The Montreal Protocol

Agreed in 1987, the Montreal Protocol coordinated the phaseout of substances that depleted the stratospheric ozone layer, including chlorofluorocarbons. Later amendments strengthened controls as research improved and substitutes became available.

The ozone layer has shown signs of recovery, though restoration is gradual and depends on continued compliance. The treaty is widely regarded as a successful environmental agreement, but it did not make outdoor life universally safe or remove all atmospheric risks.

Without coordinated controls, emissions might have continued longer and ozone depletion could have worsened. The scale of future harm would depend on chemical use, atmospheric response, and later policy; the exact counterfactual cannot be observed.

The protocol's experience suggests that global action is more feasible when risks are measurable, alternatives can be developed, and assistance helps countries meet common obligations. Those conditions do not automatically transfer to every environmental problem.

Those conditions do not automatically transfer to every environmental problem.

What would make me trust that a global promise is changing measurable harm rather than merely expressing good intentions?