Water scarcity has been on the radar as global problem for quite a while, but a new analysis says the problem will affect much more of the population than previous estimates had considered, according to a csmonitor.com story .

Researchers from the University of Twente, in Enschede, Netherlands, are saying instead of approximately two billion people being impacted by the lack of fresh water, their estimates show that the number is closer to four billion worldwide.  Dr. Mesfin Mekonnen and Dr. Arhen Hoekstra from the university say previous estimates relied on annual data to make their assumptions, and that doesn’t take into account the areas that would be impacted by shorter periods of fresh water scarcity.

The analysis of fresh water scarcity revolves around the amount of fresh water taken from the ground and not returned on a monthly level, and is commonly referred to as “blue water scarcity.”

Dr. Mekonnen says when you take an annual average, you can miss those portions of the population that face water scarcity for shorter periods of the year, but even lack of fresh water for a month can have major implications and effects on the general public.  The team’s estimates include those who won’t go a whole year facing shortages of fresh water, but will be finding it hard to find sufficient water for long periods during the year.  Mekonnen adds only about half a billion people are facing a consistent lack of fresh water for the whole of the year.

Surprisingly, the nations with the greatest fresh water shortages are some of the most populated countries on the planet.  India and China are the two most populated nations, and about half of the projected four billion live in those areas.  Bangladesh, the United States, Pakistan, Nigeria, and Mexico, five the top ten nations in terms of population, are also on the list for risk of fresh water shortages.

The researchers are calling for governments to cap water consumption from river basins to maintain sustainable levels of fresh water, but that process must begin with accurate measurements of the amount of water being taken.  This will also require unprecedented cooperation between worldwide governments, something that may be harder to achieve than developing the measurements.

The authors published the findings from their study in the journal Science Advances.