A fundamental component of engineering design and practice involves predicting future conditions so that the selected choices can be evaluated and implemented. Climate change is but one of the many dynamic processes impacting water resources management. In April 2014, the Intergovernmental Panel on Climate Change (IPCC) completed its latest assessment report, the 5th report (IPCC AR5), in which the ongoing impacts of climate change were emphasized as well as the need for mitigation and adaptation. Due to climate change and other sources of non-stationarity, the traditional approach to hydrological processes no longer exists. Complexity creates non-linear behaviour in the entire system, which needs new knowledge to be addressed. Human activities have had a significant climate effect. Critical answers to how society should respond to these changes, how scientific conclusions about climate change have been formed, and how those conclusions are reflected in the public debate about the reality and risks of climate change are on the edge of scientific research. Mitigation and adaptation policies are important to tackle climate change, extreme events, and water scarcity.