Alejandro Cearreta

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University of the Basque Country | UPV/EHU · Department of Geology

We evaluate and summarize main human disruptions and their associated impacts on estuaries and deltas, contextualizing these perturbations in terms of their effects on the recent sedimentary record. For each general category of human action (sea-level change, land reclamation and physical modification, river discharge of water and sediment, polluti...

The Moulay Bousselham Lagoon, composed of two parts, Merja Kahla and Merja Zerga, is one of the largest tidal lagoons on the Atlantic coast of NW Africa. Designated as a Ramsar Site, the Moulay Bousselham Lagoon has been identified as a significant carbon sink. Our research aims are to reconstruct regional vegetation changes and lagoonal infill his...

The effects of sea-level rise due to global climate change, coupled with socioeconomic development and population growth, have exerted constant pressure on coastal wetlands, leading to their decline. Sediment dynamics, along with other natural processes, are significantly affected, resulting in a general reduction in coastal wetland areas and alter...

Coastal populations are susceptible to relative sea-level (RSL) rise and accurate local projections are necessary for coastal adaptation. Local RSL rise may deviate from global mean sea-level rise because of processes such as geoid change, glacial isostatic adjustment (GIA), and vertical land motion (VLM). Amongst all factors, the VLM is often inad...

The decline of forest cover in the northwestern Iberian Peninsula during the recent centuries, driven by anthropogenic activities, has necessitated the establishment of a set of laws and regulations to ensure stricter control of the use of natural forest resources. However, the assessment of the effects of such legislation on plant populations is i...

From the Abstract: The technosphere sensu Peter Haff [12] has auton- omous qualities, being not so much human-directed as incorporating dependent, strongly divided human soci- eties, while parasitizing its parent biosphere for energy and materials. By far the most recent and rapidly evolving of Earth’s ‘spheres’, it is also the most unsta- ble, rec...

From the Abstract: The Anthropocene is a particularly powerful con- ceptual tool, and encapsulates the complex intercon- nectivity of all the ‘-spheres’ on this planet. It quickly became a key framing concept for Earth System re- searchers. From this, and from its subsequent geologi- cal analysis, it grew to spark off considerable cross- disciplina...

We synthesize research from complementary scientific fields to address the likely future extent and duration of the proposed Anthropocene epoch. Intensification of human-forced climate change began from about 1970 onwards with steepening increases in greenhouse gases, ocean acidification, global temperature and sea level, along with ice loss. The r...

Increasing human interactions with the biosphere over tens of millennia have left a fossil record that shows the growing geographical spread and technological sophistication of humans evident in patterns of extinction and domestication of the landscape and its plants and animals. Here, we focus on the "Great Acceleration" of the mid-20th century (e...

Applying the basic principles of carbon chemistry and physics, along with a comprehensive understanding of past climate change, Steffen and colleagues confirmed in the Proceedings of the National Academy of Sciences 115, in 2018, that fossil fuel usage and resulting carbon emissions will cause substantial global warming into future millennia. The c...

A common sense: The Anthropocene was originally understood by Crutzen as not only representing humanity’s influence on Earth’s geological record (he was well aware of earlier anthropogenic impacts), but also reflecting a system with physical characteristics that had, since widespread industrialization, departed from the prolonged, relatively stable...

The "Great Acceleration" beginning in the mid-20th century provides the causal mechanism of the Anthro-pocene, which has been proposed as a new epoch of geological time beginning in 1952 CE. Here we identify key parameters and their diagnostic palaeontological signals of the Anthropocene, including the rapid breakdown of discrete biogeographical ra...

The Anthropocene Working Group (AWG) has concluded that the Anthropocene represents geological reality and should be linked with the plethora of stratigraphic proxies that initiate or show marked perturbations at around the 1950s, and should be defined using a Global boundary Stratotype Section and Point (GSSP). We propose formalizing the Anthropoc...

This part of the Anthropocene Working Group (AWG) submission proposes that the base of the Anthropocene should be defined as series/epoch, terminating the Holocene Series/Epoch with a single Crawfordian stage/age using a Global boundary Stratotype Section and Point (GSSP) in an annually varved Crawford Lake core, Ontario, Canada, defined at 17.5 cm...

This is the Executive Summary of a report produced by the membership of the Anthropocene Working Group as part of a submission to the Subcommission on Quaternary Stratigraphy to seek formalisation of the Anthropocene as an epoch of geological time. It summarises the content of two reports and their associated appendices which provide a background t...

The Anthropocene as a prospective new, ongoing series/epoch must be defensible against all relevant concerns. We address the seven, still-relevant challenges posed to the Anthropocene Working Group by the Chair, International Commission on Stratigraphy (ICS), in 2014. (1) Concept or reality? The Anthropocene possesses a substantial, sharply distinc...

This virtual volume compiles some of the scientific contributions presented as oral communications and panels at the 10th Symposium on the Iberian Atlantic Margin (Bilbao, Spain, 7-9 July 2022). It contains a collection of 15 papers addressing various environmental settings (from shallower to deeper environments), disciplines, and methodologies in...

Instrumental and geological records indicate that the rise in the global sea level has been accelerating since the beginning of the twentieth century due to ocean thermal expansion and the melting of the cryosphere. Future sea level increase will depend on the amount of greenhouse gas emissions over the next decades, although geological evidence sh...

Galician rías provide several ecosystem services of great ecological and economic significance in the northwestern Iberian margin, requiring a good environmental quality for sustainable harnessing. More paleoenvironmental reconstructions extending to their preindustrial state are needed to predict their evolution under natural and human-induced per...

Vivons-nous vraiment dans l’Anthropocène, la période géologique marquée par l’impact global de l’activité humaine ? Et si oui, quand a-t-elle commencé et où sur Terre peut-on le mieux comprendre ses débuts ? Telles sont les questions auxquelles tente de répondre le Groupe de travail sur l’Anthropocène (AWG), créé en 2009 par la Sous-commission sur...

Benetan bizi al gara Antropozenoan, giza jardueraren inpaktu globalak markatutako denbora geologikoan? Eta hala balitz, noiz hasi zen eta Lurreko zein lekuk islatzen du ondoen aro berri horren hasiera? Galdera horiei erantzun nahi die Antropozenoari buruzko Lantaldeak (AWG, ingelesez). Talde hori Kuaternarioko Estratigrafia Azpibatzordeak sortu zue...

Vivemos realmente no Antropoceno, o tempo geológico marcado pelo impacto global da actividade humana? E se assim for, quando começou e que lugar da Terra reflecte melhor o começo desta nova época? A estas perguntas procura responder o Grupo de Trabalho sobre o Antropoceno, estabelecido em 2009 pela Subcomissão de Estratigrafia do Quaternário, com o...

Vivimos realmente en el Antropoceno, el tiempo geológico marcado por el impacto global de la actividad humana? Y si así fuera, ¿cuándo empezó y qué lugar de la Tierra refleja mejor el comienzo de esta nueva época? A estas preguntas trata de contestar el Grupo de Trabajo sobre el Antropoceno (AWG por sus siglas en inglés), establecido en 2009 por la...

Are we really living in the Anthropocene, the geological time marked by the global impact of humanactivity? And if so, when did it begin? These are questions that the Anthropocene Working Group – established in 2009 by the International Commission on Stratigraphy to propose a definition of the concept and to estimate its potential as aunit of geolo...

Coastal populations are susceptible to relative sea-level (RSL) rise and accurate projections are necessary for coastal adaptation. Local RSL rise may deviate from the global mean sea-level rise because of vertical land motion (VLM) but this is often inadequately estimated. Here, we estimated the VLM for the Oka estuary, northern Spain and compared...

Hasta hace poco tiempo, la mayor parte de la comunidad científica consideraba que el impacto humano sobre la geología de nuestro planeta era prácticamente insignificante en comparación con los procesos geológicos que han operado sobre la superficie terrestre durante millones de años. Esta idea comenzó a cambiar en la segunda mitad del siglo XX, cua...

The Holocene environmental evolution in coastal areas, including deltas and estuaries, is vital to understanding coastal dynamics and how they may change in the future. Here, we studied the Holocene environmental evolution of the Oka estuary (Urdaibai Biosphere Reserve, northern Spain) from sedimentary cores that were 11–49 m long. We applied a mul...

Swindles et al. (2023) correctly point out that there are many conceptions of the ‘Anthropocene’ in use, and they argue that this flexibility in terminology is desirable. We agree that the multiple uses of this term have stimulated much scholarly debate, but we contend that precision in terminology is far more desirable than vagueness, and promotes...

Merritts et al. (2023) misrepresent Paul Crutzen’s Anthropocene concept as encompassing all significant anthropogenic impacts, extending back many millennia. Crutzen’s definition reflects massively enhanced, much more recent human impacts that transformed the Earth System away from the stability of Holocene conditions. His concept of an epoch (henc...

Se presentan las características principales del método de datación de sedimentos recientes mediante el radioisótopo natural 210Pb y su validación utilizando radionucleidos artificiales tales como 137Cs y 239,240Pu. Se hace una revisión de los principios generales de esta metodología, se aportan recomendaciones prácticas para la recogida de testigo...

Event stratigraphy is used to help characterise the Anthropocene as a chronostratigraphic concept, based on analogous deep-time events, for which we provide a novel categorization. Events in stratigraphy are distinct from extensive, time-transgressive ‘episodes’ – such as the global, highly diachronous record of anthropogenic change, termed here an...

We examine three distinctive biostratigraphic signatures of humans associated with hunting and gathering , landscape domestication and globalization. All three signatures have significant fossil records of regional importance that can be correlated interregionally and help describe the developing pattern of human expansion and appropriation of reso...

The extensive array of mid-20 th century stratigraphic event signals associated with the 'Great Acceleration' enables precise and unambiguous recognition of the Anthropocene as an epoch/series within the Geological Time Scale. A mid-20 th century inception is consistent with Earth System science analysis in which the Anthropocene term and concept a...

The Anthropocene defined as an epoch/series within the Geological Time Scale, and with an isochronous inception in the mid-20th century, would both utilize the rich array of stratigraphic signals associated with the Great Acceleration and align with Earth System science analysis from where the term Anthropocene originated. It would be stratigraphic...

Se ha analizado el registro sedimentario reciente del estuario del Nalón a partir de dos sondeos intermareales que han sido datados mediante 210Pb y 137Cs. Los resultados muestran por primera vez sus asociaciones características de foraminíferos bentónicos, constituidas por un total de 46 especies, así como los importantes cambios experimentados po...

The Anthropocene Working Group is preparing the case for the definition of a new stratigraphic Epoch: this requires the demonstration of an objective change in properties of a geological archive over time. As each property being examined for this distinction can be considered as a time series, we encounter a classic scientific problem of distinguis...

Extinction, coupled with many other biological signals, is a major geological indicator of the Anthropocene. The introduction of non-native species, deforestation, depletion of fisheries and modification of coastal environments, domestication of animals, and the reconfiguration of terrestrial ecosystems are all evident in the geological record and...

The most recent division of geological time is based on climate events caused by variations in the Earth’s orbit and axis of rotation on a scale of thousands of years. However, the magnitude of geological change caused by humankind through its still young technosphere, particularly since the mid-20th century, is negatively affecting the other class...

Antropozeno hitzak, gizakia, Holozeno Epokaren aurreko dinamika naturalak aldatzeko gai eta indar geologiko erabakigarri bihurtu den denbora tarte geologikoari egiten dio erreferentzia. 2009az geroztik, Antropozenoko lantaldea Antropozenoa ikuspegi geologikotik definitzen zentratu da, Estratigrafiari buruzko Nazioarteko Batzordeak ezarritako arauak...

The Avilés estuary is one of the most important industrial ports in northern Spain, whose natural characteristics have been largely altered since the 1830s. Here, the environmental transformation of this estuary during the 19 th century is explored using a multi-proxy approach including benthic foraminiferal content, sedimentology (grain-size), tra...

The Anthropocene was conceptualized in 2000 to reflect the extensive impact of human activities on our planet, and subsequent detailed analyses have revealed a sub- stantial Earth System response to these impacts begin- ning in the mid-20th century. Key to this understanding was the discovery of a sharp upturn in a multitude of global socio-economi...

La división del tiempo geológico más reciente está basada en eventos de carácter climático provocados por variaciones en la órbita y el eje de rotación de la Tierra a escala de miles de años. Sin embargo, la magnitud del cambio geológico causado por la humanidad a través de su joven tecnosfera está afectando negativamente a las otras esferas clásic...

Se analizaron la composición elemental de los sedimentos y la distribución y abundancia de microfósiles en dos zonas de marisma de la laguna costera Estero de Urías (Golfo de California, México) con el fin de determinar las características ambientales de este medio marino restringido. En los sedimentos se detectó un enriquecimiento por metales (en...

A detailed study is presented of a 15.3‐m‐thick Pleistocene coastal terrace located on the Cantabrian coast (northern Spain). Stratigraphic, sedimentological, topographic and micropalaeontological information is combined with a chronology based on luminescence dating to characterize the deposits. The sedimentary succession records: (i) a basal tran...

In order to reconstruct the environmental evolution of the Deba and Urola estuaries located in the Basque Coast Geopark at millennial, centennial and decadal timescales, four long boreholes, three short cores and twelve surface samples were studied. Multiproxy analysis (foraminifera, trace metals and radioisotopes) shows the temporal transformation...

We gathered total organic carbon (%) and relative abundances of benthic foraminifera in intertidal areas and transitional waters from the English Channel/European Atlantic Coast (587 samples) and the Mediterranean Sea (301 samples) regions from published and unpublished datasets. This database allowed to calculate total organic carbon optimum and t...

The term Anthropocene initially emerged from the Earth System science community in the early 2000s, denoting a concept that the Holocene Epoch has terminated as a consequence of human activities. First associated with the onset of the Industrial Revolution, it was then more closely linked with the Great Acceleration in industrialization and globali...

While we officially live in the Holocene epoch, global warming and many other impacts of global change have led to the proposal and wide adoption of the Anthropocene to define the present geological epoch. The Anthropocene Working Group (AWG) established that it should be treated as a formal stratigraphic unit, demonstrated by a reference level com...

This work contributes to the ongoing work aiming at confirming benthic foraminifera as a biological quality element. In this study, benthic foraminifera from intertidal and transitional waters from the English Channel/ European Atlantic coast and the Mediterranean Sea were assigned to five ecological groups using the weighted-averaging optimum with...

Stratigraphy provides insights into the evolution and dynamics of the Earth System over its long history. With recent developments in Earth System science, changes in Earth System dynamics can now be observed directly and projected into the near future. An integration of the two approaches provides powerful insights into the nature and significance...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Supplementary material to Syvitski et al. 2020, see https://www.researchgate.net/publication/344685697_Extraordinary_human_energy_consumption_and_resultant_geological_impacts_beginning_around_1950_CE_initiated_the_proposed_Anthropocene_Epoch

Growth in fundamental drivers—energy use, economic productivity and population—can provide quantitative indications of the proposed boundary between the Holocene Epoch and the Anthropocene. Human energy expenditure in the Anthropocene, ~22 zetajoules (ZJ), exceeds that across the prior 11,700 years of the Holocene (~14.6 ZJ), largely through combus...

Bilboko itsasadarra Kantauri itsasoko estuariorik handiena izan zen garai batean. Azken 150 urteetan, kontrolik gabe isuri dira itsasadarrera meatzeetako, fabriketako eta etxeetako hondakinak. Horren ondorioz, ibaiaren ezaugarri fisiko-kimikoak narriatu egin ziren. Garapen jasanezin horren eraginez, 1970eko hamarkadarako itsasadarra estolda nabigag...

In July 2019, the 15th National Quaternary Meeting was held in Bilbao, under the general theme of “Environmental Changes and Human Footprint”. This congress of the Spanish Quaternary Research Association (AEQUA) was organised locally by the Quaternary Formation and Research Unit of the UPV/EHU and had the support of different organisations, as the...

This work deals with the microfaunal (benthic foraminifera) and geochemical (trace metals, ¹⁴C, ²¹⁰Pb, ¹³⁷Cs, and 239/240Pu) study of two boreholes (1200 and 1400 cm length) and three subtidal sediment cores (38–58 cm length) collected in the Pasaia estuary (northern Spain). Foraminiferal assemblages in the Holocene deposits depend on the paleogeog...

La ría de Bilbao fue originalmente el estuario más grande del Cantábrico. Durante los últimos 150 años, la Ría ha recibido vertidos incontrolados de desechos mineros, industriales y domésticos que degradaron sus condiciones físico-químicas. Como consecuencia de este desarrollo insostenible, en la década de 1970 la Ría se había convertido en una clo...

The historical anthropogenic impact on sediments from the Basque Mud Patch (southern Bay of Biscay) is explored using a multidisciplinary approach including the analysis of natural (²¹⁰Pb) and artificial (¹³⁷Cs, 239/240Pu) radiotracers, major elements (Al, Mn), metals (Zn, Pb, Cu, Cr), Pb isotopic ratios, and foraminiferal and pollen contents. The...

This study describes a rapid method for sequential determination of uranium and plutonium isotopes in soil and sediment samples and its application to the study of Anthropocene sedimentary records. Different pretreatment methods have been tested (open-vessel digestion, borate salts fusion and NaOH salt fusion) achieving the complete dissolution of...

Se han estudiado las asociaciones de foraminíferos de dos sondeos largos y uno corto en el estuario del Deba con el fin de realizar la interpretación ambiental de su registro sedimentario. Adicionalmente, se han llevado a cabo análisis geoquímicos en el sondeo corto, y análisis microfaunísticos y geoquímicos en ocho muestras superficiales tomadas a...

The transformation of two intertidal environments from northern Spain during the last 150 years shows an evolution from a tidal flat into a salt marsh environment, with an intermediate transitional stage. The environment of deposition was reconstructed based on benthic foraminifera and sand content. Sediments were put into a temporal framework usin...

El País Vasco presenta una larga tradición cuaternarista, dentro de la cual podemos destacar la publicación en el año 1917 de los primeros trabajos científicos sobre Prehistoria vasca por José Miguel de Barandiaran, Telesforo de Aranzadi y Enrique Eguren, la fundación en 1947 de la Sociedad de Ciencias Aranzadi para la investigación del medio natur...

Debido a los compromisos políticos vacíos de contenido o que no han sido respetados por los gobiernos, las emisiones de gases de efecto invernadero siguen en aumento a pesar de las advertencias de la comunidad científica.

The Bilbao estuary is one of the most polluted areas on the northern coast of Spain, owing to the direct disposal of urban effluents and wastewaters from mining and industrial activities that has occurred during the last 170 years. Recent sediment records collected from the inner Abra of Bilbao bay were examined using a multidisciplinary approach i...

Holocene environmental evolution of the Oka Estuary (Urdaibai Biosphere Reserve, southeastern Bay of Biscay): response to postglacial sea-level rise): Fluvial paleovalleys provide critical data to study the temporal superposition of depositional environments during the Holocene postglacial sea-level rise. We study eight boreholes that reached bedro...

Entre los días 1-5 de julio 2019 se ha celebrado en Bilbao la XV Reunión Nacional de Cuaternario. Este congreso de la Asociación Española para el Estudio del Cuaternario (AEQUA) ha sido organizado localmente por la Unidad de Formación e Investigación en Cuaternario de la UPV/EHU y, entre sus distintas actividades, ha incluido 2 salidas de campo. Un...

El País Vasco presenta una larga tradición cuaternarista, dentro de cuyos principales hitos se encuentra la publicación en el año 1917 de los primeros trabajos científicos sobre prehistoria vasca realizados por José Miguel de Barandiaran, Telesforo de Aranzadi y Enrique Eguren, la fundación en 1947 de la Sociedad de Ciencias Aranzadi para la invest...

Uno de los primeros trabajos cuaternaristas sobre la costa vasca fue publicado por el geólogo francés M. E. Jacquot (1864) quien exploró cuidadosamente los 15 km de acantilados que se extienden entre San Juan de Luz y Biarritz. En ese trabajo, Jacquot señaló en Bidart y Biarritz un depósito arenoso con gravas y lechos de arcillas que contenían lign...

Entre los días 1-5 de julio 2019 se ha celebrado en Bilbao la XV Reunión Nacional de Cuaternario. Este congreso de la Asociación Española para el Estudio del Cuaternario (AEQUA) ha sido organizado localmente por la Unidad de Formación e Investigación en Cuaternario de la UPV/EHU. El País Vasco presenta una larga tradición cuaternarista, dentro de c...

Rock magnetic properties of 13 samples of surficial materials and 160 samples of recent sediments obtained from 7 sedimentary cores along the Bilbao estuary have been analyzed in order to investigate the magnetic fingerprint of anthropogenic pollution in this area. The results have been correlated to previously published heavy metal concentrations,...

In order to reconstruct the possible recent anthropogenic impact recorded in the Basque mud patch, 3 cores obtained at around 100 m depth in front of the Guipuzcoan coast during the French oceanographic campaign Euskased (Euska2) have been studied. Their multiproxy analysis (metals, foraminifera, pollen, carbonaceous particles and short-lived radio...

In order to reconstruct the environmental evolution of the estuaries in the Basque Coast Geopark at different temporal scales (millennial, centennial, decadal), different long and short cores and surface samples were retrieved and studied. Their multiproxy analysis (metals, foraminifera, pollen and radioisotopes) shows their temporal transformation...

El Antropoceno geológico se diferencia en cierta medida de otras interpretaciones del Antropoceno que han ido apareciendo en los últimos años, ya que las ciencias sociales, las humanidades y las artes se han interesado por este concepto y lo han analizado a través de las herramientas conceptuales de sus propias disciplinas. Parece claro que aceptar...

El Grupo de Etnografía del Museo Plasentia de Butrón se constituyó en el año 2016 con objeto de estudiar e interpretar diferentes aspectos del patrimonio cultural y ambiental de Uribe Kosta. Los miembros del grupo se conocieron asistiendo y colaborando en las Jornadas de Historia de Plentzia-Uribe Kosta y decidieron asociarse en el seno del Museo p...

La marisma de Txipio se encuentra frente al casco urbano de Plentzia en la margen izquierda de la Ría del Butroe. Fue ocupada con fines agrícolas desde mediados del siglo XIX y abandonada un siglo después. Durante ese periodo se utilizó como zona de cultivo mediante su relleno artificial y la construcción de canales de drenaje para los aportes de a...

El Antropoceno sería una unidad de la historia de la Tierra que podría formar parte de la Escala del Tiempo Geológico. Si bien los cambios asociados con el Antropoceno han sido hasta ahora geológicamente breves, sus consecuencias han provocado una modificación muy evidente del planeta hacia una nueva trayectoria, con efectos que persistirán durante...

We analyse the ‘three flaws’ to potentially defining a formal Anthropocene geological time unit as advanced by Ruddiman (2018). (1) We recognize a long record of pre-industrial human impacts, but note that these increased in relative magnitude slowly and were strongly time-transgressive by comparison with the extraordinarily rapid, novel and near-g...

El alcance social y académico del Antropoceno ha crecido de una manera sorprendente. Este concepto se acuñó para materializar nuestra percepción de que las actividades humanas han cambiado el Sistema Tierra. El comportamiento de los océanos, la atmósfera, la superficie terrestre, la criosfera, la biosfera y el clima ya no es el mismo que ha caracte...

The Anthropocene, a term launched into public debate by Nobel Prize winner Paul Crutzen, has been used informally to describe the time period during which human actions have had a drastic effect on the Earth and its ecosystems. This book presents evidence for defining the Anthropocene as a geological epoch, written by the high-profile international...

Sea-level change is one of the most important consequences of Quaternary climate variability. The association of human population centres with lowland coastal regions dates back to early civilisations, when people congregated at river mouths, deltas and estuaries because of abundant and accessible food sources. The emergence and rapid expansion of...

The Basque estuaries represent drowned river valleys that were firstly flooded by the sea due to a climate-change-induced sea-level rise 8500 yr ago, and subsequently, infilled with a general shallowing sequence. Basque estuaries developed from an initial fluvial environment followed by a firstly marine and secondly brackish depositional system.