sporopollenin is a complex biopolymer which is the main component of the pollen grain exine and is partly composed of the aromatic compounds para-coumaric acid (pCA) and ferulic acid (FA). These compounds absorb ultraviolet-B radiation (UV-B, 280–315 nm), and their abundance in pollen and spores has been shown to increase in response to increased UV-B flux. Here, we show that the relative abundance of UV-B-absorbing compounds (UACs) measured using Fourier Transform Infrared Spectrometry (FTIR) in modern pollen of autumn-pollinating Cedrus atlantica trees increases in response to summer UV-B flux. This relationship was observed in native Moroccan samples (r2 = 0.84, p r2 = 0.00, p = 0.99). For non-Moroccan samples of known provenance, the abundance of UACs is similar to the abundance of UACs found in samples from their place of origin. The FTIR spectra of these samples also closely resemble the FTIR spectra of samples from their place of origin. This unexpected finding suggests there could be a heritable component to UAC production possibly associated with epigenetic memory, an important adaptive mechanism in conifers. Our results indicate that the relative abundance of UACs in Cedrus atlantica pollen could be used as a proxy to reconstruct historic summer UV-B flux in Northwest Africa during at least the Holocene and Late Glacial period while also highlighting how UV-B proxies should be established using pollen samples from specimens growing in their native range or environment.</div