Volcanism.
Water is still being added to Earth's hydrosphere through processes such as volcanic activity, meteorite impacts, and the outgassing of water vapor from rocks. Additionally, the melting of ice caps and glaciers contributes to the increase in water in the hydrosphere.
they are still harming the wildlife, just not in such a big way as other problems. But added up with the enviromental impacts of the other tirbes, they are causing problems.
No Globigerina still exist in the earths oceans.
Less than 0.05% but that is still a lot!!!
It is still water but contaminated.
Oxygen
No. Such stories are pure fiction and not good science at all.
Chlorine*
the answer is simple there is more, lots, lots more in the unknown universe that we have still to learn. what is at the earths core? what does pluto's surface look like? you get the idea
carbon dioxide, sulphur dioxide and still nitrogen
No. There also would be very little chance life would exist on the planet.
Nothing - people still drink it.