If you enter "Global Water Crisis" into your favorite Internet search engine, you will get pages of documents with enough information to earn a Ph.D. I actually recommend the Wikipedia article in this instance, which is very thorough and well presented. It's also very long so you might want to take a look at the more succinct entry at the World Resources Institute. That one is a couple of years old and things have already gotten worse.
The fact is that over the past century, the percentage of humans who have access to adequate clean water and sanitation has increased. However, we have now bumped up against the limit, even as the supply is contracting in many places due to climate change. Hotter temperatures mean that whatever rain does fall evaporates faster, but precipitation is also decreasing in some places, particularly near the equator. Of course population growth creates more demand for water -- for drinking and household use, for agriculture, and for industrial use. Much of the demand has been met by withdrawing ground water, but that is a finite resource and its running out in many places.
India is one of the hardest hit countries, and the city of Chennai has now completely run out of water. It's being trucked in. Several other cities in India are expected to run out of water next year, and cities in Africa are also facing imminent crises.
But we have problems right here in the U.S. of A. One fifth of U.S. agricultural production is dependent on the Ogallala aquifer, a vast underground lake in the Great Plains. This region is known as America's breadbasket, but it's actually semi-arid. As farmers have pumped out the aquifer, the water level has dropped as much as 150 feet in some places and well have been abandoned.
Today the Ogallala Aquifer is being depleted at an annual volume equivalent to 18 Colorado Rivers. Although precipitation and river systems are recharging a few parts of the northern aquifer, in most places nature cannot keep up with human demands. “We have optimistic locations. Other places we can see the end,” says David Pope, who administered groundwater regulations in Kansas from 1983 to 2007 as the state’s chief engineer.Some farmers are trying to shift to dryland crops, but the pumping continues. At the present rate the whole thing will be gone in about 50 years, but it will be gone much sooner than that in many counties. The main consumer is livestock and livestock feed, mostly beef.
So what can we do about this?
Ending greenhouse gas emissions an slowing climate change is the first, most critical measure, because it will have the most widespread impact.
Stopping human population growth is the second most critical measure.
Switching from beef to a plant based diet will make a huge difference.
We waste a lot of water, with inefficient irrigation methods, leaky pipes, and just plain profligacy.
Finally, we have to recognize the real cost of water and price it accordingly. That will require subsidies for low income people, but it's the same deal with fossil fuels. They need to be taxed to price in their real social cost. Income redistribution is necessary anyway, so let's do both.
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