Record of the Sedimentary Dynamics and Climatic Variability Within the Sedimentary Filling of Mchiguig Wetland During the Late Holocene

This work aimed to study the cyclicity of the geochemical chemical parameters and the carbonate percentages along a 59 cm core from the sebkha of Mchiguig, Central Tunisia. In fact, from the bottom upwards, six climatic phases were recorded including the Warming Present (Great Acceleration), the Late Little Ice Age (Anthropocene), the Early Little Ice Age, the Medieval Climatic Anomaly, the Dark Age, and the Roman Warm Period. In fact, the spectral analysis of the studied parameters visualized many cycles. Those cycles are related to sun activity, oceanographic, and atmospheric factors. Solar activity generated 500 yr cycles; however, the oceanographic circulation generated other cycles of 1500 yr and 700-800 yr. The 1500 yr cycle may be the result of the solar activity and NAO-like circulation.

Indicadores de cambio climático en las precipitaciones

El presente trabajo ofrece un estudio que se desarrolló en el municipio de Ciro Redondo de la provincia Ciego de Ávila, Cuba, con el objetivo de estimar los impactos del cambio climático sobre las precipitaciones. Se analizó una serie de 40 años, en el periodo comprendido de 1978 hasta el 2017, obtenidos de forma sistemática en el pluviómetro CA 808. Se realizó la estadística descriptiva para analizar los estadígrafos fundamentales de la serie de lluvias para escala de tiempo mensual y anual. Se determinó el índice de concentración de las precipitaciones, el climograma y el criterio para evaluación de cambio climático en las precipitaciones las anomalías climáticas y el cambio del patrón de lluvias. Los días con lluvia varían entre 9 y 12 días en el mes, con tendencia a la disminución en un 20% de la serie, definiendo el periodo lluvioso y seco en un 81,64% y 18,36% de las precipitaciones del año respectivamente. El climograma identificó que los meses de junio, julio y agosto superan los 30ºC de temperatura lo que califica a la localidad como una zona de altas temperaturas. Se valoró que existe una elevada anomalía climática negativa que ocurre en el 47,5% de los 40 años estudiados; mientras que en el patrón de desplazamiento de las precipitaciones en los últimos 5 años existen tendencias a disminuir las precipitaciones. Palabras clave: precipitaciones, clima, climograma, húmedo, seco. Abstract The present work offers a study that was developed in the Ciro Redondo Municipality of the province of Ciego de Ávila, Cuba, with the objective of determining the estimation of the impacts of climate change on rainfall. A series of 40 years was analyzed, in the period from 1978 to 2017, systematically obtained in the CA 808 rain gauge. The descriptive statistics was used to analyze the fundamental statistics of the rainfall series for time scale. monthly and annual. The index of concentration of precipitations, the climogram and the criterion for evaluation of climate change in rainfall were determined by the climatic anomalies and the change of rainfall pattern. The days vary between 9 and 12 days in the month, with a tendency to decrease in 20% of the series, therefore the rainy and dry period is defined in 81.64% and 18.36% of the rainfall of the year respectively. The climogram determined that the months of June, July and August exceed the 30ºC of temperature which allow to describe the location like at high temperatures zone. It was assessed that there is a high negative climatic anomaly occurring in 47.5% out of the 40 years studied was valued; while in the pattern of rainfall displacement in the last 5 years, there is a tendency to decrease rainfall monthly. Key words: rainfall, climate, climogram, wet, dry.

THE MORRO BAY FAUNA: EVIDENCE FOR A MEDIEVAL DROUGHTS REFUGIUM ON THE CENTRAL CALIFORNIA COAST

A robust collection of mammal, bird, fish, and shellfish remains from an 8,000-year residential sequence at Morro Bay, a small, isolated estuary on the central California coast, shows a strong focus on marine species during the Middle-Late Transition cultural phase (950–700 cal B.P.), which largely coincides with the Medieval Climatic Anomaly (MCA). Previous studies have provided modest evidence for increased fishing and rabbit hunting during the MCA in adjacent regions, but the Morro Bay findings suggest a distinctive marine-focused subsistence refugium during the period of drought. Specifically, the sequence shows striking all-time peaks in marine and estuarine birds, fish NISP/m3, and fish/deer + rabbits during the MCA. Heavy exploitation of fish, aquatic birds, rabbits, and shellfish suggests that the bow and arrow, which seems to have arrived in the area at this time, had little impact on local subsistence strategies.