When we think of climate change, the first things that may come to mind are our increasingly violent storms and melting Arctic ice. Another, of course, is drought and its ever-widening destructive swath. It is the latter that has led to a new threat:
The world’s largest underground aquifers – a source of fresh water for hundreds of millions of people — are being depleted at alarming rates, according to new NASA satellite data that provides the most detailed picture yet of vital water reserves hidden under the Earth’s surface.The crucial role acquifers play in our lives cannot be overestimated:
Twenty-one of the world’s 37 largest aquifers — in locations from India and China to the United States and France — have passed their sustainability tipping points, meaning more water was removed than replaced during the decade-long study period, researchers announced Tuesday. Thirteen aquifers declined at rates that put them into the most troubled category. The researchers said this indicated a long-term problem that’s likely to worsen as reliance on aquifers grows.
Underground aquifers supply 35 percent of the water used by humans worldwide. Demand is even greater in times of drought. Rain-starved California is currently tapping aquifers for 60 percent of its water use as its rivers and above-ground reservoirs dry up, a steep increase from the usual 40 percent. Some expect water from aquifers will account for virtually every drop of the state’s fresh water supply by year end.It is a problem that cannot be easily remediated, no matter our technology:
Aquifers can take thousands of years to fill up and only slowly recharge with water from snowmelt and rains. Now, as drilling for water has taken off across the globe, the hidden water reservoirs are being stressed.In addition to climate change, the other reasons for the precipitous drop in aquifer levels include heavy agricultural irrigation, mining, and oil and gas exploration.
No one knows how much groundwater is left in the world. This report simply brings to our attention once again the environmental destruction we are all a part of, either directly or indirectly.
It's the dependency factor that makes this most worrisome, Lorne. Industrial agriculture that we cannot do without if we are to feed 7+ billion mouths, soon to be 9+ depends on an uninterrupted supply of freshwater for irrigation. One of the least considered impacts of climate change is the disruption of historic rainfall patterns by cycles of drought and flood. The temperate jet stream that once moved rainstorms in a relatively orderly fashion, west to east, was the key to the intensive agriculture of the past century. With a warmer Arctic atmosphere that gently undulating jet stream is no more. This greatly increases demand for groundwater in volumes vastly beyond natural recharge rates. A perfect example is the High Plains or Ogallala acquirer that underlies the 8-states that make up America's grain belt. It's huge and it's fast running empty.
ReplyDeleteAn article in Harper's magazine last year claimed that several thousand small, farm towns in the grain belt have already been abandoned. Vast swathes of land that once produced bumper crops to feed the world are now being fallowed, returned to the original prairie grasslands. Wheat has been replaced by bison and beef cattle grazing "free range" style.
In good times the world has a 60-day reserve of cereal grains. This creates a very serious food security problem. Over the past 15-years we have experienced drought-based crop failures - in Russia, in Australia and even in the United States. What saved many lives was that, when one country went down, the other two remained productive. Yet scientists warn it's only a matter of time before two of them, or even all of them fail at once. Should that occur, the 60-day grain reserve may be insufficient to avert a serious, global outcome.
We've been playing on the margins since the late 70s. We have seen plenty of famine but it's usually been confined to a small region, one or two countries at a time. Before long we may look back on that as the "good old days."
You paint a very grim picture here, Mound. It would seem that one of our greatest failings as humans is our inability to envisage our own demise. Our arrogance (hubris?) simply won't allow us to.
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