Cambio climático en dos áreas de clima mediterráneo (España y Chile): evidencias y proyecciones

Climate change is the most important environmental problem facing humanity in this century. And it has become the great axis of public policies and private actions in developed societies. The effects of altering the planetary energy balance due to anthropogenic greenhouse gas emissions are already becoming evident in some regions of the planet. Among them, the evidence is already significant in the areas with a Mediterranean climate. This paper collects, as a review paper, the evidence and trends that are being recorded in two areas with a Mediterranean climate (the Spanish Mediterranean coast and the central sector of Chile) to assess the effect of the global warming process. The impact that the current climate change is having on the main elements of the climate and on specific environmental processes in both of these geographical spaces has been analysed. The study seeks to update, through an evaluative summary, the state of the issue of climate change in Mediterranean areas, indicating its future impact on elements of the natural environment and on the functioning of the societies that exist in these regions.El cambio climático es el problema ambiental más importante al que se enfrenta la humanidad en el presente siglo. Y se ha convertido en el gran eje de políticas públicas y acciones privadas en las sociedades desarrolladas. Los efectos del proceso de alteración del balance energético planetario por la incorporación de gases de efecto invernadero de causa antrópica ya están siendo manifiestos en algunas regiones del planeta. Entre ellas, de forma evidente, en los ámbitos de clima mediterráneo. El presente trabajo recoge, a modo de revisión de investigaciones y documentos oficiales, las evidencias y tendencias que se están registrado en dos áreas de clima mediterráneo (litoral mediterráneo español y sector central de Chile) para valorar el efecto del proceso de calentamiento planetario. Se ha analizado el impacto que está teniendo el cambio climático actual en los elementos principales del clima, así como en algunos procesos ambientales en ambos espacios geográficos. Se pretende poner al día en una aportación de síntesis valorativa, el estado de la cuestión del cambio climático en ámbitos mediterráneos, señalando su impacto futuro en elementos del medio natural y en el propio funcionamiento de las sociedades que están implantadas en estas regiones

Análisis de la fractalidad temporal de la precipitación en Cataluña, España (2010)

Se han contabilizado los intervalos con precipitación, a resoluciones de 30 minutos hasta 48 horas, de once observatorios de Cataluña durante el año 2010. Con esto se ha analizado la fractalidad temporal de la precipitación, que tiene su expresión numérica en el concepto de la dimensión fractal (D) y que es representativa de la mayor o menor regularidad temporal de la precipitación. Asimismo, se han comparado para los mismos once observatorios las dimensiones fractales del semestre cálido y del semestre frío, con valores en general mayores en este último. El patrón espacial básico anual y del semestre cálido de D muestran un aumento de los valores desde el suroeste hacia el nordeste

Sequías en Chile central a partir de diferentes índices en el período 1981-2010

The different dimensions of meteorological drought in central Chile in order to characterize their occurrence at multiple time scales and find evidence of variability and change in frequency are analyzed. For that, there are 27 meteorological stations at daily resolution arranged, which allow the identification of dry periods under the threshold of 0.1 mm. Besides establishing dry spells and its persistence (using the Besson index), the standard precipitation index (SPI) was applied to determine the internanual varibilidad of drought, precisely in a region with semiarid and Mediterranean climate. The results show greater persistence of dry days in the region of Valparaíso, which is consistent with the length of dry spells in many cases exceeding 22 days a year. The event La Niña in the winter of 1998 caused the longest streak of dry days of the rainy trimester (67 days), totaling 86 days without rain. However, it has not been able to prove their variability and changes in frequency.Se analizan las diferentes dimensiones de la sequía meteorológica en Chile central con el propósito de caracterizar su ocurrencia a múltiples escalas temporales y encontrar indicios de cambio en su variabilidad y frecuencia. Para ello se ha dispuesto de 27 estaciones meteorológicas a resolución diaria, las cuales permiten identificar períodos secos bajo el umbral 0,1 mm. Además de establecer las rachas de sequías y su persistencia (mediante el índice de Besson), se aplicó el índice estándar de precipitación (SPI) para conocer la varibilidad internanual de la sequía, justamente en una región de clima semiárido y mediterráneo. Los resultados indican mayor persistencia de días secos en la región de Valparaíso, lo cual es consistente con la longitud de las rachas de sequía, en muchos casos superior a 22 días al año. El evento La Niña en el invierno de 1998 provocó la mayor racha de días secos del trimestre lluvioso (67 días), sumando en total 86 días sin lluvia. No obstante, no se ha podido probar cambios en su variabilidad y frecuencia

Heat and cold waves in mainland Spain: Origins, characteristics, and trends

Heat and cold waves are extreme temperature events with a high potential of causing negative impacts on human health, and natural and socioeconomic systems, depending on their duration and intensity. There is, however, no consensual approach to address their definition, which is critical to set priority action areas to prevent such risks. Mainland Spain experiences heat and cold waves every year with important impacts especially in the most populated areas with mild or transition climates. Here we used a high-resolution (5 × 5 km) gridded daily temperature dataset and employed a combination of threshold exceedances of maximum and minimum temperature in the same day to identify heat and cold wave events over 75 years (1940–2014). We further examined the duration and the seasonal/annual intensities to detect potential spatial and temporal patterns. Additionally, we used the days within the most widespread events to perform a synoptic classification to categorise the atmospheric conditions leading to high-risk situations. Our results show a similar historical duration of heat and cold waves (4–5 days) and a much higher seasonal intensity of cold ones (double than heat waves). We find a tipping point in the early 1980s from which heat waves became more frequent, longer, and more intense than cold waves. Finally, we discern between 9 historical weather types with a dominance of southern advections driving heat waves and cold continental north-northeast air masses causing cold waves. Understanding the patterns and trends of heat and cold waves, as well as the mechanisms of their genesis is key to assist in risk management in mainland Spain, especially in the context of a warming climate scenario. © 2022 The Author

Precipitación extrema en la Puna del Desierto de Atacama: ¿Cómo gestionar la incertidumbre actual y futura?

Chile is one of the Latin American countries most affected by Climate Change. There is a high level of uncertainty regarding the variability of precipitation and its projections in many regions of this country. This poses challenges for climate characterization and for defining strategies to reduce its risks. The study area is the Puna of Atacama Desert, Andean highlands located to the eastern side of the extreme arid lands, a region that concentrates the main copper and lithium mining at word scale, and where meteorological observations are scarce, with missing data and unreliable projections. Considering this data limitations, a daily precipitation database of 35 weather stations was constructed in order to evaluate some extreme precipitation indices that allow establishing changes between 1981-2017, in addition to spatial interpolations based on topography. It is concluded that most of the meteorological stations do not present significant trends of change, e.g. Extremely wet days (R99p), Wet days (RR) and Consecutive wet days (CWD). The index with the highest number of stations with a trend is CDD, which shows an increase in consecutive dry days. One of the main contributions of this research was to expand the number of observations and to generate maps of the spatial distribution of the indices of extremes. We are facing open questions regarding living with uncertainty, and meeting the challenges of maintaining records to increase the levels of certainty of climatic changes.Chile es uno de los países de América Latina más afectados por el cambio climático. Existe un elevado nivel de incertidumbre respecto a la variabilidad de las precipitaciones y sus proyecciones en muchas de sus regiones. Ello plantea desafíos para su caracterización climática y para definir estrategias para reducir los riesgos asociados. Se estudia la Puna del Desierto de Atacama, paisaje andino de altura que bordea las tierras áridas por el lado este, y que concentran las principales minas de cobre y litio a escala mundial, y donde existen escasas observaciones meteorológicas, con datos perdidos y proyecciones de poca fiabilidad. Es por ello que se construyó una base diaria de precipitación de 35 estaciones con el fin de evaluar algunos índices extremos que permitan establecer cambios entre 1981-2017, además de interpolaciones espaciales basadas en la topografía. Se concluye que la mayoría de las estaciones meteorológicas no presenta tendencias significativas de cambio, destacando días extremadamente húmedos (R99p), días húmedos (RR) y días húmedos consecutivos (CWD). El índice con mayor cantidad de estaciones con tendencia es CDD, que muestra un incremento de los días consecutivos secos. Uno de los principales aportes de esta investigación fue ampliar el número de observaciones y generar mapas de la distribución espacial de los índices de extremos. Nos quedan preguntas abiertas respecto a convivir con la incertidumbre, y alcanzar desafíos de mantener los registros para aumentar los niveles de certeza de los cambios climáticos.The authors acknowledge support by the Program CLIMAT AmSud Project PRELASA (21-CLIMAT-12)

A component-based approximation for trend detection of intense rainfall in the Spanish Mediterranean coast

Rainfall behavior is a fundamental issue in areas with scarce and irregular amounts, such as the Spanish Mediterranean region. We identified 12 spatial patterns that characterized 899 torrential precipitation events (≥150 mm in 24 h) that occurred in the 3,537 rainy precipitation series in the period 1950-2020. Three of these components--eastern and ESE--showed positive and significant trends in their accumulated volumes. We then characterized the mean synoptic causes of the 10 most intense events in each component at both mean sea-level pressure and 500 hPa geopotential height, and also the integrated water-vapor transport between 1,000 and 300 hPa. We found a clear spatial distribution of the pluviometric effects related to unstable atmospheric situations (such as troughs and cut-off lows), and also to SW-SE advection fluxes that brought moist air from the Western Mediterranean. In particular, torrential rainfall in the Balearic Islands related more to E-NE advections than to southeastern ones. We also determined that the major parts of these components occurred in early autumn, especially in September and October. We expect these findings to help our understanding of the processes leading to catastrophic situations along the Spanish Mediterranean coast and to lead to improvements in early alert systems and management plans

Regioirregular and catalytic Mizoroki-Heck reactions

[EN] The palladium-catalysed cross-coupling reaction between alkenes and aryl halides (the Mizoroki-Heck reaction) is a powerful methodology to construct new carbon-carbon bonds. However, the success of this reaction is in part hampered by an extremely marked regioselectivity on the double bond, which dictates that electron-poor alkenes react exclusively on the beta-carbon. Here, we show that ligand-free, few-atom palladium clusters in solution catalyse the alpha-selective intramolecular Mizoroki-Heck coupling of iodoaryl cinnamates, and mechanistic studies support the formation of a sterically encumbered cinnamate-palladium cluster intermediate. Following this rationale, the alpha-selective intermolecular coupling of aryl iodides with styrenes is also achieved with palladium clusters encapsulated within fine-tuned and sterically restricted zeolite cavities to produce 1,1-bisarylethylenes, which are further engaged with aryl halides by a metal-free photoredox-catalysed coupling. These ligand-free methodologies significantly expand the chemical space of the Mizoroki-Heck coupling.This work was supported by MINECO (Spain, projects CTQ 2017-86735-P, PID2019-105391GB-C22 and MAT2017-82288-C2-1-P, Severo Ochoa programme SEV-2016-0683 and the Juan de la Cierva programme). F.G.-P. and R.G. thank ITQ for the concession of a contract. J.O.-M. acknowledges the Juan de la Cierva programme for the concession of a contract, and R.P.-R. and J.C.-S. thank the Plan GenT programme (CIDEGENT/2018/044) funded by Generalitat Valenciana. HR STEM measurements were performed at DME-UCA in Cadiz University, with financial support from FEDER/MINECO (PID2019-110018GA-I00 and PID2019-107578GA-I00). We acknowledge ALBA Synchrotron for allocating beamtime and CL AE SS beamline staff for their technical support during our experiment.Garnes-Portoles, F.; Greco, R.; Oliver-Meseguer, J.; Castellanos-Soriano, J.; Jiménez Molero, MC.; Lopez-Haro, M.; Hernández-Garrido, JC.... (2021). Regioirregular and catalytic Mizoroki-Heck reactions. Nature Catalysis. 4(4):293-303. https://doi.org/10.1038/s41929-021-00592-3S2933034

Definition of a temporal distribution index for high temporal resolution precipitation data over Peninsular Spain and the Balearic Islands: the fractal dimension; and its synoptic implications

Precipitation on the Spanish mainland and in the Balearic archipelago exhibits a high degree of spatial and temporal variability, regardless of the temporal resolution of the data considered. The fractal dimension indicates the property of self-similarity, and in the case of this study, wherein it is applied to the temporal behaviour of rainfall at a fine (10-min) resolution from a total of 48 observatories, it provides insights into its more or less convective nature. The methodology of Jenkinson & Collison which automatically classifies synoptic situations at the surface, as well as an adaptation of this methodology at 500 hPa, was applied in order to gain insights into the synoptic implications of extreme values of the fractal dimension. The highest fractal dimension values in the study area were observed in places with precipitation that has a more random behaviour over time with generally high totals. Four different regions in which the atmospheric mechanisms giving rise to precipitation at the surface differ from the corresponding above-ground mechanisms have been identified in the study area based on the fractal dimension. In the north of the Iberian Peninsula, high fractal dimension values are linked to a lower frequency of anticyclonic situations, whereas the opposite occurs in the central region. In the Mediterranean, higher fractal dimension values are associated with a higher frequency of the anticyclonic type and a lower frequency of the advective type from the east. In the south, lower fractal dimension values indicate higher frequency with respect to the anticyclonic type from the east and lower frequency with respect to the cyclonic type

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Detection of non-homogeneities in daily precipitation series in central and southern Chile Detección de inhomogeneidades en series de precipitación diaria en la región centro-sur de Chile

Continental Chile presents a large climate diversity due to its latitudinal spread, from 17°S to 56°S. In some areas of the country, precipitation represents a determinant factor for the development of some human activities, such as agriculture or mining. That is why having access to quality meteorological datasets is a first order necessity so as to be able to identify, within the variability of the dataset, what data corresponds to the natural variability of climate, and what corresponds to matters related to the instrumental matters and man-induced modifications. In order to evaluate this, different indices were applied to detect non-homogeneities to 152 datasets: von Neumann test, Thom test and Real Precision Index (RPI). These three tests evaluate different aspects of the series that they are applied to, so the series that are homogeneous for one of them not necessarily have to be homogeneous to another. Only 73 of the 152 datasets presented a good to tolerable quality according