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Shallow firn cores, in addition to a near-basal ice core, were recovered in 2018 from the Quelccaya ice cap (5470 m a.s.l) in the Cordillera Vilcanota, Peru, and in 2017 from the Nevado Illimani glacier (6350 m a.s.l) in the Cordillera Real, Bolivia. The two sites are ~450 km apart. Despite meltwater percolation resulting from warming, particle-based trace element records (e.g. Fe, Mg, K) in the Quelccaya and Illimani shallow cores retain well-preserved signals. The firn core chronologies, established independently by annual layer counting, show a convincing overlap indicating the two records contain comparable signals and therefore capture similar regional scale climatology. Trace element records at a ~1–4 cm resolution provide past records of anthropogenic emissions, dust sources, volcanic emissions, evaporite salts and marine-sourced air masses. Using novel ultra-high-resolution (120 μm) laser technology, we identify annual layer thicknesses ranging from 0.3 to 0.8 cm in a section of 2000-year-old radiocarbon-dated near-basal ice which compared to the previous annual layer estimates suggests that Quelccaya ice cores drilled to bedrock may be older than previously suggested by depth-age models. With the information collected from this study in combination with past studies, we emphasize the importance of collecting new surface-to-bedrock ice cores from at least the Quelccaya ice cap, in particular, due to its projected disappearance as soon as the 2050s. [ABSTRACT FROM AUTHOR]

Net accumulation records derived from alpine ice cores provide the most direct measurement of past precipitation. However, quantitative reconstruction of accumulation for past millennia remains challenging due to the difficulty in identifying annual layers in the deeper sections of ice cores. In this study, we propose a quantitative method to reconstruct annual accumulation from alpine ice cores for past millennia, using as an example an ice core drilled at the Chongce ice cap in the northwestern Tibetan Plateau (TP). First, we used laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) technology to develop ultra-high-resolution trace element records in three sections of the ice core and identified annual layers in each section based on seasonality of these elements. Second, based on nine 14 C ages determined for this ice core, we applied a two-parameter flow model to established the thinning parameter of this ice core. Finally, we converted the thickness of annual layers in the three sample sections to past accumulation rates based on the thinning parameter derived from the ice flow model. Our results show that the mean annual accumulation rates for the three sample sections are 109 mm yr -1 (2511–2541 years BP), 74 mm yr -1 (1682–1697 years BP), and 68 mm yr -1 (781–789 years BP), respectively. For comparison, the Holocene mean precipitation is 103 mm yr -1. This method has the potential to reconstruct continuous high-resolution precipitation records covering millennia or even longer time periods. [ABSTRACT FROM AUTHOR]

Mountain glacier systems are decreasing in volume worldwide yet relatively little is known about their upper reaches (>5000 m). Here we show, based on the world's highest ice core and highest automatic weather stations, the significant and increasing role that melting and sublimation have on the mass loss of even Mt. Everest's highest glacier (South Col Glacier, 8020 m). Estimated contemporary thinning rates approaching ~2 m a−1 water equivalent (w.e.) indicate several decades of accumulation may be lost on an annual basis now that glacier ice has been exposed. These results identify extreme sensitivity to glacier surface type for high altitude Himalayan ice masses and forewarn of rapidly emerging impacts as Mt. Everest's highest glacier appears destined for rapid retreat. [ABSTRACT FROM AUTHOR]

A deeper understanding of past atmospheric circulation variability in the Central Andes is a high-priority topic in paleoclimatology mainly because of the necessity to validate climate models used to predict future precipitation trends and to develop mitigation and/or adaptation strategies for future climate change scenarios in this region. Within this context, we here investigate an 18-year firn core drilled at Nevado Illimani in order to interpret its mineral dust record in relation to seasonal processes, in particular atmospheric circulation and deep convection. The core was dated by annual layer counting based on seasonal oscillations of dust, calcium, and stable isotopes. Geochemical and mineralogical data show that dust is regionally sourced in winter and summer. During austral summer (wet season), an increase in the relative proportion of giant dust particles (∅>20 µm) is observed, in association with oscillations of stable isotope records (δ D, δ18 O). It seems that at Nevado Illimani both the deposition of dust and the isotopic signature of precipitation are influenced by atmospheric deep convection, which is also related to the total amount of precipitation in the area. This hypothesis is corroborated by regional meteorological data. The interpretation of giant particle and stable isotope records suggests that downdrafts due to convective activity promote turbulent conditions capable of suspending giant particles in the vicinity of Nevado Illimani. Giant particles and stable isotopes, when considered together, can be therefore used as a new proxy for obtaining information about deep convective activity in the past. [ABSTRACT FROM AUTHOR]

The H1N1 "Spanish influenza" pandemic of 1918–1919 caused the highest known number of deaths recorded for a single pandemic in human history. Several theories have been offered to explain the virulence and spread of the disease, but the environmental context remains underexamined. In this study, we present a new environmental record from a European, Alpine ice core, showing a significant climate anomaly that affected the continent from 1914 to 1919. Incessant torrential rain and declining temperatures increased casualties in the battlefields of World War I (WWI), setting the stage for the spread of the pandemic at the end of the conflict. Multiple independent records of temperature, precipitation, and mortality corroborate these findings. Plain Language Summary: A new, high‐resolution climate record from Europe shows a once‐in‐a‐century climate anomaly that occurred during the years of World War I and the Spanish flu pandemic. Mortality data from all causes show increases in times of worsening weather, precipitation, and temperatures, a factor in many of the major battles of WWI, as well as a possible exacerbating factor for the virulence of the pandemic. Key Points: Novel, high‐resolution climate record from Europe shows strong influx of marine air in a 1914–1918 climate anomaly unmatched in 100 yearsIndependent precipitation, temperature, and historical records corroborate the timing and extent of the anomalyHistorical and epidemiological records indicate that this climate anomaly affected the mortality in WWI as well as the "Spanish flu" pandemic [ABSTRACT FROM AUTHOR]

Dust events originating from the Saharan desert have far‐reaching environmental impacts, but the causal mechanism of magnitude and occurrence of Saharan dust events (SDEs) during the preinstrumental era requires further research, particularly as a potential analog for future climate. Using an ultrahigh resolution glacio‐chemical record from the 2013 Colle Gnifetti ice core drilled in the Swiss‐Italian Alps, we reconstructed a 2000‐year‐long summer Saharan dust record. We analyzed both modern (1780–2006) and premodern Common Era (CE) major and trace element records to determine air mass source regions to the Colle Gnifetti glacier and assess similarities to modern and reconstructed climate trends in the Northern Hemisphere. This new proxy SDE reconstruction, produced using measurements from a novel, continuous ultrahigh‐resolution (120‐μm) ice core analysis method (laser ablation‐inductively coupled plasma‐mass spectrometer) is comprised of 316,000 data points per element covering the period 1–1820 CE. We found that the Colle Gnifetti ice core captures an anomalous increase in Saharan dust transport during the onset of the Medieval Climate Anomaly (870–1000 CE) and records other prominent shorter events (CE, 140–170, 370–450, 1320–1370, and 1910–2000), offering a framework for new insights into the implications of Saharan dust variability. Plain Language Summary: Plumes of dust from the Saharan desert transported across the Atlantic Ocean and Mediterranean Sea, influence land, ocean, and atmospheric systems, yet we know relatively little about how these events varied before the instrumental record. Saharan dust transport can result in flourishing ecosystems, poor air quality, and even changes in the frequency of North Atlantic hurricanes. In our study, we develop a summer Saharan dust event record with subannual resolution from an ice core drilled in the European Alps, dating back 2000 years. The Saharan dust record shows increased dust transport is caused by a combination of enhanced high‐pressure systems over the Mediterranean and drier conditions in Northern Africa, along with other atmospheric influences. Our record indicates the past century has seen an increased amount of Saharan dust transport, comparable to large occurrences over the past 2000 years. Additionally, we discuss implications for using our subannually resolved Saharan dust record in concert with historical records to improve interpretations of human‐climate interactions. Key Points: A well‐dated Saharan dust record, spanning 1–2006 CE, was produced using chemical analysis of an ice core from the Swiss‐Italian AlpsUse of a novel, nondestructive laser ablation sampling system on ice reveals subannual resolution of dust transport to the European AlpsThe tenth century is characterized by continuous, large Saharan dust events, providing evidence for drier conditions in Northern Africa [ABSTRACT FROM AUTHOR]

Abstract: 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. [ABSTRACT FROM AUTHOR]