Differences in methodology type and scope complicate comparison, assessment and synthesis . In particular, structural economic modelling and empirical aggregate output modelling are fundamentally different, which has been identified as an issue affecting the comparability of results . The different methodologies affect outcomes, with global aggregate estimates based on statistical methodologies typically higher than those from structural modelling . This is, in part, due to the relationships in observational data captured by statistical modelling, assumed persistence of impacts in statistical modelling, broader adaptation responses in structural modelling, and differences in the representation of future societies and how they might evolve, respond and interact. Within statistical modelling, results are also found to be very sensitive to the statistical model specification . Within structural modelling, differences in representations of biophysical changes and economic structural dynamics contribute to differences across structural estimates .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report