Leif S. Anderson

• Doctor of Philosophy
• Research Professor at University of Utah

Many glaciers are thinning rapidly beneath melt-reducing debris cover, including Kennicott Glacier in Alaska where glacier-wide maximum thinning also occurs under debris. This contradiction has been explained by melt hotspots, such as ice cliffs, scattered within the debris cover. However, melt hotspots alone cannot account for the rapid thinning a...

The increasingly common disappearance of glaciers is striking, and it is often used to highlight the effects of anthropogenic climate change to the public. This approach is more effective when modern glacier and climate change is placed within a frame of reference. Here we present a new, efficient method to assess the timing of glacier birth and de...

Many debris-covered glaciers have broadly similar debris thickness patterns: surface debris thickens and tends to transition from convex- to concave-up-down glacier. We explain this pattern using theory (analytical and numerical models) paired with empirical observations. Down glacier debris thickening results from the conveyor-belt-like nature of...

Debris-covered glaciers are common in rapidly eroding alpine landscapes. When thicker than a few centimeters, surface debris suppresses melt rates. If continuous debris cover is present, ablation rates can be significantly reduced leading to increases in glacier length. In order to quantify feedbacks in the debris–glacier–climate system, we develop...

Alpine ice varies from pure ice glaciers to partially debris-covered glaciers to rock glaciers, as defined by the degree of debris cover. In many low- to mid-latitude mountain ranges, the few bare ice glaciers that do exist in the present climate are small and are found where snow is focused by avalanches and where direct exposure to radiation is m...

Constraining the timescales of sediment transport by glacier systems is important for understanding the processes controlling sediment dynamics within glacierized catchments, and because the accumulation of supraglacial sediment influences glacier response to climate change. However, glacial sediment transport can be difficult to observe; sediment...

The Chaos Canyon landslide, which collapsed on the afternoon of 28 June 2022 in Rocky Mountain National Park, presents an opportunity to evaluate instabilities within alpine regions faced with a warming and dynamic climate. Video documentation of the landslide was captured by several eyewitnesses and motivated a rapid field campaign. Initial estima...

Glaciers across High Mountain Asia (HMA) are thinning and retreating in widely varying patterns. The cause of this variability has been controversial for decades, hindering predictions of water resources and hazards for 800 million people downstream. We show that this heterogeneity is strongly affected by debris cover on glaciers. We propose a new...

Glaciers expel sediment as they melt, in addition to ice and water. As a result, changing glacier dynamics and melt produce changes to glacier erosion and sediment discharge, which can impact the landscape surrounding retreating glaciers, as well as communities and ecosystems downstream. Currently, numerical models that transport subglacial sedimen...

The Chaos Canyon landslide, which collapsed on the afternoon of June 28th, 2022 in Rocky Mountain National Park presents an opportunity to evaluate instabilities within alpine regions faced with a warming and dynamic climate. Video documentation of the landslide was captured by several eyewitnesses and motivated a rapid field campaign. Initial esti...

The exhumation of bedrock is controlled by the interplay between tectonics, surface processes, and climate. The highest exhumation rates of centimeters per year are recorded in zones of highly active tectonic convergence such as the Southern Alps of New Zealand or the Himalayan syntaxes, where high rock uplift rates combine with very active surface...

The exhumation of bedrock is controlled by the interplay between tectonics, surface processes, and climate. The highest exhumation rates of centimeters per year are recorded in zones of highly active tectonic convergence such as the Southern Alps of New Zealand or the Himalayan syntaxes, where high rock uplift rates combine with very active surface...

Melt from debris‐covered glaciers represents a regionally important freshwater source, especially in high‐relief settings as found in central Asia, Alaska, and South America. Sub‐debris melt is traditionally predicted from surface energy balance models that determine heat conduction through the supraglacial debris layer. Convection is rarely addres...

Plain Language Summary Glaciers are imagined as bodies composed entirely of snow and ice. But many glaciers, especially those in steep mountains contain a substantial amount of rock as well. Rocks are deposited on glaciers from steep mountain slopes above them. This loose rock (or debris), buried by snow, can completely cover glaciers' lower reache...

Climate change affects the stability and erosion of high‐alpine rock walls above glaciers (headwalls) that deliver debris to glacier surfaces. Since supraglacial debris in the ablation zone alters the melt behaviour of the underlying ice, the responses of debris‐covered glaciers and of headwalls to climate change may be coupled. In this study, we a...

In addition to ice and water, glaciers expel sediment. As a result, changing glacier dynamics and melt will result in changes to glacier erosion and sediment discharge, which can impact the landscape surrounding retreating glaciers, as well as communities and ecosystems downstream. To date, the available models of subglacial sediment transport on t...

The cause of debris-covered glacier thinning remains controversial. One hypothesis asserts that melt hotspots (ice cliffs, ponds, or thin debris) increase thinning, while the other posits that declining ice flow leads to dynamic thinning under thick debris. Alaska’s Kennicott Glacier is ideal for testing these hypotheses, as ice cliffs within the d...

Many glaciers in High Mountain Asia are experiencing the debris-cover anomaly. The Kennicott Glacier, a large Alaskan Glacier, is also thinning most rapidly under debris cover. This contradiction has been explained by melt hotspots, such as ice cliffs, streams, or ponds scattered within the debris cover or by declining ice flow in time. We collecte...

Thick debris cover, greater than about 5 cm, insulates ice and reduces melt rates. Despite this melt- suppressing effect, glaciers often thin rapidly under thick debris cover. In High Mountain Asia, the European Alps, and Alaska many debris-covered and debris-free glacier tongues are thinning at similar rates (e.g., Kääb et al., 2012). This apparen...

High resolution topographic modeling has become more accessible due to the development of Structure from Motion (SfM) image matching algorithms in digital photogrammetry. Large archival databases of historical aerial photographs are available in university, public, and government libraries, commonly as paper copies. The photos can be in poor condit...

The mass balance of many valley glaciers is enhanced by the presence of melt hotspots within otherwise continuous debris cover. We assess the effect of debris, melt hotspots, and ice dynamics on the thinning of Kennicott Glacier in three companion papers. In Part A we report in situ measurements from the debris-covered tongue. In Part B, we develop...

The mass balance of many Alaskan glaciers is perturbed by debris cover. Yet the effect of debris on glacier response to climate change in Alaska has largely been overlooked. In three companion papers we assess the role of debris, ice dynamics, and surface processes in thinning Kennicott Glacier. In Part A, we report in situ measurements from the gl...

The mass balance of many valley glaciers is enhanced by the presence of ice cliffs within otherwise continuous debris cover. We assess the effect of debris and ice cliffs on the thinning of Kennicott Glacier in three companion papers. In Part A we report in situ measurements from the debris-covered tongue. Here, in Part B, we develop a method to de...

Strong similarities in Holocene climate reconstructions derived from multiple proxies (BSi, TOC – total organic carbon, δ13C, C/N, MS – magnetic susceptibility, δ15N) preserved in sediments from both glacial and non-glacial lakes across Iceland indicate a relatively warm early to mid Holocene from 10 to 6 ka, overprinted with cold excursions presum...

Strong similarities in Holocene climate reconstructions derived from multiple proxies (BSi, TOC, δ¹³C, C/N, MS, δ¹⁵N) preserved in sediments from both glacial and non-glacial lakes across Iceland indicate a relatively warm early-to-mid Holocene from 10 to 6ka, overprinted with cold excursions presumably related to meltwater impact on North Atlantic...

Drangajökull is a maritime ice cap located in northwest (Vestfirðir) Iceland. Drangajökull's evolution is therefore closely linked to atmospheric and ocean variability. In order to better constrain the Holocene climate and glacier history of Vestfirðir we model the past evolution of Drangajökull ice cap. Simulations from 10 ka to present are forced...

Be dating of moraines has greatly improved our ability to constrain the timing of past glaciations and thus past cold events. However, the spread in ages from a single moraine is often greater than would be expected from measurement uncertainty, making paleoclimatic interpretations equivocal. Here we present 28 new ¹⁰Be ages from ice-cored Neoglaci...

Sub-meter resolution, stereoscopic satellite images allow for the generation of accurate and high-resolution digital elevation models (DEMs) over glaciers and ice caps. Here, repeated stereo images of Drangajökull ice cap (NW Iceland) from Pléiades and WorldView2 (WV2) are combined with in situ estimates of snow density and densification of firn an...

Sub-meter resolution satellite stereo images allow the generation of high resolution, accurate digital elevation models (DEMs). Repeated acquisitions of stereo images from Pléiades, in October 2014 and May 2015, and from WorldView2 (WV2), in February 2015, over Drangajökull ice cap (NW-Iceland) are used to estimate the geodetic glacier-wide mass ba...

Non-linear climate change is often linked to rapid changes in ocean circulation, especially around the North Atlantic. As the Polar Front fluctuated its latitudinal position during the Holocene, Iceland's climate was influenced by both the warm Atlantic currents and cool, sea ice-bearing Arctic currents. Drangaj€ okull is Iceland's fifth largest ic...

Systematic mapping of the bedrock beneath the Icelandic ice caps began in 1980. We continue this effort by presenting a detailed bedrock digital elevation model (DEM) of Drangajokull ice cap in NW-Iceland, surveyed using radio echo sounding (RES) in March 2014. About 590 km of RES profiles, generally with 200-300 m spacing, were surveyed. This is t...

Debris-covered glaciers are common in rapidly-eroding alpine landscapes. When thicker than a few centimeters, surface debris suppresses melt rates. If continuous debris cover is present, mass balance gradients can be reduced leading to increases in glacier length. In order to quantify feedbacks in the debris-glacier-climate system, we developed a 2...

Glaciers respond to climate variations and leave geomorphic evidence that represents an important terrestrial paleoclimate record. However, the accuracy of paleoclimate reconstructions from glacial geology is limited by the challenge of representing mountain meteorology in numerical models. Precipitation is usually treated in a simple manner and ye...

Valley glacier moraines are commonly used to infer past mean annual precipitation and mean melt-season temperature. However, recent research has demonstrated that, even in steady climates, multi-decadal, kilometer-scale fluctuations in glacier length occur in response to stochastic, year-to-year variability in mass balance. When interpreting morain...

Over many glacial cycles, the glacial erosion of alpine valleys can be sufficient to reduce the length of glaciers in the most recent cycles. We document field cases illustrative of this erosional feedback and model the long-term evolution of glacier lengths analytically and numerically. The general feature we target is a moraine deposited well bey...

Debris covered glaciers are common in tectonically active or highly erodible ranges such as the Himalaya, Tien Shan, Alps, Southern Alps, and the Wrangell Mountains. Debris cover has a variable effect on the mass balance profile depending on its thermal conductivity, albedo, and thickness. Although debris cover generally reduces melt, melt within d...