Stay Safe on the Ice This Winter

Each winter, there are a number of stories in the news about people being rescued after falling through thin ice. To avoid these unfortunate accidents, exactly how can we tell if ice is safe to go out on?

After a particularly cold spell of weather, lakes and ponds can freeze over rapidly, and the ice will grow thicker the longer the temperature remains below freezing.

There is one easy way to get a reasonable estimate of the ice thickness, which can be performed safely from the shoreline - we can look at ice colour.

The strongest and safest colour of ice is either blue or black.This is the ice that forms as the surface of the lake or pond directly freezes in cold weather. As a result, it is very dense.

If the ice is opaque white, it can appear safe, but that is not necessarily the case.

White ice or 'snow ice' is white because it forms when a layer of wet snow freezes on top of blue ice that has already formed. Snow layers contain a lot of air, which end up as air bubbles trapped in the ice structure. While it can be reasonably thick, the presence of these air bubbles weakens the ice, so it may not be safe to walk on. It is still the thickness of the blue ice underneath that determines, ultimately, whether it is safe to stand on.

Most importantly: If the ice is grey or greyish, do not step out onto it. If the ice is any shade of grey, it is likely decaying or melting, and it is probably fairly thin and weak. The source of the grey colour is typically the dark liquid water underneath showing through the ice. Even if it is very light or pale grey, it is best to err on the side of caution.

So, if the ice is grey, stay away!