United Nations Secretary-General Antonio Guterres warned on Sunday that without further efforts, between 3.5 and 4.4 billion people in the world will live with limited access to water, with more than 1 billion of them living in cities. 

In his message to the World Water Day, which falls on March 22, the UN chief said that "the world's water resources are under unprecedented threat." 

"Today, some 2.2 billion people lack safe drinking water, and 4.2 billion people live without access to adequate sanitation. Unless we act with urgency, the impacts of climate change are projected to exacerbate these figures," he said. 

Noting that this year's World Water Day focuses on water and climate change, the secretary-general said that "with 2020 a make-or-break year for climate action, this focus is timely." 

"Water is the primary medium through which we perceive the effects of climate disruption, from extreme weather events, such as droughts and floods, to glacial melting, saltwater intrusion and sea level rise," he added. 

"Global heating and unsustainable use will create unprecedented competition for water resources, leading to the displacement of millions of people. This will negatively affect health and productivity and act as a threat multiplier for instability and conflict," said the UN chief. 

Talking about the solution, Guterres said, "We must urgently scale up investments in healthy watersheds and water infrastructure, with dramatic improvements in the efficiency of water use." 

"We must anticipate and respond to climate risks at every level of water management. We need to urgently step up efforts to strengthen resilience and adaptation for people affected by climate disruption," he said. 

"Above all, we must use this year and COP26 (the 2020 UN Climate Change Conference) in Glasgow to bend the emissions curve and create a secure foundation for water sustainability," said the secretary-general. 

The UN chief asked everyone to play a role to help alleviate the shortage of water. 

"I call on all stakeholders to increase climate action and invest in robust adaptation measures for water sustainability. By limiting global heating to 1.5 degrees Celsius, the world will be in a much better position to manage and solve the water crisis that we all face," he said. 

World Water Day is an annual UN observance that highlights the importance of freshwater. The day is used to advocate for the sustainable management of freshwater resources.