Business-as-Usual Scenario (BAU)

A business-as-usual (BAU) scenario is the reference emissions trajectory a sector or vessel would follow without new climate policy, technology, or behavior change, used as the counterfactual against which reductions are measured. In carbon crediting it sets the baseline that determines additionality and the volume of credits a project can claim. In shipping decarbonization studies it is the no-action pathway against which IMO targets and fuel-transition scenarios are compared, for example projecting fleet CO2 growth from cargo demand at current carbon intensity. A weak or inflated BAU baseline overstates measured reductions, which is why baseline integrity is central to credit quality.