By Mickey Z.

Bill Schaefer/Getty Images

An underrated issue that impacts humans, marine life, climate change, and more.

Much of today's environmental conversation revolves around personal choices (perhaps an offshoot of An Inconvenient Truth.) However, while every change we make--e.g. shorter showers--is a tiny step, we can't lose sight of the big picture. For example: dams. More than 45,000 large dams (45 feet or higher) were built in the 20th century and these structures are a serious green issue that impacts all life on earth. How serious?

"I've written books and done activism, but it is neither a lack of words nor activism that is killing salmon here in the Northwest. It's the dams. Anyone who knows anything about salmon knows the dams must go," says Derrick Jensen. "Anyone who knows anything about politics knows the dams will stay. Scientists study, politicians and business people lie and delay, bureaucrats hold sham public meetings, activists write letters and press releases, and still the salmon die."

Dams are expensive, destructive, and ineffective. In California alone, dams have resulted in the loss of 90% of that state's river environment and 95% of the salmon and steelhead habitat--all at a cost fifty times higher than more efficient solutions. FEMA may tell us, "Dams provide a range of economic, environmental, and social benefits, including recreation, flood control, water supply, hydroelectric power, waste management, river navigation, and wildlife habitat." But Jacques Leslie, author of Deep Water: The Epic Struggle over Dams, Displaced People, and the Environment, explains: "The world's dams have shifted so much weight that geophysicists believe they have slightly altered the speed of the earth's rotation, the tilt of its axis, and the shape of its gravitational field."

Yeah, it's that serious--and there's more. We've already touched on the threatened salmon, the water loss, and the earth's impacted gravitational field, now read on for the rest.

5 Reasons Why Large Dams Have to Go Now:

1. Dams cause greenhouse gas emissions. According to a study done by the National Institute for Space Research, India's 4,500 dams (third highest behind the US and China) "emit an amount of methane that is equivalent to 850 million tons of carbon dioxide per year." It seems both carbon dioxide and methane are "released from the decaying vegetation of spillways, reservoirs and turbines of hydropower dams, but methane is twenty-three times more formidable in trapping heat than carbon dioxide."

2. Dams displace people. As many as 80 million people have been displaced by dams worldwide. This is due to the reservoir created by the dam. In addition, those who live downstream from the dam will no longer have the dynamic river ecosystem that created their environment in the first place. Obviously, these are not humans with wealth and power.

3. Dams promote erosion. The folks at International Rivers explain that dams hold back sediments that would naturally replenish downstream ecosystems. "When a river is deprived of its sediment load, it seeks to recapture it by eroding the downstream river bed and banks, undermining bridges and other riverbank structures," they continue. "Riverbeds downstream of dams are typically eroded by several meters within the decade of first closing a dam; the damage can extend for tens or even hundreds of kilometers below a dam."

4. Dams lead to plant and animal extinctions. As touched on above about salmon, the introduction of such an unnatural structure and concept quite predictably has led to the extinction of many fish and other aquatic species, the disappearance of birds in floodplains, and massive losses of forest, wetland and farmland.

5. Dams are temporary solutions. And like many temporary solutions, dams ultimately create more problems than they were supposed to solve. Because they eventually fill up with silt, by definition, they are not a sustainable solution.

5 Ways to Help Rid the Planet of Large Dams:

1. Link up with the growing international anti-dam movement and experience the joy of bringing down a dam.

2. Promote other ways of supplying water to farmers and cities. According to International Rivers, "most water from large dams goes to large agriculture plantations-only a very small percentage goes to cities. Irrigation systems around the world are in general very wasteful of water. The cheapest and most effective way of providing more water to cities is therefore to increase the efficiency of irrigated agriculture."

3. Make this issue part of your green repertoire. Blog about it, talk about it, and more. The greenest goal of all is a major overhaul of "our way of life" and this is a great way to start.

4. Conserve water. Sure, what you use is nothing compared to Corporate America but that doesn't give anyone carte blanche to waste. Learn simple do's and don'ts of water conservation, e.g. fix leaks, use a rain barrel, etc.

5. Be pro-beaver. Nature's dam builders were doing it first and greener all along.

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http://planetgreen.discovery.com/tech-transport/reasons-dams-happen.html

Mickey Z. is the author of two upcoming books: Self Defense for Radicals (PM Press) and his second novel, Dear Vito (The Drill Press). Until the laws are changed or the power runs out, he can be found on the Web at http://www.mickeyz.net