The deforestation and plankton damage have acted in concert with the increase in carbon dioxide and other gases released into the atmosphere to endanger the Bio-sphere's ability to sustain itself. As we zero in on this disease, we find that this is all being done by a tiny little species of animal that has decided to operate on his own rather than in harmony with the rest of the Bio-sphere. We can plainly see that all of the trouble is caused by this one creature, like a cancerous cell run amuck. Being from the Galactic Paramedic Squad, we are familiar with the situation. Something interferes with the information channels of the species and causes them to reproduce in astounding numbers.
Cancer is the only fitting analogy.
Myself, I feel a little uncomfortable with the idea of being a cancerous growth that is killing this Planet. From the vantage point of our orbiting satellite, and without our human ego-centric bias, there can be no other diagnosis.