Canada glacier, Antarctica. Glaciers are slow-moving rivers of ice, fed by compacted snow.

Fast ice is a type of sea ice that isn’t really speedy—it’s “stuck fast” to land.

Pancake ice forms when flat chunks of ice are battered into rounds by wave action.

Sea ice breaks up into brash ice, ice chunks less than 6.5 feet (2 m) across.

For those who think ice is all the same: think again. At the poles, ice takes many forms—from shiny “grease ice” on the sea surface to mile-thick ice sheets that cover entire continents.

The many varieties of ice found at the poles arise from the various environments in which they form: on land, at sea, and at the boundary between the two.

On land, snow falls and hardly ever melts. Year after year, snowfall piles up and compacts into ice that flows like a slow-motion river—a glacier. When glaciers are bounded by mountains, they carve deep U-shaped valleys on their way to the sea, valleys that remain long after the glacier has melted away; Yosemite Valley in California is an example.

When glaciers stretch out across flat land or over an entire continent, they’re called ice sheets; both Greenland and Antarctica are almost entirely covered by ice sheets that are miles thick. Within ice sheets, faster-moving zones called ice streams occur over water or smooth ground. Smaller ice sheets that sit on mountaintops are called ice caps.

When ice from glaciers and ice sheets reaches the sea, it can spread across the water as a slab called an ice shelf. Ice shelves can extend for miles—even hundreds of miles—over the ocean. Chunks of ice can break off from an ice shelf, forming floating icebergs.

In Arctic climates, even land that seems ice-free may hide a layer of ice beneath its surface. Permafrost is a layer of soil that remains frozen year round.

Sea ice forms when temperatures dip so low that the ocean itself begins to freeze. Sea ice can be free-floating drift ice, or fast ice that is “stuck fast” to land. When sea ice first begins to form, it appears as fine bits of frazil ice, then thickens into soupy grease ice, and then sometimes forms pancake ice, pieces of drift ice that have been battered into rounds by waves and collisions. When pieces of drift ice get packed together, they become pack ice. An ice floe is a solid chunk of drift ice up to 6 miles (9.7 km) across; if it grows larger than this, it’s called an ice field.

We finally finished our zooplankton survey and since we had two days to spare, we steamed down into the Gerlache Straight, off the Antarctic Peninsula for a fun day off. The Gerlache Straight is famous for its scenery, but when I awoke it was snowing and it continued to snow all day. At first we were all slightly disappointed; the snow blocked our view of the landscape. But as the day carried on, the gently falling snow covered the boat, cultivating a surreal landscape. The water was calm and covered in a thick layer of snow which began to clump, forming what’s known as ‘pancake ice.’ There were icebergs and bergy bits everywhere, all covered in a fresh layer of white.

Our weather in the Gerlache Straight.

A close-up of the pancake ice forming on the water.

The falling snow covering the boat.

Seabirds of all kinds and fur seals were taking refuge on the small bergs. We couldn’t see the mountains but once the whales came by we hardly noticed.

We had come upon a feeding ground and there were whales everywhere, rolling, fluking, and flipper slapping in front of the boat and on both sides.

Humpbacks rolling, flipper slapping, and putting on a show by the side of the boat last year.
Photo by Kim Dietrich

The captain cut the engine so we could stop and watch. The water was so still, that in the ice free areas I could make out the white and blue silhouette of the whale just below the surface. It was incredible that this ice filled, snowy, cold environment was just teeming with life.

Gathering on the bow to watch the whales.

Most of the scientific crew as well as the field camp personnel and the Russian crew were out on the bow of the boat taking in the scene, furiously snapping photographs, and throwing the occasional snowball of course. No matter how many times some of us have been down here, no matter how much snow and ice we’ve seen, it’s still awe-inspiring for us all.

Nearly the entire crew came out on deck to see the scene.

International Responsibility

In 1961, with the initiation of the Antarctic Treaty, Antarctica was officially deemed international territory. Over forty nations are involved, nine of which are represented by this year’s AMLR crew. The Antarctic treaty established Antarctica as a place dedicated to science, and though many countries conduct research throughout the continent and surrounding waters, no one can claim sovereignty here.

These flags at the South Pole represent the twelve original signatory nations of the Antarctic Treaty.
Photo by Liesl Schernthanner, National Science Foundation

We all have a responsibility to manage Antarctica for the international good, to do our best to learn as much as possible about this polar environment. That includes how humans are affecting it via climate change, which will affect everyone.

We have a responsibility to protect its resources and ecosystem, to make the best choices about how we fish Antarctic waters and how we manage Antarctic resources, and to educate each other, as I have tried to do through these dispatches.

I thank you for sharing the adventure with me.

Thanks for coming along on our journey.
Photo by Lara Asato

Nations represented in this year’s AMLR cruise: Poland, Turkey, Russia, USA, Canada, Columbia, Chile, Australia and South Africa.