The biggest experiment of its kind is camped out on the ocean north of Alaska. The machines could revolutionise our understanding of Arctic sea ice

Jobs for the buoys (Image: Jeremy Wilkinson/British Antarctic Survey)

A TIRELESS scientific expedition is currently encamped across a huge stretch of Arctic pack ice. The daytime temperature is just above freezing. Regardless, the team sends data day and night to a string of labs around the world.

There isn’t a single human among them. This remotely monitored outfit is made up entirely of machines – and they’re aiming to revolutionise our understanding of Arctic sea ice.

The Marginal Ice Zone (MIZ) programme is the biggest experiment of its kind in the Arctic Ocean. A host of specially designed instruments work in concert to build a picture of how the ice responds to changes in the surrounding conditions.


For example, 20 wave buoys built by the British Antarctic Survey have been implanted in the pack ice. They are equipped with sensors that measure air and ice temperature, air pressure and ice thickness as well as cameras that send updates via satellite link four times a day. There are also 10 polar profiling floats, modified by the Woods Hole Oceanographic Institution, each with a cord descending 1000 metres into the water. A robot travels the length of this cord every day, measuring water temperature and salinity (see diagram).

In a few weeks, these will be joined by four “sea gliders” – rocket-shaped underwater vehicles which will operate autonomously for four months, travelling around under the ice shelf measuring water turbulence and dissolved oxygen levels.

“Technologically this would have been impossible up until the last couple of years,” says Craig Lee of Washington University in Seattle, one of the team overseeing the sea gliders. “It’s a gigantic step forward in what we can do.”

The US navy has invested $12 million in the project because it wants better predictions about how much of the sea north of Canada and Alaska will be accessible to shipping in years to come. Until recently, much of the area was solid ice all year round. That is no longer the case and what’s more, computer models have consistently failed to predict with any accuracy the extent of the melting. Now, a large marginal zone made of smaller, broken-up pieces of ice appears each summer.

Although this year’s melt has only just begun, observations are already challenging model-informed assumptions about the process. In late June, cameras on one wave buoy showed how its surroundings changed from solid ice to a vast, glossy “melt pond” in just three days.

Cameras showed how solid ice turned into a vast melt pond in three days – much faster than in the models

“The speed of that transition was something that the classic models wouldn’t give,” says Peter Wadhams, who researches ocean physics at the University of Cambridge. “They always show processes as happening slowly and sedately, but what seems to be happening is quite sudden.”

Simulations have so far been inaccurate because models are only as good as the parameters fed into them – and little is known of the processes involved in Arctic sea ice melting. For example, the precise relationship between underwater turbulence and the marginal ice zone, in terms of temperature and salinity, is unclear. Satellite observations leave gaps too. “The amount of snow that falls on top of sea ice can’t be measured from space and that is a big factor in the accuracy with which we can measure its volume,” says Andy Shepherd at the University of Leeds in the UK.

The MIZ programme should deliver answers – without making life hard for humans. The Arctic is a tough place to work, says Martin Jeffries at the Office of Naval Research in Arlington, Virginia. “It’s an experiment focused on autonomous technology and obtaining data with a minimal human presence.”

This article appeared in print under the headline “Ice work for the machines”