Defining success. Adaptation is an ongoing process rather than an endpoint, with few benchmarks that signify when a project has achieved "success." Even if such road-markers existed, there is no universally agreed-upon understanding of success. Identifying a standard of comparison with which to measure results against is also challenging as practitioners typically struggle with shifting baselines, lack of a credible counterfactual, and difficulties associated with establishing a control.

Coping with uncertainty. Adaptation practitioners face significant uncertainties across program cycles that can create moving targets and alter key assumptions within ME&L frameworks.

Managing timeframes that often extend far beyond project cycles. The effects of adaptation projects often become clear after decades of climate change impacts. Time lags between implementation and observed changes often occur, and these delays rarely fall within project cycles. Adaptation programs, particularly EbA initiatives, may also take a long time to implement – planting slow-growing trees or recharging aquifers, for example – and require monitoring and evaluating impact across extended time horizons.

Measuring adaptation outcomes across different scales and sectors. Because adaptation is fundamentally a local challenge, assessing progress requires indicators that track outcomes specific to a particular context. Thus, there is no standard set of indicators from which ME&L practitioners can draw, and without common metrics, it can be difficult to analyze adaptation across global portfolios. The need to build resilience across all sectors further complicates efforts to standardize indicators.

Determining attribution. Establishing a causal link between an intervention and impact requires an experimental design with a control or counterfactual and the ability to limit confounding variables. Instead, practitioners should measure contribution to adaptation outcomes.