The science and wonder of ice

I’ve always had a fascination with ice. I love its clarity, and the way it shines and sparkles in the noonday sun. I love the scrape and spray of the skating rink, the clink and tinkle of broken icicles, and the crunch and shatter of frozen puddles underfoot.

St. Albert’s Barry Collier shares this love, having spent years carving chunks of ice into sculptures seen across the Edmonton region, often in -30 C weather with naught but the sound of his headphones to keep him company.

“It’s just such a beautiful moment in time,” he said.

“You’re in the zone. It’s great.”

I’ve been thinking of ice lately because we’ve had so little of it this winter. St. Albert has just come out of what was likely the hottest year on record, and with it barely a hint of snow or ice on the ground.

“This year is definitely an anomaly,” Collier said of the warmth, and it has thrown events like the upcoming Deep Freeze festival in Edmonton into question.

“People talk about global warming. Well, it’s happening.”

This week, I decided to take a closer look at the nature of ice, and what the future holds for it.

Simple, yet complicated

“Ice is one of the most important and most studied materials on Earth,” write Victor Petrenko and Robert Whitworth in The Physics of Ice, and it possesses a wealth of unique and intriguing physical properties.

Glaciologists and meteorologists study ice’s effects on weather, while chemists and crystallographers appreciate its bonds and structural disorder, Petrenko and Whitworth note. Humans in general use it to cool drinks and play sports, and have to invent new feats of engineering to keep it from cracking roads and pipes.

Ice is the crystalline solid form of water, said Stephen Morris, a retired professor of physics at the University of Toronto and co-author of The Icicle Atlas. Unlike liquid water, whose molecules are a jumble, ice molecules form hexagonal crystals under normal atmospheric pressure at or below 0 C.

Those ice molecules are connected by hydrogen bonds, which are weaker than other forms of atomic bonds, said John Beamish, a retired professor of low-temperature physics at the University of Alberta. Hydrogen bonds leave a lot of space between molecules, which makes ice less dense than water and allows it to float — a very rare phenomenon among solids.

“The whole universe would be a very different place if ice sank,” Morris noted.

Ice is slippery. Beamish said researchers at first thought this was because it melted under pressure — which is weird, as everything else solidifies under pressure — but that turned out to only be true near -0.5 C.

More recent studies suggest ice is slippery because of surface melting. Water molecules inside an ice cube are restrained on all sides by each other, keeping them solid, Beamish explained. On a cube’s surface, those molecules are held on just one side, letting them move around more to form a tiny layer of slippery liquid.

Ice is solid but is ductile, and can flow under pressure, Beamish noted. Glaciers do this, which is why they can move without melting.

Ice can appear cloudy when impurities such as gas bubbles become trapped in it, Collier said. Freeze flowing water slowly over several days, as happens in lakes and rivers, and you prevent this trapping and get clear ice. Ice manufacturers use pumps to create this flow to craft the 300-pound chunks of clear ice used for carving.

Snowflakes are single crystals of ice that form when water freezes out of the air onto particles, Morris said. Icicles are made from many jumbled crystals formed from flowing water, with their overall shapes determined by temperature, impurities, flow rates, and other factors. Pure water icicles will be conical, while water with anything in it will have ripples.

“The amazing thing is those ripples are always the same no matter how you grow the icicle,” Morris said, in that they always have a wavelength of about one centimetre — why this happens is a mystery.

Almost all the ice seen on Earth consists of hexagonal crystals and is dubbed Ice Ih (“One H”), Beamish said. But if you put ice under extreme pressures and temperatures, those crystals shift into new configurations, producing other forms of ice. You get cubic Ice Ic at about -195 C, for example, and orthorhombic Ice XI at about -268 C. Researcher Christoph Salzmann created a new type of amorphous ice (which is a solid with the disorganized molecular structure of a liquid) in 2023 by putting regular ice and steel balls into a -200 C container and shaking it vigorously. Researchers have now observed 20 crystalline and three amorphous types of ice, with computer models suggesting there may be some 74,963 forms of ice out there to discover.

“It’s not of very much practical interest,” Beamish said of these exotic ices, but they can teach us more about ice on other planets.

Why ice matters

Ice in the form of glaciers is of huge importance to Earth’s climate, affecting temperatures, ocean currents, and salinity, Beamish said.

“It’s unbelievably complicated and unbelievably important.”

Glaciers form when snow compresses into ice over thousands of years, explained Alison Criscitiello, director of the Canadian Ice Core Lab at the U of A. This process traps atmospheric gases researchers can later extract to determine past atmospheric conditions.

“Everything we know about long-term CO2 (levels) in the atmosphere comes from ice cores,” she noted.

“As you drill down, you’re drilling back in time.”

Criscitiello said ice core data shows how human activities and burning fossil fuels have greatly increased CO2 concentrations in the atmosphere, and with them, global temperatures. That heat puts ice on Earth at risk, with some 70 per cent of the glaciers in western Canada set to vanish by 2100. That’s a huge problem for St. Albert, as those glaciers provide much of the drinking water we get from the North Saskatchewan during the summer.

Warmer conditions mean artists such as Collier must carve their statues at night when it’s cooler, and avoid diagonal and vertical joints that could split in the heat. They must screen their statues with tarps and tents and carve just before or during events.

“Longevity wise, it doesn’t last anymore,” Collier said.

We’re a bit beyond the point where individual actions such as low-flow toilets will be enough to ensure ice has a future, Criscitiello said. Instead, people need to call on their leaders to enact policy shifts to boost renewable energy and get off fossil fuels.

Ice brings a wonder and magic to the world that we should not live without — a wonder Criscitiello said she feels every time she steps out onto a glacier.

“Every time I see them, I can’t believe they’re real.”