TITAN estimates the precipitation sensitivity to warming between the early anthropocene and the recent past, using the response to volcanic eruptions as well as greenhouse gas increases combined with aerosol increases over a long time horizon (Zhang et al., 2007; Noake et al., 2012). Volcanic and greenhouse gas forcing influences precipitation differently in ways that are understood (Allen and Ingram, 2002). The analysis pays careful attention to variability recorded in instrumental records, and how it compares to that in climate model data. This is necessary as present evidence suggests problems in model simulated precipitation variability. An analysis of precipitation variability in the SST forced simulations (WP3), using both the high-resolution model to determine robust responses to SST variability, and the Oxford ensemble to determine robust precipitation statistics, identifies what changes in precipitation can be attributed to SST forcing.
The challenge is to make use of noisy and uncertain precipitation data, the benefit a much improved understanding of precipitation dynamics.
This WP addresses question iv).