Abatement cost is the cost of reducing pollution. Economists distinguish between the cost of one more unit of cleanup, called marginal abatement cost, and the total cost of achieving a given emissions reduction.
Marginal Vs. Total Abatement Cost
If A is the amount of pollution reduced, then the marginal abatement cost is MAC(A), the cost of cutting one more unit. Total abatement cost is the cumulative cost of reaching that amount of cleanup:
\[ TAC(A) = \int_0^A MAC(a),da \]
This matters because environmental policy is usually about choosing both how much cleanup to require and who should do it.
Why Costs Usually Rise At The Margin
The easiest reductions usually come first: basic maintenance, simple fuel switching, or low-cost process changes. Once those are exhausted, deeper reductions require more expensive technologies or bigger changes to production.
That is why marginal abatement cost curves usually slope upward.
Least-Cost Allocation Across Firms
Suppose two firms must jointly reduce pollution by a fixed amount. The cheapest allocation is the one that equalizes marginal abatement cost across firms:
\[ MAC_1 = MAC_2 \]
If one firm can reduce pollution at much lower cost than the other, total cost falls when more of the cleanup is shifted toward the cheaper source.
Why Policy Design Uses Abatement Costs
Abatement costs help compare policy instruments:
- a tax lets firms choose how much to clean up at a given pollution price,
- cap-and-trade lets firms trade until abatement costs are equalized through the permit price,
- rigid standards can miss those cost differences and produce the same cleanup at a higher total cost.
Cost matters because the same environmental target can be reached with very different economic burdens.