This report provides a synthesis of previous studies into the impacts of climate change on runoff and recharge across the Murray Basin Natural Resource Management (NRM) Cluster region. This comprises multiple individual NRM regions spread across southern New South Wales, the Australian Capital Territory, northern Victoria and southeastern South Australia.

The most recent studies into climate change impacts on runoff and recharge have been used. The runoff results were part of the South East Australian Climate Initiative (http://www.seaci.org/) which used 15 global climate models (GCMs) with two global warming (emissions) scenarios and were reported in Post et al. (2012). The recharge results were part of the Climate Change Impacts on Groundwater Resources Project (Barron et al., 2011) which used 16 GCMs and three global warming (emissions) scenarios and were reported in Crosbie et al. (2013).

For this report, these existing modelling results were analysed according to representative climate futures (Whetton et al., 2012) as an aid to effective communication. The most frequent climate futures amongst the suite of GCMs were for warmer temperatures and little change in rainfall, and slightly hotter temperatures and drier rainfall for both the runoff and recharge modelling. Across the Region these representative climate futures projected a decrease in both runoff and recharge as a median; however, the extreme outlier projections for both runoff and recharge can exceed ±50%.

As a result, there was considerable variation in model results both across NRM regions as well as within regions across different climate models. This suggests that planning within and across regions needs to be adaptive and responsive to changing conditions as the precise degree and even direction of change cannot be determined for certain.