‘Most Ice on Earth is Very Close to Melting Conditions’

Even if we change our emissions now, we are committed to a lot of ice melt, says Prof. Kääb. Image credit – Sharada Prasad CS, licensed under CC BY 2.0

We need to understand how glaciers are shrinking in order to better adapt to climate change impacts such as changes to water supply, landslides and avalanches, says Professor Andreas Kääb, a glacier expert from the University of Oslo in Norway. 

Measuring ice melt and the unprecedented changes in our cryosphere––the frozen parts of the planet which regulate the climate by reflecting the sun’s heat––is crucial for understanding future situations, he says.

We spoke to Prof. Kääb about the importance of the cryosphere and what we know about how it’s changing.

‘Glaciers are typically found comparably close to where people live. That means their changes affect people quite directly.’

‘Glaciers are typically found comparably close to where people live. That means their changes affect people quite directly.’

Professor Andreas Kääb, University of Oslo, Norway

Why is the cryosphere important?

‘The cryosphere––that is glaciers and ice sheets, snow, sea ice, permafrost, and lake and river ice––and changes of the cryosphere affect the lives of hundreds (of) millions (of people) and many ecosystems in various direct and indirect ways. Seasonal or year-round snow covers around 45 million sq km, and glaciers and the Greenland and Antarctic ice sheets an additional 15 million sq km, together (constituting) around 40% of the Earth’s land area.

‘Importantly, most ice on Earth is very close to melting conditions, a few degrees below 0°C, and thus reacts very sensitively to changes in air temperatures. Small temperature changes can trigger melt and (large) environmental changes. Sea level change through increased melt of glaciers and ice sheets is certainly the most far-reaching effect of ice melt on Earth.’

How are sea levels changing?

‘Melting of glaciers, (and) the two ice sheets in Greenland and Antarctica contributes to more than half of the currently measured sea level rise and they are projected to contribute more. The other half is thermal expansion––as the ocean gets warmer it expands––and all this sea level change affects people around the world, especially in coastal areas, (and) even if living far away from the melting ice.

‘Mean sea level is projected to rise about 1 metre by 2100 and will threaten coastal societies. How much the ocean would rise in (the) case of an, unrealistic, complete melt of the Antarctic ice sheet is around 60m.’

What are the other impacts of ice melt?

‘In terms of more local effects, there are a number of hazards relating to glaciers and thawing permafrost that we expect to increase. For instance, if glaciers retreat they leave steep mountain flanks uncovered so there is debris and rocks that are set to destabilise. So, we expect more rockfalls or debris flows from such areas.

‘Greenhouse gas emissions from thawing permafrost are much less understood, but could have an equally wide, actually global, impact by enhancing manmade emissions.

‘Then there are also hazard situations that could actually improve. (Ice avalanches from glaciers) can destroy infrastructure, houses and kill people. But (there’s) the extreme case (where) if a glacier retreats very much, then the hazard from related ice avalanches could actually reduce.’

Glaciers are typically found close to where people live and changes can directly affect people’s lives, says Prof. Kääb. Image credit – Andreas Kääb

Do you think we have passed a tipping point when it comes to ice melt?

‘The term tipping point is a bit controversial, because in most cases we don’t really know. Another term that is better is what the IPCC (International Panel on Climate Change) uses––committed (climate) change. So, climate change that man has contributed to has committed changes to the future.

‘That means the excess energy that mankind has already caused (through greenhouse gas emissions capturing the sun’s heat) will commit a long-term change in glaciers, ice sheets and ocean temperatures. Change that, let’s say, over a hundred years is irreversible. Even if we change our emissions now, a lot of ice melting has been committed.’

You focus on glaciers. Why do we need to understand glacier change?

‘Glaciers are typically found comparably close to where people live. That means their changes affect people quite directly. Understanding glacier change helps to adapt to related climate change impacts such as changes in dry-season run-off and water supply, changes in glacial landslides and avalanches, or changes in the touristic value of glaciers.

‘Glaciers reflect climate change in a very visible and clear way. Their shrinkage has become for good reason an icon of climate change. For scientists, glaciers are important to illustrate climate change and make it understandable for a large audience.’

You were the coordinator of ICEMASS, a project using satellite imagery to measure and analyse changes to glaciers. How did you analyse change?

‘We have increasingly more and more different satellite data, and what the satellites measure is very different. My main goal, my main achievement, of the ICEMASS project was actually bringing different data together and integrating them. For instance, we use optical satellite images repeatedly to measure glacier flow. This works perfectly fine unless you have cloud cover or polar night (24-hour darkness). Then we use radar images that penetrate through clouds for the same purpose. But this does not give us the volume of glaciers.

‘For that we use, among others, satellites that shoot laser beams, like your laser pointer, and they measure the return time of this signal. The signal is sent from a satellite, bounces (off) the glacier surface, and comes back to the satellite. The time difference is directly related to the distance from the satellite to the (glacier surface). So, if you know the satellite position very well, which we do, then you can measure the height. And if you do that, over time, repeatedly, you get also the changes in glacier thickness and volume.’

The ICEMASS project analysed glacier avalanches in Tibet, with satellite images showing before (left) and after (right) the events. Image credit – Contains modified Copernicus Sentinel data (2019)/processed by A. Kääb, Department of Geosciences, University of Oslo, 2019

And what did you find?

‘For me, personally, the most important results are more regional scale results. We developed glacier volume changes over a number of areas where little was known before. One of the examples that made it into the Nature journal, for instance, was glacier volume changes over the Himalayas and Central Asia. There was a lot of different numbers around for these melting glaciers––some actually massively contradicted each other––from very little change to massive change. And we (really) narrowed this uncertainty down.’

What did your project reveal about the state of glaciers around the world?

‘We found glacier mass loss in almost all regions we looked at. Unexpected large losses we measured in the European Arctic, on Svalbard. The massive retreat of sea ice in this sector of the Arctic raises air temperatures at a rate of roughly double the global average. The result is glacier melt rates (that are) much higher than one would expect so far north. In addition, about half of the glacier mass loss comes not from direct glacier melt but from glaciers that massively increased their ice flow and thus their ice discharge into the ocean.

‘(We found) unexpected low changes in glacier mass, lower than the global average, in parts of Central Asia, in the Karakoram, Pamir, and western parts of Tibet. There is even a region where glaciers grow a little bit. By also measuring changes of lakes without direct river outflow, we could show that the region received in recent years more precipitation, which let the lakes and the glaciers grow, despite air temperatures increasing at the same time.’   

This year’s IPCC Special Report on the Ocean and Cryosphere says climate change will cause up to 80% loss of glaciers in some places by the year 2100. What can research do to help society prepare for this future melting?

‘Carbon dioxide levels are much higher than they have been for the last 1 million years or more. This means our climate is at a stage where we don’t have historical experience to build sound statistics on extreme events. So, we need to monitor more what is going on now and then we need to better model future scenarios.  

‘The EU has their own fleet of satellites, the Sentinels within the Copernicus programme. They are really a game changer because before them there were mostly occasional scientific satellites.

‘These EU satellite constellations, in my experience, help develop models and strategies for really long-term perspectives. (We need these) satellites to allow for the long-term, consistent, observations that we need to predict and adapt to climatic changes.’

This interview has been edited and condensed.

This Q&A was written by Steve Gillman and originally appeared in Horizon Magazine. The research in this article was funded by the EU’s European Research Council.

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Iceberg calving can create powerful waves when large chunks of ice fall from glaciers into the ocean. A recent study conducted 66 experiments to better understand the features of iceberg calving to determine iceberg-tsunami strength and parameters.

Read the story by Elza Bouhassira on GlacierHub here.

The pool used by the researchers during the experiments. In the image, a gravity-dominated experiment is being conducted (Source: Figure 2/Heller et al).

Crowded Backcountry Ski Slopes Increase Risk of Skiers Endangering Each Other

Avalanche risk is on the rise as more people enter backcountry alpine terrain. A new study seeking to quantify the risk to multi-party avalanches hopes to raise awareness and provoke discussion.

Read the story by Grennan Milliken on GlacierHub here.

A skier during a run down Hurricane Ridge in Olympic National Park, Washington State. (Credit: National Park Service)

Cruikshank Awarded Polar Knowledge Canada’s 2019 Northern Science Award

From the Polar Knowledge Canada press release: “Polar Knowledge Canada is pleased to announce that the recipient of the 2019 Northern Science Award is Dr. Julie Cruikshank. The award was presented at the ArcticNet Annual Scientific Meeting on December 5, 2019, in Halifax, Nova Scotia.

“Dr. Cruikshank, Professor Emerita of Anthropology at the University of British Columbia, has a long and distinguished record of documenting the oral histories and life stories of Athapaskan and Tlingit elders, and exploring Yukon First Nations’ systems of narrative and knowledge. Her work, built on a foundation of respectful relationships, has helped Yukon First Nations recognize and honour the strengths of their cultural traditions, and has brought new insight into the nature of history and the interplay of different knowledge systems. Yukon Indigenous governments regularly draw on Dr. Cruikshank’s work and her knowledge.”

Read the story published by Polar Knowledge Canada here.

Dr. Julie Cruikshank (Source: University of British Columbia).

Crowded Backcountry Ski Slopes Increase Risk of Skiers Endangering Each Other

Year by year, more backcountry skiers travel to mountain ranges across America. There is some worry that avalanche accidents involving multiple groups of people will grow as a result. A recent paper published on the open access website arXiv suggests that this risk increases with the density of skiing parties in a given area. Put simply, the closer together multiple groups of skiers are on a slope, the higher their chances are of endangering one another with an avalanche.

As their name suggests, inter-party avalanches involve at least two people or groups: one inadvertently triggers the avalanche, and the others are swallowed up by it. This type of hazard—and its increasing likelihood in the age of an overpopulated backcountry—has been discussed by the skiing community before, but this paper’s author, Charlie Hagedorn, has put it in a mathematical context so it can be measured. In the paper, he builds a model that attempts to predict at what point the risk of an avalanche starts to increase—and by how much—as the density of skiing groups ticks up in a given area.

Hagedorn, a physics researcher at the University of Washington and a backcountry skier himself, was inspired to pursue the topic after a backcountry traveller disappeared on a slope he has skied many times. The paper is written as a discussion piece, to spur a professional conversation among avalanche experts on inter-party accidents.

“The idea with this paper is to create a mathematical framework and start a rigorous professional conversation about inter-party incidents while the rate remains small,” Hagedorn told GlacierHub. 

His model indicates that the key variable affecting the likelihood of an inter-party avalanche is the density of ski groups (consisting of one or more people). The likelihood of one of these avalanches increases as the square of the density of groups in the area.

Mt Rainier (foreground) sticks above the clouds in the Cascades mountain range of the Pacific Northwest. One of the incidents in the paper occurred by the Nisqually and Wilson glaciers on Rainier. (Credit: Dllu)

The incident that stirred Hagedorn to make this model occurred on December 19, 2015. Two parties of backcountry travelers were skiing just below the ridgeline on Kendall Peak in Mt. Baker-Snoqualmie National Forest in the Cascades in Washington State. This area is considered “avalanche terrain”—a tract of land where avalanches occur. The region had been hit by record breaking snowfall, and deep powdery snow had piled up on the peak.

After a run, one of the groups recalled passing a solo skier further down the slope. As they ascended through the glades for another go, they witnessed a series of avalanches triggered by the other party of skiers further up by the ridgeline.

Later that day the solo skier they had passed was reported missing. A 3,000-man-hour search and rescue effort ended six months later, when the skier’s body was found face down, ski poles scattered 40 to 50 feet above him, and some personal belongings strewn about further downhill. According to the accident report, an avalung pack—a device meant to help people breathe while buried under snow—lay next to his body, the mouthpiece visible.

Hagedorn was in the vicinity on the day when the skier disappeared and was involved with the six-month search and post-accident investigation. The subsequent report concluded it was possible the skier was killed by one of the human-caused avalanches. The experience, he told GlacierHub, was impactful. “Friends and I were easily within half a kilometer of him the day he disappeared,” he said.  

A skier during a run down Hurricane Ridge in Olympic National Park, Washington State. (Credit: National Park Service)

There are many kinds of avalanches, all of which depend on a particular recipe of conditions to occur, but snow and avalanche scientist Jordy Hendrikx of Montana State University told GlacierHub that slab avalanches typically require four ingredients: a slab of cohesive snow, a weak layer (below the slab), a slope of 30 degrees or greater, and a trigger. 

Triggers come in many forms: new snow, wind, a cornice drop; but when fatal accidents occur they’re usually triggered by people. “Research shows that ninety percent of avalanche accidents are triggered by either a victim or a member of the victim’s group,” said Hendrikx.

Hagedorn described trigger points as being “not unlike a minefield.” The more groups of people passing through avalanche terrain, the higher the chances of someone plodding on one. “There have been many accidents, where a slope that has been skied many times has avalanched when a person has hit just the right spot at just the right time.”

In addition to the Kendall Peak accident, Hagedorn chronicled 12 other incidents of inter-party avalanches, including one from the Nisqually and Wilson glaciers on Mt. Rainier. That one, from 2008, was triggered by a descending party of skiers and caught a splitboarder and skier on its way down. It nearly swallowed a party of ice climbers as well, as it plowed passed the convergence of the two glaciers. 

Backcountry skiing can sometimes require arduous hiking as well. This skier is huffing it up a slope in the Gallatin Mountains of Yellowstone National Park. (Credit: National Park Service)

There are discussions in the backcountry community of skiers using radios to communicate with each other, or mapping/sharing information on their ski runs in order to keep an awareness of who is above and below on the slope.

Safe behavior cannot always protect you from someone else’s unsafe behavior, however. One study found that overconfident skiers expose themselves to more “black swan” events like avalanche pileups. Even experienced skiers, according to another study, are susceptible to skiing risky terrain because of social pressures.

The best action, said Hagedorn, is to avoid densely skied areas altogether. He has sharply curtailed visits to such places and instead skis regions that are harder to access or have lower quality snow. In his paper, he writes that there are still “lonely places with great skiing” out there. 

Hendrikx expressed a similar sentiment. “We have plenty of mountains and space—it’s just that we all crowd into certain spots, in increasingly marginal conditions” he said. And it’s mostly because those spots have “easy access and good snow.”

Hagedorn hopes this paper can spark quantitative study of inter-party avalanches—especially in Europe which has dealt with high mountain population densities for some time. But, perhaps more than that, “this paper,” he said, “is an attempt, among several, to push back at entropy a little, to find something helpful from within a tragedy.”

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Last Remaining Glaciers in the Pacific Will Soon Melt Away

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