Faced with growing disruption to the water cycle, leading to severe flooding and drought together with increasing water pollution, humans are struggling to adapt. But are ever-greater water storage and control of river flows really the right solutions? Hydroclimatologist Florence Habets shared her views with CNRS News.
Water is fundamental to the very existence of life. But that’s not the only reason why it is so important. Water is also home to living organisms, many of which – such as fish, amphibians and crustaceans – are unfortunately under threat.
In addition, it regulates the climate, both in space and over time, due to its role in evapotranspiration and condensation processes, and to the ease with which it is transported by atmospheric currents. Water is also a powerful chemical agent that dilutes and distributes geochemical flows, in much the same way as blood supplies our cells with nutrients. It is a means of transportation used by humans since ancient times, in addition to providing energy through hydroelectricity. Last but not least, it is a source of pleasure for all those who like to swim, or walk along its shores.
The water cycle and climate change
Although we mainly use fresh water, which is easily accessible, and preferably not too polluted, this resource accounts for only a tiny fraction of the world’s total water (<0.1%), most of which is either salty or locked up in the form of glaciers or very deep groundwater. In fact, available resources can be defined as the proportion of precipitation that falls on land without evaporating, in other words, a mere one third of France’s total rainfall.
However, this evapotranspiration/transport/precipitation process is being strongly disrupted by climate change, the most striking impacts of which are also associated with the water cycle: torrential rains (e.g. the rain bombs that recently hit Australia), flooding, and increasingly long and severe droughts. These apparently contradictory phenomena actually have the same physical origin: by consuming fossil energy, humans have raised the concentrations of greenhouse gases in the atmosphere, increasing the planet’s energy and hence its temperature.
READ FULLY @ CNRS