Since large-scale environmental disruptions have become chronic, policymakers need to consider the long-term consequences of urgent crisis decisions. We develop design principles for a decision platform addressing strategic environmental crisis management, by which we mean coordinated decisions during an environmental urgency that are sensitive to long-term path dependencies and policy errors. To enhance critical questioning of formal doctrines, the decision platform includes policymakers and sectoral experts as equal participants. The agenda for decisionmaking is structured around future scenarios to encourage the participants to imagine alternative ways of framing the decision problem. The agenda also discourages defensive heuristics with which decision-makers attempt to preserve their short-term reputation. The design principles for strategic environmental crisis management are based on urban experimentation. The barrier of implementation for similar experiments in other contexts is low because they assume no major overhaul in existing administration.