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Here, we present direct measurements of atmospheric composition and Antarctic climate from the mid-Pleistocene (∼1 Ma) from ice cores drilled in the Allan Hills blue ice area, Antarctica. The 1-Ma ice is dated from the deficit in ⁴⁰Ar relative to the modern atmosphere and is present as a stratigraphically disturbed 12-m section at the base of a 126-m ice core. The 1-Ma ice appears to represent most of the amplitude of contemporaneous climate cycles and CO ₂ and CH ₄ concentrations in the ice range from 221 to 277 ppm and 411 to 569 parts per billion (ppb), respectively. These concentrations, together with measured δD of the ice, are at the warm end of the field for glacial–interglacial cycles of the last 800 ky and span only about one-half of the range. The highest CO ₂ values in the 1-Ma ice fall within the range of interglacial values of the last 400 ka but are up to 7 ppm higher than any interglacial values between 450 and 800 ka. The lowest CO ₂ values are 30 ppm higher than during any glacial period between 450 and 800 ka. This study shows that the coupling of Antarctic temperature and atmospheric CO ₂ extended into the mid-Pleistocene and demonstrates the feasibility of discontinuously extending the current ice core record beyond 800 ka by shallow coring in Antarctic blue ice areas. Significance Bubbles of ancient air trapped in ice cores permit the direct reconstruction of atmospheric composition and allow us to link greenhouse gases and global climate over the last 800 ky. Here, we present new ice core records of atmospheric composition roughly 1 Ma from a shallow ice core drilled in the Allan Hills blue ice area, Antarctica. These records confirm that interglacial CO ₂ concentrations decreased by 800 ka. They also show that the link between CO ₂ and Antarctic temperature extended into the warmer world of the mid-Pleistocene.

Contrary to widespread assumptions, next‐generation high (annual to multiannual) and ultra‐high (subannual) resolution analyses of an Alpine glacier reveal that true historical minimum natural levels of lead in the atmosphere occurred only once in the last ~2000 years. During the Black Death pandemic, demographic and economic collapse interrupted metal production and atmospheric lead dropped to undetectable levels. This finding challenges current government and industry understanding of preindustrial lead pollution and its potential implications for human health of children and adults worldwide. Available technology and geographic location have limited previous ice core investigations. We provide new high‐ (discrete, inductively coupled plasma mass spectrometry, ICP‐MS) and ultra‐high resolution (laser ablation inductively coupled plasma mass spectrometry, LA‐ICP‐MS) records of atmospheric lead deposition extracted from the high Alpine glacier Colle Gnifetti, in the Swiss‐Italian Alps. We show that contrary to the conventional wisdom, low levels at or approaching natural background occurred only in a single 4 year period in ~2000 years documented in the new ice core, during the Black Death (~1349–1353 C.E.), the most devastating pandemic in Eurasian history. Ultra‐high chronological resolution allows for the first time detailed and decisive comparison of the new glaciochemical data with historical records. Historical evidence shows that mining activity ceased upwind of the core site from ~1349 to 1353, while concurrently on the glacier lead (Pb) concentrations—dated by layer counting confirmed by radiocarbon dating—dropped to levels below detection, an order of magnitude beneath figures deemed low in earlier studies. Previous assumptions about preindustrial “natural” background lead levels in the atmosphere—and potential impacts on humans—have been misleading, with significant implications for current environmental, industrial, and public health policy, as well as for the history of human lead exposure. Trans‐disciplinary application of this new technology opens the door to new approaches to the study of the anthropogenic impact on past and present human health. Plain Language Summary Current policies to reduce lead pollution in the air are based on the assumption that preindustrial levels of lead in the air were negligible, safe, or nonexistent. This trans‐disciplinary article shows that this is not the case, using next‐generation laser technology in climate science, in combination with detailed historical and archaeological records in as many as seven languages from all over Europe. We show that lead levels in the air have been elevated for the past 2000 years, except for a single 4 year period. This 4 year period corresponds with the largest pandemic ever to ravage Western Europe (the Black Death), resulting in a 40–50% reduction in population and interruption mining and smelting of lead in the European continent. This unprecedented population collapse and severe economic decline halted lead mining and smelting and related emissions of lead in the air. This trans‐disciplinary study is a collaboration between the Initiative for the Science of the Human Past at Harvard University and the Climate Change Institute at the University of Maine. It uses next‐generation technology and expertise in history, climate science, archaeology, and toxicology, brought to bear in a highly detailed contribution to planetary health, with crucial implications for public health and environmental policy, and the history of human exposure to lead. Key Points Preindustrial, atmospheric lead (Pb) levels have been grossly underestimated, with significant implications for human health and development Overwhelming historical evidence shows that catastrophic demographic collapse caused atmospheric Pb to plummet to natural levels only once in the last ~2000 years Next‐generation ice core analysis by laser ablation inductively coupled plasma mass spectrometry allows for the first time an ultra‐high resolution (subannual) record of Pb deposition

Understanding the context from which evidence emerges is of paramount importance in reaching robust conclusions in scientific inquiries. This is as true of the present as it is of the past. In a trans‐disciplinary study such as More et al. (2017, https://doi.org/10.1002/2017GH000064) and many others appearing in this and similar journals, a proper analysis of context demands the use of historical evidence. This includes demographic, epidemiological, and socio‐economic data—common in many studies of the impact of anthropogenic pollution on human health—and, as in this specific case, also geoarchaeological evidence. These records anchor climate and pollution data in the geographic and human circumstances of history, without which we lose a fundamental understanding of the data itself. This article addresses Hinkley (2018, https://doi.org/10.1002/2018GH000105) by highlighting the importance of context, focusing on the historical and archaeological evidence, and then discussing atmospheric deposition and circulation in the specific region of our study. Since many of the assertions in Bindler (2018, https://doi.org/10.1002/2018GH000135) are congruent with our findings and directly contradict Hinkley (2018), this reply refers to Bindler (2018), whenever appropriate, and indicates where our evidence diverges. Plain Language Summary This article highlights the crucial importance of historical and archaeoscientific data in trans‐disciplinary studies of planetary health, in the form of a reply to two comments to a previous article (More et al., 2017, https://doi.org/10.1002/2017GH000064). This reply emphasizes the crucial importance of geographic and historical context in assessing the significance and reach of scientific findings. The article also showcases the growing role of “Big‐Data” scale data sets of demographic, epidemiological, and historical records for understanding how past pollution and climate data affected populations, especially when cutting‐edge methods (e.g., laser ablation inductively coupled plasma mass spectrometry) in climate science provide an ever more detailed chronology of past crises and long‐term pollution trends. Key Points Historical and archaeological evidence and context are crucially important in understanding past health, climate, and pollution data Geographic context and proximity to sources of lead (Pb) mining and smelting have a significant impact on the ice core record

The seventh-century AD switch from gold to silver currencies transformed the socio-economic landscape of North-west Europe. The source of silver, however, has proven elusive. Recent research, integrating ice-core data from the Colle Gnifetti drill site in the Swiss Alps, geoarchaeological records and numismatic and historical data, has provided new evidence for this transformation. Annual ice-core resolution data are combined with lead pollution analysis to demonstrate that significant new silver mining facilitated the change to silver coinage, and dates the introduction of such coinage to c. AD 660. Archaeological evidence and atmospheric modelling of lead pollution locates the probable source of the silver to mines at Melle, in France.

The S27 ice core, drilled in the Allan Hills Blue Ice Area of East Antarctica, is located in southern Victoria Land, ∼80 km away from the present-day northern edge of the Ross Ice Shelf. Here, we utilize the reconstructed accumulation rate of S27 covering the Last Interglacial (LIG) period between 129 ka and 116 ka (where ka indicates thousands of years before present) to infer moisture transport into the region. The accumulation rate is based on the ice-age–gas-age differences calculated from the ice chronology, which is constrained by the stable water isotopes of the ice, and an improved gas chronology based on measurements of oxygen isotopes of O2 in the trapped gases. The peak accumulation rate in S27 occurred at 128.2 ka, near the peak LIG warming in Antarctica. Even the most conservative estimate yields an order-of-magnitude increase in the accumulation rate during the LIG maximum, whereas other Antarctic ice cores are typically characterized by a glacial–interglacial difference of a factor of 2 to 3. While part of the increase in S27 accumulation rates must originate from changes in the large-scale atmospheric circulation, additional mechanisms are needed to explain the large changes. We hypothesize that the exceptionally high snow accumulation recorded in S27 reflects open-ocean conditions in the Ross Sea, created by reduced sea ice extent and increased polynya size and perhaps by a southward retreat of the Ross Ice Shelf relative to its present-day position near the onset of the LIG. The proposed ice shelf retreat would also be compatible with a sea-level high stand around 129 ka significantly sourced from West Antarctica. The peak in S27 accumulation rates is transient, suggesting that if the Ross Ice Shelf had indeed retreated during the early LIG, it would have re-advanced by 125 ka.

High-resolution analysis of the ice core from Colle Gnifetti, Switzerland, allows yearly and sub-annual measurement of pollution for the period of highest lead production in the European Middle Ages, c . AD 1170–1220. Here, the authors use atmospheric circulation analysis and other geoarchaeological records to establish that Britain was the principal source of that lead pollution. The comparison of annual lead deposition at Colle Gnifetti displays a strong similarity to trends in lead production documented in the English historical accounts. This research provides unique new insight into the yearly political economy and environmental impact of the Angevin Empire of Kings Henry II, Richard the Lionheart and John.

The ice flow, stable water isotopic composition, and glaciochemistry of ice within the Allan Hills Blue Ice Area (AH BIA), Antarctica, is investigated to determine its potential for contributing to and extending the currently available 800 ka ice core record of paleoclimate. The investigation began with a study of ice dynamics within the AH BIA. The horizontal (u ) and vertical (ż) ice velocities, determined using high-precision GPS measurements, are 1.5 to 50 (+0.12) cm a–1 and 2-3 (±0.50) cm a–1, respectively. The significant positive ż and low u verify that old ice is present at the surface. Surface topography, in combination with u, was used to delineate a flowline (A-B) along which ice of continuous age was collected for the next stage of the investigation. Surface ice was recovered along 5 km of A-B and a 225 meter core was drilled at its midpoint. Ice samples were analyzed for stable isotopes of water (δD, δ 18O), which are common proxies for temperature. The resulting profiles exhibit variability consistent with the magnitude of glacial-interglacial transitions in East Antarctica. These variations, in combination with 40Aratm, and δ18O atm constrain the age of sampled ice to 90-250 ka. However, the 100 meters of directly above bedrock was not collected and the bottom depth is calculated to be at least 400 ka. The final phase of the investigation involved determining the concentrations of terrestrial and marine chemical species in ice from multiple points along A-B. Concentrations ranged from pg L–1 level for rare earth elements to µg L –1 level for multi-sourced compounds like sulfate. The concentrations of all analytes were anti-correlated with stable water isotope values indicating they had preserved a record of changes in atmospheric circulation, source strength, and continental aridity. The composition of rare earth elements points to Australia as an important interglacial dust source, while molar ratios of major ions, particularly Ca2+:C1– and Mg2+:C1–, suggest that transport pathways through the McMurdo Dry Valleys cannot be disregarded. In summary, the data collected suggest that ice within the AH BIA is stratigraphically conformable, is older than that recovered in surrounding regions and does contain a well-preserved environmental record.

The Mars 2020 Perseverance rover landing site is located within Jezero crater, a  ∼ 50 km diameter impact crater interpreted to be a Noachian-aged lake basin inside the western edge of the Isidis impact structure. Jezero hosts remnants of a fluvial delta, inlet and outlet valleys, and infill deposits containing diverse carbonate, mafic, and hydrated minerals. Prior to the launch of the Mars 2020 mission, members of the Science Team collaborated to produce a photogeologic map of the Perseverance landing site in Jezero crater. Mapping was performed at a 1:5000 digital map scale using a 25 cm/pixel High Resolution Imaging Science Experiment (HiRISE) orthoimage mosaic base map and a 1 m/pixel HiRISE stereo digital terrain model. Mapped bedrock and surficial units were distinguished by differences in relative brightness, tone, topography, surface texture, and apparent roughness. Mapped bedrock units are generally consistent with those identified in previously published mapping efforts, but this study’s map includes the distribution of surficial deposits and sub-units of the Jezero delta at a higher level of detail than previous studies. This study considers four possible unit correlations to explain the relative age relationships of major units within the map area. Unit correlations include previously published interpretations as well as those that consider more complex interfingering relationships and alternative relative age relationships. The photogeologic map presented here is the foundation for scientific hypothesis development and strategic planning for Perseverance’s exploration of Jezero crater.

Background. Reachers are common assistive devices prescribed to help individuals carry out their day-to day activities. Purpose. The purpose of this study was to examine the effect of muscle activity in the arm and forearm when using two commercially available reachers of different lengths. Method. Fifteen women between the ages of 23 and 25 performed a reaching activity that simulated moving a soup can from a cupboard to a counter. Surface electromyography was used to measure the muscle activity in the arm and forearm and to gain an understanding of the relative contributions of different muscles when using the short-handled reach in comparison to the long-handled reacher. Result. The results showed no significant differences between the short and the long reacher conditions for any of the muscles investigated. Practice Implications. The length of a reacher does not necessarily affect the amount of muscle strength required in some muscles and may not be a major factor in the therapist's choice of reacher length.