“Antarctic bottom water” is the coldest, saltiest water on the planet. These waters play a crucial role in the ocean’s ability to act as a buffer against climate change by absorbing excess heat and human-caused carbon pollution. They also circulate nutrients across the ocean.
“Some of these sections were first visited as far back as 1989, making them some of the most comprehensively sampled regions in the Weddell Sea,” Povl Abrahamsen, a physical oceanographer at BAS and co-author, said in a statement. The reason these deep waters are shrinking is down to changes in sea ice formation caused by weakening winds, the study found. Stronger winds tend to push ice away from the ice shelf, which leaves areas of water open for more ice to form. Weaker winds have meant these gaps are smaller, slowing sea ice creation, according to the study.
Oceans have absorbed more than 90% of the world’s excess heat since the 1970s and absorb almost a third of human-produced carbon pollution. “To have combined decades of ship-based observations and satellite data is a big leap in our understanding of the formation process, and may be helpful in our understanding of how Antarctic bottom water will form in the future,” Ayres told CNN.