Ice-sheet melt is one of the more visible and key signs of man-made global warming from the burning of fossil fuels.
Good weather seldom lasts more than a few hours off the coast of Antarctica, and after a remarkable day of cloudless fine conditions, the next day dawns grey and cold.
The research vessel, Akademik Treshnikov, moves back from its parking spot against the glacier and sails to a nearby location, where the submarine is again launched. Instead of exploring the underside of the glacier, this time the focus is on marine life on the ocean floor.
As the unmanned sub reaches a depth of 900m, a giant sponge resembling an enormous gourd looms into view. A tiny fragile crinoid, or sea lily, clings to its side.
The four-man team operating the robotic sub manoeuvre it into place, and then, using a robotic arm, lift the beautiful creature from its perch and place it in one of the sampling boxes.
There are relatively few fish, for these are some of the coldest seas on the planet and only a few species have the necessary anti-freeze in the blood, but krill dance before the submarine’s lights and cameras and on a nearby rock more than a dozen species are spotted.
Bright red sponges, tiny clams, brittle stars and sea cucumbers crowd each other.
Over the course of the next few hours the submarine’s giant robotic arms take samples from the bottom, including cores of sediment, rocks and a wide variety of the creatures they find.
Normally dredging is the only way to take samples from such an environment but the $5m submarine gives the science teams an unprecedented view of the creatures in their natural surroundings, and allows them to selectively take samples.
Changes to the Southern Ocean’s deep currents, believed to be linked to global warming, are altering the temperature, salinity and acidity of the water.
This has an impact on many marine animals. A sampling expedition, using methods including DNA analysis, aims to map where these species are living and how, over time, they are adapting to the changing world.
Needing to continue the journey east to stay on schedule, the ship sets sail that night for the Balleny Islands, south of New Zealand. Later in the evening we come up against thick sea ice, an enormous, densely packed sheet of white crumpled ice covering the surface of the ocean.
The ship breaks its way slowly through the pack, which undulates as a growing swell from the East ripples through the ice. The vessel rides into each ice-laden swell, and crunches down on the next, producing an extraordinary chorus of groans and thumps.
Over the next hour the pack loosens and the swell rises until the ship is no longer breaking ice, but instead cutting a course though a soupy mixture of ice and water.
The next day we arrive at the Balleny Islands on the edge of the Ross Sea. These frozen islands are an impressive sight from sea level, with cliffs rising hundreds of metres into the clouds.
These walls of ice and stone are hung with giant icicles up to 30m in length. Above the cliffs there’s an ice cap a few hundred metres thick.
At points this spills down to the sea in the form of a glacier, which fans out over the water, its divergent crevasses giving it an unusual clam-like appearance.
As landing on the islands by boat is considered too dangerous, if not impossible, a team of ice core scientists are flown by helicopter on to the top of one of the islands. Here they will take the first ever ice core from this island.
There is little detailed information about the three main islands in the group. This makes selecting a drilling site difficult. The Balleny Islands have never been surveyed, so as part of a project to create a 3D map I’m asked to help film the islands from the open door of the helicopter.
We mount a 4K stabilised camera on the side of the aircraft and then, with temperatures below -10C, we spend a freezing but breathtaking hour and a half flying around the islands filming their remarkable glaciated coastline.
The resulting film will be a stunning record of a remarkable part of the world.