I'm going to guess it has to do with how quickly the temperature change occurs, or other environmental factors prior to the freeze. It seems to be a somewhat rare occurrence, even in places where it gets very cold

It was raining here two weeks ago. Temperatures were in the 20-30s earlier this week. It's being far below freezing AND recent warm weather that's the danger.

It isn't common, and explode is an exaggeration for what I have seen - just cracked bark (though the crack was probably abrupt and loud). Montana gets some every now and again, so I am guessing at least some parts of Alberta do too. Nobody has made a big deal about it in the past outside of folks interested in trees. This is some weird media hype.

The use of the word "explode" is misleading. It's definitely misinformation.

Here's an arborist talking about it, but basically:

Trees move sap and other liquids up and down their trunk from the soil underneath regularly. For trees like maples, this is where maple syrup comes from, except you have to collect a lot of sap and reduce it down to syrup.

The arborist claims that these liquids present in the tree when the temperature swings faster than the tree can respond expand due to freezing, which buckles tree trunks causing the outer bark to crack open and separate. The cracks can be from the ground up, or they can look like gashes in the side of the tree. There's moisture in the soil too, which can shift tree roots and cause similar cracking.

People say "explode" because there's usually a popping sound when this happens.

In other contexts, people call this frost upheave. Engineers know about this phenomenon, and try to bury equipment like pipes and cable and conduit below the frost line so frost upheave doesn't crack and break that stuff. With trees, this frost upheave just takes place inside the trees themselves.

I'd guess it's the species that grow there. If they regularly see -40C they'd have to have evolved to cope with it.

t could also be part of how they grow - i dunno maybe narrower / more flexible rings, better insulation, or better ways to store sap in winter conditions.

I assume this is in an area where such a temperature is very rare.

Most trees do have some radial cracks in them though - probably just some very rare cases those cracks get big enough for the tree to fall or split visibly on the outside and someone calls it an "explosion" for dramatic effect.

The trees don't "explode" but young spindly trees can shatter if the conditions are just right, (and they are not right now). It's very rare to have happen.

Source: I live in northern Minnesota. And I live closer to Winnipeg than the Twin cities.

I have been in extreme cold and not heard of this either. When it gets below 0 f, they make noises, like cracking, but just noise.