8 Things to Know About New Research on Earth’s Rapid Drying and the Loss of Its Groundwater

The continents are rapidly drying out and the earth’s vast freshwater resources are under threat, according to a recently released study based on more than 20 years of NASA satellite data. Here are the report’s key findings and what they portend for humankind:

Much of the Earth is suffering a pandemic of “continental drying,” affecting the countries containing 75% of the world’s population, the new research shows.

The study, published in the journal Science Advances, examined changes to Earth’s total supply of fresh water and found that nearly 6 billion people live in the 101 countries facing a net decline in water supply, posing a “critical, emerging threat to humanity.”

Mining of underground freshwater aquifers is driving much of the loss.

According to the study, the uninhibited pumping of groundwater by farmers, cities and corporations around the world now accounts for 68% of the total loss of fresh water at the latitudes where most people live.

Much of the water taken from aquifers ends up in the oceans, contributing to the rise of sea levels.

Mined groundwater rarely seeps back into the aquifers from which it was pumped. Rather, a large portion runs off into streams, then rivers and ultimately the oceans. According to the researchers, moisture lost to evaporation and drought, plus runoff from pumped groundwater, now outpaces the melting of glaciers and the ice sheets of either Antarctica or Greenland as the largest contributor of water to the oceans.

As droughts grow more extreme, farmers increasingly turn to groundwater.

Worldwide, 70% of fresh water is used for growing crops, with more of it coming from groundwater as droughts grow more extreme. Only a small amount of that water seeps back into aquifers. Research has long established that people take more water from underground when climate-driven heat and drought are at their worst.

Drying regions of the planet are merging.

The parts of the world drying most acutely are becoming interconnected, forming what the study’s authors describe as “mega” regions. One such region covers almost the whole of Europe, the Middle East, North Africa and parts of Asia.

Drying of the Earth has accelerated in recent years.

The study examines 22 years of observational data from NASA’s Gravity Recovery and Climate Experiment, or GRACE, satellites, which measure changes in the mass of the earth and have been applied to estimate its water content. Since 2002, the sensors have detected a rapid shift in water loss across the planet. Around 2014, the study found the pace of drying appears to have accelerated. It is now growing by an area twice the size of California each year.

Water pumped from aquifers is not easily replaced, if it can be at all.

Major groundwater basins underlie roughly one-third of the planet, including about half of Africa, Europe and South America. Many of those aquifers took millions of years to form and might take thousands of years to refill. The researchers warn that it is now nearly impossible to reverse the loss of water “on human timescales.”

As continents dry and coastal areas flood, the risk for conflict and instability increases.

The accelerated drying, combined with the flooding of coastal cities and food-producing lowlands, heralds “potentially staggering” and cascading risks for global order, the researchers warn. Their findings all point to the likelihood of widespread famine, the migration of large numbers of people seeking a more stable environment and the carry-on impact of geopolitical disorder.