Potential Positive Effects of a ‘Polar Vortex’

Record-setting low temperatures have gripped North America this week

Has it ever been cold in London, Ontario this week! We broke some weather records around these parts with temperatures that dipped between -35°C and -40°C, with the wind chill factored in. That was cold and wintry enough to keep all area schools closed for an extra two days on the heels of winter holidays (note, there are still a few rural schools closed for a third day today).

An interesting note for my American friends, -40°C is also -40°F. That’s pretty darn cold.

But I really can’t complain to anyone in North America, as our weather was just a small part of a ‘Polar Vortex’ that swept the continent, freezing states as far south as Florida and Texas. Welcome to a Canadian winter my friends! Gotta love those Arctic blasts.

Emerald Ash Borer

The frigid temperatures aren’t all bad though. Sure there have been a few flight delays here are there (no offence to the hundreds of poor travellers that were left frustrated at Pearson International Airport yesterday), but there is a glimmer of hope in all those icicles. That hope is that the deep freeze that we shivered through just might have been cold enough to wipe out some nasty bugs, bacteria and insects that lay sleeping in area trees. Namely the Emerald Ash Borer.

You see when the mercury plummets, it freezes anything left outside in it. That would be uncovered skin, pets, rivers, trees, and also anything inside of those trees. Once the outer layer of a tree is frozen, any insects and fungi that are hunkered down for the winter inside of it are at risk of freezing and consequently dying as well. It is Old Man Winter’s way of controlling bugs that are not naturally found here. Non-native species cannot easily adapt to the extreme cold temperatures and hence perish. That goes for species like the Asian Long-Horned beetle, Spruce Bug Worm and Pine Weevils too.

EAB Larva

How long can these invasive pests last in our ice box weather though? Well, that varies, but temperatures of -30°C are enough to kill emerald ash borer (EAB) larvae. That is considered its supercooling point (the point at which the insect freezes), and the larvae cannot survive being frozen. If temperatures stay in that range for even a few hours, it has the potential to kill even more EAB larvae. A recent report from the USDA Forest Services corroborates this;

“From our simple model that related the coldest temperature experienced by emerald ash borer larvae to the extent of mortality, we predicted that when larvae reach -17.8°C (0°F), 5% will die; at -23°C (-10°F), 34% will die; at -29°C (-20°F), 79% will die; and at -34°C (-30°F), 98% will die…”

So while we might have been collectively moaning and groaning over a few days of cold winter weather, in a few months time we might be cheering over this deep-freeze. Invasive species can be frustratingly adaptable, but with any luck, perhaps this particular Polar Vortex has wiped out a few pesky insects that we have struggled against for far too long. Time will tell.

In the interim, remember to stay warm and dry. Try donning some wool socks and stay away from cotton that sweats, leaving you shivering all too quickly. The mercury will be rising before you know it!