A United Nations report estimates that more than 5 billion people may suffer from water shortages by the year 2050. The complex reasons include the interplay between polluted water supplies, climate change and increased demand. The increased stresses on populations are expected to play a role in increased conflicts, including wars, and will shape political decisions in most countries around the world.

Scientists are finding water pollution in most water sources we consider “natural,” including oceans, lakes, rivers, wetlands and aquifers. The UN’s World Water Development Report says positive changes are possible, and calls for the use of more nature-based solutions that rely on soil and trees instead of concrete and steel – the so-called “grey” infrastructure used in water management.

Greener approaches are key, according to Gilbert Houngbo, the chair of UN Water. “In the face of accelerated consumption, increasing environmental degradation and the multi-faceted impacts of climate change, we clearly need new ways of manage competing demands on our freshwater resources,” he said. Recent studies show, for example, that vegetation helps recycle and distribute water, and deforestation plays a role in worsening water crises.

The world’s demand for water currently increases about one percent a year, the report says, and has increased six-fold over the past 100 years. The world’s population, 7.7 billion today, will be between 9.4 billion and 10.2 billion by 2050. At the same time that water demand grows, water supplies will dwindle due to drought, soil degradation, water pollution, and distressed ground water supplies.

We need to implement the solutions we already have and conduct research for many more because in many places, the crisis is already here. Cape Town South Africa this year severely restricted water to residents because of the once-in a 384-year drought. Officials in Brasilia, Brazil turned off taps to residents once every five days because of an unusually long dry-weather pattern.

Read the full UN report here.