If passing by a black hole surrounded by super-cooled water, Earth loads up on ice that subsequently melts and generates the great floods; in another perspective, this is the way Earth reloads on water.
The flood water eventually evaporates away and expose habitable land.
Water is constantly evaporating away into space. Avoiding a collision with the super-cooled water sphere around the black hole, spares Earth from an Ice age but leaves it short of water.
In the future, Earth might dry up, as water is constantly evaporating away into space, before we meet with the black hole again along Earth's orbit in precession around the Sun.
We have to replenish water on earth in a controlled manner. Prompting the black hole into a Sun is unwise, because as a black hole it is Earth's source of water.
