Coastal property decisions under deep uncertainty: build a decision threshold before choosing a forecast

The useful lesson is the decision method

The source examines an idealized investment decision at the Port of Los Angeles: whether to harden a terminal against future flooding when it next undergoes an upgrade. It compares Robust Decision Making with a full probabilistic analysis. Both approaches reached similar recommendations in this particular application, but they organized uncertainty and stakeholder judgment differently. For a family office holding coastal property or infrastructure, the transferable insight is how to expose the conditions that change a decision. The paper does not supply a current flood forecast, valuation adjustment or recommended protection height for another asset.

The study was published in 2018 and uses simplified physical and economic assumptions. It does not include all regional sea-level dynamics, uses an idealized representation of abrupt changes, and examines a specific facility configuration. The source's numerical thresholds must not be copied into a present investment memorandum as if they applied to a hotel, residence, warehouse or port elsewhere. Current local engineering and hazard evidence are separate requirements.

Start with an actual choice and a consequence

The asset manager should define a concrete choice: protect equipment at the scheduled refurbishment, preserve the option to relocate it later, change the use of a vulnerable area, or defer a commitment while gathering specified information. State the decision date, expected service life and operational consequence of failure. A broad question such as whether climate risk is material is too vague to organize useful analysis. The model needs to connect an action to a consequence that the owner actually cares about.

List costs beyond physical repair, including interruption, access loss and obligations to occupants or counterparties where relevant. Distinguish insured losses from losses the owner must fund and verify the actual coverage rather than assuming insurance removes exposure. The finance lead should document discount-rate choices, residual values and the assumptions governing early retirement. These are proposed local inputs; the source does not validate any particular cost schedule for the family's properties.

Do not hide disagreement inside one probability

The risk lead should classify inputs according to the strength of the supporting evidence. Some may have well-supported estimates; others may involve disputed models, uncertain future uses or conflicting preferences. Record those distinctions explicitly. In the paper, terminal life and tolerated flooding frequency are not merely engineering constants: they involve future management choices. A property model similarly should not present future tenant needs or the owner's tolerance for disruption as settled physical facts.

Where probabilities are uncertain, examine a range of plausible combinations and identify which combinations make the proposed action fail its objective. Do not label the fraction of simulated cases that fail as the real-world probability of failure unless the sampling design supports that interpretation. The paper explicitly distinguishes its exploratory Latin-hypercube sample from probability-weighted Monte Carlo sampling. That distinction belongs in the committee presentation as well as in the technical appendix.

Use thresholds to organize evidence gathering

The analyst should identify the conditions under which protection becomes worthwhile and the conditions under which it does not. For example, a long remaining useful life may make a protective investment more valuable, while near-term redevelopment could change the comparison. The relevant question is whether credible evidence places the asset near a decision boundary, not simply whether a dramatic scenario can be imagined. Keep the boundary tied to the stated objective and cost model.

In the source, hardening passed the benefit-cost test in 173 of 500 exploratory cases. The authors then characterized a scenario involving rapid sea-level rise, long terminal life and changes in hourly anomalies. Those case counts are a description of the experiment, not a portfolio loss probability. A family office should reproduce the logic with its own verified inputs and appropriate specialists, not reuse the counts or the paper's probability threshold as a universal rule.

Make options and disagreement visible

The committee chair should request a short decision table showing each option, the conditions where it performs poorly, the assumptions that matter most and the evidence that could change the recommendation. Include meaningful alternatives instead of comparing only an expensive engineering intervention with doing nothing. Monitoring, staged works and changes aligned with planned maintenance may deserve analysis, but their benefits must be calculated rather than presumed.

Maintain a record of disagreement. If an engineer, operator and investment team assign different importance to downtime or remaining asset life, show the disagreement before aggregating it. Robust Decision Making requires judgment and can require more analysis than a single expected-value calculation. It is useful when that added transparency improves a consequential decision; it should not become an elaborate ritual for choices that are already insensitive to the uncertain inputs.

Link monitoring to action and stopping rules

The asset manager owns a dated action plan. The engineering lead owns local physical assumptions and technical feasibility. The finance lead owns cost and liquidity assumptions, while the risk lead maintains the scenario register and model versions. Measures should include unresolved decision-critical inputs, time needed to implement a response, changes in exposure and the margin between observed conditions and the chosen trigger. Keep the evidence date visible so an old climate input cannot quietly become a current forecast.

Pause an irreversible commitment when a material input is unverified, when the protection option cannot be implemented before the relevant exposure, or when small plausible changes reverse the recommendation without a documented response. Reopen the decision when new evidence changes an identified boundary or the planned use of the asset changes. This is AI-assisted editorial analysis of an adjacent infrastructure case, not new research or engineering advice. No source-author endorsement or documented human acceptance is asserted, and the proposed workflow has not been validated for family-office portfolios.

Source, attribution and limits

[1] Ryan L. Sriver; Robert J. Lempert; Per Wikman-Svahn; Klaus Keller. Characterizing uncertain sea-level rise projections to support investment decisions. PLOS ONE (2018-02-07). https://doi.org/10.1371/journal.pone.0190641. CC BY 4.0.

2018 idealized Port of Los Angeles infrastructure decision, not current property-specific hazard advice. Simplified physical/economic models and global-versus-local approximations; exploratory case frequencies are not real-world probabilities. Local updated engineering evidence is necessary.

Prepared by the Family Office Private Wealth Journal editorial research desk with AI assistance at the direction of Dr. Freedom Cheteni. Original research authors retain full credit and are not authors or endorsers of this companion. This proposed process has not been evaluated in a new empirical study; no independent peer-review acceptance is claimed. This is educational analysis, not individualized investment, legal or tax advice.

Implementation record

Open the cited sources

1. [1] Ryan L. Sriver; Robert J. Lempert; Per Wikman-Svahn; Klaus Keller. Characterizing uncertain sea-level rise projections to support investment decisions. PLOS ONE (2018-02-07). ↗