Long-lived trees support biodiversity at multiple scales, maintain ecosystem functionality, serve as natural archives, and hold cultural and aesthetic value. Despite their importance, the maximum longevity of many tree species remains poorly understood, limiting the design of effective conservation strategies. Challenges in obtaining reliable tree ages are commonly represented by natural wood decay, sampling obstacles, and indistinct or absent annual rings, which prevent or limit the application of tree-ring analyses (dendrochronology). Radiocarbon dating, increasingly accessible and applicable to all species, provides a flexible approach to study tree longevity and its ecological implications. For tropical trees, which mostly lack annual rings, radiocarbon dating is one of the few reliable methods to determine tree ages. Even in sections of the calibration curve characterized by oscillations and plateaus, statistical methods such as wiggle-matching or deposition models may be used to reduce the range of probable tree ages. In this paper, we illustrate a mismatch between tree-ring and radiocarbon-derived estimates of the longevity of angiosperm trees, with tree-ring maximum ages often half of those obtained through radiocarbon dating. We also present the most up-to-date estimates of maximum longevity for 42 arboreal angiosperm species worldwide, based on a literature review. Radiocarbon results indicate that ages of 400–500 years are a common feature of many broadleaved species, while exceptional old ages are restricted to a small minority of individual trees. Our results underscore the need for increased efforts to locate old and ancient trees, investigate their role in ecosystem ecology and ensure their protection.

The Nerja Cave is a key archaeological site in the Southern Iberian Peninsula. It was inhabited by humans from the Upper Palaeolithic until recent Prehistory (30 and 3.7 ka cal BP). Various excavation campaigns performed in its external chambers (Vestíbulo, Mina and Torca) have recovered evidence of its use as habitat and burial site. Multiple studies on these matters have been published, but, until now, no Bayesian chronological modeling that utilized radiocarbon dates of the three chambers has been performed. To do so, all the available radiocarbon dates and stratigraphic and archaeological data have been compiled. These comprehend ample and diverse information about which, firstly, individual phase models based on the stratigraphic sequence of each one of the chambers have been created. After critically evaluating the results for each of the chambers, a general phase model for the prehistoric occupation of the external chambers has been created considering the cultural adscription of the samples. This has enabled the identification of 11 phases which correspond to the different technocomplexes of the Gravettian, Solutrean, Magdalenian, Epipalaeolithic, Mesolithic, Neolithic and Chalcolithic. Still pending are the refinement and improvement of the model for the Neolithic horizon among other phases of the sequence. The individual and the general models have evidenced important differences between the different archaeological phases in radiocarbon information as well as in the occupation of the three chambers.

The reduction of anthropogenic methane emissions is a priority due to its potent global warming potential. Radiocarbon (14C) can distinguish between methane from natural biogenic and fossil fuel sources, however, the analysis of methane 14C by conventional accelerator mass spectrometry (AMS) techniques is demanding. At SUERC, a prototype positive ion mass spectrometer (PIMS) is set up to directly analyze 14C in methane with minimal sample preparation. Methane gas was mixed with a stoichiometric amount of oxygen in an open split and admitted directly into the source. A series of modern, blank and unknown methane samples were clearly distinguishable by their 14C/13C raw ratios. The collision cell gas flowrate was then increased to lower the limit of detection. We obtained a corrected 14C/13C raw ratio of less than 2 × 10–13 for blank fossil methane which corresponds to a radiocarbon age greater than 50 kyr. Modern biogenic methane had a measured 14C/13C raw ratio approaching 1 × 10–10 which is consistent with the nominal value of contemporary atmospheric methane. These first results indicate that PIMS has the potential to be a valuable new analytical technique for screening the 14C content of biogas and in climate research studies.

We report the results of radiocarbon dating performed at the ETH laboratory on soft tissue of the mummified body found in September 1991 on the Hauslabjoch in the Ötztaler Alps (near the Similaun Mountain), South Tyrol. Over the past three decades, additional analyses of the sample, which had been stored frozen in a glass jar, have improved the precision of the first published radiocarbon ages. The frozen jar and the story of a mummified body found in the Alps fascinated visitors to the laboratory, mostly primary and high-school students. As part of educational projects, 11 samples were prepared and analyzed, yielding a combined radiocarbon age of 4525 ± 7 BP. This agreement with 4550 ± 27 BP, i.e., the very first results by Bonani et al. (1994), highlights the quality of the analysis performed decades ago. The combined age of all the 14C ages measured at the ETH laboratory is 4527 ± 7 BP.

A database of ca. 970 radiocarbon dates on bones, teeth, and tusks of the woolly mammoth (Mammuthus primigenius Blum.) from Siberia was created in order to understand the spatiotemporal distribution of this species over the last 50,000 14C years (BP). Mammoths populated all parts of Siberia until ca. 12,000 BP. After that, a few refugia exited south of ca. 60°N at ca. 10,600–12,000 BP, and in the northern part of mainland Siberia mammoths survived until ca. 9700 BP. At ca. 9500–3700 BP, they existed only in today’s insular regions such as the New Siberian Islands and Wrangel Island in the High Arctic. The relationship between the dynamics of mammoth populations and climatic fluctuations is complicated. In the warmer intervals (interstadials), the number of mammoths in Siberia was generally slightly larger than in the colder times (stadials); however, the difference is often not significant. The connection between the dynamics of mammoth populations and climatic fluctuations in Siberia is therefore complicated and non-linear.

We present a short database of the mole fraction of CO2 and 14CO2 in atmospheric air samples from an urban area in Gliwice, Silesia, Poland. The research covered a period from August 2023 to July 2024. A new laboratory air sampler stand was established to monitor carbon dioxide levels in Gliwice, giving the possibility to determine CO2 levels in the air using appropriate instruments to collect the air samples, extract CO2 from them, and thus measure carbon isotopes ratio 14C/12C. The analysis of the mole fraction of CO2 was determined using a low-cost system (CARBOCAP GMP343), while the carbon isotopes concentration was measured using MICADAS. The 14C in the air samples varied randomly from –55 to –24‰, while the monthly mole fraction of CO2 varied from 428 to 470 ppm. It has been also observed also that CO2 concentration is linked with the planetary boundary layer. The fraction of fossil of total CO2 has been estimated at the level of 2.5% during the investigated period of time. Another aim of this study was to investigate pine needles as 14C archives in a contemporary environment. The examination of the needles was based on the analysis of the similarities and differences in radiocarbon concentrations in pine needles of various ages collected in the middle of consecutive seasons, with 3 months resolution in Gliwice. The concentration of 14C in the needles was determined using a liquid scintillation counter. The mean F14C from all the samples was 99.80(70) pMC.

The date of the Thera eruption has been a subject of intense debate since the mid-20th century. In recent years, the disagreements have escalated with the introduction of IntCal20. The increased number of annual measurements around the time period of the eruption has highlighted potential fluctuations in the atmospheric radiocarbon record, shedding new light on the date of the disastrous event. The Centre for Isotope Research in Groningen has already contributed data from this time period to IntCal20, and here, we report a new set of annual data of approximately 90 radiocarbon measurements between 1660 and 1507 BCE. We investigate the potential anomalies in the calibration curve and compare our dataset with those from other leading laboratories. Although we do not find compelling evidence of any rapid increases in radiocarbon production during this period, the results do point to the presence of minor differences between datasets which could be species, region or laboratory pretreatment related. By quantifying such offsets, we assess their impact on chronological models related to the eruption of Thera.

Between 2021 and 2023, the Center for Applied Isotope Studies (CAIS) tested over 500 samples for biobased carbon content under the United States Department of Agriculture’s (USDA) Biopreferred Program using the American Society for Testing and Materials (ASTM) biobased testing standard D6866. We describe some of the novel approaches we used to prepare a diverse array of biobased products and summarize those radiocarbon test results and success rates in meeting the USDA Minimum Biobased Content (MBC).

The suitability of marine limpet shells for radiocarbon dating may depend on potential offsets due to diet and habitat, especially with regard to grazing mollusks on carbonate substrates (Dye 1994; England et al. 2013). A previous study on one grazing limpet species on the coast of Ireland found no offsets from carbonate substrates (Allen et al. 2019), but a similar study from mediterranean coasts found significant offsets on carbonate substrates (Ferguson et al. 2011). We carried out a new study of radiocarbon and stable carbon isotopes, using multiple species of mollusks collected live from the coasts of Gibraltar and Sardinia, from both carbonate and non-carbonate substrates. The 14C results indicate that one species, inhabiting the upper shore, has a significant offset at the carbonate locations. This species, Patella rustica, has adapted to tolerate desiccation and may have biological traits that result in higher metabolic-derived carbon incorporated in its shell. The results of this preliminary study imply that selected species of grazing mollusks are suitable for radiocarbon dating, even in areas of carbonate geology.

Welwitschia mirabilis, a unique gymnosperm native to Namibia and Angola, is a keystone plant species in the Namib Desert. It represents the only extremely long-lived non-clonal plant species occurring under hyperarid desert conditions, yet limited attempts have been made to accurately determine its age. Here, we present radiocarbon dates from a dead, sectioned Welwitschia of moderate size. We find the outer caudex tissue growth to progressively increase in age from the leaf base towards the ground level in this dwarf tree, while the inner cortex tissue becomes younger. Our sampling strategy revealed that the oldest tissue from this Welwitschia, found at the base of the caudex in the middle of the lobe, was dated to 531 ± 20 14C years, suggesting a vertical growth rate of approximately 0.47 to 0.67 mm/year. These findings can serve as a basis for future dating of larger, living individuals.

Radiocarbon dating by accelerator mass spectrometry (AMS) requires transforming samples into graphite, a step that typically depends on liquid nitrogen and high-purity carrier gases, increasing both cost and operational complexity. We present μGRAPHILINE, a fully automated, modular combustion–graphitization line that removes these dependencies by combining dual-zone combustion with iron–zinc reduction. Performance was evaluated on more than 180 standards and reference materials targets measured on two independent AMS systems. The μGRAPHILINE consistently achieved >90% graphitization yields, stable backgrounds of ∼0.24 pMC (≈48,500 BP), and sample throughput of ∼3.5 hours per target. Reliable operation was demonstrated for a broad sample-size range, from routine 1 mg C down to ∼0.2 mg C, with ion currents sufficient for precise AMS analysis. The system’s automation, modularity, and low memory effect support improved laboratory throughput and operator efficiency. These results indicate that μGRAPHILINE provides a robust and efficient approach to radiocarbon sample preparation with broad potential applications.

In Brazil, laws are being adopted prohibiting the use and distribution of non-recyclable plastic bags and encouraging the use of recyclable, biodegradable and bioplastic bags. However, there is no specific standard method in Brazil to inspect the carbon content of bioplastics. This work aims to implement the sample preparation for radiocarbon biogenic fraction determination in bioplastics in the new radiocarbon laboratory at the Federal University of Bahia (LAPA14C-UFBA). Six plastic samples from Brazilian markets with bio-based seals were collected in regular Brazilian markets, four bags and two tubes. All samples were combusted and graphitized in the LAPA14C-UFBA and the graphites were measured at the Radiocarbon Laboratory (LAC-UFF). The biogenic fraction analysis followed the Standard Test Methods for Determining the Biobased Content of Solid, Liquid, and Gaseous Samples Using Radiocarbon Analysis (ASTM D6866-24). Since the bioplastic manufactured in Brazil is derived from sugarcane, a C4 plant where δ13C values are different from those of petroleum-derived plastic, the biogenic fraction was obtained via the isotopic mixture equation. The results showed a robust direct correlation (r=0.998) between the fractions obtained by the two methods, indicating that δ13C analysis can be used, in this case, as an alternative in determining the biogenic fraction of plastics. From the results obtained, four out of the six samples analyzed showed biogenic fraction values below the 51% required by the I’m Green label, with values ranging from 4% to 43%, according to the δ3C and 14C analysis, showing the efficiency of both techniques in determining the biogenic fraction.

La Viña rock shelter is a relevant archaeological site for understanding the late Middle and Upper Palaeolithic cultural development in northern Iberia as evidenced by the Mousterian, Aurignacian, Gravettian, Solutrean and Magdalenian bone and lithic industries, parietal engravings and human subsistence remains recovered during the 1980s excavations by J. Fortea in the western and central excavation areas. This paper aims to present 16 new radiocarbon dates, which are added to the previous radiocarbon dates obtained, using different analytical methods on bone and charcoal. These are now 57 dates in total. Bayesian models have been applied to assess and discern the chronology of the archaeological sequence in each sector of the rock shelter. The results provide details on the chronostratigraphy of each excavation area, documenting the duration of the different technocultural phases and confirming in-site postdepositional events.

A large-scale outcrop was exposed along the newly constructed road access to the Kumamoto Earthquake Museum “KIOKU” (former Tokai University Aso Campus). Multiple layers of tephra and paleosols cover the Sawatsuno lava (27 ± 6 K-Ar ka) in this outcrop. Three (3) characteristic tephra layers: Kusasenrigahama Pumice (Kpfa: ca. 32.5 cal ka BP) from Kusasenrigahama crater in Aso caldera, Aira Tn (AT: ca. 30 cal ka BP) and Kikai Akahoya (K-Ah: ca. 7.3 cal ka BP) from southern Kyushu are intercalated between thick sandy volcanic ash layers erupted from the post-caldera volcanoes of Aso caldera. Thirteen (13) radiocarbon ages were obtained from soil samples and charcoal fragments. Among these, a sample just below AT shows a younger age, indicating that the upper soil/tephra sequence including AT, was re-deposited on ground surface at the time immediately after ca. 13.4 cal ka BP indicated by this age. This suggests that the duplicated sequence, confirmed by our detailed dating is a product of either near-surface hidden faulting or a small local landslide associated with one of the paleoseismic events similar to the 2016 Kumamoto Earthquake.

Iraya Volcano, situated at the northern tip of Batan Island in the Batanes group, marks the northernmost extent of the Philippine archipelago. Aside from the presence of accessible tephra deposits, the numerous archaeological sites on the island provide key insight into tephrochronology and volcanic hazard assessment. This paper presents stratigraphy and 21 radiocarbon ages of Holocene tephra layers distributed on the island. The eruption ages of the Holocene tephra are approximately 12.4 cal ka BP for Rolling Hills at the bottom, 4.5–4.9 cal ka BP for San Antonio, 2.1–2.5 cal ka BP for Mahatao, 1.6 cal ka BP for Basco, and 1.2–1.6 cal ka BP for Boulder Beach, with most of the tephra concentrated in the latter half of the Holocene. Artifacts excavated from Reydante Cabizon Property Site, San Antonio, Basco can be thought to date to around 4 to 2 cal ka BP, which is consistent with tephrochronology.

This work aims to clarify the absolute chronology of the construction phases of the St. Peter and Paul Rotunda at Budeč, focusing on the erection of the rotunda and the tower. Fifteen mortar samples were taken from various structural parts, two of which also contained remnants of charcoal. The mortar samples were mechanically treated to extract a purified calcitic binder that was dated by radiocarbon analysis. The effectiveness of the sample pretreatment methodology was assessed by means of cathodoluminescence microscopy. Thin sections of mortars were characterized by polarized light microscopy. The petrographic characterization allowed for the samples to be grouped according to their binder, aggregate, and structure. This was compared with the evaluation of the calibrated dates, expected chronology known from legends, as well as with formal and stylistic analyses of the structure. The radiocarbon dating distinguished the different construction phases well, and the accuracy and reliability of the dating is discussed. The presence of silts and clays probably led to geogenic carbon contamination of the samples from the foundations, as the obtained dates are older than expected. These dating results were thus regarded as inconclusive. However, the samples from the vaulted dome of the rotunda did not show any anomalies, and the calibrated date period obtained was regarded as relevant and thus successfully dated. The dating based on the legends also fits the determined interval.

Estimates of marine reservoir corrections (ΔR) in the southeastern Arabian Sea region are limited. To better constrain the region’s marine reservoir corrections, additional pre-bomb radiocarbon records are needed. In this context, a coral core from the Lakshadweep archipelago in the southeastern Arabian Sea has been analyzed to measure its radiocarbon content. Pre-bomb radiocarbon values from the coral record are used to estimate the marine reservoir correction value of the region. The mean ΔR value of the Lakshadweep region is calculated to be –128 ± 130 yr. The comparison of available ΔR values from the Arabian Sea region shows that the mean ΔR value of the eastern Arabian Sea is significantly lower than that of the northern and western Arabian Sea. The low ΔR values from the eastern Arabian Sea likely indicate the influence of relatively 14C-enriched Bay of Bengal water in the region.

The study provides a radiocarbon sequence for the Iron Age occupation in the elevated areas of the Phoenician settlement of Lisbon, located in the Tagus estuary (Portugal). The dataset is based in ten animal and human samples recovered during archaeological excavations at Largo de Santa Cruz do Castelo. These samples are associated with distinct phases of the Iron Age, dated by the ceramic findings between the 7th and 5th century BCE, as well as a latter sample from the Roman Republican Period (2nd half of the 2nd century BCE). Despite the challenges posed by the 1st millennium BCE radiocarbon calibration, this dataset proves valuable for establishing a more detailed chronological framework. It represents a significant contribution to refining the timeline of Lisbon’s Iron Age settlement and provides a stronger basis for interpreting local developments within the broader regional context.

Archaeological investigations in the Prut-Dniester region during the Roman Imperial Period have yielded numerous Sarmatian culture necropolises and isolated graves. Establishing a precise chronology for these remains has long been a challenge due to the limitations of typological dating alone. This study integrates radiocarbon (14C) analysis of 11 human bone samples from selected funerary contexts with traditional typological methods, refining the chronological framework of the Sarmatian culture in this region. The radiocarbon analyses were subjected to Bayesian modeling, which allowed for the delineation of these samples into distinct phases, thereby adjusting and improving the periodization established through traditional methods. The results not only confirm but also refine previously established chronologies, offering deeper insights into the cultural, social, and economic dynamics of Sarmatian communities in the Prut-Dniester Barbaricum. These findings represent a significant contribution to the broader understanding of the Roman Imperial Period beyond the Eastern Limes.

Quantifying marine reservoir effects (MREs) across time and space is crucial for establishing accurate archaeological chronologies, including the activities of past hominines. Although the northern Iberian Peninsula shows a high density of Upper Paleolithic sites and marine shells are frequently found in these assemblages, quantification of MREs in this coastal region remains limited. We performed Bayesian modeling of radiocarbon measurements from both terrestrial (Capra pyrenaica, Cervus elaphus and other herbivores unidentified at species level) and marine (Littorina littorea Linnaeus, 1758 and Patella vulgata Linnaeus, 1758 taxa) archaeological samples recovered from the Tito Bustillo cave (Asturias, Spain) in order to determine the ΔR values for northern Iberia during the Lower Magdalenian period (ca. 20–17 ka cal BP). For the time span between 18.6 and 18.2 ka cal BP we estimated ΔR values of –298±44 14C yr and –495±122 14C yr for the periwinkle L. littorea and the common limpet P. vulgata, respectively. This finding has significant implications for future archaeological research in the northern Iberian Peninsula, as researchers must apply distinct ΔR values depending on the mollusk species selected for radiocarbon dating. Furthermore, the consistency between our calculated ΔR value for P. vulgata and previously recorded data for the same taxon from a neighboring coastal region (Cantabria, Spain) suggests remarkable stability in the marine environment of this area during the Lower Magdalenian period.