The importance of indirect effects of climate change adaptations on alpine and pre-alpine freshwater systems

Freshwater is vital to much life on Earth and is an essential resource for humans. Climate change, however, dramatically changes freshwater systems and reduces water quality, poses a risk to drinking water availability and has severe impacts on aquatic ecosystems and their biodiversity. The direct effects of climate change, such as increased temperatures and higher frequency of extreme meteorological events, interact with human responses to climate change, which we refer to here as 'indirect effects'. The latter possibly have even greater impact than the direct effects of climate change. Specifically, changes in land-use practices as responses to climate change, such as adjusted cropping regimes or a shift to renewable hydroelectricity to mitigate climate change, can very strongly affect freshwater ecosystems. Hitherto, these indirect effects and the possibility of idiosyncratic outcomes are under-recognized. Here, we synthesize knowledge and identify threats to freshwater environments in alpine and pre-alpine regions, which are particularly affected by climate change. We focus on the effects of adapted agriculture and hydropower production on freshwater quality and ecological status, as these examples have strong indirect effects that interact with direct effects of climate change (e.g., water temperature, droughts, isolation of populations). We outline how failure to effectively account for indirect effects associated with human responses to climate change may exacerbate direct climate change impacts on aquatic ecosystems. If managed properly, however, human responses to indirect effects offer potential for rapid and implementable leverage to mitigate some of the direct climate change effects on aquatic ecosystems. To better address looming risks, policy- and decisionmakers must account for indirect effects and incorporate them into restoration planning and the respective sectorial policies.