The Ecological Time Bomb

As far as how we humans are impacting our environment, I would say that we are living on borrowed time.

Let's face it - pollution, CO₂ emissions, overpopulation, and plenty of other environmental dangers will not ensure our environment's survival. 

The B.P. oil spill crisis is no exception. 

Undoubtedly the spill caused a lot of oceanic damage, killing myriads of fish and making the waters uninhabitable. 

While not an event so catastrophic that it destroys all of Earth's ecosystems, it is a fuse that brings us closer to the one 'big one' that will fulfill that job. 

Such is what the cartoonist is trying to paint.
BP is the fuse for a bomb - representing an environmental catastrophe or perhaps something more gradual - that will destroy the world as we know it.

Either the event that transpires will be a massive one that consumes all of the environment in its wake, or slowly but surely we are approaching the point at which the environment will be destroyed, and BP's spill only increased the speed at which we are approaching such a point.

Regardless of the cartoon's meaning, one thing is clear - we must do more to protect our environment and circumvent her destruction, or we will all die with her.