By Mark Smulian | 3 September 2013

More than half the world’s population will live at risk of either water shortages or floods by 2050, the Organisation for Economic Co-operation and Development has warned.

It said that 40% of the world’s population will live under severe water stress by 2050, while nearly 20% could be exposed to floods that could endanger assets worth $45 trillion (£28.9 trillion).

These risks were exacerbated by climate change and pollution and in turn endangered economic growth and food and energy security.

OECD secretary-general Angel Gurría said: ‘Instead of just reacting to water crises, governments must assess, target and manage water risks proactively.

‘We have been forewarned - there is no doubt these risks are increasing. We must now arm ourselves with risk management strategies that will prevent water shortages and pollution and protect against the droughts and floods that are endangering human lives, ecosystems and economies.’

The OECD has published two reports to coincide with World Water Week, taking place this week.

In Water Security for Better Lives it sets out a risk-based approach to water security and practical steps to establishing an acceptable level of water risk by weighing the costs of improving water security against the expected benefits.

The other report, Water and Climate Change Adaptation: Policies to Navigate Uncharted Waters, reviews countries’ initiatives to adapt water management to climate change.

About half the countries surveyed said the impact of climate change impacts on water supply and sanitation was a key concern.