What are ecosystem services?
The benefits people obtain from ecosystems — a framework for making nature's contribution visible in decisions that would otherwise treat it as worth nothing.
The four categories, from the Millennium Ecosystem Assessment:
Provisioning — tangible products: food, fresh water, timber, fibre, fuel, genetic resources and medicines.
Regulating — processes that moderate conditions: climate regulation, flood control, water purification, pollination, pest control, disease regulation and erosion control.
Cultural — non-material benefits: recreation, aesthetic value, spiritual significance, sense of place, education and inspiration.
Supporting — the underlying processes everything else depends on: soil formation, nutrient cycling, photosynthesis and water cycling. These are not consumed directly but nothing works without them.
Why the framing exists. Nature's contributions are mostly unpriced, so in any cost-benefit calculation they count as zero. A wetland producing flood protection, water filtration and fisheries appears worthless against a development with a clear financial return. Quantifying the services makes the comparison honest rather than structurally rigged against retaining the habitat.
Where it has changed decisions. Cases where cities calculated that watershed protection was cheaper than water treatment infrastructure, and where natural flood management was assessed against engineered defences, are frequently cited — and the arithmetic favoured nature in both.
The criticisms, which are substantial and come from within conservation:
It is anthropocentric by construction — value is defined by usefulness to people, so a species with no identified service has no value in the framework.
Monetisation is contested. Placing a price on nature can imply it is substitutable, and that destruction is acceptable if the price is paid.
Valuation is technically weak for cultural and existence values, which are frequently the ones people care most about.
It can be captured to justify offsetting and trading.
Not everything can be replaced by an engineered substitute at any price, which the framing tends to obscure.
The related frameworks: natural capital, treating ecosystems as an asset stock producing a flow of services, now incorporated into some national accounting and into UK government appraisal guidance.