Regime Shifts in Glacier and Ice Sheet Response to Climate Change: Examples From the Northern Hemisphere

Marshall, Shawn J.

doi:10.3389/fclim.2021.702585

Cited by 10 publications

(11 citation statements)

References 135 publications

(199 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As a result, englacial temperatures generally rise, and part of the glaciers or ice caps in the inner Tien Shan can undergo a transition from a cold to a polythermal or from a polythermal to a temperate regime (Arkhipov et al, 2004;Gusmeroli et al, 2012). Such a transition enhances ice flow and can fundamentally alter the ice dynamics (Marshall, 2021).…”

Section: Thermal Regime Since the Lia And Into The Futurementioning

confidence: 99%

Thermal regime of the Grigoriev ice cap and the Sary-Tor glacier in the inner Tien Shan, Kyrgyzstan

Tricht

Huybrechts²

2022

The Cryosphere

View full text Add to dashboard Cite

Abstract. The thermal regime of glaciers and ice caps represents the internal distribution of ice temperatures. An accurate knowledge of the thermal regime of glaciers and ice caps is important to understand their dynamics and response to climate change and to model their evolution. Although the assumption is that most ice masses in the Tien Shan are polythermal, this has not been examined in appropriate detail so far. In this research, we investigate the thermal regime of the Grigoriev ice cap and the Sary-Tor glacier, both located in the inner Tien Shan in Kyrgyzstan, using a 3D higher-order thermomechanical ice flow model. Input data and boundary conditions are inferred from a surface energy mass balance model, a historical air temperature and precipitation series, ice thickness measurements and reconstructions, and digital elevation models. Calibration and validation of the englacial temperatures are performed using historical borehole measurements on the Grigoriev ice cap and radar measurements for the Sary-Tor glacier. The results of this study reveal a polythermal structure of the Sary-Tor glacier and a cold structure of the Grigoriev ice cap. The difference is related to the larger amount of snow (insulation) and refreezing meltwater (release of latent heat) for the Sary-Tor glacier, resulting in higher surface layer temperature, especially in the accumulation area, which is subsequently advected downstream. Further, ice velocities are much lower for the Grigoriev ice cap, with consequent lower horizontal advection rates. A detailed analysis concerning the influence of temperature and precipitation changes at the surface reveals that the thermal structure of both ice bodies is not constant over time, with recent climate change causing increasing ice temperatures in higher areas. The selected ice masses are representative examples of the (inner) Tien Shan glaciers and ice caps. Therefore, our findings and the calibrated parameters can be generalised, allowing improved understanding of the dynamics and future evolution of other glaciers and ice caps in the region.

show abstract

Section: Thermal Regime Since the Lia And Into The Futurementioning

confidence: 99%

Thermal regime of the Grigoriev ice cap and the Sary-Tor glacier in the inner Tien Shan, Kyrgyzstan

Tricht

Huybrechts²

2022

The Cryosphere

View full text Add to dashboard Cite

show abstract

“…Alpine glaciers are the focus of the longest running observational records of glacier flow (Seligman, 1949; Clarke, 1987) and respond rapidly to changes in climate (Marcott and others, 2019; Marshall, 2021). Thus, they provide empirical constraints on decadal to centennial dynamic responses that remain poorly understood in other parts of the cryosphere (review in Davison and others, 2019, see their Fig.…”

Section: Introductionmentioning

confidence: 99%

Multi-decadal basal slip enhancement at Saskatchewan Glacier, Canadian Rocky Mountains

Stevens

Roland²,

Zoet³

et al. 2022

J. Glaciol.

View full text Add to dashboard Cite

Glacier motion responds dynamically to changing meltwater inputs, but the multi-decadal response of basal sliding to climate remains poorly constrained due to its sensitivity across multiple timescales. Observational records of glacier motion provide critical benchmarks to decode processes influencing glacier dynamics, but multi-decadal records that precede satellite observation and modern warming are rare. Here we present a record of motion in the ablation zone of Saskatchewan Glacier that spans seven decades. We combine in situ and remote-sensing observations to inform a first-order glacier flow model used to estimate the relative contributions of sliding and internal deformation on dynamics. We find a significant increase in basal sliding rates between melt-seasons in the 1950s and those in the 1990s and 2010s and explore three process-based explanations for this anomalous behavior: (i) the glacier surface steepened over seven decades, maintaining flow-driving stresses despite sustained thinning; (ii) the formation of a proglacial lake after 1955 may support elevated basal water pressures; and (iii) subglacial topography may cause dynamic responses specific to Saskatchewan Glacier. Although further constraints are necessary to ascertain which processes are of greatest importance for Saskatchewan Glacier's dynamic evolution, this record provides a benchmark for studies of multi-decadal glacier dynamics.

show abstract

“…Nevertheless, firn changes due to climate change (e.g. Barzycka et al, 2020;Marshall, 2021) must also be assumed for Central Asian glaciers. Kutuzov (2005) discusses the potential of a firn facies change from the cold infiltration-recrystallisation (cold firn) to the infiltration (firn-ice zone) for Gregoriev ice cap.…”

Section: State Of Firnmentioning

confidence: 99%

“…Locations that were previously located in the recrystallisation and recrystallisation-infiltration zones might recently have and will in the future likely experience higher melt rates. The cold and also warm infiltration zones will therefore become more abundant under climate change (Barzycka et al, 2020;Marshall, 2021). Under such conditions, it will become increasingly necessary to combine core data with modelling approaches to interpret the firn core records as it was done in van Pelt et al (2014).…”

Section: Relevancementioning

confidence: 99%

See 1 more Smart Citation

Changing glacier firn in Central Asia and its impact on glacier mass balance

Kronenberg

View full text Add to dashboard Cite

Glaciers in the Central Asian mountain ranges Tien Shan, Pamir and Pamir Alay are important water reservoirs for the dry low lands. These mountain glaciers attracted scientific interest already early. Soviet research programs investigated several sites from the 1960s until the 1990s. The resulting historical data are unique for the region and essential to answer open questions about the glaciers’ response to climate change. Regional-scale remote sensing studies reported balanced or positivemass changes for glaciers in Western High Mountain Asia for the last decades. With glaciers losing mass globally, this is a unique phenomenon. A precipitation increase is discussed to be a potential reason of this mass balance anomaly. However, the lack of in situ data hampers strengthening these assumptions and impedes quantifying the uncertainties of studies based on remote sensing data and gridded precipitation products. The Pamir Alay is located at the edge of the anomalous regions. Soviet researchers collected unique glaciological and meteorological data for Abramov glacier, located in this data-scarce region. Of particular interest are very detailed firn studies that provide information about the past precipitation rates and allow studying accumulation processes. Thanks to the availability of further, exceptionally detailed measurements, it is possible to relate the accumulation processes to the glacier-wide mass balance. This thesis aims at investigating the historical and present firn conditions of Abramov glacier as well as the changes therein over the past five decades. The firn processes were related to the surface energy andmass balance of Abramov glacier. Thereby, the influence of firn changes on the glacier-wide mass balance was studied. The underlying work involved (i) compiling and processing of historical firn, mass balance and meteorological data; (ii) measuring current firn conditions; and (iii) applying a coupled surface energy balance – multilayer subsurface model to Abramov glacier. The comparison of historical and current in situ data showed that the firn conditions of Abramov glacier have changed little between the 1970s and 2018. The data, however, also suggested a precipitation increase. The results of the coupled firn-mass balance model indicate that the firn properties of the 1970s were the result of specific meteorological conditions with low precipitation and high incoming solar radiation. These conditions were also reflected in very negative glacier mass balances. Precipitation increased during the following decades and allowed the firn to recover in the upper areas of the accumulation zone. Therefore, the internal accumulation (refreezing of melt water in the firn) increased. It is also shown that internal accumulation substantially contributed to the glacier-wide mass balance of Abramov. For the most recent years, firn conditions become again icier and mass losses increased. The presented thesis found in situ evidence of increased precipitation rates and their positive impact on themass balance for a glacier located in the data scarce western High Mountain Asia. The work highlights the importance of firn processes for understanding the response of mountain glaciers to climate change. Moreover, it demonstrates the importance of historic (Soviet) research and the suitability of the Russian terminology for analysing firn processes. Die Gletscher imZentralasiatischen Pamir-, Pamir Alay- und Tien Shan-Gebirge sind wichtige Wasserspeicher für das tiefer gelegene trockene Vorland. Schon früh haben diese Gletscher wissenschaftliches Interesse geweckt. Sowjetische Forschungsprogramme haben mehrere Standorte von den 1960er bis in die 1990er Jahre intensiv untersucht. Diese historischen Daten sind für die Region einmalig und könnten helfen, offene Fragen bezüglich der dortigen Gletscherveränderungen als Folge des Klimawandels zu beantworten. Mehrere regionale fernerkundungsbasierte Studien haben gezeigt, dass Gletscher in den westlichen Hochgebirgen Asiens in den letzten Jahrezehnten eine positive oder ausgeglicheneMassenbilanz hatten, während weltweit ein Gletscherschwund vorherrscht. Als Ursache für dieseMassenbilanzanomalie wird vermutet, dass der Niederschlag angestiegen ist. Umdiese Vermutungen zu festigen und umUnsicherheiten von Studien, die auf Fernerkundungsdaten oder meteorologischen Datensätzen basieren, zu klären, fehlt es leider an in-situ Daten. Der Pamir Alay liegt amRande der anomalen Gebiete. Sowjetische Forschende haben einmalige glaziologische und meteorlogische Daten für den sich dort befindenden Abramov Gletscher erhoben. Von besonderem Interesse sind die ausführlichen Firnuntersuchungen. Diese Daten vermitteln Hinweise zu den vergangenen Niederschlagsraten und erlauben es, die Akkumulationsprozesse zu untersuchen. Dank der Verfügbarkeit von weiteren, aussergewöhnlich detailliertenMessungen für diesen Gletscher ist esmöglich, die Akkumulationsprozesse mit der Gletschermassenbilanz in Zusammenhang zu bringen. Diese Arbeit hat zum Ziel, die historischen sowohl als auch die gegenwärtigen Firnbedingungen des Abramov Gletschers sowie deren Veränderungen über fünf Dekaden zu untersuchen. Firnprozesse wurden mit der Oberflächen Energie- undMassenbilanz des Gletschers in Zusammenhang gebracht, umden Einfluss der Akkumulations- und Firnveränderungen auf die Gletschermassenbilanz zu verstehen. Dafür wurden die historischen Firn-,Massenbilanz- und meteorologischen Daten aufgearbeitet, neue Firndaten erhoben und ein gekoppeltes Firn-Massenbilanz-Modell angewendet. Der Vergleich von historischen und aktuellen in-situ Daten hat aufgezeigt, dass sich der Firn des Abramov Gletschers zwischen den 1970er Jahren und 2018 kaum verändert hat. Die Daten weisen jedoch auf einen Niederschlagsanstieg hin. Die Resultate des gekoppelten Firn-Massenbilanz-Modelles zeigen auf, dass die meteorologischen Bedingungen in den 1970ern unvorteilhaft für den Abramov Gletscher waren. In den folgenden Jahrzehnten nahm der Niederschlag zu und der Firn konnte sich in den höheren Lagen des Akkumulationsgebietes vollständig erholen. Dies führte zu einer erhöhten internen Akkumulation (Wiedergefrieren des Schmelzwassers imFirn), welche einen bedeutenden Anteil an der Gletschermassenbilanz hatte. In den letzten Jahren haben sich die Firnbedingungen und Massenveränderungen wiederum verschlechtert. Die vorgelegte Arbeit zeigt aufgrund von in-situ Daten, dass der vermutete Niederschlagsanstieg in den westlichenHochgebirgen Asiens auf den Abramov Gletscher zutrifft und dass dieser Anstieg einen positiven Einfluss auf dieMassenbilanzentwicklung des Gletschers hat. Die Ergebnisse dieser Arbeit unterstreichen die Bedeutung von Firnprozessen für das Verständnis der Reaktion von Gebirgsgletschern auf den Klimawandel. Die Arbeit weist ausserdemauf die Relevanz historischer (sowjetischer) Forschung und die Bedeutung der russischen Terminologie für die Analyse von Firnprozessen hin.

show abstract

Regime Shifts in Glacier and Ice Sheet Response to Climate Change: Examples From the Northern Hemisphere

Cited by 10 publications

References 135 publications

Thermal regime of the Grigoriev ice cap and the Sary-Tor glacier in the inner Tien Shan, Kyrgyzstan

Thermal regime of the Grigoriev ice cap and the Sary-Tor glacier in the inner Tien Shan, Kyrgyzstan

Multi-decadal basal slip enhancement at Saskatchewan Glacier, Canadian Rocky Mountains

Changing glacier firn in Central Asia and its impact on glacier mass balance

Contact Info

Product

Resources

About