The ISIMIP2b scenarios are designed to elicit the contribution of climate change to impacts arising from low-emissions climate-change scenarios. Pre-industrial control runs are included to facilitate statistical comparison with a no-climate-change case.
The ISIMIP2b protocol covers several new sectors, including tropical cyclones, temperature-related mortality and lakes.
The scientific rationale for the scenario design is documented in a GMD discussions paper by Frieler, et al.