what does water usage mean? is that 4bn cubic meters of water permanently out of circulation somehow? is the water corrupted with chemicals or destroyed or displaced into the atmosphere to become rain?
Depending on the locatin of the hot water you can cause disruptions to water currents, the north atlantic waterway is being studied to how much global warming is affecting it.
If greenland melts, and the water doesnt get cold up there, then the mexico current to europe ends and England becomes colder than Canada.
If your AI model has a data center in the atlantic, it could be furthering that issue.
(Millions of animals are also dead)
Fresh clean water in your area is a wonderful thing.