Terrorism has many types, like Cyber-terrorism which involves hacking of government portal, databases to get information on employees and citizens. Also, Gene-terrorism which is use of modifying DNA of virus and bacteria and spreading the cause disease to people.
Climate change simply refers to those undesirable effects in world in atmosphere and on land that have a negative effect on people and nature.
GST is an Indirect Tax implemented by the government on consumption. It is a destination based tax and is the tax biggest reform in India since economy opened up.