Learning to predict ‘life-threatening slush’ in Norway

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Dr. Christopher D’Amboise of UiT – The Arctic University of Norway (image courtesy of UiT)

This article is based on the geo research platform geoforskning.no article ‘Life-threatening slush’ (in Norwegian) by Ronny Setså.

The emergency services and traffic authorities in northern Norway had a busy winter this year. At the start of 2023, stormy wind and rain along the coast caused a higher than usual number of landslides. Many of these crossed roads, railway lines or power lines. And many of these were a kind of landslide that had been seen as unusual – slush avalanches. These fast-moving flows of waterlogged snow and debris are more destructive and unpredictable than snow avalanches. As winters become increasingly mild and wet, such events could occur more frequently. So, understanding the phenomenon and how to predict slush avalanches would be a useful step towards protecting communities and the infrastructure on which they rely. This is the focus of research by Christopher D’Amboise of the Department of Geoscience in IMPETUS partner organisation UiT – The Arctic University of Norway.

It is uncertain whether the many slush avalanches that occurred in Norway this past winter are due to the weather conditions alone, or whether the increased number is because professional institutions and the media have become better at distinguishing them from snow avalanches or loose mass avalanches such as mudslides. However, the expectation is that a warmer climate could lead to more slush avalanche events in the future.

I expect more slush avalanches if the weather continues to vary in winter, because rain on snow is particularly dangerous.

Christopher D’Amboise, researcher with the Department of Geoscience, UiT – The Arctic University of Norway

How and where slush avalanches happen

Mild temperatures in snow-covered areas causes ice and snow to melt. Meltwater or rainfall passing through snow can accumulate within the snow and drag snow molecules with it as it flows. This process can build and speed up, resulting in a fast-flowing slush avalanche. Containing at least 15 percent liquid water, these are much denser than snow and can flow much further and faster over much shallower slopes. This makes a slush avalanche far more difficult to stop. Also, slush avalanches often take all the snow with them and erode the ground underneath. According to a 2020 report by the Norwegian Directorate of Water Resources and Energy (NVE), slush avalanches can reach speeds of 100 km/h and create paths stretching several kilometres. This can make them particularly devastating to infrastructures such as roads and railways.

Although slush avalanches are probably widespread in all the countries around the Arctic, Norway has more infrastructure and a denser population in the high latitudes as compared to e.g. Canada. This makes the need and the opportunity to study them in Norway more fitting. This kind of landslide can also occur in snowy regions such as the Alps, but Norway’s midnight sun and more exposed bedrock are thought to be factors that increase the chances of slush avalanches happening there.

How to predict them

Relatively little is known about slush avalanches, Christopher D’Amboise says. This may be because previous events were classified as snow avalanches or mudslides instead. It could be because they are less likely than snow avalanches to recur in the same location, making them harder to ‘catch’ and observe. Or it could be simply that they have, indeed, always been a much rarer phenomenon than snow avalanches.

Through his work in the EU-funded IMPETUS project, D’Amboise will acquire new knowledge about where and when slush avalanches are triggered, whether a warmer climate in the future will bring more such avalanches, and how warnings of slush avalanches can be improved.

Next to me in the office is my drone, fully packed in case there are warnings from NVE about possible mudslides. I am prepared to visit all places in northern Norway. Then I can fly the drone and examine traces of water in the snow. If the snow is greyish or bluish, it will be a sign that it has started to become saturated with water. We can also identify the drainage routes and see if the water finds a way out or accumulates in the snow. If water-saturated snow lies on a gentle slope above an area with a steeper slope, a slush avalanche may be imminent.

Christopher D’Amboise, researcher with the Department of Geoscience, UiT – The Arctic University of Norway

The researcher believes that this method of combining regional warnings from NVE with investigations in the field can be part of developing an early warning system. This work is part of the activities in the IMPETUS ‘Arctic’ demonstration site, where a range of solutions are being developed to help the community adapt to the local impacts of climate change.

Further information

Dr. D’Amboise’s work in IMPETUS to understand and predict slush avalanches was described in another recent article: NRK, the Norwegian Broadcasting Corporation, provides additional background and historical data context along with perspectives from other experts in, ‘Slush landslides may become more common in the future‘.


High temperatures

Record-breaking summertime temperatures have been recorded in the Netherlands in recent years. With global temperatures rising, such extreme weather events will occur more often, and for longer periods. Prolonged high temperatures, with warm nights as well as hot days, can cause heat stress* and related health issues, particularly among city populations.

*Heat stress occurs when the human body cannot get rid of excess heat and can impact wellbeing through conditions such as heat stroke, exhaustion, cramps and rashes.

"We want to enable municipality decision makers who are working on spatial developments to identify heat stress 'hot spots' and cool areas, analyse the future effects of climate change, and model the effect of different heat stress-reducing measures. The tool must provide them with an easy starting point to integrate heat stress risks in their projects."


Despite the cooling effect of the sea in the region of Zeeland, the growing risk of heat stress has become a concern.

Elderly and other vulnerable people are more impacted by the effects of prolonged heat, which can cause headaches, dizziness, insomnia and other health issues – even death. Excess temperatures also affect general comfort and liveability of cities. Water quality can be reduced, both for drinking and swimming, and infrastructure can be affected. Buildings and concrete surfaces trap heat, potentially leading to damage, and release it during the night, keeping temperatures warm.

During heat waves, it is important that everyone has access to a cool and comfortable place. Appropriate spatial planning can help to decrease and deal with heat stress. Environmental factors like water bodies, trees, and shade have a major impact on stress caused by high temperatures. Therefore, planting trees, removing concrete surfaces, creating green roofs and cool spaces can improve our comfort and health. The IMPETUS Atlantic team is developing a digital tool to support regional decision making for city planning to address these needs.


Flood risk

By 2050, sea-level within this region is predicted to rise by 15-40 cm, with more frequent extreme weather and more (severe) storms triggered by climate change. These changes will exacerbate the natural risk of flooding in the IMPETUS ‘Atlantic’ region, because it is surrounded by rivers and the sea, and is below sea level.

*Risk takes into account two aspects; the chance that an event will occur and the negative impact of such an event once it occurs. When there is a low chance that an event will occur, but its impacts are huge, the risk is still significant.

“In the Netherlands, an extensive system of dikes protects us against sea and river flooding. We have always put our faith in this defence and focused almost solely on flood prevention. However, pressure on our system will increase with climate change and rising sea levels. To adapt and maintain a safe living environment, we should develop other safety measures, like more robust spatial planning and contingency plans."


Rotterdam city, is located in Rijnmond – ‘mouth of the Rhine’. The Rhine river flows through this densely populated area and characterises the region. Protections such as sea dikes and storm surge barriers have been constructed to protect the region, but flooding still occurs.

People living in the city are accustomed to seeing smaller floods. The changing climate affects the interplay between rainfall, river levels and sea storms, increasing the flooding risk. Water levels could rise by a few metres, even in populated areas, with potentially massive impacts. 

Mitigation measures such as storm surge barriers reduce the chance that high water reaches the city, but to minimise the impact of floods when they do occur, adaptation strategies are also needed. A city that can adapt to be safe from floods must be carefully designed. How best to design such an adaptive city?

Critical infrastructure, such as hospitals and evacuation routes, must be accessible at all times. Planning how to best protect them, homes and lives is complex. Flood water behaves in a complex way and flood risks show strong spatial variations. The IMPETUS Atlantic team is developing a digital tool to support regional decision making for adaptive city planning. 


Energy and waste water

To become climate-neutral by 2050, climate mitigation* efforts are crucial in our strategy for how to deal with climate change. Reducing our energy consumption is a significant mitigation step. In the Netherlands, 15% of energy is consumed in the Rijnmond area around the port of Rotterdam, in large part by a major petrochemical industry cluster.

*Climate mitigation encompasses measures such as technologies, processes, or practices that reduce carbon emissions or enhance the sinks of greenhouse gases.


The Rotterdam port petrochemical industry cluster is Europe’s largest. It consumes 70% of the Rijnmond region’s energy. A large part of this energy is wasted (64%, 203 petajoules). More than half of that energy is lost with wastewater. In addition, most energy processes within these industries rely on fossil fuels, which has a significant impact on the climate.

Energy use must be minimised and fossil fuels should be replaced by renewable sources if climate change is to be mitigated. Electrification of processes opens up the possibility to use more renewable energy and can greatly impact decarbonisation. Recovering wasted heat would significantly reduce energy consumption and is a first step towards a more circular industry. 

Supporting industries in a transition towards climate-neutrality depends on identifying how best to reduce their carbon footprint without sacrificing production or performance. The IMPETUS Atlantic team is creating a digital tool that supports decision making about pathways towards an effective energy transition for EU industry.