What are Scope 1, 2 and 3 emissions?

Scope 1 emissions are those which you make directly, such as heating used for your business premises. Scope 2 emissions are those you make indirectly, for example the electricity you buy which is being produced on your behalf. Scope 3 emissions are any emissions associated with your business activity such as employee commuting, manufacturing of the products you use, and customer activity that is happening as a result of your organisation.  

See this page from Deloitte for more information.