How is polar ice connected to ocean circulation?

The answer

Polar ice formation is a critical engine of global ocean circulation. When seawater freezes in the Arctic and around Antarctica, it expels salt into the surrounding water, creating extremely cold, dense brine that sinks rapidly to the deep ocean. This sinking water drives the global thermohaline circulation, also known as the ocean conveyor belt, which transports warm surface water toward the poles and cold deep water toward the equator. In Antarctica, this process produces Antarctic Bottom Water, the densest water mass in the world ocean, which fills the deepest layers of all three major ocean basins. Accelerating ice melt threatens to disrupt this process by adding freshwater that reduces surface water density, potentially weakening the entire global circulation pattern.