Given the task definition and input, reply with output. Given a list of steps and an additional step, determine where the step fits into the original list of steps. A correct answer, correctly places the given step into the set of steps so that it creates a new plausible set of steps. Output must be formatted as 'After step n', where n is the step number after which the given additional step is to be inserted.

Steps: (1) Solar radiation reaches Earth's atmosphere (2) Some is reflected back into space (3) The rest of the energy is absorbed by land and oceans, heating the Earth (4) Heat radiates from Earth to space (5) Some of this heat is trapped by greenhouse gases in the atmosphere (6) This causes more heat radiation to stay trapped in our atmosphere (7) The Earth's temperature rises  
Where does the following step fit into the given list of steps: Human activities such as burning fuel are increasing the amount of greenhouses gases 

 After step 5. 