When its altitude is matched by the pull of the Earth's gravity, a satellite circles Earth. The satellite will fly off into orbit in a straight line or crash down to Earth without this equilibrium.
By juggling two things, a satellite retains its orbit: its velocity (the speed it takes to travel along a straight line) and the gravitational force on it that the Planet provides. To resist the greater gravitational force, a spacecraft orbiting closer to the Earth needs more velocity.
For many years sea life such as oysters and clams have been acostumed to the temperature of the water. Rising levels of CO2 will cause more heat in water temperatures. This would make the shells of the oysters and clams 'wear away'.