Many communities in northern Canada rely on ice roads to access food and other goods during the winter. But in recent years, climate change has threatened the safety of these roads — as well as the remote communities they serve.
Thanks to two satellite missions, however, a team of researchers may have found a way to help. Their research demonstrates how a satellite-based technique known as radar altimetry can reveal when these roads are safe to travel on.
Climate change is threatening ice roads
Ice roads built over frozen waterways are vital for many remote communities in the north. They allow communities to access important sources of goods and resources without relying on more expensive modes of transportation, such as aircraft.
“In Arctic regions, frozen rivers provide a unique transportation infrastructure for the movement of goods and people via winter ice roads and provide local populations with access to fishing and hunting/trapping grounds and in some cases […] to freshwater,” the authors explained in their paper.
Unfortunately, these ice roads aren’t safe year-round — and in recent years, climate change has made this problem even worse. For example, the Tibbitt to Contwoyto Winter Road in northern Canada used to be accessible for 70 days each year, but is now projected to be safe for only 54 days per year going forward.
Each day of accessible travel time is crucial for these remote communities, but knowing whether or not the ice roads are safe is tricky.
Scientists have typically determined ice thickness by physically drilling into the ice, or visually inspecting it, in order to determine whether the roads are safe. Because these measurements require scientists to be present on site, they are called in situ measurements — however, regularly accessing these roads isn’t easy.
Space-based measurements can help
To get around this, Duguay and colleagues decided to test whether measurements from space could accurately measure the thickness of ice on the ground.
The researchers used satellites to send radar pulses to the ice roads, and measured the time it took for the pulses to travel to the ice and back. They also measured the power of the pulse when it returned. This technique is known as radar altimetry.
By studying the radar pulses that had returned to the satellites, the team was able to determine how long it took the pulses to reach and reflect off the ice-water boundary, which in turn told them how thick the ice was. They could then use these measurements to calculate whether the ice was thick enough for safe travel.
It turns out that a number of factors (for example, snow or rain cover on top of the ice roads) can impact the travel time and power of the radar pulses. The researchers developed an algorithm that accounted for these factors when determining the ice thickness.
The team compared 15 years worth of radar altimetric data to in situ measurements that had been taken during the same period of time. They found that their satellite-based measurements were consistent with the in situ measurements, meaning that they could accurately determine when ice conditions were no longer safe for travel.
A key advantage of this technique over in situ measurements is that satellites can cover a much wider area in a shorter period of time. This technique also doesn’t require scientists to be present at the ice roads, which aren’t always accessible, or to drill into the ice itself.
How can we help northern communities?
Going forward, this technique will help remote communities know when their ice roads are safe for travel. With climate change degrading the ice quality more and more each year, every safe travel day counts.
In the longer term, however, it will also be important to advocate for climate policies that protect these northern communities.
Northern communities experience the greatest effects of climate change, and it’s vital that we focus our efforts on safeguarding these regions in the future.