We are well and truly in the Anthropocene. Humans can no longer be considered as mere external drivers or boundary conditions in the hydrologic systems we study. The interactions and feedbacks between human actions and water cycle dynamics on the planet, combined with the evolution of human norms/values in relation to water, are throwing up a range of emergent ''big problems.'' Understanding and offering sustainable solutions to these ''big problems'' require a broadening of hydrologic science to embrace the perspectives of both social and natural scientists. The new science of socio-hydrology was introduced with this in mind, yet faces major challenges due to the wide gulf that separates the knowledge foundations and methodologies of natural and social sciences. Yet, the benefits of working together are enormous, including through adoption of natural science methods for social science problems, and vice versa. Bringing together the perspectives of both social and natural scientists dealing with water is good for hydrologic science, having the salutary effect of revitalizing it as use-inspired basic science. It is good for management too, in that the broader, holistic perspectives provided by socio-hydrology can help recognize potential ''big'' problems that may otherwise be unforeseen and, equally, identify potential ''alternative'' solutions to otherwise intractable problems.Organizations with narrow fields of vision become institutionally incapable of spotting where the icebergs ahead are located.Demby [2012] 1. Debating Socio-hydrology I am delighted to join this timely debate on socio-hydrology. The starting point for me is the accompanying paper by Di Baldassarre et al. [2015], which addresses the issue of estimating and managing flood risk under human-induced changes in the emergent Anthropocene. The paper contrasts the traditional scenariobased approach based on assumed quasi-stationarity with a more sophisticated approach that permits analysis of the dynamic interactions and feedbacks between floods and societies. In the old paradigm, for a chosen design period, flood risk is estimated as a combination of the probability of flooding under assumed quasi-stationarity and the potential damages. In the new paradigm, however, a coupled socio-hydrologyflood model is proposed that permits exploration of the resulting coevolution of floods and societies, with a focus on estimation of emergent flood risk.In my opinion, there are two important lessons to be learned from this paper that go beyond mere estimation of flood risk. First, the paper is an example of the broadening of the foundations of hydrologic science to accommodate the emergent dynamics resulting from the two-way coupling of social and hydrological systems, the defining feature of the new discipline of socio-hydrology [Sivapalan et al., 2012. Second, it is the richness of the resulting socio-hydrologic dynamics, including possible (otherwise unimaginable) vistas about the future, in two different types of societies (e.g., green and techn...