More than 5 billion people could suffer water shortages by 2050 due to climate change, increased demand and polluted supplies, according to a UN report on the state of the world’s water.
“For too long, the world has turned first to human-built, or ‘grey’, infrastructure to improve water management.
Global demand has increased sixfold over the past 100 years and continues to grow at the rate of 1% each year.
Demand for water is projected to rise fastest in developing countries.
This was apparent in the São Paulo drought of 2014-15, which the city’s water authorities and scientists have linked to Amazon deforestation.
The key for change will be agriculture, the biggest source of water consumption and pollution.
This would also be crucial to reverse erosion and degradation, which currently affects a third of the planet’s land, a different UN study found last year.
The authors stress the goal is not to replace all grey infrastructure, because there are situations where there is no other choice, for example in building reservoirs to supply cities with water.
But they urge greater take-up of green solutions, which are often more cost-effective as well as sustainable.
They are staging an alternative forum in Brasília that puts greater emphasis on community management of water as a free public resource.