There is a significant and growing body of scientific evidence documenting that climate change will intensify the risks of water-related hazards. By creating a warmer lower atmosphere, climate change is altering the water cycle through an increase in evaporation, evapotranspiration and precipitation and changes to atmospheric circulation, which can lead to wet regions becoming wetter while dry regions become drier.
Compounding these risks, a deteriorating natural environment worldwide is increasing vulnerability to water-related hazards. A range of interlinked pressures, such as the loss and degradation of natural areas like wetlands, soil sealing and the densification of built-up areas are undermining ecosystem functionality. This challenges the provisioning of ecosystem services, resulting in negative impacts on human well-being.
To reduce the exposure to water-related risks, countries have made significant investments in grey infrastructure, such as dikes or dams. While they have provided protection and other vital services on which human lives depend, such as regulating water supply and generating hydropower in the case of dams, they equally have limitations. First, grey infrastructure can be costly to build and to maintain, and when it fails, it has shown to cause significant ripple effects. Second, grey infrastructure is long lasting and inflexible, and in the past has been designed assuming static hydro-climatic conditions. For example, coastal defences have become increasingly expensive to adapt to rising sea levels (e.g. by widening or raising) and to maintain over time. The high costs of adapting inflexible grey investments can lead to vulnerability to failure under changing climatic conditions. This puts large, costly infrastructure projects at risk of becoming ‘stranded assets’, failing to deliver their designed services when conditions change, with potential catastrophic consequences (such as a dam breach). Finally, grey infrastructure can undermine the ability of natural systems to regenerate – for example, coastal dikes can intensify land subsidence and prevent the natural accumulation of sediments by tides, waves and wind.