Past sea level has varied by somewhat more than a hundred metres. This is primarily due to the growth and decay of ice sheets (mostly in the northern hemisphere) with water evaporated from the sea. The Mediterranean Basin's gradual growth as the Neotethys basin, begun in the Jurassic, did not suddenly affect ocean levels. While the Mediterranean was forming during the past 100 million years, the average ocean level was generally 200 metres above current levels. However, the largest known example of marine flooding was when the Atlantic breached the Strait of Gibraltar at the end of the Messinian Salinity Crisis about 5.2
Weddell Sea Bottom Water exposes more surface water to the wind allowing it sink. This makes the WSBW colder than normal allowing it to inject colder water into much of the world's oceans. If the ENSO even is weak enough, the surface winds off the Antarctic coast can shift direction which creates a reduction in shelf water. This will warm the WSBW as it does not have as much access to the cold, dense surface water. Weddell Sea Bottom Water Weddell Sea Bottom Water (WSBW) is a subset of Antarctic Bottom Water (AABW) that is at a temperature of -0.7 °C or colder. It