ALBERT

Description: This julia package implements various tools for working with simple, non-marked, one dimensional point processes. In special it implements a bootstrap-based goodness-of-fit test for parametric models.

Description: Europe’s recent summer droughts have had devastating ecological and economic consequences, but the severity and cause of these extremes remain unclear. Here we present 27,080 annually resolved and absolutely dated measurements of tree-ring stable carbon and oxygen (δ13C and δ18O) isotopes from 21 living and 126 relict oaks (Quercus spp.) used to reconstruct central European summer hydroclimate from 75 BCE to 2018 CE. We find that the combined inverse δ13C and δ18O values correlate with the June–August Palmer Drought Severity Index from 1901–2018 at 0.73 (P 〈 0.001). Pluvials around 200, 720 and 1100 CE, and droughts around 40, 590, 950 and 1510 CE and in the twenty-first century, are superimposed on a multi-millennial drying trend. Our reconstruction demonstrates that the sequence of recent European summer droughts since 2015 CE is unprecedented in the past 2,110 years. This hydroclimatic anomaly is probably caused by anthropogenic warming and associated changes in the position of the summer jet stream.

Description: Observations of spatio-temporal variability of the deep ocean are rare and little is known about occurrence of deep ocean mesoscale dynamics. Here, we make use of 2.5 years of time series data from three distributed sensor arrays, which acquired high-resolution temperature, pressure and sound speed data of the bottom layer offshore northern Chile. Estimating salinity and density from the direct observations enable access to the full spectrum of hydrographic variability from a multi-hourly to annual time scale and with average inter-station distances of less than 1 km. Analyses revealed interannual warming over the continental slope of 0.002 °C yr−1–0.003 °C yr−1, and could trace periodic hydrographic anomalies, likely related to coastal-trapped waves, as far as to the lower continental slope. A concurrent change in the shape of the warm anomalies and the rate of deep-sea warming that occurs with the crossing of the deep-sea trench suggests that the abyssal part of the eastern boundary current system off Chile does not extend past the deep sea trench. Furthermore, the comparison of anomaly timing and shape in between stations implies southwards flow over the mid to lower continental slope, centred closer to the trench.

Description: Phytoplankton forms the base of the marine food web by transforming CO2 into organic carbon via photosynthesis. Some of the organic carbon is then transferred through the food web and exported into the deep ocean, a process known as the biological carbon pump. Despite the importance of phytoplankton for marine ecosystems and the global carbon cycle, projections of phytoplankton biomass in response to climate change differ strongly across Earth system models, illustrating uncertainty in our understanding of the underlying processes. Differences are especially large in the Southern Ocean, a region that is notoriously difficult to represent in models. Here, we argue that water column-integrated phytoplankton biomass in the Southern Ocean is projected to largely remain unchanged under climate change by the CMIP6 multi-model ensemble because of a shifting balance of bottom-up and top-down processes driven by a shoaling mixed layer depth. A shallower mixed layer is projected to improve growth conditions and consequently weaken bottom-up control. In addition to enhanced phytoplankton growth, the shoaling of the mixed layer also compresses phytoplankton closer to the surface and promotes zooplankton grazing efficiency, thus intensifying top-down control. Overall, our results suggest that while changes in bottom-up conditions stimulate enhanced growth, intensified top-down control opposes an increase in phytoplankton and becomes increasingly important for phytoplankton response under climate change in the Southern Ocean.

Description: We evaluated how ranges of four endemic and non-endemic aquatic ostracode species changed in response to long-term (glacial–interglacial cycles) and abrupt climate fluctuations during the last 155 kyr in the northern Neotropical region. We employed two complementary approaches, fossil records and species distribution models (SDMs). Fossil assemblages were obtained from sediment cores PI-1, PI-2, PI-6 and Petén-Itzá 22-VIII-99 from the Petén Itzá Scientific Drilling Project, Lake Petén Itzá, Guatemala. To obtain a spatially resolved pattern of (past) species distribution, a downscaling cascade is employed. SDMs were reconstructed for the last interglacial (∼120 ka), the last glacial maximum (∼22 ka) and the middle Holocene (∼6 ka). During glacial and interglacial cycles and marine isotope stages (MISs), modelled paleo-distributions and paleo-records show the nearly continuous presence of endemic and non-endemic species in the region, suggesting negligible effects of long-term climate variations on aquatic niche stability. During periods of abrupt ecological disruption such as Heinrich Stadial 1 (HS1), endemic species were resilient, remaining within their current areas of distribution. Non-endemic species, however, proved to be more sensitive. Modelled paleo-distributions suggest that the geographic range of non-endemic species changed, moving southward into Central America. Due to the uncertainties involved in the downscaling from the global numerical to the highly resolved regional geospatial statistical modelling, results can be seen as a benchmark for future studies using similar approaches. Given relatively moderate temperature decreases in Lake Petén Itzá waters (∼5 ∘C) and the persistence of some aquatic ecosystems even during periods of severe drying in HS1, our data suggest (1) the existence of micro-refugia and/or (2) continuous interaction between central metapopulations and surrounding populations, enabling aquatic taxa to survive climate fluctuations in the northern Neotropical region.

Description: Highlights • Investigation into the potential of Porites microatolls for SST reconstruction. • Comparison between recent and more conventional coral paleoclimatology methods. • Application of Srsingle bondU and Li/Mg paleothermometer. • Accuracy and reproducibility of Sr/Ca proved to be the most suitable proxy for SST reconstruction. Abstract Massive dome-shaped coral Porites are the predominant choice for paleoclimate studies due to their consistent and reliable growth. When growing close to sea level, they become limited in their vertical growth and form so-called ‘microatolls’. Microatolls have not yet been extensively explored for paleoclimate reconstruction. Here, we investigate how reliable modern Porites microatolls are against empirical sea-surface temperature using Sr/Ca, δ18O, Li/Mg and Srsingle bondU paleothermometry methods on samples from the Society Islands, French Polynesia. Our results show Sr/Ca ratios have the lowest Standard Error of the Inverse Prediction (SEIP) at 0.415 °C (N = 41) with a calibration of Sr/Ca (mmol mol−1) = −0.082 ± 0.006 SST (°C) + 11.256 ± 0.170 and with high reproducibility across multiple corals. The reproducibility of δ18O was less good, with SEIP increasing to 0.829 °C (N = 41). Considering methods directly from the literature, Li/Mg ratio empirically corrected for Sr/Ca had the best balance between bias and precision where no local calibration could be available. This study independently evaluates and confirms the suitability of Porites microatolls from well-flushed environments for paleoclimate studies. Fossil dome-shaped Porites grow anywhere between near-surface and roughly 20 m depths which inherently incorporates uncertainty into any sea surface temperature reconstruction. This uncertainty is significantly reduced for microatolls due to their well-constrained bathymetry. The study represents a fundamental step in paleoclimate research targeting consistently near the water-air interface bringing reliability and, especially when combined with their ability to reconstruct past sea-level changes, microatolls have the potential to be central for future paleoenvironmental studies.

Description: After a successful conquest of large parts of Syria in 1258 and 1259 CE, the Mongol army lost the battle of 'Ayn Jālūt against Mamluks on September 3, 1260 CE. Recognized as a turning point in world history, their sudden defeat triggered the reconfiguration of strategic alliances and geopolitical power not only in the Middle East, but also across much of Eurasia. Despite decades of research, scholars have not yet reached consensus over the causes of the Mongol reverse. Here, we revisit previous arguments in light of climate and environmental changes in the aftermath of one the largest volcanic forcings in the past 2500 years, the Samalas eruption ~1257 CE. Regional tree ring-based climate reconstructions and state-of-the-art Earth System Model simulations reveal cooler and wetter conditions from spring 1258 to autumn 1259 CE for the eastern Mediterranean/Arabian region. We therefore hypothesize that the post-Samalas climate anomaly and associated environmental variability affected an estimated 120,000 Mongol soldiers and up to half a million of their horses during the conquest. More specifically, we argue that colder and wetter climates in 1258 and 1259 CE, while complicating and slowing the campaign in certain areas, such as the mountainous regions in the Caucasus and Anatolia, also facilitated the assault on Syria between January and March 1260. A return to warmer and dryer conditions in the summer of 1260 CE, however, likely reduced the regional carrying capacity and may therefore have forced a mass withdrawal of the Mongols from the region that contributed to the Mamluks’ victory. In pointing to a distinct environmental dependency of the Mongols, we offer a new explanation of their defeat at 'Ayn Jālūt, which effectively halted the further expansion of the largest ever land-based empire.

Description: Social-ecological transformation has become an important concept in the face of profound planetary crises (loss of biodiversity, climate crisis). Recently, the needs for social scientific transformation research have become more clearly defined. We reflect on the role of the social sciences and the humanities in democratically shaping social transformation in interaction with other sectors of society. Finally, we sketch three examples that illustrate the kind of new methodological and institutional approaches to be pursued.

Description: Some forty years ago, the UN Convention on the Law of the Sea 1982 (UNCLOS) created an unusual regime for states to collectively manage common natural resources on the international seabed beyond national jurisdiction (known as the Area) through the International Seabed Authority (ISA). In the intervening years, scientists have increasingly been warning about the serious environmental risks of mining seabed minerals. At this pivotal point in time, when states are negotiating whether or not to allow seabed mining, this essay explores the risk of undermining by mining, that is, contravening international marine environmental law and the obligations and responsibilities of states thereunder by allowing commercial mining activities to commence. We argue that allowing seabed mining in the Area at this juncture, when so much about the deep ocean remains unknown, would risk frustrating a host of measures, achievements, and progress to enhance marine environmental protection, particularly in areas beyond national jurisdiction. We begin with an overview of the ISA and its work to date, before discussing potential interactions between seabed mining and marine environmental law and policies, with a particular focus on the new ocean biodiversity agreement. We conclude by urging states to take cognizance of their overarching duty to protect and preserve the marine environment and ensure that all decisions taken with respect to seabed mining are consistent with their obligations and responsibilities under international law.