Why should anybody be concerned about what they can't see?
But now NASA's Orbiting Carbon Observatory has returned its first global maps of the greenhouse gas carbon dioxide.
The satellite was sent up in July to help pinpoint the key locations on Earth where carbon dioxide is being emitted and absorbed.
This should help scientists better understand the ways human activities are influencing the climate, says BBC News.
And perhaps have an effect on public opinion?
Check out the map, which shows, for example, spiking emissions over China.