In many ways, life on Earth as we know it depends on ice. It provides most of the world’s fresh water supply, keeps global sea levels from rising disastrously and gives us vital data about past and future climate. Here are a few more intriguing facts about ice, both on our planet and beyond.
1. THE CRYOSPHERE IS WHAT WE CALL ICE ON EARTH.
Later we’ll talk about ice on other planets. But if we want to talk about ice on Earth, that’s the cryosphere—the NOAA breaks it down as the “frozen water part of the Earth system.” Cryo comes from the Greek for cold, “kryos.” It includes not only all types of frozen water, but permafrost, which is soil that has existed below freezing for extended periods of time, but doesn’t necessarily have any water.
2. WATER IS USUALLY MORE DENSE THAN ICE.
Ice and liquid water may be made of the same stuff, but those molecules arrange themselves in different ways depending on whether they’re in a liquid or solid state. In liquid water, molecules are able to fill in gaps and pack themselves in more closely than in the spread out and ordered crystalline structure of ice, which makes ice less dense and therefore able to float on water. At least that’s what usually happens. Heavy water ice (where the hydrogen atoms have a proton and a neutron, as opposed to just the proton in normal hydrogen) does sink. That may happen because the water molecules themselves become heavier thanks to the heavier hydrogen atoms, and the hydrogens form stronger bonds.
3. THERE ARE A LOT OF DIFFERENT NAMES FOR ICE.
Sea ice alone comes in myriad varieties, and Arctic and Antarctic sea ice have their own distinct vocabularies. Brash, frazil, nilas, and pancake ice are a few of the varieties found in both. If you’re ever navigating near the poles, you’d better be able to distinguish an iceberg from an icefoot, a bummock from a hummock, and a floe from a floeberg.
But if you think that’s a lot to remember, the Inupiaq of Alaska have 100 names for ice—which makes sense for a people whose survival requires expert knowledge of the characteristics and behavior of frozen water in all its variations. Of course, linguistically, it’s not quite that simple; their language is polysynthetic, meaning that words are formed by combining roots and endings to form countless words. Moreover, some words do double duty; a mapsa, for instance, is both an overhanging ledge of snow and a human spleen, which “overhangs” other organs, as far as Inupiaq see it. Nevertheless, that’s a lot of nuance for a substance we usually refer to with a single term.
4. ICE STORMS HAPPEN WHEN SNOW PASSES THROUGH WARM AND COLD LAYERS IN THE ATMOSPHERE.
Ice storms can be deadly. Here’s how they happen: Snow enters a warm layer of the atmosphere and melts into drops of rain, then passes through a cold layer of air. The rain drops don’t have time to refreeze as they fall through this thin cold layer. But when they finally hit a cold surface, they immediately turn to ice.
The result is an especially thick, heavy coating of ice that turns sidewalks and roads into skating rinks, making driving and walking very dangerous. As ice thickens on power lines and trees, its weight can snap cables and damage branches, leading to widespread power outages and turning tree limbs into deadly falling objects. Now scientists are modeling how and where these storms are likely to strike in the future by simulating ice storms in New Hampshire research forest plots.
5. DRY ICE ISN'T MADE OF WATER.
It’s frozen carbon dioxide, which can change from a solid to a gas at room temperature and pressure without going through a liquid state. Dry ice is quite useful in keeping things cold because it freezes at a chilling minus 109.3 degrees Fahrenheit. And of course, it’s also a great way to set the scene for spooky theatrical productions and haunted houses.
6. ICE PAVED THE WAY FOR MODERN REFRIGERATION.
The use of ice for food preservation has been around for millennia. In the United States, people depended on a variety of methods to prevent food from spoiling, including canning, salting and drying. But the most effective method was to keep food cool with blocks of ice. In the early 1800s, ice harvesting as an industry took hold as horse-drawn ice cutters pulled thick blocks of ice from frozen lakes for use in insulated ice houses and cellars. By the late 19th century, household iceboxes, forerunners to the electric refrigerator, were common.
Ice didn’t only provide convenience for individual homes. It was key to advancing mass production and distribution of meat and other perishables, which in turn supported urbanization and a variety of other industries. By the end of the century, however, pollution and sewage dumping had contaminated many natural ice supplies. This problem helped spur innovations that led to the modern electric refrigerator. While there were earlier versions in the 19th and early 20th centuries, GE’s Monitor-Top fridge, released in 1927, was the first to see widespread commercial success.
7. GREENLAND'S ICE SHEET CONTAINS 10 PERCENT OF THE WORLD'S GLACIAL ICE—AND IT'S MELTING FAST.
It’s the second largest ice mass on Earth after the Antarctic ice sheet, and it contains enough water to raise ocean levels by at least 20 feet. (If you’re wondering, global sea levels would rise by more than 260 feet if every glacier and ice sheet on Earth melted.)
The Greenland ice sheet’s melt rate is accelerating at a sobering rate: According to a study published earlier this year in the journal Nature Climate Change, the ice sheet now loses a mind-boggling 8000 tons per second. Scientists are studying Greenland’s ice sheet to document its past behavior in the hopes of better understanding how it may respond to climate change.
8. ICEBERGS AND GLACIERS DON'T JUST COME IN WHITE.
White light is made up of a rainbow of colors and each has a different wavelength. As snow accumulates atop an iceberg, the air bubbles in the snow get compressed and more light penetrates the ice rather than getting reflected by bubbles and tiny ice crystals. And here’s where the magic happens: Longer color wavelengths, like red and yellow, get absorbed by the ice, while shorter wavelengths of color, like blue and green, reflect the light. That’s why icebergs and glaciers often appear blueish green.
9. THERE HAVE BEEN MANY ICE AGES ON EARTH.
We tend to think of The Ice Age, as if there was just one. Actually, many others occurred before humans arrived on the scene, and they were often much more severe. At certain points the entire planet was likely frozen, something scientists call “Snowball Earth.” Some theorize that some ice ages were caused by the evolution of new life forms — plants as well as both unicellular and multi-celled organisms — which changed atmospheric carbon dioxide and oxygen concentrations in ways that altered the greenhouse effect. New Scientist has a nice recap of the history of ice on Earth.
Earth will continue to cycle through periods of ice and warming. But the current predicted rate of warming for the next century is at least 20 times faster than past periods of warming, raising questions about how human-induced climate change will affect those natural cycles over the long term.
10. MORE THAN TWO-THIRDS OF EARTH'S FRESH WATER IS STORED IN GLACIERS.
Melting glaciers aren’t just a problem for glaciers. The loss of all that ice will affect the global water cycle and have a big impact on water supply and quality, energy generation and incidences of extreme weather. In some places, like the Andean region of South America and the Himalayas, those problems are already starting to be felt.