A carbon budget is a concept used in climate policy to help set emission reduction targets in a fair and efficient way. It examines “the maximum amount of cumulative net global anthropogenic emissions of carbon dioxide (CO ₂), which would lead to limiting global warming to a given level". It can be expressed relative to the pre-industrial period (year 1750). In this case it is about total carbon budget. Or it may be expressed as of a recent specified date. In that case, it is about remaining carbon budget . (More on wikipedia.org)