Heather M. Clifford

Boston University | BU · Institute for Global Sustainability

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...

Over the past eight hundred thousand years, glacial–interglacial cycles oscillated with a period of one hundred thousand years (‘100k world’¹). Ice core and ocean sediment data have shown that atmospheric carbon dioxide, Antarctic temperature, deep ocean temperature, and global ice volume correlated strongly with each other in the 100k world2,3,4,5...

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 pre‐instrumental era requires further research, particularly as a potential analog for future climate. Using an ultra‐high resolution glacio‐chemical record from the 20...

Graphical Abstract Highlights d Microplastics were found in snow and stream water samples on Mt. Everest d The highest microplastics were discovered in a sample from 8,440 m.a.s.l. d Most microplastics were polyester fibers, likely from clothing and equipment d Technological advances could minimize microplastic pollution from exploration In Brief A...

This case study provides a framework for future monitoring and evidence for human source pollution in the Khumbu region, Nepal. We analyzed the chemical composition (major ions, major/trace elements, black carbon, and stable water isotopes) of pre-monsoon stream water (4300-5250 m) and snow (5200-6665 m) samples collected from Mt. Everest, Mt. Lobu...

The goal of this dissertation is to assess past and present changes in the chemical climate of three high mountain regions: the Himalayas, Peruvian Andes, European Alps. In the first analysis, we report a comprehensive case study of chemical composition from streams, snow samples, and an ice core collected from around Mt. Everest Basecamp in the Kh...

Ice core records provide a robust tool for reconstructing past climate variability and for improving our understanding of the relative contributions of natural and anthropogenic emissions into the atmosphere. In particular, heavy metal pollution from anthropogenic emissions poses a significant health and environmental risk. We present a sub-annuall...

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 (Sout...

In 2019, the National Geographic and Rolex Perpetual Planet Everest expedition successfully retrieved the greatest diversity of scientific data ever from the mountain. The confluence of geologic, hydrologic, chemical and microbial hazards emergent as climate change increases glacier melt is significant. We review the findings of increased opportuni...

Mt. Everest, one of the most coveted climbing mountains on earth, also contains the highest altitude chemical contamination on land. For the first time, meltwater and snow samples from Mt. Everest's Khumbu Glacier were analyzed for "forever chemicals" per-and polyfluoroalkyl substances (PFAS). Our research team utilized solid-phase extraction (SPE)...

In April and May 2019, as part of National Geographic and Rolex's Perpetual Planet Everest Expedition, an interdisciplinary scientific effort conducted a suite of research on the mountain and recognized many changing dynamics, including emergent risks resulting from natural and anthropogenic changes to the biological system. In this Primer, the div...

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...

In April and May 2019, as a part of the National Geographic and Roxel Perpetual Planet Everest Expedition, the most interdisciplinary scientific ever was launched. This research identified changing dynamics, including emergent risks resulting from natural and anthropogenic change to the natural system. We have identified compounded risks to ecosyst...

Alpine ice and the annual political economy of the Angevin Empire, from the death of Thomas Becket to Magna Carta, c. AD 1170–1216 - Christopher P. Loveluck, Alexander F. More, Nicole E. Spaulding, Heather Clifford, Michael J. Handley, Laura Hartman, Elena V. Korotkikh, Andrei V. Kurbatov, Paul A. Mayewski, Sharon B. Sneed, Michael McCormick

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has changed ice core sampling from ~1 cm (high resolution) to ~120 μm(ultra-high resolution) allowing examination of low net mass balance and highly compressed old ice core records for several elements (eg., Pb, Na, Mg, Fe, Cu, Ca, and Al). Laser ablation sampling of even highl...

Ice core archives provide the most direct and detailed evidence of past climate and atmospheric conditions, however, traditional ice core sampling (~1-cm resolution) does not provide significant environmental detail in low accumulation and compressed ice core sites. Advances in ice core sampling techniques allows for the capability to detect enviro...

A 2100-Year Ultra-High-Resolution Saharan Dust Record from a European Alps ice core

The vadose zone is a highly interactive heterogeneous system through which water enters the subsurface system by infiltration. This paper details the effects of simulated plant exudate and soil component solutions upon unstable flow patterns in a porous medium (ASTM silica sand; US Silica, Ottawa, IL, USA) through the use of two-dimensional tank li...

Ice core archives provide the most direct and detailed evidence of past climate state and atmospheric conditions. However, the resolution of traditional ice core sampling methods limits the scope of information that can be extracted from the ice regarding meteorological type of events (e.g., dust storms, volcanic eruptions, anthropogenic emissions...

In the hydrological cycle, the infiltration process is a critical component in the distribution of water into the soil and in the groundwater system. The nonlinear dynamics of the soil infiltration process yield preferential flow which affects the water distribution in soil. Preferential flow is influenced by the interactions between water, soil, p...

Nanofluids are suspensions of nanometer-sized particles in any fluid base, where the nanoparticles affect the properties of that base. While they have been the subject of recent study regarding their use in heat and mass transfer applications, a fundamental analysis of nanofluids has yet to be undertaken. Here the authors sought to understand the f...

The vadose zone is a highly interactive heterogeneous system through which water enters into the subsurface system by infiltration. This paper details the effects of simulated plant exudate and soil component solutions upon unstable flow patterns in a porous media (ASTM silica sand; US Silica, Ottawa, IL, USA) through the use of two-dimensional (2D...