Make decisions that work or function over a wide range of possible conditions. Aim for flexibility, robustness, and resilience.

• Flexibility: The adaptation can accommodate different conditions by adjusting. 

• Robustness: The adaptation can withstand a variety of conditions. 

• Resilience: The adaptation can recover from shocks. In the context of climate change, resilience has been used to also include withstanding shocks. 

• Consider economics: benefits should exceed costs. It’s complicated when benefits (avoided impacts) may not happen or be much larger decades into the future. 

  • Discounting—do not spend a lot now to avoid risks many years from now.

Traditional assessment approaches are often used to help identify an optimal solution. Deep uncertainty approaches recognize that “deep uncertainty” is part of the problem and try to identify adaptations that can work across an array of possible outcomes. Traditional approaches work best when uncertainties are well-characterized. However, since probabilities are not assigned, it’s hard to apply traditional approaches.

1. Benefit-Cost Analysis (BCA)
   • Expresses all benefits and costs in a common unit, typically money
   • Seeks to maximize net benefits and benefit-cost ratio
2. Cost-effectiveness
   • Seeks the least costly and most feasible way to achieve a common outcome
3. Multi-criteria assessment
   • Typically applied where different metrics are used; useful when some metrics aren’t easy to compare
4. Triple Bottom Line (TBL)
   • Splits out financial, social, and environmental benefits
   • Can be used along with the above approaches. Other methods often overlook social and environmental benefits, but TBL provides more than just finances.

Multi-Criteria Assessment (MCA) is useful for qualitatively comparing different attributes of options. The example compares options based on effectiveness, feasibility, and costs. Rather than using a common metric such as money, MCA uses ordinal ranking, such as high, medium and low or good, fair, and poor.

• Recognizes that we can adjust decisions as conditions change

• Design systems/decisions so that changes in future conditions can be incorporated

• Option to use land for investment in future, such as a reservoir

• Example: Thames River barrier was built to protect London from storm surges over the rest of the century. They’ve implemented an adaptive management system that allows them to make their next decisions based on future sea level rise.

Adaptive Management System for the Thames River Barrier

The Thames River Metropolitan Water District organized near-term investments in local supplies expecting that some will need to expand and some will be contracted as demand, regulations, climate, and other factors change. The American Society for Civil Engineers recommends an adaptive management approach. 

Adaptive management can also spread out decisions over time, as seen in the figure below, which shows decisions on flood risk in Rotterdam.

Adaptation pathway map for flood risk management in the Rotterdam area (Delta Programme 2014)