On Jan. 17, scientists downloaded fresh data from a pair of NASA satellites and distributed the findings among the small group of researchers who track the world’s water reserves. At the University of California, Irvine, hydrologist James Famiglietti looked over the data from the gravity-sensing GRACE satellites with a rising sense of dread.
The data, released last week, showed California on the verge of an epic drought, with its backup systems of groundwater reserves so run down that the losses could be picked up by satellites orbiting 400km above the Earth’s surface.
“It was definitely an ‘Oh my gosh moment,’” Famiglietti said. “The groundwater is our strategic reserve. It’s our backup, and so where do you go when the backup is gone?”
That same day, California Governor Jerry Brown declared a drought emergency and appealed to Californians to cut their water use by 20 percent.
“Every day this drought goes on we are going to have to tighten the screws on what people are doing,” he said.
Seventeen rural communities are in danger of running out of water within 60 days and that number is expected to rise, after the main municipal water distribution system announced it did not have enough supplies and would have to turn off the taps to local agencies.
There are other shock moments ahead — and not just for California — in a world where water is increasingly in short supply because of growing demands from agriculture, an expanding population, energy production and climate change.
Already a billion people, or one in seven people on the planet, lack access to safe drinking water. Britain is currently at the other extreme. Great swathes of the country are drowning in misery, after a series of Atlantic storms off the southwestern coast. However, that too is part of the picture that has been coming into sharper focus over 12 years of the GRACE satellite record. Countries at northern latitudes and in the tropics are getting wetter, but those countries at mid-latitude are running increasingly low on water.
“What we see is very much a picture of the wet areas of the Earth getting wetter,” Famiglietti said. “Those would be the high latitudes like the Arctic and the lower latitudes like the tropics. The middle latitudes in between, those are already the arid and semi-arid parts of the world and they are getting drier.”
On the satellite images the biggest losses were denoted by red hotspots, he said. And those red spots largely matched the locations of groundwater reserves.
“Almost all of those red hotspots correspond to major aquifers of the world. What GRACE shows us is that groundwater depletion is happening at a very rapid rate in almost all of the major aquifers in the arid and semi-arid parts of the world,” Famiglietti said.
The Middle East, North Africa and South Asia are all projected to experience water shortages over the coming years because of decades of bad management and overuse.
Watering crops, slaking thirst in expanding cities, cooling power plants, fracking oil and gas wells — all take water from the same diminishing supply. Add to that climate change — which is projected to intensify dry spells in the coming years — and the world is going to be forced to think a lot more about water than it ever did before.
The losses of water reserves are staggering. In seven years, beginning in 2003, parts of Turkey, Syria, Iraq and Iran along the Tigris and Euphrates rivers lost 144km3 of stored freshwater — or about the same amount of water as in the Dead Sea, according to data compiled by the GRACE mission and released last year.