Less structured approaches

While I think there's a lot to be gained from the systematic attention to detail that structured approaches provide, Polasky et al. [3] describe less structured alternatives that may also be useful in some circumstances.

• Thresholds approach: Rather than trying to choose explicitly among alternatives it may be sufficient to identify boundaries that define acceptable from unacceptable or safe from dangerous outcomes. If the we are approaching a threshold that would lead to drastic changes, e.g., loss of the stratospheric ozone layer, it may lead to a policy response. One danger of a focus on thresholds is that it may lead to the impression that values below the threshold are harmless or without risk.

• Scenario planning: There may be a host of variables that are difficult to quantify or unravel. Nonetheless, it may be possible to develop plausible scenarios that describe different possible outcomes, e.g., the different emission scenarios envisioned by the IPCC. If the consequences of different scenarios are clear, that may be sufficient to facilitate decision making. One danger is that those who identify the scenarios may fail to identify important possibilities. Scenario planning requires a great deal of creativity, and it's difficult to be sure that all relevant scenarios have been considered.

• Resilience thinking: In my mind, resilience thinking could be considered a subset of the thresholds approach: first, identify the critical thresholds a system might cross; second, develop early warning systems to identify when the system is approaching those thresholds; and third, develop plans that will either pull the system back from those thresholds or allow it to function appropriately under the new regime.