This question is about Earth's greenhouse gases and climate.
The graph below shows how atmospheric methane concentration and global average temperature variation have changed between 1980 and 2020.

Evaluate the information shown in the graph. To what extent does the graph support a link between atmospheric methane levels and global warming?
Describe and explain how the greenhouse effect maintains the temperature of the Earth.
State one human activity that can cause an increase in atmospheric methane levels.
State two environmental effects of an enhanced greenhouse effect.