When air gets heated up, the particles get lots of energy. This means that pressure is not able to keep the bouncy particles down any more. The energy filled particles rise high in the air.
The continents that currently have sufficient water to meet the needs of their populations are North America, South America, Africa, and Australia.
The remaining continents do not - and they have to find their water elsewhere in order to provide all people with enough water for their everyday needs.
