Penny Ice Cap Research Articles

Modeling the surface mass balance of Penny Ice Cap, Baffin Island, 1959–2099

Abstract Glaciers of Baffin Island and nearby islands of Arctic Canada have experienced rapid mass losses over recent decades. However, projections of loss rates into the 21st century have so far been limited by the availability of model calibration and validation data. In this study, we model the surface mass balance of the largest ice cap on Baffin Island, Penny Ice Cap, since 1959, using an enhanced temperature index model calibrated with in situ data from 2006–2014. Subsequently, we project changes to 2099 based on the RCP4.5 climate scenario. Since the mid-1990s, the surface mass balance over Penny Ice Cap has become increasingly negative, particularly after 2005. Using volume–area scaling to account for glacier retreat, peak net mass loss is projected to occur between ~2040 and 2080, and the ice cap is expected to lose 22% (377.4 Gt or 60 m w.e.) of its 2014 ice mass by 2099, contributing 1.0 mm to sea level rise. Our 2015–2099 projections are approximately nine times more sensitive to changes in temperature than precipitation, with an absolute cumulative difference of 566 Gt (90 m w.e.) between +2 and −2°C scenarios, and 63 Gt (10 m w.e.) between +20% and −20% precipitation scenarios.

Glacier area changes in the Arctic and high latitudes using satellite remote sensing

ABSTRACT Glaciers have been retreating over the last century as a result of climate change, particularly in the Arctic, causing sea levels to rise, affecting coastal communities and potentially changing global weather and climate patterns. In this study, we mapped 2203 glaciers in Novaya Zemlya (Russian Arctic), Penny Ice Cap (Baffin Island), Disko Island (Qeqertarsuaq, Greenland) and part of Kenai (Alaska), using Object-Based Image Analysis (OBIA) applied to multispectral Landsat satellite imagery in Google Earth Engine (GEE) to quantify the glacier area changes over three decades. Between 1985–89 and 2019–21, the results show that the overall glacier area loss in Novaya Zemlya is 1319 ± 419 km2 (5.7% of area), 452 ± 227 km2 (6.6%) for Penny Ice Cap, 457 ± 168 km2 (23.6%) in Disko Island and 196 ± 84 km2 (25.7%) in Kenai. A total of seventy-three glaciers have disappeared completely, including sixty-nine on Disko Island, three in Novaya Zemlya and one in Kenai.

A 600‐year marine record associated with the dynamics of the eastern Penny Ice Cap (Baffin Island, Nunavut, Canada)

ABSTRACTTwo composite sedimentary sequences sampled in the ice‐proximal (12CS) and ice‐distal (02CS) areas of Coronation Fjord (Baffin Island, Nunavut, Canada) were investigated in order to reconstruct the effect of climate variability on 600 years of changes in sediment transfer from the eastern Penny Ice Cap (PIC). Detrital proxies, and physical and sedimentological analyses revealed that glacial meltwater discharges led to frequent rapidly deposited layers (RDLs) in ice‐proximal settings. RDLs in ice‐distal settings involved the sudden release of a large quantity of sediment‐laden water during floods probably originating from adjacent fjords with large sandur deltas. Laminated sediments with ice‐rafted debris throughout the Little Ice Age interval in the ice‐proximal environment suggest that colder conditions promoted glacier growth, leading to successive episodes of turbid hyperpycnal meltwater plumes and iceberg calving in Coronation Fjord. Since 1850 ce, the accelerated Coronation retreat in response to modern warming has led to increased sedimentation rates, abrupt mineralogical and grain size proxy variations and more frequent RDLs. Similar trends between the detrital proxies of the ice‐proximal core and Atlantic Multidecadal Oscillation record and Arctic surface air temperature suggest high connectivity between atmospheric and sea surface temperature variations and PIC dynamics over the last 600 years.

Changes in Glacial Area Extent in Auyuittuq National Park, Pangnirtung

With global temperatures rising four times faster in the Canadian Arctic compared to global averages, glaciers in the Canadian Arctic Archipelago (CAA) are starting to shrink at an alarming rate (Paul et al., 2020). To quantify rates of change, frequent updates of glacial outlines to provide an accurate database for monitoring are needed (Schaffer et al., 2017). Rundle, Nerutusoq, and Fort Beard Glaciers are all located on the Penny Ice Cap within Auyuittuk National Park, Baffin Island, Canada. Using a combination of aerial photography and ArcGIS Pro, I examined the historical and recent changes in glacial area extents. High resolution historical aerial photographs from the National Air Photo Library dating to September 1959 were manually georeferenced onto ArcGIS Pro. Photogrammetry techniques were then used to combine the aerial photographs into one combined orthographic image. The historic glaciers were then outlined using a manual technique based on the pixel size (8 μm) of the images using ArcGIS Pro. This allows me to compare glacial outlines from 2010 using the Randolph glacier inventory and 2022 using manual outline techniques described, respectively. Because using a manual technique can create accuracy limitation, specifically during the georeferencing process, I compared results for both time periods using an automatic method. Results from my work will provide estimates of changes in glacier area over time, the relative precision of different methods, and weather rates of shrinkage have increased over time. ReferencesPaul, F., Rastner, P., Azzoni, R. S., Diolaiuti, G., Fugazza, D., Le Bris, R., Nemec, J., Rabatel, A., Ramusovic, M., Schwaizer, G., & Smiraglia, C. (2020). Glacier shrinkage in the Alps continues unabated as revealed by a New Glacier Inventory from sentinel-2. Earth System Science Data, 12(3), 1805–1821. https://doi.org/10.5194/essd-12-1805-2020 Schaffer, N., Copland, L., & Zdanowicz , C. (2017). Ice velocity changes on Penny Ice Cap, Baffin Island, since the 1950s. Journal of Glaciology, 63(240), 716–730. https://doi.org/10.1017/jog.2017.40

Dispatches from the Ice

Dispatches from the Ice Todd Anderson (bio) Click for larger view View full resolution todd anderson, i-165 deep field basecamp, allan hills, transantarctic mountains, antarctica detail shot, 15 in. x 35 in., 10 runs, 18 colors, reductive woodcut with watercolor and pencil In 2019 Todd Anderson journeyed to the Allan Hills with fellow artist Ian van Coller to visit and document an eight-person ice coring science team led by Princeton University professor and geoscientist John Higgins. Additional Allan Hills team members included Austin Carter (Scripps UC–San Diego), Jenna Epifanio (Oregon State University), Jacob Morgan (Scripps UC–San Diego), Sarah Shackleton (Princeton University), drill operators Tanner Kuhl and Elizabeth Morton (University of Wisconsin–Madison), and USAP camp coordinator Anna Zajicek. Journal Entry, 19 November 2019: Arrival at Allan Hills blue ice area … This is the farthest afield I will ever be —visually and geographically. Reflecting on this journal entry now in 2022, I am reminded that definitive statements about the future rarely hold up. But sometimes they do. Earlier in 2019, I hiked amongst glaciers in the Rwenzori Mountains of Uganda and a month later north of the Arctic Circle to the Penny Ice Cap on Baffin Island in Nunavut, Canada. I found the Rwenzori Mountain Range unworldly in its beauty; had an emergency arisen while traveling on the Penny Ice Cap—three days' wait for a rescue was the best I could have hoped for. On both of these expeditions I felt moments of wonder and physical caution that seemed absolute. When I wrote the above journal entry, I had just arrived at the Allan Hills blue ice area, which is part of the East Antarctic Ice Sheet. I was approximately 675 [End Page 36] miles north of the South Pole and 135 miles from the nearest medical services at McMurdo Station, the United States' premier Antarctic research center. My initial experience with the landscape at Allan Hills was akin to feeling adrift in an ocean of ice. There was a seemingly endless horizon to behold there, and the magnitude of the expanse allowed my eyes to discern a slight bend in the horizon line as it adhered to the earth's spherical shape. Owing to exceedingly low levels of atmospheric humidity, visual clarity in Antarctica is unrivaled. Unaided, one can see for hundreds of miles. And what I saw was a tremendously vast plane of cerulean blue ice canopied by a similarly hued sky. There was a steady, southern wind coming from the pole that day. I would soon learn that even on relatively calm days a strength of wind is not just felt but always heard in the Allan Hills. Above all else, though, the Allan Hills is an extremely cold place. Rarely does the temperature rise above fifteen degrees Fahrenheit, while subzero temperatures are the norm. Within days of my arrival, it hit negative twenty degrees Fahrenheit. I began using three chemical heat warmers in each boot—one under the sole of the foot and one above and one below the toes. I had never seen or been to any place quite like this. Journal Entry, 24 November 2019: Day 6, Higgins Ice Coring Tent, Allan Hills … Earth breathes in and out —remember carbon dioxide. The Allan Hills is one of the few spots in Antarctica where intense katabatic winds (wind generated by gravity) from the interior of East Antarctica prevent the accumulation of new snow on the ground. When the area's fierce katabatic winds are combined with its tremendously dry atmosphere and severely cold temperatures, ice and snow transition from a solid state directly to a gas (altogether bypassing a liquid state, a process called sublimation). Put simply, any type of precipitation or snow in the Allan Hills either evaporates instantly before touching the ground or is disappeared elsewhere by the wind. When ice is formed, air bubbles and dust become trapped. Under analysis, ice bubbles can relay physical records such as the concentrations of atmospheric greenhouse gases, like carbon dioxide (CO2) and methane (CH4), from when the ice formed. Examination of trapped dust similarly helps scientists understand past planetary events and conditions (such as dates of volcanic eruptions and...

Sediment fill of Baffin Island fjords: Architecture and rates

This Review quantitatively and qualitatively describes 10 representative Baffin Island fjords chosen to explore the nature of a glaciation in delivering sediment to a fjord, with focus on deglacial (within 13–6.7 kyr BP) and postglacial conditions (within 8.2–0 kyr BP). Fjords are compared using observed sediment thicknesses (49–175 m, averaged) and volumes (0.7–14.6 km3), and modeled sediment yields: (1) deglacial 140–1060 t/m2/yr; (2) paraglacial 45–350 t/m2/yr; (3) neoglacial 30–150 t/m2/yr; (4) Little Ice Age 70–440 t/m2/yr; and (5) Anthropocene 60–290 t/m2/yr. Modeled sediment loads, when converted to deposit volumes, compare favorably to observations from geophysical surveys and terrestrial mapping, or separately to sediment accumulation rates (SAR) determined from marine sediment cores. Fjord-averaged SAR during deglaciation range from 4.6 to 25 mm/yr, and 0.6–3.1 mm/yr for the postglacial interval. Fjords directly impacted by the Laurentide Ice Sheet (central and northern Baffin Island) are 2–3 times larger in dimensions than southern Baffin Island fjords, with ∼4.5x deglacial and ∼5x postglacial larger deposits, including well-defined ice-proximal outwash deposits. To the south, Penny Ice Cap associated fjords with no withholding sills, lose 30–40% of their incoming fjord sediment to Broughton Trough that dissects the continental shelf. Sunneshine is the only sampled fjord that was neither directly nor indirectly impacted by the Wisconsin continental ice sheet; Sunneshine responded instead to local maritime conditions and an alpine glaciation.

A 5000‐year paleoclimate record from Nettilling Lake (Baffin Island) based on diatom assemblages and oxygen isotope composition

ABSTRACTSedimentary diatoms have been used to quantitatively reconstruct climate‐related variables, such as temperature at different timescales. Even though temperature is often less of a key driver of diatom ecology than other environmental parameters (water chemistry), diatom inference models have been shown to be reliable in deducing past temperature trends. In addition, the oxygen isotope composition (δ18Odiatom) preserved in buried diatom frustules has demonstrated its potential to reflect climatic and hydrological conditions at the time of frustule formation. This study combines results from both diatom‐based climate proxies to reconstruct summer water and mean annual air temperatures, and hydrological trends in Nettilling Lake, Baffin Island, from ca. 5000 to 500 cal a bp. Diatom‐inferred temperatures revealed an overall ca. 2 °C cooling throughout the Late‐Holocene. The δ18Odiatom values showed an increasing trend up to ca. 1900 cal a bp, where they reached their highest values (+24.8‰ at 15 cm) and thereafter decreased to their lowest values (+21.4‰ at 4 cm). These trends were linked to meltwater inflows associated with Penny Ice Cap thaw rate that was in turn controlled by regional climatic conditions which went from intensified cooling during the Neoglacial period to slight warming thereafter. Our results suggest that diatom‐ and diatom‐isotope‐based temperature and hydrological reconstructions can identify trends related to the natural climate system variability. The diatom oxygen isotopes are useful for paleoenvironmental studies of terrestrial aquatic ecosystems, but not for all hydrological systems are the ideal temperature proxy. Hence, the combination of proxies helps to disentangle temperature and hydrological effects for paleoclimatic reconstructions and may support future studies of postglacial environmental change in northern lakes.

Revised Estimates of Recent Mass Loss Rates for Penny Ice Cap, Baffin Island, Based on 2005–2014 Elevation Changes Modified for Firn Densification

AbstractRepeat airborne or satellite measurements of surface elevation over ice caps are often used to calculate glacier‐wide surface mass changes over time. However, these measurements typically do not account for vertical ice motion caused by firn densification and/or ice flow, so the effect of these factors for mass change measurements over an entire ice cap are currently poorly constrained. In this study, we update NASA Airborne Topographic Mapper (ATM) altimetry elevation changes across Penny Ice Cap (Baffin Island, Canada) to assess total changes in ice mass from 2005–2014, relative to 1995–2000. Dual‐frequency GPS measurements and temporal changes in ice core density profiles are used to calculate firn densification and ice flow to isolate the component of elevation change due to surface mass change. Envisat satellite imagery is used to delineate the areas impacted by firn densification. These calculations, the first for a Canadian Arctic ice cap, indicate that accounting for firn densification may reduce the inferred surface mass loss by ~13–15%. Overall, there has been a fourfold increase in mass loss from Penny Ice Cap between 1995–2000 (−1.3 ± 0.7 Gt a−1) and 2005–2013 (−5.4 ± 1.9 Gt a−1). The rapid upglacier migration of the equilibrium line has left large areas of subsurface firn in the current ablation area and has far outpaced the ice flow response, illustrating that the ice cap is not in equilibrium and out of balance with the current climate.

Reply to Carlson (2020) comment on “Deglaciation of the Greenland and Laurentide ice sheets interrupted by glacier advance during abrupt coolings”

This Review quantitatively and qualitatively describes 10 representative Baffin Island fjords chosen to explore the nature of a glaciation in delivering sediment to a fjord, with focus on deglacial (within 13–6.7 kyr BP) and postglacial conditions (within 8.2–0 kyr BP). Fjords are compared using observed sediment thicknesses (49–175 m, averaged) and volumes (0.7–14.6 km3), and modeled sediment yields: (1) deglacial 140–1060 t/m2/yr; (2) paraglacial 45–350 t/m2/yr; (3) neoglacial 30–150 t/m2/yr; (4) Little Ice Age 70–440 t/m2/yr; and (5) Anthropocene 60–290 t/m2/yr. Modeled sediment loads, when converted to deposit volumes, compare favorably to observations from geophysical surveys and terrestrial mapping, or separately to sediment accumulation rates (SAR) determined from marine sediment cores. Fjord-averaged SAR during deglaciation range from 4.6 to 25 mm/yr, and 0.6–3.1 mm/yr for the postglacial interval. Fjords directly impacted by the Laurentide Ice Sheet (central and northern Baffin Island) are 2–3 times larger in dimensions than southern Baffin Island fjords, with ∼4.5x deglacial and ∼5x postglacial larger deposits, including well-defined ice-proximal outwash deposits. To the south, Penny Ice Cap associated fjords with no withholding sills, lose 30–40% of their incoming fjord sediment to Broughton Trough that dissects the continental shelf. Sunneshine is the only sampled fjord that was neither directly nor indirectly impacted by the Wisconsin continental ice sheet; Sunneshine responded instead to local maritime conditions and an alpine glaciation.

Ice velocity changes on Penny Ice Cap, Baffin Island, since the 1950s

ABSTRACTPredicting the velocity response of glaciers to increased surface melt is a major topic of ongoing research with significant implications for accurate sea-level rise forecasting. In this study we use optical and radar satellite imagery as well as comparisons with historical ground measurements to produce a multi-decadal record of ice velocity variations on Penny Ice Cap, Baffin Island. Over the period 1985–2011, the six largest outlet glaciers on the ice cap decelerated by an average rate of 21 m a−1 over the 26 year period (0.81 m a−2), or 12% per decade. The change was not monotonic, however, as most glaciers accelerated until the 1990s, then decelerated. A comparison of recent imagery with historical velocity measurements on Highway Glacier, on the southern part of Penny Ice Cap, shows that this glacier decelerated by 71% between 1953 and 2009–11, from 57 to 17 m a−1. The recent slowdown of outlet glaciers has coincided with increases in mass loss, terminus retreat and an inferred reduction in basal sliding. Measured decelerations are greater than the total short-term variability measured from both seasonal and interannual fluctuations, and support the hypothesis that glacier thinning and/or increased meltwater production promotes a long-term reduction in ice motion.

Palaeoenvironmental history of the last six centuries in the Nettilling Lake area (Baffin Island, Canada): A multi-proxy analysis

The Baffin Island region in the eastern Canadian Arctic has recently experienced a rapid warming, possibly unprecedented in millennia. To investigate the response of freshwater environments to this warming and place it in a secular perspective, we analyzed a 90-cm-long sediment core from Nettilling Lake, the largest lake of the Canadian Arctic Archipelago. The core was taken from a part of the lake basin that receives meltwater and sediment inputs from the nearby Penny Ice Cap. The core time scale, established using 137Cs and palaeomagnetic techniques, spans an estimated 600 years. A multi-proxy approach was used to document changes in the physical, chemical, and biological properties of the sediments. We found evidence for a relatively warm period (mid/late 15th century to mid/late 16th century) during the early part of the ‘Little Ice Age’ (LIA), characterized by high sedimentation rates and laminations. This was followed by colder, drier, and windier conditions corresponding to the coldest phase of LIA and coinciding with the latest and most extensive period of regional ice cap expansion (early 16th to late 19th centuries). A rapid warming occurred at the beginning of the 20th century. Variations in titanium (Ti) content in the core, a proxy for detrital sediment inputs, showed good agreement with reconstructed secular variations in summer melt rates on Penny Ice Cap between the mid-14th century and the present-day, providing supporting evidence for a climatic–hydrological connection between the ice cap and Nettilling Lake.

Paleo-environmental gateways in the eastern Canadian arctic – Recent isotope hydrology and diatom oxygen isotopes from Nettilling Lake, Baffin Island, Canada

Abstract Nettilling Lake is located on Baffin Island, Nunavut, Canada between the areas of past warming (Canadian High Arctic to the North) and climatic stability (Northern Quebec and Labrador region to the South). Despite being the largest lake in the Nunavut region with a postglacial marine to lacustrine transition history only a few paleo-environmental investigations were completed in this area. The oxygen isotope composition of diatoms (δ18Odiatom) can provide valuable insights into paleo-environmental conditions. Here, the recent (isotope) hydrology and hydrochemical data from the lake are presented to facilitate the interpretation of a δ18Odiatom record from an 82 cm sediment core (Ni-2B). The well-mixed lake (δ18Owater = −17.4‰) is influenced by a heavier (less negative) isotope composition (−18.80‰) from Amadjuak River draining Amadjuak Lake to the South and water of lighter (more negative) isotopic composition (−16.4‰) from the Isurtuq River originating from Penny Ice Cap in the North-East. From the δ18Owater and δ18Odiatom of the topmost sample of core Ni-2B a Δ18Osilica-water of 1000 ln α(silica-water) = 40.2‰ for sub-recent diatoms of Nettilling Lake was calculated matching the known water-silica fractionation for fossil sediments well and thereby showing the general applicability of this proxy for paleo-reconstructions in this region. Extremely large δ18Odiatom variations in the core of more than 13‰ are mainly induced by changes in the isotopic composition of the lake water due to a shift from glaciomarine (δ18Odiatom = +34.6‰) through brackish (+23.4 to +27.2‰) towards lacustrine (+21.5‰) conditions (transition zones glaciomarine to brackish at 69 cm/7300 yr cal. BP and brackish to lacustrine at 35 cm/6000 yr cal. BP) associated with a shift in the degree of salinity. Our study provides the first evidence that paleo-salinity can be reconstructed by δ18Odiatom. Additionally, for the lacustrine section it could be demonstrated that δ18Odiatom may serve as a proxy for past air temperature within the same core recording a late Holocene cooling of about 4 °C being consistent with other published values for the greater Baffin region.

Pre-industrial and recent (1970–2010) atmospheric deposition of sulfate and mercury in snow on southern Baffin Island, Arctic Canada

Sulfate (SO42−) and mercury (Hg) are airborne pollutants transported to the Arctic where they can affect properties of the atmosphere and the health of marine or terrestrial ecosystems. Detecting trends in Arctic Hg pollution is challenging because of the short period of direct observations, particularly of actual deposition. Here, we present an updated proxy record of atmospheric SO42− and a new 40-year record of total Hg (THg) and monomethyl Hg (MeHg) deposition developed from a firn core (P2010) drilled from Penny Ice Cap, Baffin Island, Canada. The updated P2010 record shows stable mean SO42− levels over the past 40years, which is inconsistent with observations of declining atmospheric SO42− or snow acidity in the Arctic during the same period. A sharp THg enhancement in the P2010 core ca 1991 is tentatively attributed to the fallout from the eruption of the Icelandic volcano Hekla. Although MeHg accumulation on Penny Ice Cap had remained constant since 1970, THg accumulation increased after the 1980s. This increase is not easily explained by changes in snow accumulation, marine aerosol inputs or air mass trajectories; however, a causal link may exist with the declining sea-ice cover conditions in the Baffin Bay sector. The ratio of THg accumulation between pre-industrial times (reconstructed from archived ice cores) and the modern industrial era is estimated at between 4- and 16-fold, which is consistent with estimates from Arctic lake sediment cores. The new P2010 THg record is the first of its kind developed from the Baffin Island region of the eastern Canadian Arctic and one of very few such records presently available in the Arctic. As such, it may help to bridge the knowledge gap linking direct observation of gaseous Hg in the Arctic atmosphere and actual net deposition and accumulation in various terrestrial media.

Correction to “Summer melt rates on Penny Ice Cap, Baffin Island: Past and recent trends, and implications for regional climate”

Correction to “Summer melt rates on Penny Ice Cap, Baffin Island: Past and recent trends, and implications for regional climate”

Response of benthos to stress factors in Holocene Arctic fjord settings: Maktak, Coronation, and North Pangnirtung Fjords, Baffin Island, Canada

Maktak, Coronation and North Pangnirtung Fjords are situated on Cumberland Peninsula, Baffin Island, Canada, having a common freshwater source from the Penny Ice Cap. Bottom photographs were examined to identify epifaunal trails and shallow endobenthic burrow openings exposed on the seafloor surface. These were compared to biogenic sedimentary structures revealed through x-radiograph images and direct observations of Lehigh gravity core samples. Intermediate- and deep-tier structures characterize the ichnofabrics of the glaciomarine sediments. Extensive bioturbation by the shallow-tier and epibenthic tracemakers, most notably ophiuroid echinoderms (brittlestars) and other organisms, has destroyed much of the primary sedimentary fabric (i.e. lamination) resulting in homogenous silty clay sediments. The dominant deep-tier structure consisting of an open, three-dimensional boxwork burrow system is the most pervasive biogenic structure observed within the core samples. Interestingly, although proximal–distal trends in benthic macrofaunal composition are evident in the bottom photographs, ichnofabrics remain relatively constant along the length of the fjords. Environmental factors influencing the biological community in these modern high latitude fjords differ from conditions described in Paleozoic and Cenozoic fjord environments. An increasing number of recent studies are expanding significantly on the fjord ichnology database, and provide the basis for the revision of the currently proposed fjord trace-fossil model, accommodating the complexity and diversity of fjord settings.

Accumulation, storage and release of atmospheric mercury in a glaciated Arctic catchment, Baffin Island, Canada

Part of the mercury (Hg) entering Arctic ecosystems is believed to be delivered from the atmosphere in snow but this source is difficult to quantify due to limited spatial coverage of Hg data in snow. Here we evaluate the atmospheric deposition, storage and release of total Hg (THg) and monomethyl mercury (MeHg) on Penny ice cap, Baffin Island. This is the first such study in the Baffin region. THg levels in snow and firn (mean=0.61ngL−1) are comparable to those on High Arctic glaciers but MeHg levels are noticeably higher (mean=0.11ngL−1). We find little evidence of springtime enhancement of Hg deposition in snow attributable to atmospheric mercury depletion events. Estimated accumulation rates of THg and MeHg in firn are ∼0.33 and 0.03μgm−2a−1, higher than on High Arctic glaciers, possibly due to higher precipitation on southern Baffin Island. The estimated net annual release of THg by glacial snow and ice melt is small (THg: 1.86kg; MeHg: 0.18kg). In the study area, geogenic Hg contributions from sediment-loaded glacial meltwater could be as large or larger than those from melting ice. MeHg levels are very low in meltwater-fed streams and lakes (⩽0.01ngL−1), suggesting that MeHg is released early in the snowmelt season and/or quickly removed from meltwater by various processes. Summer melt and percolation on Penny ice cap remobilise Hg in firn after deposition, and this imposes resolution limits of at least 3years on depositional trends inferred from ice cores.

Accelerated contributions of Canada's Baffin and Bylot Island glaciers to sea level rise over the past half century

Abstract. Canadian Arctic glaciers have recently contributed large volumes of meltwater to the world's oceans. To place recently observed glacier wastage into a historical perspective and to determine the region's longer-term (~50 years) contribution to sea level, we estimate mass and volume changes for the glaciers of Baffin and Bylot Islands using digital elevation models generated from airborne and satellite stereoscopic imagery and elevation postings from repeat airborne and satellite laser altimetry. In addition, we update existing glacier mass change records from GRACE satellite gravimetry to cover the period from 2003 to 2011. Using this integrated approach, we find that the rate of mass loss from the region's glaciers increased from 11.1 ± 3.4 Gt a−1 (271 ± 84 kg m−2 a−1) for the period 1963–2006 to 23.8 ± 6.1 Gt a−1 (581 ± 149 kg m−2 a−1) for the period 2003–2011. The doubling of the rate of mass loss is attributed to higher temperatures in summer with little change in annual precipitation. Through both direct and indirect effects, changes in summer temperatures accounted for 70–98% of the variance in the rate of mass loss, to which the Barnes Ice Cap was found to be 1.7 times more sensitive than either the Penny Ice Cap or the region's glaciers as a whole. This heightened sensitivity is the result of a glacier hypsometry that is skewed to lower elevations, which are shown to have a higher mass change sensitive to temperature compared to glacier surfaces at higher elevations. Between 2003 and 2011 the glaciers of Baffin and Bylot Islands contributed 0.07 ± 0.02 mm a−1 to sea level rise accounting for 16% of the total contribution from glaciers outside of Greenland and Antarctica, a rate much higher than the longer-term average of 0.03 ± 0.01 mm a−1 (1963 to 2006).

Summer melt rates on Penny Ice Cap, Baffin Island: Past and recent trends and implications for regional climate

At latitude 67°N, Penny Ice Cap on Baffin Island is the southernmost large ice cap in the Canadian Arctic, yet its past and recent evolution is poorly documented. Here we present a synthesis of climatological observations, mass balance measurements and proxy climate data from cores drilled on the ice cap over the past six decades (1953 to 2011). We find that starting in the 1980s, Penny Ice Cap entered a phase of enhanced melt rates related to rising summer and winter air temperatures across the eastern Arctic. Presently, 70 to 100% (volume) of the annual accumulation at the ice cap summit is in the form of refrozen meltwater. Recent surface melt rates are found to be comparable to those last experienced more than 3000 years ago. Enhanced surface melt, water percolation and refreezing have led to a downward transfer of latent heat that raised the subsurface firn temperature by 10°C (at 10 m depth) since the mid‐1990s. This process may accelerate further mass loss of the ice cap by pre‐conditioning the firn for the ensuing melt season. Recent warming in the Baffin region has been larger in winter but more regular in summer, and observations on Penny Ice Cap suggest that it was relatively uniform over the 2000‐m altitude range of the ice cap. Our findings are consistent with trends in glacier mass loss in the Canadian High Arctic and regional sea‐ice cover reduction, reinforcing the view that the Arctic appears to be reverting back to a thermal state not seen in millennia.

Repeat optical satellite images reveal widespread and long term decrease in land-terminating glacier speeds

Abstract. By matching of repeat optical satellite images it is now possible to investigate glacier dynamics within large regions of the world and also between regions to improve knowledge about glacier dynamics in space and time. In this study we investigate whether the negative glacier mass balance seen over large parts of the world has caused the glaciers to change their speeds. The studied regions are Pamir, Caucasus, Penny Ice Cap, Alaska Range and Patagonia. In addition we derive speed changes for Karakoram, a region assumed to have positive mass balance and that contains many surge-type glaciers. We find that the mapped glaciers in the five regions with negative mass balance have over the last decades decreased their velocity at an average rate per decade of: 43 % in the Pamir, 8 % in the Caucasus, 25 % on Penny Ice Cap, 11 % in the Alaska Range and 20 % in Patagonia. Glaciers in Karakoram have generally increased their speeds, but surging glaciers and glaciers with flow instabilities are most prominent in this area. Therefore the calculated average speed change is not representative for this area.

Origin, age, and paleoenvironmental significance of carbonate precipitates from a granitic environment, Akshayuk Pass, southern Baffin Island, Canada

This study documents the discovery of calcite crusts on the upper surface of clasts within morainic complexes in Akshayuk Pass, southern Cumberland Peninsula (Baffin Island), a region underlain by granitic and gneissic rocks of the Precambrian Canadian Shield. Strontium isotope ratios (87Sr/86Sr) indicate that the major source of calcium is derived from the local dissolution of fracture-filling calcite and a minor source is derived from silicate weathering. The calcite crusts have δ13C values between 1.6‰ and 12.0‰ and δ18O values in the –13.0‰ and –7.9‰ range. These values are highly enriched over the predicted isotopic values based on the δ13CDIC and δ18O of the local water and temperature at which calcite precipitation occurred. The isotopic enrichments are attributed to a combination of both equilibrium and kinetic evaporation and were verified experimentally. The series of evaporative experiments indicate that kinetic evaporation produces a far-from-equilibrium isotope effect on both the δ13C and δ18O composition of the precipitating calcite (13CKIE CaCO3–CO2 between 20.2‰ and 40.5‰ VPDB; 18OKIE averaging 34.9% ± 3.7% VSMOW). Based on these results, the formation of the calcite crusts is ascribed to the evaporation of stagnating ephemeral lakes and streams following the retreat of valley glaciers. Given the >1500 m difference in heights between the highland and the valley, the katabatic winds originating from the Penny Ice Cap can act as a catalyst to increase the rate of evaporation. In addition, radiocarbon dating of ten of these crusts yielded Holocene ages (7640 cal (calibrated) BP to modern). These results suggest that the maximum expansion of Holocene valley glacier in Akshayuk Pass, previously thought to have occurred during the Little Ice Age, is probably much older.