SEA ice is a key indicator for assessing the impact of global warming on the planet. A team of researchers from Brown University in the United States has identified a new molecule to reconstruct information about the abundance of sea ice over the last few centuries. According to the scientists, this discovery could prove valuable in the current assessment of climate change.

Mainly starting to form at the fall in the Arctic Ocean, pack ice plays a key role in regulating the climate system. In particular, it insulates the cold waters of the oceans in winter.

According to this new study, published in Nature Communications, studying the evolution of sea ice going several centuries back could help us understand climate change triggered by human activity.

Scientists have focused on an organic molecule often present in ocean sediments at high latitudes, known as tetra-unsaturated methyl alkenone (C37:4).

"Looking at the concentration of this molecule in sediments of different ages could allow us to reconstruct sea ice concentration through time," said Karen Wang, PhD student from Brown University and main author, in a press release.

"That was mostly what the C37:4 alkenone was known for -- throwing off the temperature ratios," said Yongsong Huang, co-author of the study. "Nobody knew where it came from, or whether it was useful for anything. People had some theories, but no one knew for sure," added the scientist.

To unravel this mystery, the researchers studied samples of seawater sediment containing C37:4, sampled from ice-covered areas around the Arctic. They performed DNA sequencing to identify the organisms present in the samples.

Better predict future climate change

At the end of the experiment, scientists identified several previously unknown species of glacial algae. Then they cultivated these algae in a laboratory and found that they produced an exceptionally high quantity of C37:4.

Their research showed that the highest concentrations of C37:4 occurred when the climate was coldest, such as during the recent Dryas Ice Age, which occurred more than 12,000 years ago. In other words (and quite logically) the warmer the climate was, the more the volume of ice and the concentration of C37:4 decreased.

The scientists behind the publication hope that this discovery will lead to a better understanding of sea ice dynamics over time. According to the researchers, this information would help improve past climate models and thus better predict future climate change.

Last October, the scientific community warned about the surface area of the Arctic ice pack, which was the smallest recorded since the 1980s. A direct consequence of the record heat wave in the summer of 2020.