Water - Mar 15
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Are We Running Out of Water?
Brian Richter, National Geographic
The glass-half-full answer is no……. at least not at the planetary level. Today there is just as much water on the planet as there was when the first signs of life appeared.
Every year, about 110,000 billion cubic meters of water falls on the land surface of our planet as rain or snow. That annual endowment of water would cover all land to nearly a meter deep if it was spread evenly...
So what’s the problem? Surely we can’t be in trouble if we’re depleting less than 10% of the Earth’s naturally renewable water, and the water cycle keeps bringing that water back year after year?
Here’s the catch: the water that falls from the sky isn’t evenly distributed around the globe, and our needs for that water aren’t the same everywhere.
So why can’t we just move water from places of abundance to places of shortage? Why can’t we take the fresh water flowing to the Arctic Circle and redirect it to the parched cities of the American Southwest?...
Even if we could move water over great distances in a cost-effective manner, it takes a tremendous amount of energy to do so. Nearly 20% of all electricity used in California – whose statewide plumbing system is reminiscent of a Rube Goldberg design – is spent moving water around. The energy required to move water – and its associated carbon emissions — is not inconsequential in the efforts to arrest climate change. Until we have abundant clean energy sources to power such re-plumbing of the planet’s water sources, we should not be investing in them.
And yet one more important consideration: We should be careful about ‘robbing Peter to pay Paul.’ As we dry up a river or lake to harvest or export its water, the health of fish populations and natural freshwater ecosystems plummet. In virtually all of the large rivers that have begun to go dry, fisheries have been decimated, leading to severe hardship for local people that depend upon that food source for their subsistence and livelihoods. Last year, I published a journal paper with colleagues at The Nature Conservancy that suggested that depletion of a freshwater source by more than 20% will likely have harmful ecological and social consequences.
The conclusion that should be drawn from all of this: we need to take stock of our local water sources and manage them wisely. As my water colleagues like to say, that “All politics — and water — are local.”...
(14 March 2012)
From Texas to India to the Horn of Africa, Concern about Weather, Water, and Crops
Sandra Postel, National Geographic
Hardly a week goes by without new reasons to be concerned about the impact of changing precipitation patterns and mounting water stress on food production.
This past week, officials in Texas cut off irrigation water to rice farmers downstream of reservoirs depleted by the worst one-year drought in Texas history. Even with recent rains, lakes Buchanan and Travis remain at 42 percent of capacity. Farmers, who pay the least for water, will be denied their liquid lifeline in order to prevent curtailments to urban and industrial water users.
It was the first time in its seventy-eight year history that the Austin-based Lower Colorado River Authority had cut off water to farmers.
On February 29, United Nations officials announced that the crucial March through May rainy season in the Horn of Africa would likely fall short again this year. The warning comes on the heels of last year’s drought, the worst in sixty years, and the devastating famine it triggered.
Scientists analyzed data on rainfall, temperature, ocean currents and the strength of the La Niña before making their forecast at a climate outlook conference in Kigali, Rwanda...
Still another report from the last week casts a pall over California’s upcoming harvest. State officials found that the water content of California’s mountain snowpack is only 30 percent of normal historic levels for this point in the season. Officials estimate they will deliver only 50 percent of the water requested from the State Water Project, a system of reservoirs and canals that distributes water to 25 million Californians and nearly one million acres of irrigated farmland.
“Absolutely, we should be concerned,” Frank Gehrke, chief snow surveyor for the California Department of Water Resources, commented to the San Francisco Chronicle...
Climatic change and its impacts on the global water cycle guarantee that we’ll increasingly find ourselves outside the bounds of normal. The implications for food security, social cohesion and political stability are of the utmost concern both to our national security and our humanitarian impulse.
It’s time to connect the dots– and to prepare, as best we can, for the new scenarios unfolding before our eyes.
(8 March 2012)
China irrigation system responsible for rising emissions, research shows
Jonathan Watts, The Guardian
The irrigation of Chinese farm fields with more water pumped from ever deeper underground is responsible for 33m tonnes of carbon dioxide per year – equivalent to the entire emissions of New Zealand – a new study revealed on Wednesday.
The research, carried out by a team of UK and Chinese scientists, highlights the rising but often overlooked energy and climate costs of irrigating crops in drought-plagued northern China, where farmers have to mine aquifers because surface rivers and lakes are increasingly polluted and over-exploited by factories and cities.
The authors found that groundwater used for crop irrigation in China has grown from 10bn cubic metres in 1950 to more than 100bn today. The country is now second only to India in tapping largely unreplenishable aquifers.
As a result, water tables in some of the worst affected areas are falling at the rate of more than two metres a year...
This is increasingly energy intensive and now accounts for almost half a percent of the carbon dioxide released in China, the world's biggest emitter, says the paper published by Environmental Research Letters...
(15 March 2012)
Climate, food pressures require rethink on water: U.N
Gus Trompiz, Reuters
The world's water supply is being strained by climate change and the growing food, energy and sanitary needs of a fast-growing population, according to a United Nations study that calls for a radical rethink of policies to manage competing claims.
"Freshwater is not being used sustainably," UNESCO Director-General Irina Bokova said in a statement. "Accurate information remains disparate, and management is fragmented ... the future is increasingly uncertain and risks are set to deepen."...
The report will be debated at the World Water Forum, which starts in the French city of Marseille on Monday.
A "silent revolution" has taken place underground, the report warns, as the amount of water sucked from below the surface has tripled in the past 50 years, removing a buffer against drought.
And just as demand increases, supply in many regions is likely to shrink because of changed rainfall patterns, greater droughts, melting glaciers and altered river flows, it says...
(11 March 2012)