Using radar to stop polar-bear run-ins before they happen | Polarjournal
A lurking threat (Photo: Michael Wenger)

One of the great ironies of global warming is that, despite the threat is poses to polar bears, run-ins with humans are becoming more frequent, sometimes with unfortunate outcomes for both species. The remedy to this most often involves scaring off bears using loud noises once they get close to settlements. But what if it were possible to detect polar bears long before they became a concern? A new technology being tested in several parts of the North to track not just polar-bear movements, but also where they den, may keep both man and bear safe by doing just that.

“Bear-dar”, which takes its name from the radar systems that the method employs, has been under development since 2014, and, though there is still a ways to go before it can be used with any reliability, the hope is that, once it is fully developed, it can be used for two different purposes: firstly, to identify occupied bear dens, and, secondly, to track where bears are after they emerge in search of the food that brings them in the direction of human settlements.

Neither is easy: the current system of identifying dens — using infrared sensors — has been shown to miss more than half of known dens, according to Polar Bears International, a conservancy that is co-ordinating efforts to develop the radar systems. In addition to being able to peer through snow — which often insulates so well that the heat given off by the bears inside is imperceptible to infrared scanners — the SAR radar technology that is being tested has a number of advantages. Chief among them is that it can take measurements from a higher altitude, allowing biologists to avoid using lower-flying helicopters that cover less area and create more noise that could potentially disturb denning bears.

As SAR evolves, it must also learn to identify what the objects it senses actually are. On its own, SAR is, according Polar Bears International, too effective at identifying objects to be of much use, since it registers everything it sees. During testing of an early-warning system carried out this past autumn in Churchill, Manitoba, for example, 107 alerts were sent out, but only 28 of them were confirmed as polar bears. Now that the system has been proven to work, the next milestone will be to combine for there to be more positive identifications than false alarms. To achieve this, scientists will seek to learn what a polar bear looks like to a SAR system by matching up confirmed sightings of polar bears with the SAR signal of the same bear. Once they know that, they can tell the system to ignore signals that do not resemble polar bears.

Another challenge developers will need to address is cost; SAR is expensive. That may be less of a concern for the national agencies or firms that are more likely to be looking for dens, but obtaining them and using them as an early warning system could prove cost-prohibitive for small communities. The solution to this may be a system that uses lidar instead of SAR to identify moving objects. Lidar, popularly known as visual radar, is a scanning system that is already widely used in things like autonomous vehicles. It is less effective than SAR, but because it is cheaper and more portable than the current SAR systems, it would provide a feasible and reliable supplement to existing remedies.

Kevin McGwin, PolarJournal

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