MACC meaning in General ?

Abatement cost is the cost of reducing environmental negatives such as pollution. Marginal cost is an economic concept that measures the cost of an additional unit. The marginal abatement cost, in general, measures the cost of reducing one more unit of pollution.

Although marginal abatement costs can be negative, such as when the low carbon option is cheaper than the business-as-usual option, marginal abatement costs often rise steeply as more pollution is reduced.

Marginal abatement costs are typically used on a marginal abatement cost curve, which shows the marginal cost of additional reductions in pollution.