Tokyo today is unusually liveable—safe, clean, functional and vibrant—for a megacity of its size: 37m in its greater metropolitan area, including 14m people in the central wards.
(source) Places like Dubai are going to have to figure out a way to stay liveable while not being swallowed whole by the sheer number of new people populating them.
This keeps the planet at a liveable temperature, but without the ocean and with a compromised atmosphere, lots of the warmth our sun provides would be sent right back out into space.
But the fact is, sponges not only survived Snowball Earth, they may have actually shaped the future of our planet, making the world's oceans more liveable and paving the way for all animal life to come.
You know, if you want a planet that's going to work and actually be liveable and not see mass migration of people and complete devastation of our way of life, we actually have to address this.