Based on recent studies, scientists estimate that a total of nearly 23 million cubic kilometers of water lies beneath the surface of the Earth.
This incredible amount of water is according to researchers, enough to flood most of our planets continents and leave some areas of America, Europe and Africa under more than 50 meters of water.
This new calculation was made by a group of Canadian researchers led by Tom Gleeson and published in the journal Nature Geoscience, showing the first estimate of the total reserves of groundwater on Earth.
According to the study there are nearly 23 million cubic kilometers of groundwater, of which 0.35 million cubic kilometers are under 50 years old. The research results also show that “less than 6 percent of groundwater in the upper two kilometers from the mass of the Earth is renewable within a course of human life.”
“It’s the groundwater that is the most quickly renewed – on the scale of human lifetimes,” explained study leader Tom Gleeson from the University of Victoria. “And yet this modern groundwater is also the most sensitive to climate change and to human contamination. So, it’s a vital resource that we need to manage better,” he added.
Gleeson states that we know that water levels in portions of aquifers are falling. We are using our groundwater resources very fast, faster than they are being renovated.
The hydrologist clarifies that only a small part of the groundwater reserves can be used. Old groundwater lie deep below the surface and is nearly impossible to extract. In addition, the ancient waters are almost always saltier than ocean water and sometimes contain arsenic or uranium.
The map provided above demonstrates the distribution of ‘modern groundwater’ around the globe. According to the team of researchers, the dark blue colors indicate where it is very quickly renewed. The light blue colors show the older groundwater which is likely to be mostly stagnant and non-renewable writes BBC News.
“Old water is highly variable,” Dr. Gleeson told BBC News. “Some places it is quite deep, in some places not. In many places, it can be poor quality.
“It can be more saline even than ocean water and it can have lots of dissolved metals and other chemicals that would need to be treated before it could be used for drinking or agriculture.”
Interestingly, in his “Journey to the Center of the Earth” (1864) Jules Verne imagined an ocean inside our planet.
Although not in the form of liquid water as visualized the French writer, the water could be “trapped” in the earth’s crust minerals in the so-called transition zone between the upper and lower mantles, at a depth of between 410 and 660 kilometers.