The economic, environmental and social impacts of the 1997-2009 Millennium Drought in the MDB  and projections of a drier future under climate change have accelerated significant water policy reforms costing more than AUD$12 billion . These reforms included the development of a Basin Plan  requiring consistent regional water resource plans  and environmental watering strategies  across the MDB. Despite contestation, the reforms have resulted in some substantive achievements, including returning an equivalent of about one-fifth of consumptive water to the environment through the purchase of irrigation water entitlements and infrastructure projects  . However, the overall impacts of these water management initiatives are difficult to measure due to hydroclimatic variability, time lags and environmental, social and institutional complexity .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report