Issues

Environmental Economics: Costs That Nobody Was Billed For

Morning mist over a river valley with a distant industrial chimney on the horizon

Environmental questions look like scientific arguments and are reported as political ones, but the part that decides most policy is economic. The central problem is old, well understood, and completely uncontroversial within the discipline: some costs of production land on people who were never party to the transaction, and a market that does not see those costs will produce too much of whatever generates them.

Externalities, the textbook market failure

An externality is a cost or benefit borne by someone outside an exchange. A factory that emits smoke imposes real costs — on health, on property, on other producers — that appear in nobody's accounts. Because the price of the product omits those costs, it is too low, and more of the product is made and bought than would be if the full cost were visible.

It is worth being clear about what this argument is and is not. It is not an objection to markets from outside economics; it is a standard result inside it, and it is taught alongside the case for markets rather than against it. The diagnosis is precisely that a price is failing to carry the information a price is supposed to carry. Most of the remedies economists propose are therefore attempts to make the price correct, not to replace it. The Environmental Protection Agency's economics programme publishes the working methodology used in United States rule-making, and the OECD's environment directorate maintains international comparisons of the instruments in use.

Three ways to put a price on emissions

Broadly, three instruments are available, and the differences between them explain most of the policy argument.

A tax on emissions fixes the price and lets the quantity fall where it will. Its virtue is predictability for anyone making an investment; its weakness is that the resulting emissions reduction is uncertain until it happens.
A tradable permit system fixes the quantity and lets the market discover the price. Its virtue is a guaranteed environmental outcome; its weakness is price volatility, which is uncomfortable for long-lived capital investment.
Direct regulation — a technology standard or an emissions limit per unit — is administratively simple and politically durable, but it cannot find the cheapest reductions across an economy the way a price can, and it tends to lock in whichever technology was current when the rule was written.

In practice most jurisdictions use a mixture, and the interactions between overlapping instruments are a live research area of their own: a standard layered on top of a permit system, for example, may reduce emissions in one sector while freeing permits that raise them in another.

Cost-benefit analysis, and where it strains

Regulatory decisions in many countries formally require a comparison of expected costs and expected benefits. The method is transparent and disciplined — it forces everything to be stated, quantified where possible, and defended — and it is also where the hardest assumptions hide.

Two are worth knowing about. The first is valuation: putting a monetary figure on outcomes that are not traded, such as a reduction in mortality risk or the loss of a habitat. Economists have careful methods for this, and they produce wide ranges rather than single numbers. The second, and larger, is the discount rate: the factor by which a benefit arriving decades from now is converted into today's terms. For a policy whose costs are immediate and whose benefits are distant, the discount rate can change the calculated answer more than any measurement in the study. Two analysts using identical physical assumptions and different but defensible discount rates will reach opposite recommendations. This is not a flaw being concealed; it is an explicit, published choice, and it is usually the first thing worth checking in any headline about what a policy "will cost".

Growth, resources and substitution

A recurring public argument concerns whether economic growth necessarily means more resource use. The empirical record is mixed and more interesting than either side's summary. Rich economies have repeatedly reduced specific pollutants — lead, sulphur dioxide, particulates — while continuing to grow, largely through a combination of regulation and technological substitution. Whether that pattern generalises to greenhouse gases, which are global rather than local and lack the cheap substitutes that made the earlier cases tractable, is genuinely contested.

The mechanism behind the successful cases is worth noting because it is the same one throughout this primer: once a cost was priced or capped, industry found cheaper ways to avoid it than anyone had forecast, and the actual compliance cost typically came in below the pre-implementation estimates. That has happened often enough to be a documented pattern, and it cuts against confident cost projections in either direction.

Reading environmental coverage

Three questions again. Cost to whom, and over what horizon? A figure that sounds enormous may be an aggregate over decades across an entire economy. What discount rate, and what baseline? Both are choices, both are usually stated in the source document, and both are usually absent from the coverage. Is this a projection or a measurement? Modelled results and observed results are different kinds of claim and deserve different confidence.

The longer treatment of how these studies get built and reported is in the special report on climate policy and cost analysis. For the market side, see energy.