If Arctic sea water is generally -1.8C, while the freezing point of water is 0C, why is the Arctic not fully frozen?

Question

If Arctic sea water is generally -1.8C, while the freezing point of water is 0C, why is the Arctic not fully frozen?

In: Earth Science

Answer 1

Have you ever made homemade ice cream?

You take the ice, 0°C. But then you add salt to the ice, and the temperature dropped to below 0°C.

This is the same reason the Arctic sea water is colder, because it is salty. Adding salt to the water changes the freezing point.

0°C is only the freezing point of PURE WATER, not salt water. The actual freezing temperature depends on the concentration of salt that is dissolved.