• Researchers used satellite data to examine global freshwater resources and humans' influence on them.
  • The research uncovered the extent of human influence on the global hydrological cycle.
  • World Water Day works to raise awareness of the importance of freshwater.

Researchers have used NASA satellite data to examine 227,386 bodies of water to understand more about the extent of human influence on the global hydrological cycle.

Such research is "essential for the sustainability of freshwater resources on Earth", the scientists involved say in introducing their research.

Their most striking finding? Humans are responsible for more than half (57%) of the fluctuations in seasonal surface water storage.

Human interventions

The satellite measurements were used to build a dataset of global water levels from October 2018 to July 2020, covering bodies from water from the North American Great Lakes to ponds with an area less than a tenth of a square mile.

Seasonal variability in human-managed reservoirs averaged 0.86 metre, compared with 0.22 metre in natural water bodies.

Humans are responsible for a majority of the seasonal surface water storage variability on Earth

"We tend to think of the water cycle as a purely natural system: Rain and snowmelt run into rivers, which run to the ocean where evaporation starts the whole cycle again," Stanford geophysicist Sarah Cooley from Stanford University told Brown University, where she launched the project while a graduate student there.

"But humans are actually intervening substantially in that cycle. Our work demonstrates that humans are responsible for a majority of the seasonal surface water storage variability on Earth."


What is the World Economic Forum doing about closing the gap between global water demand and supply?

The world is not on track to achieve Sustainable Development Goal No. 6 on water and sanitation. At the current rate, there will be a 40% gap between global water supply and demand by 2030.

We’re helping to close the gap between global water demand and supply. The 2030 Water Resources Group (2030 WRG) was launched at the World Economic Forum Annual Meeting 2008 in Davos, Switzerland, to help close the gap between global water demand and supply by 2030.

Since its inception, the Forum-initiated 2030 WRG has grown into a vibrant network of more than 700 partners from the private sector, government and civil society. To date, the 2030 WRG and its network have facilitated over $893 million of financing for water-related programmes and demonstrated tangible results in a number of areas, including agricultural water efficiency, urban and industrial water management, wastewater treatment and improved livelihoods for farmers.

Want to join our mission to close the gap between global water supply and demand? Find out more about our impact, and help us improve the state of the world.

Why it matters

The researchers explained their work will provide a baseline for future research on how humans impact the water cycle and what that means for ecosystems around the world.

“Of all the volume changes in freshwater bodies around the planet — all the floods, droughts and snowmelt that push lake levels up and down — humans have commandeered almost 60% of that variability,” Laurence Smith, a professor of environmental sciences at Brown, said.

“That’s a tremendous influence on the water cycle. In terms of human impact on the planet, this is right up there with impacts on land cover and atmospheric chemistry.”

You can read more about the research and how they did it here.

World Water Day

World Water Day is held on 22 March every year to raise awareness of the importance of freshwater and the challenges billions face in getting access to safe water.

A growing population, the increasing demands of human use for agriculture and industry, plus the effects of climate change all put water under threat.

The theme of this year's World Water Day is what water means to people and its true value.

World Water Day valuing water
Tough to put a price on.
Image: UN-Water

Protecting a valuable resource

Efforts at raising awareness need to be coupled with action.

The World Economic Forum's Global Water Initiative attempts to 'embed water at the centre of economic growth planning'.

From the role of technology - such as the innovative use of satellite data in this research - to changing how we value water, the initative brings together public and private organizations to tackle the challenges we're faced with.

The threat is significant as well, with natural resource crisis 5th in the list of top global risks by impact in the latest World Economic Forum Risks Report.

Global Risks Landscape 2021
Natural resource crisis was 5th on this years risks by impact.
Image: World Economic Forum