Space is not very far away.
Aircraft on long-haul flights travel at a height of about 10 km.
The lowest layer of the atmosphere, the Troposphere, ends at about 15 km.
The air in the layers above the troposphere is very thin indeed.
Think of a place around 15 km (9 miles) from where you are.
That's pretty much how near you are to space.
All the waste gases people dump into the air are trapped in the thin layer of air around the Earth.
Atmospheric concentrations of some greenhouse gases over the last 2,000 years.
Increases since about 1750 are due to human activities in the industrial era.
Concentration units are parts per million (ppm) or parts per billion (ppb), indicating the number of molecules of the greenhouse gas per million or billion air molecules in an atmospheric sample.