Why is a trace gas the sole focus of most climate change debates?

Here.

Excerpt:

Attributing global climate change to human CO2 production is akin to trying to diagnose an automotive problem by ignoring the engine (analogous to the Sun in the climate system) and the transmission (water vapour) and instead focusing entirely, not on one nut on a rear wheel, which would be analogous to total CO2, but on one thread on that nut, which represents the human contribution.