Answer:
To be sustainable is to be able to maintained at a certain rate. It's to keep things continuous and viable. For example, wind energy is sustainable compared to oil because wind is easier to get than oil. Another example is if a country only has about 10-13 crimes a year for 20 years, crime is sustainable in that country.
Cold water<span> has a higher density than warm </span>water<span>. </span>Water<span> gets colder with depth because cold, salty </span>ocean water<span> sinks to the bottom of the </span>ocean<span> basins below the less </span>dense<span> warmer </span>water<span> near the surface.</span>