Phytosphere

After settlement negotiations between humanity and the alien Tarsalans go horribly wrong, the Earth is engulfed in a mysterious green sphere-blocking all sunlight from reaching the surface. Only two scientists-one isolated on the Moon's lunar colony, the other trapped on a dying Earth-possess the minds and the means to destroy the sphere before it renders the world completely barren... When negotiations between the alien Tarsalans and Earth's rulers go horribly wrong, a strange green sphere begins enveloping the planet, causing major devastation, and two brilliant scientists must find a way to destroy this alien phytosphere before it is too late