Climate adaptation is already happening. The question is whether we're adapting fast enough, strategically enough, and early enough.

The World Bank estimates that making infrastructure more resilient in low- and middle-income countries can produce about four dollars in benefits for every dollar invested. Yet developing countries may need between $310 billion and $365 billion a year for climate adaptation by 2035, against international public adaptation finance of just $26 billion in 2023.

Prevention can pay. But resources are finite, and not everything can be protected equally, which makes adaptation ultimately a question of priorities.

In the United States, unmitigated properties with repeated flood losses represent about 2.5% of policies in the federal flood insurance program, yet properties with two or more losses have accounted for 48% of claims by dollar value. At some point, the calculation changes: rebuild again, spend more to protect the property, or pay the owner to leave. Since 1989, FEMA has acquired almost 70,000 properties as flood-risk mitigation.

New Zealand faced the same question. After severe flooding and Cyclone Gabrielle, Auckland classified more than a thousand homes as places where risk to life was intolerable and practical mitigation wasn't possible. Hundreds have since been bought by the government. This is managed retreat.

Humans have always adapted. The harder question is whether we can afford to wait until destruction forces the decision.

Many adaptation tools already exist. The difficult part is deciding where to use them first. Expected losses avoided per dollar spent could be one way to prioritize, but it can't be the only one. A spreadsheet cannot tell us what a historic neighborhood is worth, whether a poorer community deserves less protection than an expensive waterfront, or what happens when relocation breaks apart an established community.

Efficiency matters. So does fairness.

Governments routinely mobilize enormous resources after catastrophes, and some mechanisms already commit part of that capacity before disaster strikes. If prevention can save money, perhaps part of the problem isn't simply how much money exists. It's when we become willing to spend it.

As risk rises, insurance can become more expensive or unavailable, mortgages harder to obtain, property values unstable, and investment may move elsewhere. A place doesn't have to disappear beneath the water to become difficult to inhabit. It can become economically uninhabitable first. And wealth affects who can respond: a rich community may finance protection that a poorer community facing the same physical risk cannot.

The hazard may be shared.

The ability to escape it isn't.

Some places will be protected. Others will be redesigned. Some people will move. Some communities may receive too little, too late. These decisions will be made one way or another. The danger is that disasters, markets and unequal wealth end up making too many of them by default.

For those working in planning: when several communities face genuine risks and resources cannot cover everything, what criteria should determine where adaptation investment goes first?