Is it smart to run cars on hydrogen?

Answer

The earth needs greenhouse gases to maintain its temperature. Without this effect it would be a cold affair here. It’s mainly about balance.

Water vapor is present in the atmosphere in large quantities anyway, and its quantity is controlled by the fact that water vapor condenses and forms clouds. Those clouds shield the sunlight and provide a cooling effect.

the CO₂ that we are now releasing en masse into the air will never condense. This is not an equilibrium, but a constant increase. How important the effect of human production of CO₂ relative to naturally occurring greenhouse gases (a volcanic eruption also emits a lot) is still not completely clear. It’s clear that runaway warming is not easy to reverse, so we’d better be careful.