Social vs scientific perception of change in hydrology and climate Reply to the Discussion on the Opinion Paper “Hydrology and change” by Arie Ben-Zvi

I am indebted to Arie Ben-Zvi for his Discussion (Ben-Zvi 2014) on my Opinion Paper (Koutsoyiannis 2013). He makes several points of philosophical and social importance. In this respect, the Discussion is also interesting from the perspective of the “Panta Rhei” decade (2013–2022) of the International Association of Hydrological Sciences (Montanari et al. 2013), which focuses on change in hydrology and society. It is difficult to disagree with the points made in the Discussion, and this does not favour dialogue. However, I will try to add a few thoughts. Ben-Zvi correctly points out that “man’s intensifying activities, since the agricultural revolution, through the industrial and the electronic ones and onwards into the future, affect the climate” and that “consideration of the anthropogenic effects aggravates our uncertainty about the future climate. ” But why restrict change to climate? Change is everywhere and currently has accelerated, mostly due to unprecedented human achievements in technology. Many aspects of unprecedented change (including agricultural and industrial revolutions and civil infrastructures) have been intentional and planned, not byproducts of other activities (in contrast to the increased emissions of CO2 which are a by-product of the intensification of energy production and use). Such environmental changes, which are visible, rather than hypothetical, have remarkable effects on hydrological systems and can be studied in a rather direct manner. Sometimes, the effects are negative, as exemplified by the greatly increased economic losses from floods over the past several decades. But, this is principally driven by the expanding exposure of assets at risk, while it has not been possible to attribute rain-generated peak streamflow trends to anthropogenic climate change (Kundzewicz 2014). One may also blame the uncontrolled urbanization and its expansion into flood plains (Di Baldassarre et al. 2010), and even the opposition to engineering solutions by the dominating “green” ideology as well as by politico-economic agendas (Koutsoyiannis 2014). In my view, it is bewildering that, instead of focusing on existing real changes with quantifiable effects on hydrological and societal systems, the scientific community has been encouraged, e.g., by research funding opportunities, to study hypothetical scenarios for the distant future. On the other hand, I fully agree with Ben-Zvi that change is tightly connected with uncertainty. Accelerating change inevitably results in increased uncertainty. In turn, the increased uncertainty makes society apprehensive about the future, insecure and credulous to a developing future-telling industry. The social demand for certainties, no matter if these are delusional, is combined by a misconception in the scientific community (cf. Taylor and Ravetz 2013) to confuse science with removing uncertainty. However, I believe that the hydrological community, instead of becoming part of a burgeoning system promoting unreliable predictions for the distant future, can help trace a different, more pragmatic path. Such a path need not be driven by political agendas, economic interests and the zeal for activism, Hydrological Sciences Journal – Journal des Sciences Hydrologiques, 59 (8) 2014 http://dx.doi. org/10.1080/02626667.2014. 935382 1625