51猎奇入口

Sometimes science throws up the unexpected.

When a team of researchers set out to model river erosion in Canada鈥檚 High Arctic, they did not expect the findings to defy common sense.

鈥淲e literally expected to see the opposite of what we ended up seeing,鈥� says Jonas Eschenfelder, a PhD candidate in SFU鈥檚 School of Environmental Science.

鈥淲e re-ran the experiments a whole bunch of times until my supervisor actually believed the results.鈥�

For his supervisor, Shawn Chartrand, the findings ran counter to basic science.

鈥淲e saw the results, we looked at ourselves, we said, 鈥榯his can't be correct,鈥欌�� says Chartrand, an assistant professor in the School of Environmental Science.

鈥淚 emailed some colleagues. They didn't believe me. We ran a second experiment. Same outcome.鈥�

When science confounds

Earth scientists have long believed that ice in riverbeds acts as a sort of glue, holding the landscape together and slowing down erosion.

But when Chartrand noticed changes in the Arctic landscape during a 2019 visit, he began to wonder whether the conventional school of thought might be missing something.

Against the backdrop of climate change and a rapidly warming Arctic, Chartrand鈥檚 observations set in motion a body of work, involving both 51猎奇入口and University of British Columbia (UBC) scientists and students, to investigate how exactly erosion takes place when the ground freezes and thaws annually.

Eschenfelder took up the mantle in summer 2024 and set about designing an experiment to simulate the rate of erosion in a frozen riverbed compared to one in a temperate climate.

In an underground lab deep beneath the Earth Science building at UBC, the team assembled a highly-sophisticated system using cutting edge technology and the latest AI monitoring tools. Or not.

鈥淓verything down there is essentially from Home Depot,鈥� says Eschenfelder.

鈥淲e were able to build something that correctly shows how the Arctic and Arctic river systems are changing. Then to be able to combine it and actually travel to the Arctic and see those unique landscapes itself is just a really wonderful part of doing research.鈥�

The lab stream, aka a flume experiment, is a channel filled with glass beads, representing the riverbed. Water flows over the beads simulating river flow and the thawing process.  

The water disturbs the beads, which get picked up and flow out of the channel where they are counted to give an erosion rate. By running the experiment at different temperatures, the team could simulate rivers in the Arctic and in temperate climates. 

To their surprise, they found that frozen ground can actually erode faster during initial thawing by up to 10 times compared to unfrozen ground. They also found that the erosion created small steps and depositional pools in the riverbed. 

鈥淵ou think you understand the basics of how things work, but it doesn't work that way sometimes,鈥� says Chartrand. 

Once the initial skepticism and incredulity had subsided, they could begin to explain their findings.

The Arctic essentially only has two seasons 鈥� summer and winter. In early summer, there is still ice in the ground as it starts to thaw. This is when erosion rates are highest, according to the results.

A riverbed is made up of small particles, sand and gravel, that can be picked up by the fast-flowing surface water and transported downstream. When more particles are dislodged than deposited in a given area, that leads to erosion.

In an unfrozen river, particles in the riverbed have spaces between them, allowing for water to flow through, limiting erosion under normal conditions.

In a completely frozen riverbed, the ice in the ground prevents water from flowing through it. So all of the water in the river remains at the surface and flows faster as a result.

As the ice in the riverbed starts to melt, surface water injects into the bed again, except now it hits the layer of ice in the riverbed, giving it something to push against.

The water injections are redirected upwards, loosening riverbed sediment from below and leading to greater erosion as the particles get carried away downstream.

The melting and subsequent erosion is also uneven, creating small steps and depositional pools in the riverbed.  

Arctic geopolitics

Arctic landscapes are eroding faster than previously thought. So what?

鈥淭he Arctic is warming about four times faster than the rest of the globe. And with it, landscapes 鈥� polar deserts that have been largely unchanged for more than 10,000 years 鈥� are waking up and beginning to form new river systems,鈥� explains Eschenfelder.

鈥淲e鈥檝e seen new rivers form within tens of years, much faster than we would expect even in temperate landscapes where erosion can happen year-round.鈥�

As the Arctic warms, previously frozen ground is thawing faster. Weather patterns are becoming less predictable and more intense, with heavy rainstorms increasing the flow speed of waterways, further increasing erosion.

With the Arctic gaining increasing attention for geopolitical reasons, the research could be instrumental in helping to inform human activity in the region.

鈥淭he findings are important because it's the first time that people have really focused on this particular issue,鈥� says Chartrand.

鈥淭hat matters. Because as the Arctic continues to change, and as we see more people present in the Arctic doing different things, we might want to have a sense of how the landscape is changing and what that will mean for human presence.

鈥淭here is also the broader environmental concern. The landscape creates sediment and the erosion means the sediment is carried downstream, normally ending up in the ocean.

鈥淚f you increase the amount of sediment coming off the landscape into the ocean, then you鈥檙e also bringing other stuff, like nutrients, with it. That has implications for sensitive ocean biology.鈥�

The Arctic also contains peatlands and carbon-rich soils. As the climate warms and previously frozen ground thaws, more carbon dioxide and methane could be released.  

Bridging the gap

Running an experiment in the lab is one thing. Researching your theory in the field is quite another, especially when it involves travelling to Devon Island (Tallurutit), in the Canadian High Arctic.

鈥淚t's a beautiful landscape. It's very quiet,鈥� says Chartrand, who was part of the team that visited the island in summer 2024. A two-day journey by plane and road from Vancouver, it is the largest uninhabited island in the world.

鈥淚t's called a polar desert, so there's not much precipitation. That generally means there's not much vegetation. It's a rocky environment with rivers littered across the landscape fed by seasonal snowfall and ground ice melt, as well as the ice cap on the eastern side of Devon Island.鈥�

The team wanted to study developing river networks to see if they could find anything that may support their lab findings.

鈥淲e found similar features in the landscape, these kind of relatively steep steps in riverbeds, interspersed with depositional pools, which are very similar to what we saw in the experiments,鈥� says Eschenfelder.

鈥淥ur thaw depth measurements in the field showed a similar undulating thaw front that we saw develop in the experiments.鈥�

The thaw front is where the melting surface layer meets the still-frozen ground below.

The research was recently published in . The next step for the team is to explore how Arctic landscapes will change under different climate change scenarios over the next tens to hundreds of years.

鈥淭his project really showed me again why I love doing research,鈥� says Eschenfelder.

鈥淭he Arctic is becoming an increasingly important place, in terms of geopolitics, environmental concerns and infrastructure projects. But we clearly don't really know how it is behaving with climate change.

鈥淥ur science tries to bridge that gap so we can project future conditions and answer questions about how the landscape is evolving.鈥�