Answer:
Due to human activities.
Step-by-step explanation:
This change in the concentration of carbondioxide and methane gas is happening due to human activities because human used fossil fuels which can be burn in the engines of vehicles that releases carbondioxide gas in the atmosphere. Humans are responsible for the change of atmosphere which leads to change in the climate all over the world. Methane gas is also released by human activities such as using methane for cooking food.