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The warming of the global climate system is expected to result in significant socio-economic stress, primarily through the occurrence of extreme weather and climate events, with the potential for severe impacts on societies. This was evidenced by the vulnerability of European nations during the 2003 summer heatwave, which resulted in the death of tens of thousands of individuals due to heat-related complications. In this analysis, we examine the summer of 2022 in Spain, a Mediterranean country that is among the most impacted by the effects of climate change. A distinct pattern of the subtropical ridge in the 500 hPa geopotential height, which is typically linked to the occurrence of heatwaves in the Iberian Peninsula (IP), and the atmospheric blocking in the North Atlantic region facilitated the southerly flow of exceptionally warm air masses from Africa towards the IP, contributing to the sustained high temperatures throughout the summer season. Our results show that Spain experienced record-breaking temperatures in nearly half of the country that favored more frequent, intense, and longer-lasting heatwaves compared to previous historical records available from 1893. In general, despite normal rainfall conditions, the extremely high temperatures led to intense drought conditions in most areas. Finally, the paleoclimatic records suggest that the average summer temperature of 2022 was unprecedented within the last 700 years, and the driest within the last 279 in NE Spain. These findings highlight the need for measures to mitigate the effects of heat on at-risk populations, and to increase resilience and adaptation to climate change in the future.

Este trabajo presenta una cartografía detallada de las temperaturas medias mensuales de los Pirineos, elaborada a partir de una amplia base de datos única, con control de calidad y homogeneizada del conjunto de la cordillera, generada por el proyecto CLIMPY-OPCC de caracterización de la evolución del clima, en el que han colaborado los tres países pirenaicos, Francia, España y Andorra. La información se ofrece en modo grid o rejilla a escala diaria de 1 x 1 km de resolución, que permite una buena aproximación al análisis de los patrones espaciales y de las variaciones mensuales de las temperaturas. El mapa muestra un conjunto de doce rasters que reflejan la temperatura media de cada mes del año del periodo 1981-2015. El resultado del trabajo, además de contribuir al conocimiento del clima pirenaico, pretende proporcionar herramientas para la investigación científica, la gestión de recursos naturales y la concienciación pública sobre el cambio climático.

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.

Base de datos de indicadores agroclimáticos para la España peninsular

The long‐term hydroclimatic variability in Santiago (Chile) was analysed by means of a new 481‐year (1536–2016 CE) tree‐ring reconstruction of the Standardized Precipitation Evapotranspiration Index (SPEI) of August, integrating the hydroclimatic conditions during the preceding 14 months. Results show a high frequency of extreme drought events in the late 20th and early 21st centuries, while the frequency of extreme wet events was higher in the 17th–18th centuries. The mid‐20th century represents a breaking point for the hydroclimatic history in the region, including some significant changes: (a) the interannual variability increased; (b) the wet events became less intense; (c) the extreme dry events became more frequent; and (d) the most intense dry event of the entire period was identified, coinciding with the so‐called Megadrought (2006–2016). A correlation analysis between the reconstructed SPEI and three climate indices (PDO, SOI and Niño3.4) was performed at monthly scale, considering different multi‐annual aggregations. The analysis shows diverse impacts on the hydroclimatic variability, with positive correlations between SPEI and PDO as well as Niño3.4, and negative correlations between SPEI and SOI. The most significant correlations were, overall, found at multi‐annual time scales (>7 years). Results help to better understand the current hydroclimatic changes (Megadrought) in a long‐term context.

Wildfires are gaining importance in the Mediterranean regions owing to climate change and landscape changes due to the increasing closeness between urban areas and forests prone to wildfires. We analysed the dry season wildfire occurrences in the Mediterranean region of Central Chile (32°S–39°30′ S) between 2000 and 2017, using satellite images to detect burned areas, their landscape metrics and the land use and covers (vegetal) pre-wildfire, in order to determine the population living in areas that may be affected by wildfires. The existing regulations in western Mediterranean countries (Portugal, Spain, France, and Italy) were used to identify and define the wildland-urban interface (WUI) areas, quantifying the people inhabiting them and estimating the population affected by burned areas from 2001 to 2017. We used the Google Earth Engine to process MODIS products and extract both burned areas and land covers. We detected that 25% of the urban population inhabits WUI areas (i.e. Biobío, Araucanía and Valparaíso regions) where the urban population exposed to burned areas exceeds 40%. Most of the land use and land covers affected by wildfires are anthropogenic land covers, classified as savannas, croplands, evergreen broadleaf forests and woody savannas, representing >70% of the burned areas. Urban areas show only 0.6% of the burned surface from 2001 to 2017. We estimate that 55,680 people are potentially affected by wildfires, and 50% of them are in just one administrative region. These results show the imperative need for public policies as a regulating force for establishing WUI areas with the purpose of identifying wildfire risk in urban areas, such as establishing prevention methods as firewalls and prescribed fires.

Northern Chile is a region characterised by an extremely dry climate; however, there is a brief rainy season from December to March (austral summer), mainly above 3000 m a.s.l. It is interesting to consider where the humid air masses that generate such rain come from. For this purpose, daily precipitation data from 161 meteorological stations located in this area (18° S–19° S) were considered, and four clusters formed by k-means clustering. For each cluster, days of extreme precipitation (above 90th percentile) were selected to obtain flow strength (F), direction (D), and vorticity (Z) for each event according to the Jenkinson and Collison (JC) method. The back trajectory, for the previous 72 h, of air masses affecting the centroid of each cluster was determined by means of the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The analyses were carried out at sea level (1013 hPa) and in the middle (500 hPa) and upper (250 hPa) troposphere. Surface circulation was not a determining factor in the occurrence of extreme events, but it did influence circulation at 500 and 250 hPa. For stations located in the northern Altiplano, moisture advection from the Amazon basin is evident due to the configuration of the Bolivian high—an upper level anticyclone that develops over the Bolivian Altiplano during austral summer. For stations located in the southern part of the study area, the main source of moisture is the Pacific Ocean, and the weather is related to the arrival of frontal systems and to the configuration of cut-off low pressure systems in the mid-troposphere.