Martin Sharp

University of Alberta | UAlberta · Department of Earth and Atmospheric Sciences

Short chain perfluoroalkylcarboxylic acids (scPFCAs, CxF2x+1COOH, x ≤ 3) are persistent compounds formed from atmospheric oxidation of fluorotelomer compounds and chlorofluorocarbon (CFC) replacements introduced as a result of the Montreal Protocol. Understanding sources and impacts of scPFCAs has been limited by observational data. We report multi...

The Canadian Arctic Archipelago contains >300 glaciers that terminate in the ocean, but little is known about changes in their frontal positions in response to recent changes in the ocean-climate system. Here, we examine changes in glacier frontal positions since the 1950s and investigate the relative influence of oceanic temperature versus atmosph...

Repeat airborne laser altimetry measurements show widespread thinning (surface lowering) of glaciers in Canada's Queen Elizabeth Islands since 1995. Thinning rates averaged for 50 m elevation bins, were more than three times higher during the period 2005/06 to 2012/14 pentad than during the previous two pentads. Strongly negative thickness change (...

Using a whole-watershed approach and a combination of historical, contemporary, modeled and paleolimnological datasets, we show that the High Arctic's largest lake by volume (Lake Hazen) has succumbed to climate warming with only a ~1 °C relative increase in summer air temperatures. This warming deepened the soil active layer and triggered large ma...

This volume charts our interlinked research pathways, which began with an interest in water flow paths at glacier beds and expanded into an exploration of the role of glaciers and ice sheets in local, regional, and global biogeochemical cycles. Along the journey, we discovered that glacier beds are habitats for microbes, and that the microbes are s...

Ch 7. Regional Climates: f. Europe and the Middle East

The Randolph Glacier Inventory (RGI) is a globally complete collection of digital outlines of glaciers, excluding the ice sheets, developed to meet the needs of the Fifth Assessment of the Intergovernmental Panel on Climate Change for estimates of past and future mass balance. The RGI was created with limited resources in a short period. Priority w...

During the International Polar Year (IPY), comprehensive observational research programs were undertaken to increase our understanding of the Canadian polar cryosphere response to a changing climate. Cryospheric components considered were snow, permafrost, sea ice, freshwater ice, glaciers and ice shelves. Enhancement of conventional observing syst...

The Arctic cryosphere is a critically important component of the earth system, affecting the energy balance, atmospheric and ocean circulation, freshwater storage, sea level, the storage, and release of large quantities of greenhouse gases, economy, infrastructure, health, and indigenous and non-indigenous livelihoods, culture and identity. Current...

Though much attention has been focused in recent years on the melting of ice from Greenland and Antarctica, nearly half of the ice volume currently being lost to the ocean is actually coming from other mountain glaciers and ice caps. Ice loss from a group of islands in northern Canada accounts for much of that volume.In a study published in April 2...

Field measurements were necessary to initialize, force, and validate the surface energy balance model for the Belcher Glacier. Hourly and daily averages of air temperature, relative humidity, wind speed and direction, net radiation, and surface elevation were recorded over the 2008 summer (June-September) by two automatic weather stations (AWS) on...

Dissolved organic matter (DOM) is an important component of aquatic carbon and nutrient budgets and is a metabolic substrate for organisms at the base of aquatic food chains. Active microbial communities in glaciers affect the abundance and characteristics of organic matter (OM) that is exported to downstream ecosystems. However, how OM is biogeoch...

1] The basal regions of continental ice sheets are gaps in our current understanding of the Earth's biosphere and biogeochemical cycles. We draw on existing and new chemical data sets for subglacial meltwaters to provide the first comprehensive assessment of sub‐ice sheet biogeochemical weathering. We show that size of the ice mass is a critical co...

An analysis of the local topographic setting of very small (<0.4 km2) glaciers within a small region of the Monashee Mountains, British Columbia, was conducted to investigate its influence on recent changes in the extent of these glaciers. Net changes in glacier extent were determined from a detailed manual comparison of remotely sensed imagery acq...

The molecular characteristics of dissolved organic matter (DOM) reflect both its source material and its biogeochemical history. In glacial systems, DOM characteristics might be expected to change over the course of a melt season as changes in the glacier drainage system cause the mobilization of DOM from different OM pools. To test this hypothesis...

Satellite microwave and scatterometer measurements are very sensitive to the presence of liquid water in snow cover, and have been utilized to develop melt onset detection algorithms for various elements of the cryosphere. Given observed and predicted perturbations in the high latitude climate system as a result of global warming, an integrated pan...

1] Long-term rates of thickness change were derived at several spatial scales using a variety of methods for most of the Devon Island ice cap, Nunavut, Canada. Basin-wide thickness change calculations were derived for the accumulation zones of all major drainage basins as the area-averaged volume difference between balance and InSar fluxes at the a...

Subglacial environments are a previously neglected component of the Earth's global carbon cycle, a reflection of the view held until recently that they are dominated by abiotic and oxic conditions. Here we provide a realistic assessment of the theory that the basal regions of the ice sheets that formed over North America and Europe during glaciatio...

Glaciers are the source for many important rivers globally. Increased rates of glacier melt in response to climate warming result in an increased flux of glacially-derived organic material to downstream aquatic ecosystems. This is particularly true in polar regions where glaciers are most abundant and climate warming is most significant. Dissolved...

Net changes in glacier area in the region 50–518 8 N, 116–1258 W, which includes the Columbia and Rocky Mountains (1951/52–2001) and the Coast Mountains (1964/65–2002), were determined through a comparison of historic aerial photography and contemporary Landsat 7 ETM+ imagery. The volumes of individual glaciers were estimated using an empirical vol...

The hydrology of ice sheets is of current interest because of the linkage between water storage in high pressure subglacial drainage systems and the dynamics of ice sheet margins. However, little is known about the hydrology and hydrochemistry of runoff from the Greenland Ice Sheet (GIS) or the nature of the subglacial drainage system beneath the i...

To improve our understanding of the interactions between hydrology and dynamics in mostly cold glaciers (in which water flow is limited by thermal regime), we analyse short-term (every two days) variations in glacier flow in the ablation zone of polythermal John Evans Glacier, High Arctic Canada. We monitor the spatial and temporal propagation of h...

ABSTRACT Pebble fabric data are available from several facies of glacigenic sediments deposited by modern glaciers, where sedimentary processes can be observed or inferred with relatively little ambiguity. Over 100 samples from contemporary environments illustrate fabrics characterizing melt-out till, deformed and undeformed lodgement till, sedimen...

Spatial and temporal variations in aerodynamic roughness length (z 0) on Haut Glacier d'Arolla, Switzerland, during the 1993 and 1994 ablation seasons are described, based on measure-ments of surface microtopography. The validity of the microtopographic z 0 measurements is established through comparison with independent vertical wind profile z 0 me...

The surface velocity field of Devon Ice Cap, Nunavut, Canada, was mapped using interferometric synthetic aperture radar (InSAR). Ascending European Remote-sensing Satellite 1 and 2 (ERS-1/-2) tandem mode data were used for the western and southeast sectors, and 3 day repeat pass ERS-1 imagery for the northeast sector. Speckle-tracking procedures we...

Dye-tracer experiments undertaken over two summer melt seasons at polythermal John Evans Glacier, Ellesmere Island, Canada, were designed to investigate the character of the subglacial drainage system and its evolution over a melt season. In both summers, dye injections were conducted at several moulins and traced to a single subglacial outflow. Tr...

Climate change during the 20th and 21st centuries has resulted in extensive modification of polar regions; this trend is expected to continue as predicted temperature increases there exceed those elsewhere on the globe (IPCC, 2001). The instrumental temperature record in the Canadian High Arctic extends back only ˜55 years, therefore, it is essenti...

The biogeochemical cycling of organic carbon (OC) has important implications for aquatic system ecology because the abundance and molecular characteristics of OC influence contaminant transport and bioavailability, and determine its suitability as a substrate for microbial metabolism. There have been few studies of OC cycling in glacier systems, an...

Canada's Arctic islands contain over 110,000 km2 of ice caps and glaciers, the largest area of land ice in the world outside Antarctica and Greenland. This region is projected to experience summer warming of 1-4°C over the next century due to the build-up of greenhouse gases in the atmosphere. The small ice masses in this region are likely to respo...

Microbes are abundant at the water-rock-ice interface beneath valley glaciers at Haut Glacier d'Arolla, Switzerland (HGA) and at John Evans Glacier, Ellesmere Island Nunavut, Canada (JEG). However, the importance of in-situ microbial activity in driving subglacial weathering reactions remains unknown. This is a key question when considering the pot...

A combination of shallow ice-coring field experiments and degree-day melt modelling was employed to reconstruct the spatial pattern of mass balance across the Devon Ice Cap. This research is part of a wider program to quantify and to determine the causes of changes in the geometry and mass of the Devon Ice Cap over the last 40 years. In April-May 2...

A systematic review of 1959/60 aerial photography, and 1999/2000 Landsat 7 imagery, has identified 51 surge-type polythermal glaciers in the Canadian High Arctic. These were identified from the presence of features such as looped medial moraines, intense folding visible at the surface, rapid terminus advance, heavy surface crevassing, and high surf...

Repeat surveys of a velocity stake network at Haut Glacier d'Arolla, Switzerland during the summer of 1994 revealed one major glacier-wide speed-up event between June 19 and 29. Proglacial discharge, borehole water level records and uplift of the ice surface across the lower 2.2 km of the 4 km long glacier suggest the event was likely initiated by...

Recent studies have demonstrated the presence of abundant and metabolically active microbial communities in subglacial systems. However, the composition of these communities and the effect that they have on the geochemical dynamics of these systems is unclear. We compared the microbial community composition of samples from two glaciers: the Bench G...

This article is Restricted Access. It was published in the journal, Chemical Geology [© Elsevier] and is available at: http://www.sciencedirect.com/science/journal/00092541 Chemical erosion in glacial environments is normally a consequence of chemical weathering reactions dominated by sulphide oxidation linked to carbonate dissolution and the carbo...

The runoff and riverine fluxes of HCO3−, Si and Ge that arise from chemical erosion in non-glaciated terrain, are modelled at six time steps from the Last Glacial Maximum (LGM) to the present day. The fluxes that arise from the Great Ice Sheets are also modelled. Terrestrial HCO3− fluxes decrease during deglaciation, largely because of the reductio...

Waters were sampled from 17 boreholes at Haut Glacier d'Arolla during the 1993 and 1994 ablation seasons. Three types of concentrated subglacial water were identified, based on the relative proportions of Ca2+, HCO3- and SO42- to Si. Type A waters are the most solute rich and have the lowest relative proportion of Si. They are believed to form in h...

High rates of surface uplift and horizontal velocities were measured during a hydrologically induced spring speed-up event. Spatial patterns of surface uplift are analyzed to estimate components of vertical motion due to flow along an inclined bed and vertical strain. Areas are identified where surface uplift was most likely due in part to the open...

It is increasingly recognised that seasonal evolution of subglacial drainage systems can be driven by processes that take place in the supraglacial drainage systems that feed them. However, understanding of the nature of this relationship is based largely on observations made on temperate mid-latitude glaciers. In this paper, we document some of th...

This paper describes the physical and chemical properties of the snowpack on John Evans Glacier, Ellesmere Island, Canadian Arctic Archipelago, and investi- gates the controls on snowpack solute concentrations and atmospheric deposition. The snowpack contains three layers that are traceable across the whole glacier. These represent fall accumulatio...

Varved sediments from Nicolay Lake, Canadian High Arctic, record major summer rainfall events over the last five centuries. Increased incidences of summer rainfall occurred during the coldest periods of the ‘Little Ice Age’ and were strongly clustered in the years immediately following major volcanic events. Comparison of the summer rainfall and pr...

The surface motion of Haut Glacier d'Arolla, Switzerland, was monitored at a high spatial and temporal resolution. Data are analyzed to calculate surface velocities, surface strain rates and the components of the glacier force budget before, during and after an early melt season speed-up or "spring event". We investigate the extent to which variati...

Spatial and temporal variations of surface albedo on Haut Glacier d'Arolla, Switzerland, during the 1993 and 1994 ablation seasons are described. Correla- tion and regression analyses are used to explain the albedo variations in terms of independent meteorological and surface property variables. Parameterizations are developed which allow estimatio...

CONTENTS 6.1 Overview 263 6.1.1 Rationale for studying the cryosphere 263 6.1.2 Components of the cryosphere 264 6.1.2.1 Snow 266 6.1.2.2 Sea ice 267 6.1.2.3 Lake ice and river ice 268 6.1.2.4 Frozen ground and permafrost 269 6.1.2.5 Glaciers and ice sheets 269 6.2 Major scientific questions 271 6.2.1 Representation of cryospheric processes in clim...

The impact of spatial and temporal variations in the surface albedo and aerodynamic roughness length on the surface energy balance of Haut Glacier d'Arolla, Switzerland, was examined using a semi-distributed surface energy-balance model (Arnold and others, 1996). The model was updated to incorporate the glacier-wide effects of albedo and aerodynami...

The environs of the Glacier de Tsanfleuron, Switzerland, was used as a study site to investigate the controls on the relative efficiency of solute generation and removal from glacial and proglacial environments. Here, a 1500 m wide glacier forefield consists of a karstic limestone plateau flanked to the north by a till-floored valley. Bedrocks and...

Measurements made at John Evans Glacier, eastern Ellesmere Island, Nunavut, Canada in 1994 and 1996 provide new insight into the internal hydrology of polythermal glaciers. During the early part of each melt season, supraglacial waters enter the glacier via a crevasse field about 4 km from the terminus and are stored in a subglacial reservoir. Rele...

Recent research on permanent-ice associated microorganisms has focused on surficial ice environments. We present evidence that, to the authors' knowledge, is the first example that aerobic and anaerobic bacteria can be cultured at 4C from sediment-rich basal ice from a large polythermal Arctic glacier (John Evans Glacier). This builds on previous w...

Meltwaters collected from boreholes drilled to the base of the Haut Glacier d'Arolla, Switzerland have chemical compositions that can be classified into three main groups. The first group is dilute, whereas the second group is similar to, though generally less concentrated in major ions, than contemporaneous bulk glacial runoff. The third group is...

The δ34S of SO42- and 87Sr/86Sr ratio of runoff from the Haut Glacier d'Arolla are presented for four periods during May through August, 1994. Neither δ34S nor 87Sr/86Sr are constant. The bedrock of the glaciated catchment contains a number of different lithologies. Analysis of samples from four of the five main lithologies shows that all have diss...

The formation of superimposed ice at the surface of high-Arctic glaciers is an important control on glacier mass balance, but one which is usually modelled in only a schematic fashion. A method is developed to predict the relationship between the thickness of superimposed ice formed and the mean annual air temperature (which approximates the ice te...

Two-hourly suspended sediment concentration variations observed during the summer of 1987 in the proglacial stream draining Midtdalsbreen, Norway are modelled using multiple regression and time series techniques. Suspended sediment fluctuations are influenced by stream discharge variations, diurnal hysteresis effects, medium-term sediment supply an...

The magnitude and processes of solute acquisition by dilute meltwater in contact with suspended sediment in the channelized component of the hydroglacial system have been investigated through a suite of controlled laboratory experiments. Constrained by field data from Haut Glacier d'Arolla, Valais, Switzerland the effects of the water to rock ratio...

This paper determines the provenance of solute in bulk meltwaters draining Haut Glacier d'Arolla, Valais, Switzerland, during the 1-989 ablation season. Dissolved species are partitioned into components derived from sea salt, acid aerosol, dissolution of atmospheric CO2, and lithogenic sources, namely carbonates, sulphides and aluminosilicates. A m...

The formation of superimposed ice at the surface of high-Arctic glaciers is an important control on glacier mass balance, but one which is usually modelled in only a schematic fashion. A method is developed to predict the relationship between the thickness of superimposed ice formed and the mean annual air temperature (which approximates the ice te...

Research at 11 glaciers in the western European Alps has resulted in the definition of 7 basal ice facies. The formation of each is investigated on the basis of its debris distribution, sedimentology, and stable isotope composition. Isotopic data are interpreted within an analytical framework that allows for variations in the isotopic composition o...

Late-summer subglacial water pressures have been measured in a dense array of boreholes in the ablation area of Haut Glacier d'Arolla. Interpolated surfaces of minimum diurnal water pressure and diurnal water-pressure variation suggest the presence of a subglacial channel within a more widespread distributed drainage system. Water-pressure variatio...

Until now, alpine glacial meltwaters have been assumed to consist of two components, dilute quickflow and concentrated delayed flow, the mixing of which has been regarded as chemically conservative for the major dissolved ions and electrical conductivity. Dye tracing results suggest that this two-component model adequately represents the sub-glacia...

Recent models of chemical weathering in alpine glacial meltwaters suggest that sulphide oxidation is a major source of solute in the distributed component of the subglacial hydrological system. This reaction requires O2, and may lower dissolved oxygen levels to below saturation with respect to the atmosphere. This should result in an inverse associ...

Where there is little contribution of distributed system drainage (water which has spent prolonged periods at the glacier bed) to runoff, such as at the Austre Broggerbreen, Svalbard, NO3- concentrations show a rapid, exponential decline as the snowpack becomes progressively leached. There is also little association of NO3- with discharge throughou...

The spatial and temporal patterns of water discharge, shapes of the dye-return curves, through-flow velocities, dye-recovery rates, dispersivities, and velocity/discharge relationships suggest the existence of distinct catchments beneath the eastern and western halves of the glacier which are characterized by different types of drainage system. Com...

Aims to identify some of the processes responsible for the formation of basal ice sequences and to demonstrate the links likely to exist between these processes and the characteristics of the resultant sequences. The postulated rheological consequences of these properties are also discussed in the light of several recent studies. Mechanisms respons...

The propagation of the surge of Variegated Glacier into its terminal lobe was observed by daily surveying of a longitudinal line of closely spaced markers extending up glacier from a ``stangant zone'' of thin (~40 m), nearly motionless ice near the terminus, across a ``front zone'', to a ``surge zone'' of thicker (~ 100 m), rapidly moving (>20 m d-...

Moraine ridges have formed annually at Skálafellsjökull, south-east Iceland since about A.D. 1912. These ridges are asymmetrical with a steeper distal slope, and their surface morphology reflects their internal structure. Most ridges are formed at the glacier margin, and they form a series of concentric arcs about it. Their plan form reflects small...

Moraine ridges have formed annually at Skalafellsjokull, SE Iceland