A 200-year 210Pb record from Greenland

A continuous profile of 210Pb activity extending back to 1766 has been developed for a firn/ice core collected at Site D in central Greenland in 1984. Unexpectedly high activities of 210Pb were found at the base of this core (0.032 pCi kg−1 in samples more than 200 years old), calling into question the common assumption that supported 210Pb can be neglected when constructing chronologies in glacial snow and ice. It is problematic to assert that all of the 210Pb measured at depth should be attributed to the supported fraction, given previous estimates of dust loading in Greenland ice cores. However, even if an estimated constant value of 0.032 pCi supported210Pb kg−1 is subtracted from the measured values to estimate excess 210Pb, the 210Pb chronology for Site D yields ages that are significantly younger (mean accumulation rate too high) than an independent depth-age scale based on annual layer counting. It is apparent that the flux of excess and/or supported 210Pb to this site must have decreased over the past 2 centuries, with decreasing trends in both fractions most likely. Previously published 210Pb profiles for cores from Summit and Dye 3, Greenland, show similar trends, which had been interpreted as decreasing fluxes of excess 210Pb only. For all three sites, it is not possible to separate variations in the fluxes of the excess and supported fractions of 210Pb, but variations in the total 210Pb flux will impact 210Pb-based chronologies generally if these variations have not been restricted to the Greenland ice sheet

The spatial variation of Asian dust and marine aerosol contributions to glaciochemical signals in central Asia

Short-term (6 months to 17 years) glaciochemical records have been collected from several glacier basins in the mountains of central Asia. The spatial distribution of snow chemistry in central Asia is controlled by the influx of dust from the large expanse of arid and semiarid regions in central Asia. Glaciers in the Northern and Western Tibetan Plateau show elevated concentrations and elevated annual fluxes of calcium, sodium, chloride, sulphate and nitrate due to the influx of desert dust from nearby arid and semi-arid regions. Glaciers in the Southeastern Tibetan Plateau show lower concentrations and lower annual fluxes of major ions due to longer transport distances of dust from the arid and semi-arid regions of Western China. Snow from the Karakoram and Western Himalaya show ion concentrations similar to those in Southeastern Tibetan Plateau, but much higher annual fluxes suggesting that much of the aerosol and moisture transported with the westerly jet stream is removed as it ascends the Southwest margin of the Tibetan Plateau. Snow from the Southern slopes of the Eastern Himalayas shows very low concentrations and very low annual fluxes of major ions, indicating that this region is relatively free from the chemical influence of Asian dust. The glaciochemical data suggest that glaciers which are removed from large source areas of mineral aerosol, such as those in the Himalaya, the Karakoram, and the Southeastern Tibetan Plateau, are the ones most likely to contain longer-term glaciochemical records which detail annual to decadal variation in the strength of the Asian monsoon and long-range transport of Asian dust

US ITASE Glaciochemistry Phase 2: East Antarctica

This award supports a project to undertake glaciochemical investigations of the Ross Sea Embayment Drainage System, and portions of Wilkes Land for purposes of understanding annual to multi-centennial scale climate variability. The glaciochemical data that will be collected will contribute to the U.S. component of the International Trans-Antarctic Scientific Expedition and will occur over a period of two years on an overland traverse that will begin at Taylor Dome in Northern Victoria Land and travel to the South Pole. This data, along with similar information collected on a series of earlier traverse in West Antarctica, will contribute to providing an in-depth understanding of natural climate variability and will provide a baseline for assessing modern climate variability in the context of human activity; and a contribution to the prediction of future climate variability. By choosing appropriate sites for sampling, the traverse will make important contributions to the understanding of the behavior of major atmospheric phenomena such as the Antarctic Oscillation, ENSO, and changes in the chemical composition of the atmosphere, plus controls on all of these changes. US ITASE research addresses important questions concerning the role of Antarctica in global change and will make an important contribution to IPY. Results are translated into publicly accessible information through lectures, media appearances, and a major outreach activity shared between the University of Maine and the Museum of Science (Boston). US ITASE activities provide material for curriculum development in K-12 education and university courses and opportunities for field and laboratory experiences for graduate and undergraduate students. The Climate Change Institute has a long history of gender and ethnically diverse student and staff involvement in research

A Science Management Office for the United States Component of the International Trans Antarctic Expedition (US ITASE SMO) - A Collaborative Program of Research from Taylor Dome to

This award supports the science management office (SMO) for a series of collaborative science proposals that are part of the U.S. contribution to the International Trans-Antarctic Scientific Expedition (US ITASE). It supports the science administration and the coordination of logistics needed in order to accomplish the research. The SMO will work with the Antarctic support contractor to coordinate field operations for the traverse platform so that US ITASE can undertake a series of scientific traverses in the region from Taylor Dome, in Northern Victoria Land to South Pole (NVL-SP) inclusive of interior portions of the East Antarctic plateau such as Dome A. US ITASE is the terrestrial equivalent of a polar research vessel. It offers the ground-based opportunities of traditional style over-snow travel coupled with the modern technology of GPS navigation, crevasse detecting radar, satellite communications, and multi-disciplinary research. By operating as a ground-based transport system US ITASE offers scientists the opportunity to experience the dynamic environment they are studying. US ITASE also provides a stimulating interactive venue for research similar to that afforded by oceanographic research vessels and large polar field camps, without the cost of the former or the lack of mobility of the latter. More importantly the combination of disciplines represented by US ITASE provides a unique, logistically efficient, multi-dimensional view of the atmosphere, the ice sheet and their histories. Data collected by US ITASE and its international partners is available to a broad scientific community and will contribute to many of the goals of the upcoming International Polar Year (IPY). US ITASE has an extensive program of public outreach and provides significant opportunities for many students to experience multidisciplinary Antarctic research

Colle Gnifetti Ice Core (KCC) Progress Report (Year One)—Arcadia Ice Core Proposal: Initiatives on the Science of the Human Past

The Colle Gnifetti glacier of the Monta Rosa Massif on the Swiss-Italian border is perfectly situated to offer insight into the intersection of environment (climate) and culture (history of the economy, political stability, pollution, disease) in medieval Europe. While ice cores previously collected at Colle Gnifetti were sampled at state-of-the-art resolution for the time, it was nevertheless impossible to differentiate annual or finer layering in the period older than 1500 A.D. The 2013 Colle Gnifetti expedition thus sought to collect a new ice core that could be analyzed using the ultra-high-resolution laser based technology developed in the Climate Change Institute’s W.M. Keck Laser Ice Facility.a

ITASE Synthesis Workshop

This award supports a workshop to bring together scientists involved in the International Trans-Antarctic Scientific Expedition (ITASE). Since 1999 the US has supported a program of traverses across both East and West Antarctica (US ITASE). US ITASE is part of the ITASE multi-national effort to understand the past 200-1000+ years of climate change over Antarctica and the Southern Ocean. ITASE is organized under the auspices of Scientific Committee for Antarctic Research (SCAR) and now comprises twenty-one countries. The international representatives from ITASE have met several times in the past to discuss national traverse plans; coordinate efforts; synthesize results; and develop statistical and other techniques for the interpretation of data. The workshop will provide additional momentum to the process of synthesizing the Antarctic-wide ITASE reconstruction of past climate. An emerging compilation of all ITASE and other ice core sites is available through the Ice READER database sponsored by SCAR and one workshop goal is to update this metadata listing. The workshop will also focus on identifying the characteristics of climate change that have impacted the Antarctic and surrounding ocean in the past 200-1000+ years in order to provide a basis for assessing the dramatic changes expected as a consequence of the ~4-6 degrees C warming projected for this region by the Inter-governmental Panel for Climate Change (IPCC). Results from this workshop will also form the basis for future collaborative efforts between ITASE ice core researchers, meteorologists, oceanographers, and climate modelers stemming from international initiatives such as the International Partnerships in Ice Core Sciences (IPICS) and the International Polar Year (IPY). Finally, workshop findings will be included in the forthcoming document: Antarctic Climate Change and the Environment initiated by SCAR

A review of Central Asian glaciochemical data

The glaciers of central Asia provide suitable locations from which to recover continuous, high-resolution glaciochemical records on a continental scale. Although the glaciochemical investigations undertaken to date in central Asia are few in number and limited in terms of spatial coverage and length of record, some preliminary observations can be made concerning regional and seasonal trends in snow chemistry in this region. The sodium chloride ratio for most snow samples collected in central Asia approaches the ratio found in sea water (0.86 in /Leq kg-I ), reflecting a marine source for these constituents. Sodium and chloride concentrations are, on average, 3-10 times higher in the Himalayas than in the Karakoram, demonstrating the greater influence of monsoonal sources of moisture in the Himalayas. Very high sodium concentrations from Khel Khod Glacier probably reflect a local crustal source from surrounding ice-free areas. Low nitrate concentrations were found in snow collected from the southern margin of the Himalayas and high concentrations in snow deposited on the north margin of the Himalayas. This strong regional trend in the spatial distribution of nitrate suggests the influx of continental aerosols, rich in nitrate, originating from the arid regions of central Asia. High calcium concentrations measured in snow from Mount Everest and the north-west corner of China are also indicative of dust derived from the arid regions of central Asia. Very high sulfate concentrations found in snow from the Tien Shan and the Bogda Shan most likely reflect local anthropogenic sources. The altitude effect on isotopic composition is not apparent from snow samples collected in central Asia. Understanding the processes which control the chemical content of snow, the local-to-regional scale complexities, and the seasonal variability are fundamental steps necessary to assess the potential for recovering representative long-term glaciochemical records from central Asia

Science Management for the United States Component of the International Trans-Antarctic Expedition

US ITASE is effectively a polar research vessel. It offers the ground-based opportunities of traditional style traverse travel coupled with the modern technology of GPS, crevasse detecting radar, satellite communications and multi-disciplinary research. By operating as a ground-based transport system US ITASE offers scientists the opportunity to experience the dynamic environment they are studying. US ITASE also offers an important interactive venue for research (currently eleven integrated science projects) similar to that afforded by oceanographic research vessels and large polar field camps, without the cost of the former or the lack of mobility of the latter. More importantly the combination of disciplines represented by US ITASE provides a unique, multi-dimensional (x, y, z and time) view of the ice sheet and its history. Over the past four field seasons (1999-2003) US ITASE sampled the environment of West Antarctica into East Antarctica over spatial scales of \u3e5000 km, depths of \u3e3000 m, heights in the atmosphere of \u3e20 km, and time periods of several hundred years (sub-annual scale) to hundreds of thousands of years (millennial scale)

Paleoclimate from Mount Everest Ice Cores

The primary goal of this research is to analyze three ice cores collected by a joint Chinese-US team of researchers in the spring of 2001. At that time, a 117-meter ice core was recovered from the East Rongbuk (ERC) glacier at 6500 meters above sea level. In addition to these analyses, the researchers will participate in a joint Chinese-US expedition to the region to retrieve modern day glaciological and meteorological data to aid in the interpretation of the ice core data.Based on local accumulation rates and layer thinning estimates, the new 117-meter ERC core likely represents at least several centuries of snow deposition. Thus, the researchers have the opportunity to develop a calibrated, high-resolution paleoclimate record from the region that will complement previous paleoclimatological research from Mt. Everest and Central Asia.The analysis of the ice cores will focus on producing a detailed time-series of major ion concentrations (i.e., chloride, nitrate, sulfate, calcium, magnesium, sodium, potassium and ammonium), stable isotope ratios (i.e., oxygen and deuterium), and total element concentration (i.e., iron, aluminum, calcium, and sulfur). These data will be used to develop:-- high-resolution time series of Late Holocene climate variability for the region involving atmospheric circulation, temperature, and precipitation, and -- detailed environmental records of biomass burning, dust storms, anthropogenic pollutants, and marine and continental biogenic source productivity. The analyses of the ice cores could increase our understanding of the atmospheric dynamics of an important weather system that impacts a heavily populated region of the world. The interaction and cooperation of scientific colleagues from the United States and China will enhance the prospects for success

US ITASE Glaciochemistry

The UMaine Continuous ice core Melter (UMCoM) system is a modified Wagenbach-style continuous melter system (Rothlisberger et al., 2000) with three important differences. First, we have constructed the melthead as two separate pieces, a base and a melter plate, so that it can be easily dismantled and cleaned between melting sessions. Second, the melter plate in contact with the ice is composed of pure nickel (\u3e99.9% Ni) so that trace element measurements can be made from the meltwater stream. Third, in contrast to ice core melter systems in which the meltwater is directly channeled to online instruments for continuous flow analyses (e.g. Sigg et al., 1991; Rothlisberger et al., 2000; Huber et al., 2001; McConnell et al., 2002; Knusel et al., 2003), the UMCoM system collects discrete, high-resolution (\u3c1-2 cm/sample), co-registered samples for each chemical analysis under ultraclean conditions using three or more (if needed) Gilson® fraction collectors (a fraction collector is a device that automatically apportions a liquid flow into discrete samples based on volume). This third modification provides exceptional flexibility in tailoring specific chemical analyses to each project. Currently, the UMCoM system is producing samples from the 2001 Mt. Logan summit ice core for analysis of 30 trace elements (Ca, Al, Fe, S, Sr, Cs, Bi, U, Tl, As, Ti, V, Cr, Mn, Co, Cu, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) by inductively coupled plasma mass spectrometry (ICP-MS), 8 major ions (Na+, Mg2+, K+, Ca2+, Cl-, SO4 2-, NO3 -, MSA) by ion chromatography (IC), stable water isotopes (δ18O, δD, d) by isotope ratio mass spectrometry (IRMS), and volcanic tephra. The list of analytes can be adjusted to address the specific needs of each project