Scientists were previously puzzled by the fact that the amount of sea ice is actually increasing from one year to the next, and this latest research only adds to the confusion as to what is going on in the seas around Antarctica.

Robot Antarctic Sea Ice

Existing climate models predict that levels of sea ice in Antarctica should be decreasing because of the effects of global warming. However satellite images show that the ice is expanding, and has broken records for the past three winters. However levels of glacial ice on land have been decreasing.

The latest Antarctic Sea Ice study

Scientists used an underwater robot to measure the thickness of the sea ice because it is crucial to understanding why it is growing, according to study co-author Ted Maksym, an oceanographer at the Woods Hole Oceanographic Institution in Massachusetts. It is essential to evaluate whether the growth of sea ice includes thickening as well as expansion.

“If we don’t know how much ice is there is, we can’t validate the models we use to understand the global climate,” Maksym told Live Science. “It looks like there are significant areas of thick ice that are probably not accounted for.”

Robotic assistance to measure Antarctic sea ice

The robots are used because it is hard to take accurate measurements through drilling, due to the fact that the thickest ice is the most difficult to reach. In undertaking the study the researchers became stuck for over a week in 6 meter thick pack ice, which illustrates the risks inherent in such research.

The study took four years to complete, with a team of international researchers mapping the bottom of sea ice with an underwater robot, otherwise known as an autonomous underwater vehicle (AUV), over the course of two research missions around Antarctica. The device can reach depths of around 30 meters and uses an upward-facing sonar to survey the ice from below.

“With the AUV, you can get under ice that is either difficult to access or difficult to drill, and in each region, we found some really thick ice, thicker than had been measured anywhere else,” Maksym said.

The findings were published in the journal Nature Geoscience on November 24(Nov. 24) .