There is a conspiracy to cause global warming.

Think about it. The consequence of global warming is a rising sea level.

Sea life will benefit from this. The smartest animals are Dolphins and Octopii. Dolphin Rape Caves are widely known about, and the Japanese have been warning the world through anime what happens when an octopus gets its tentacles on and in you.

The endgame? Flood the world and rape every land creature.

How do we fight this?

I think it's the lizardmen. Remember, they're cold-blooded. If certain parts of the Earth become dangerously hot, it's all the better for them.