“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. But in the Weddell Sea, along the northern coast of Antarctica, this vital water mass is in decline, due to long-term changes in winds and sea ice, according to the study published Monday by the British Antarctic Survey.
As the water freezes, it pushes out salt and as salty water is denser, it sinks to the bottom of the ocean. The changes in these deep waters can have far-reaching consequences. They are a vital part of global ocean circulation, transporting human-caused carbon pollution into the deep ocean where it remains for centuries, said Silvano. If this deep circulation weakens, “less carbon can be absorbed by the deep ocean, limiting the ability of the ocean to mitigate global warming,” Silvano told CNN.