A global water crisis is already apparent to those who look beyond humans and consider what is happening to other species. Planet Earth is at the beginning of a mass extinction event that is eliminating species at a faster rate than at any time in the history of the planet. This is the sixth mass extinction event in Earth’s history; the fifth saw the extinction of the dinosaurs, around 70 million years ago. While much media attention is focused on the destruction of tropical forests around the world, it is, in fact, biodiversity in the world’s freshwater habitats that are declining the fastest.
Freshwater is unevenly distributed throughout the world, e.g. Canada has 30 times as much freshwater available to each of its citizens as China. Freshwater is being contaminated by saltwater influxes (tidal waves, rising sea levels), human waste and other by-products of human activity (e.g. industrial chemicals, acid rain), as well as agricultural fertilisers, pesticides and herbicides. Since 1950, the number of people on Earth has increased from 2.5 to 6.5 billion, and the per capita use of freshwater (i.e. the amount each person uses annually) has tripled.
By 2050 the human population is predicted to reach 8.9 billion; per capita, water use is also expected to continue to increase. More than 60% of all freshwater used in the world is diverted for agriculture. People in many parts of the world currently face a chronic shortage of water. This is a developing crisis that is expected to get worse. Several factors underlie this dire prediction. In addition, climate change is expected to cause major changes in the distribution of freshwater.
