GeoLog

Cryospheric Sciences

Imaggeo on Mondays: High above the top of Europe

Imaggeo on Mondays: High above the top of Europe

Sentinel-2B imaged the highest mountains of western Europe, just the moment an airplane was about to fly over the granite peaks of Grandes Jorasses and cross the border from France to Italy. The passengers on the right side of the plane must have enjoyed a spectacular view on Mont Blanc, just nine kilometers away to the south-west, and Mer de Glace, the longest glacier in France flowing down from its peak.

Note the shadow of the granite “aiguilles” on fresh early winter snow in the upper part of the glacier. The famous Aiguille de Midi is casting its shadow on the village of Chamonix on the top-left, as late autumn colours are still visible on the larch in Val Ferret in the bottom-right corner of the image. Contains Copernicus Sentinel data (2018). Processed with Sentinelflow (v0.1.3).

Description by Julien Seguinot, as it first appeared on imaggeo.egu.eu.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: Exploring the underground cryosphere

Imaggeo on Mondays: Exploring the underground cryosphere

The winter season is a good time to take advantage of cold weather activities, whether that’s hitting the ski slopes or warming up by a fire, but for Renato R. Colucci, it’s also one of the best time’s to study the Earth’s underground cryosphere.

Colucci, who took this featured photograph, is a researcher at Italian Institute for Marine Sciences (ISMAR) of the National Research Council (CNR) and is a scientific lead partner for the Cave’s Cryosphere and Climate project, C3 for short. The C3 project aims to monitor, study, date, and model alpine ice cave environments.

This photo was taken by Colucci while he and the C3 project team were surveying a large ice deposit in the Vasto cave, situated within the Southeastern Alps of Italy. Speleologists of the E. Boegan Cave Commission began documenting the caves in this region in the 1960s, making it a great site for studying underground cryosphere today. For the past few years the C3 team has been monitoring the microclimates of these caves as well as analysing how the ice masses within are melting and accumulating ice.

There are many different kinds of ice deposits in caves, but the main difference is how these types accumulate their frozen mass. For some cave ice deposits, like the one featured in this photo, the snowfall that reaches the cave interior amasses over time into solid layers of ice, as is typical for many glaciers. However, other deposits take form when water from melting snow or rain percolates through rock’s voids and fractures, then freezes and accumulates into permanent ice bodies in caves.

These high-altitude underground sources of ice are a lesser-known faction of the cryosphere since they are not very common or reachable to scientists, but still an important one. Often the permanent ice deposits in caves contain pivotal information on how Earth’s climate has evolved over time during the Holocene.

However, if the Earth’s global temperatures keep increasing, this data might not be available in the future. While ice masses in caves are more resilient to climate change compared to their aboveground counterparts, many of these deposits, and the vital data they store, are melting away at an accelerating rate. “Global warming is rapidly destroying such important archives,” said Colucci.

Through this project, the researchers involved hope to better understand the palaeoclimate information stored in these deposits and how the ice will respond to future climate change.

By Olivia Trani, EGU Communications Officer

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Geosciences Column: Scientists pinpoint where seawater could be leaking into Antarctic ice shelves

Geosciences Column: Scientists pinpoint where seawater could be leaking into Antarctic ice shelves

Over the last few decades, Antarctic ice shelves have been disintegrating at a rapid rate, likely due to warming atmospheric and ocean temperatures, according to scientists. New research reveals that one type of threat to ice shelf stability might be more widespread that previously thought.

A study recently published in EGU’s open access journal The Cryosphere identified several regions in Antarctica were liquid seawater could be leaking into vulnerable layers of an ice shelf.

Scientists have known for some time now that seawater can seep into an ice shelf’s firn layer, the region of compacted snow that is on its way to becoming ice. This seawater infiltration presents an issue to the ice shelf’s stability, since as the seawater spreads throughout the firn layer, the water can create fractures and help expand crevasses already present in the frozen material. Past research has shown that the presence of liquid brine from seawater within an ice shelf is correlated to increased fracturing and calving.

While ice shelf collapse doesn’t directly contribute to sea level rise, since the ice is already floating, stable ice shelves often push back on land-based ice sheets and glaciers, slowing down ice flow into the ocean. Past research has suggested that once an ice shelf collapses, the rate of ice flow from unsupported glaciers can greatly accelerate.

To better understand Antarctic ice shelves’ risk of collapse, the researchers involved with this new study sought to identify where ice shelf firn layers are vulnerable to seawater infiltration. Using Antarctic geometry data, they mapped out the potential ‘brine zones’ within the continent’s ice shelves. These are regions of the ice shelf where the firn layer is both below the sea level and permeable enough to let seawater percolate through.

The results of their analysis revealed that almost all ice shelves in Antarctica have spots where seawater can potentially leak through their layers, with about 10-40 percent of the continent’s total ice shelf area possibly at risk of infiltration.

Map of potential brine zones areas around Antarctica. Map shows areas where permeable firn lies below sea level (the brine zone), with the threshold for firn permeability defined as 750 kg m−3 (red), 800 kg m−3 (yellow) and 830 kg m−3 (blue) calculated using Bedmap2 surface elevation. Bar charts show the mean percentage area of selected ice shelves covered by the brine zone. (Credit: S. Cook et al. 2018)

The researchers compared their estimated points to a map of previously confirmed brine zones, observed through ice cores or radar surveys. After reviewing these records, they identified only one record of brine presence that hadn’t been highlighted by their developed model.

The study found many areas in Antarctica where seawater infiltration could be possible, but has not been previously observed. The findings suggest that this firn layer vulnerability to seawater might be more widespread than previously believed.

The researchers suggest that the most likely new regions where brine from seawater may be present includes the Abbot Ice Shelf, Nickerson Ice Shelf, Sulzberger Ice Shelf, Rennick Ice Shelf, and slower-moving areas of Shackleton Ice Shelf. The regions all contain large swathes of permeable firn below sea level while also subject to relatively warm air temperatures and low flow speeds, the ideal conditions for maintaining liquid brine.

The study points out that there are still many uncertainties in this research, considering the unknowns still present in the data used for mapping and the factors that may influence seawater infiltration. For example, some areas that have large predicted brine zones have an unusually think layer of firn from heavy snowfall. This is the case for the Edward VIII Bay in eastern Antarctica. “Our results indicate the total ice shelf area where permeable firn lies below sea level, but this does not necessarily imply that the firn contains brine,” the authors of the study noted in their article.

Given their findings, the researchers involved recommend that this potentially widespread influence on ice shelves should be further examined and assessed by future studies.

By Olivia Trani, EGU Communications Officer

References

Cook, S., Galton-Fenzi, B. K., Ligtenberg, S. R. M. and Coleman, R.: Brief communication: widespread potential for seawater infiltration on Antarctic ice shelves, The Cryosphere, 12(12), 3853–3859, doi:10.5194/tc-12-3853-2018, 2018.

Hoegh-Guldberg, O., D. Jacob, M. Taylor, M. Bindi, S. Brown, I. Camilloni, A. Diedhiou, R. Djalante, K.L. Ebi, F. Engelbrecht, J.Guiot, Y. Hijioka, S. Mehrotra, A. Payne, S.I. Seneviratne, A. Thomas, R. Warren, and G. Zhou, 2018: Impacts of 1.5ºC Global Warming on Natural and Human Systems. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I.Gomis, E. Lonnoy, T.Maycock, M.Tignor, and T. Waterfield (eds.)]. In Press

Scambos, T. A.: Glacier acceleration and thinning after ice shelf collapse in the Larsen B embayment, Antarctica, Geophysical Research Letters, 31(18), doi:10.1029/2004gl020670, 2004.

Scambos, T., Fricker, H. A., Liu, C.-C., Bohlander, J., Fastook, J., Sargent, A., Massom, R. and Wu, A.-M.: Ice shelf disintegration by plate bending and hydro-fracture: Satellite observations and model results of the 2008 Wilkins ice shelf break-ups, Earth and Planetary Science Letters, 280(1–4), 51–60, doi:10.1016/j.epsl.2008.12.027, 2009.

State of the Cryosphere: Ice Shelves. National Snow & Ice Data Center

Imaggeo on Mondays: The changing landscape of Patagonia

Imaggeo on Mondays: The changing landscape of Patagonia

Pictured here is a snapshot of an environment in transition. Today’s featured photo was taken at the foot of Monte Fitz Roy, a jagged Patagonia mountain located in Los Glaciares National Park on the border between Argentina and Chile.

The Patagonia region in South America is the second biggest source of glaciers in the southern hemisphere, behind Antarctica, but the region is losing ice at a rapid rate.

Satellite imagery analysis over the last few years has suggested that the Patagonia region is losing ice more than any other part of South America, with some glaciers shedding ice faster than any place in the world.

A recent study reported that the northern and southern Patagonia ice fields in particular are losing roughly 17 billion tons of ice each year. Los Glaciares National Park alone is home to around 50 large glaciers, but because of warming temperatures, almost all of these large ice masses have been shrinking over the last 50 years.

This level of glacial ice loss can be hard to fully imagine, but in 2017, Shauna-Kay Rainford, a PhD student at Pennsylvania State University in the United States and photographer of this featured image, got a first-hand glimpse of Patagonia’s changing landscape.

“Ensconced between the granite boulders I felt like I was at a pivotal moment of continued change,” said Rainford. “While the peaks of Mt. Ritz Roy remain and will likely remain tall and majestic, with each passing year the glacier continues to retreat further towards the peak and the glacial lake continues to expand more and more.”

Rainford had reached this scenic yet tragically ephemeral view after a strenuous hike up the mountain. “It was very emotional to think about what this view will look like in the future if I should ever visit the mountain again,” Rainford recalls. “It is always striking to be confronted with the adverse consequences of human actions.”

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.