This review examined evidence on climate change adaptation interventions and their effectiveness between 2007 and 2018. Results from 464 studies are included in an evidence gap map which shows large disparities in evidence by geographic region, sector, interventions, and outcomes.
The evidence gap map and intervention heat map answered the following questions:
What is the state of evidence on adaptation interventions, and what is their efficacy in helping people in low- and middle-income countries adapt to climate change?
Findings: Evidence was most concentrated in sub-Saharan Africa and within the agricultural sector. Conversely, there was a lack of evidence in Latin America and within the water and built environment sectors. In terms of interventions and outcomes, nature-based solutions have been studied the most whilst there were very few studies that have focused on institutional systems.
Where has the GCF allocated project finance to date within the intervention/outcome framework developed for the evidence gap map?
Findings: The heat map uses data from both the GCF and German development cooperation. Overlaying the heat map on the evidence map revealed a considerable disparity between the available evidence and funding allocated to interventions. Funding was mostly targeted towards infrastructure. Despite the wealth of evidence on social and behavioural actions, little funding has been targeted towards these interventions. These disparities between the available evidence base and current flows of funding can provide insights for portfolio development.
The systematic review and associated meta-analysis answered the following question:
What role has access to credit played in explaining the decision to adopt adaptation strategies in the agricultural sector, in low- and middle-income countries?
Findings: The review showed a great disparity of effects. Non-significant effects were apparent for a large proportion of studies which examined credit-related variables and the decision to adopt adaptation measures. A meta-regression revealed that some study design elements – such as the estimation method used, the number of covariates included, and the selection of certain control variables – were significantly correlated with the studies' results. More narrow definitions of credit variables together with the use of counterfactual study designs should be used to obtain more reliable and robust evidence on the subject.
Recommendations: The evidence gap map revealed a dearth of evidence on adaptation interventions in the water and built environment sectors. Given their importance in climate change adaptation, these sectors demand a greater number of impact evaluations on the efficacy of their associated interventions. This need is underscored by the fact that both the GCF and German development cooperation currently allocate one-quarter of available funds to the water sector.
There was also a high proportion of evidence for outcomes related to economic benefits and adoption. This wealth of evidence could credibly inform the types of interventions funded by both the GCF and German development cooperation.
From a policy perspective, the meta-analysis showed that access to credit – while important and relevant for building resilience and encouraging investments – might be insufficient to encourage autonomous adaptation. When designing financial products, the structure of preferences by highly vulnerable communities and individuals should be considered. Indeed, these communities may channel resources towards other uncovered needs.