Freshwater biodiversity loss - why and steps to combat it

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Maanantai 6.4.2020 klo 16:15 - Mikko Nikinmaa


Only less than 2 % of the earth’s water is fresh water. The overall percentage that humans use is over 30, but it also includes northern latitudes, where human use is only a couple of percent of the total availability. Even in those areas waters have often become polluted to such an extent that they are not suitable habitats to many organisms. Fresh water is also bountiful in tropical rainforests. However, in many arid areas, humans use more than 3/4 of all available freshwater. Recently, one has emphasized a lot that clean water for cooking and washing is close to impossible to find in many densely populated arid areas. Because of this, it has been pointed out by health experts that the advice of avoiding Covid-19 by washing your hands frequently is not plausible in many places: they have pointed out that this option is only available in rich temperate areas (and for the very rich).

Fresh water is not a limiting factor only for human health. At presIMG-20191230-WA0003.jpgent, the total biomass of humans is more than ten times greater than that of all the wild mammals, so humans are using most of the water needed also by the animals. Further, the biomass of production animals is approximately twice as large as that of humans, and much of the crop cultivation depends on irrigation. Because of this, the water flow from many rivers is diverted virtually completely to irrigation to enable plant cultivation. Another problem has been, and still is that industrial and household effluents are discharged to inland rivers with varying degrees of purifications; in several cases the effluents are not purified at all. When rivers are used for generating hydroelectric power, dams are built whereby lakes are created, and they are often a good breeding place for disease-causing organisms. Altogether, human effects on freshwater are so large that freshwater biodiversity has decreased much more than terrestrial one – already approximately a third of the freshwater species have disappeared. If no decisive actions are done against freshwater biodiversity loss, it is possible that within the present century four-fifths of it is lost.

What needs to be done? In their article “Scientists’ warning to humanity on the freshwater biodiversity crisis” in Ambio (https://doi.org/10.1007/s13280-020-01318-8), Albert et al state the following: “We currently have technologies to manage and ameliorate many aspects of the freshwater biodiversity crisis—what we lack is political will.” One can hope that after the Coronavirus pandemic, one is ready to go to new directions, which address global problems. In fact, the biggest political problem is that the present nationalistic thinking makes it very difficult to address anything that crosses national boundaries – one has seen this with combatting Coronavirus. To be able to work effectively towards maintaining freshwater biodiversity, we would need to think solutions from global perspective as “United World”. The second problem is human population growth, which must be stopped, if we are to halt freshwater biodiversity loss, because if that cannot be done, food production will need any available water even if the water is used in expense of freshwater biodiversity. Compared to these major questions, other are simple. For example, the choice of cultivated plants should be done in order to get water use to sustainable level: avocados and cotton should not use up all the water. Water should not be used in order to obtain natural gas, building dams for hydroelectric power should net destroy habitats and prevent te migration of migratory species.

If we want to have sustainable development, these actions should be taken. Tey do not really carry financial burden, but require new direction in thinking.

Avainsanat: climate change, agriculture, irrigation, hydroelectric power


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