North-South ocean currents are shown at different depths in the ocean, with their strength and direction indicated by the arrows. The density of the water increases with depth, from low (orange) to high (brown). During cold climates (right), sea ice around Antarctica grows, preventing some outgassing of carbon from the ocean to the atmosphere. Also, brine formation increases, which causes the Antarctic Bottom Water to become more dense, decreasing mixing with waters above. The two processes result in more carbon stored in the deep ocean.