The Montreal Protocol, signed in 1987, committed its signatory countries to phasing out chemicals responsible for depleting the ozone layer, and it's widely regarded by environmental policy researchers as one of international environmental cooperation's clearest and most complete successes, achieving near-universal country participation and substantial real reductions in the relevant chemicals within a relatively short span of years. International agreements addressing climate change and carbon emissions have, by comparison, taken considerably longer to develop and have generally achieved less complete or immediate real-world traction, despite climate change representing an arguably larger and more consequential global environmental problem.
A narrower, more substitutable problem made ozone easier to solve
Part of what made the Montreal Protocol's rapid success achievable was the specific, comparatively narrow nature of the underlying problem: a relatively small, well-identified set of chemicals, used in a limited number of clearly identifiable industrial applications, were responsible for ozone depletion, and workable chemical substitutes for most of those applications were already available or reasonably close to being developed by the time the agreement was signed. This meant complying with the agreement didn't require most signatory countries to fundamentally restructure large parts of their broader economy — a comparatively contained, technically substitutable problem, made more tractable to solve quickly and comprehensively through binding international agreement than a more deeply structural one would be.
Carbon emissions touch nearly every part of a modern economy
Climate change agreements addressing carbon emissions face a substantially more difficult underlying problem: carbon emissions are deeply embedded across nearly every major sector of a modern economy, including energy production, transportation, agriculture and manufacturing, rather than being concentrated in a narrow, easily substitutable set of specific chemical applications. Reducing emissions at the scale climate scientists argue is genuinely necessary generally requires substantial, economically significant changes across many different major sectors simultaneously, not a single substitutable chemical swap — a fundamentally larger, more structurally embedded and more economically disruptive kind of change to negotiate binding, universal international agreement around, which is a major part of why climate agreements have generally progressed more slowly and unevenly, with weaker binding enforcement, than the Montreal Protocol's comparatively narrower, more substitutable target problem.
What we're still unsure about
The Montreal Protocol's rapid, near-universal adoption and its substantial measured success in reducing ozone-depleting chemicals are well documented and not genuinely disputed among environmental policy researchers. What remains more actively debated is exactly how much of that comparative success actually transfers as a genuinely useful policy lesson for climate change agreements, given how structurally different the two underlying problems are — some policy researchers argue the Montreal Protocol offers real transferable lessons about effective international environmental cooperation more broadly, while others argue its success depended so heavily on the ozone problem's own narrower, more substitutable nature that the comparison offers considerably less practical guidance for the much larger, more structurally embedded challenge climate agreements actually face.
This sits inside Environmental Policy & International Agreements, one of seven topics in Environmental Geography, one of five domains in Geography, one of seventeen subjects the app can quiz you on.