This study investigates how Climate Policy Uncertainty (CPU) influences investments in the Renewable Energy Transition (ET), a relationship widely presumed to be negative, despite the empirical literature reporting mixed and highly heterogeneous results. Using a preregistered systematic review following PRISMA guidelines, we identify seventeen peer-reviewed studies from Web of Science and Scopus. Their quantitative estimates are harmonized using Fisher z-transformations and analyzed within a meta-analytic framework. A global random-effects meta-analysis reveals a small and statistically insignificant average effect of CPU on ET-related investment outcomes, together with extremely high heterogeneity, indicating that a single pooled coefficient is not an informative universal summary. To examine whether part of this dispersion follows an interpretable pattern, we estimate an exploratory mixed-effects meta-regression based on a four-channel transmission framework derived from the reviewed literature. This model accounts for 50.4% of the between-study variance, and only the Macroeconomic channel shows a negative and statistically significant deviation from the reference category (β = 1.0700, p = 0.0060). This result should be interpreted cautiously, however, given the small number of studies in each subgroup and the persistence of substantial residual heterogeneity. Overall, the evidence suggests that the CPU does not affect ET-related investment outcomes in a uniform way; rather, the reported relationship varies across contexts, with the strongest negative pattern appearing in studies that capture macroeconomic conditions related to the energy transition, such as foreign direct investment, trade openness, and aggregate green investment. By providing the first meta-analytic quantification of this relationship and a structured mapping of transmission mechanisms, this study offers novel empirical clarity to a fragmented literature. The policy implication is direct, and governments seeking to accelerate the energy transition must prioritize long-term credibility, regulatory stability, and macroeconomic predictability, as these are the domains through which climate policy uncertainty most severely constrains low-carbon investment.
Matias et al. (Wed,) studied this question.