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By Sonya Angelica Diehn
Dams are often touted as environmentally friendly. Although they do represent a renewable source of energy, a closer look reveals that they are far from green. DW lays out the biggest environmental problems of mega-dams.
1. Dams Alter Ecosystems
Water is life — and since dams block water, that impacts life downstream, both for ecosystems and people. In the case of the Grand Ethiopian Renaissance Dam (GERD), which is being built in Ethiopia and is set to be Africa's largest source of hydroelectric power, Egypt is concerned it will receive less water for things like agriculture.
Downstream ecosystems rely not only on water, but also on sediment, both of which are held back by big dams. As solid materials build up in a manmade reservoir, downstream land becomes less fertile and riverbeds can become deeper or even erode away. Emilio Moran, a professor of geography and environment at Michigan State University in the US, described sediment loss of 30 to 40% as a result of large dams.
"Rivers carry sediment that feeds the fish, it feeds the entire vegetation along the river. So, when you stop sediment flowing freely down the streams, you have a dead river."
And ecosystems may have adapted to natural flooding, which dams take away.
Mega-dams also often have a large footprint on land upstream. Aside from displacing human communities, flooding to create a reservoir also kills plants, and leaves animals to drown or find new homes. Reservoirs can also further fragment valuable habitat and cut off migratory corridors.
2. Dams Reduce Biodiversity and Cause Extinction
Aquatic species, particularly fish, are vulnerable to the impacts of dams. Moran says the Itaipu Dam, which was constructed on the border between Paraguay and Brazil in the 1970s and 1980s, resulted in a 70 percent loss of biodiversity.
"On the Tucuruí Dam that was built in the 80s in the Amazon," he added, "there was a 60% drop in productivity of fish."
Many fish species rely on the ability to move about freely in a river, be it to seek food or return to where they were born. Migratory species are badly affected by the presence of dams. In 2016, the International Union for the Conservation of Nature (IUCN) reported a 99% drop in catches of sturgeon and paddlefish — both of which are migratory — over a period of three decades. Overfishing and river alteration were cited as major threats to the species' survival.
A 2018 study predicted that fish stocks on Asia's Mekong River could drop by 40% as a result of dam projects – with consequences not only for biodiversity, but for the people whose lives and livelihoods depend on those fish.
The stakes for biodiversity are particularly high for animals threatened with extinction. And not only for aquatic species. The Tapanuli orangutan — the Earth's rarest ape, with only 500 individuals left — could finally be pushed to the brink if a planned hydroelectric project in Sumatra, Indonesia, is completed. Dams can literally snuff out species.
3. Dams Contribute to Climate Change (and Are Affected by It)
As reservoirs fill, upstream forests are flooded, eliminating their function as carbon sinks. As the drowned vegetation decomposes, decaying plants in manmade reservoirs release methane, a powerful greenhouse gas. That makes reservoirs sources of emissions — particularly those in tropical forests, where there is dense growth. It's estimated that greenhouse gas emissions from dams amount to about a billion tons annually, making it a significant global source.
And as the climate changes, more frequent and prolonged drought means dams will capture less water, resulting in lower electricity production. Countries dependent on hydropower will be especially vulnerable as temperatures keep rising.
Moran described a vicious circle, for example in Brazil, which gets 60 to 70% of its energy from hydropower: "If you wipe out half the rainforest, there will a loss of half the rainfall. And then there won't be enough water to provide the amount of power from those dams," he explained.
4. Dams Reduce Water Quality
Manmade reservoirs trap fertilizers that run into the water from surrounding land. In addition, in some developing countries, sewage flows directly into the reservoirs. This kind of pollution can result in algae blooms that suck the oxygen out of the water, making it acidic and potentially harmful to people and animals.
Still water in large manmade lakes is warm at the top and cold at the bottom, which can also affect water quality. While warm water promotes the growth of harmful algae, the cold water that is often released through turbines from the bottom of a reservoir may contain damagingly high mineral concentrations.
In some cases, water in manmade reservoirs is of such bad quality that it is not even fit to drink.
5. Dams Waste Water
Since more surface area of the water gets exposed to the sun, reservoirs result in much more evaporation than the natural flow of the river before that dam existed. It's estimated at least 7% of the total amount of freshwater needed for human activities evaporates from the world's reservoirs every year.
This effect is made worse in hot regions, Moran pointed out. "Certainly if you had a reservoir in a tropical area with high temperatures, there is going to be a lot of evaporation," he said. And big reservoirs "are, of course, evaporating constantly."
Reservoirs are also a haven for invasive plant species, and weed-covered reservoir banks can lead to evapotranspiration — or the transfer of water from the land to the atmosphere through evaporation from soil and transpiration from plants. Such evapotranspiration amounts to six times more than the evaporation from the water's surface. And there is even evidence that dams increase water use and promote water waste by creating a false sense of water security.
In the face of dwindling global freshwater resources, some question whether dams should be reconsidered.
So What Are the Alternatives?
The evidence is damning. But if mega-dams have so many harmful environmental effects, what are the alternatives? Although some green groups point to small hydropower as being more ecologically sound, Moran is skeptical. "A dam is a dam - it's blocking the fish, it's blocking the sediment."
He pointed to the need to consider not just how to maximize energy production, but also maintain ecological productivity. One option he cited is the use of in-stream turbines.
And many environment advocates agree that other renewable energies such as solar and wind can provide clean electricity at a far lower environmental cost.
Reposted with permission from Deutsche Welle.
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By Brian Bienkowski
Fish exposed to endocrine-disrupting compounds pass on health problems to future generations, including deformities, reduced survival, and reproductive problems, according to a new study.
Low Levels Lead to Generational Impacts<p>Researchers exposed inland silverside fish to bifenthrin, levonorgestrel, ethinylestradiol, and trenbolone to levels currently found in waterways.</p><p>"Our concentrations were actually on the low end" of what is found in the wild, DeCourten said, adding that it was low amounts of chemicals in parts per trillion.</p><p>Bifenthrin is a pesticide; levonorgestrel and ethinylestradiol are synthetic hormones used in birth controls; and trenbolone is a synthetic steroid often given to cattle to bulk them up.</p><p>Such endocrine-disruptors have already been linked to a variety of health problems in directly exposed fish including altered growth, reduced survival, lowered egg production, skewed sex ratios, and negative impacts to immune systems. But what remains less clear is how the exposure may impact future generations.</p><p>For their study, DeCourten and colleagues started the exposure when the fish were embryos and continued it for 21 days.</p><p>They then tracked effects on the exposed fish, and the next two generations.</p>
Inherited Problems<p>DeCourten said the altered DNA methylation is one of the plausible ways that future generations would experience health impacts from previous generations' exposure. Hormone-disrupting compounds have been shown to impact DNA methylation, which is an important marker of how an organism will develop.</p><p>"Methyl groups are added to specific sites on the genome, [the exposure] is not changing the genome itself, but rather how the genome is expressed," she said. "And that can be inherited throughout generations."</p><p>In addition, Brander said there are essentially different "tags" that exist on DNA molecules, which tell genes how to turn on and off. She said the exposure to different compounds may be "influencing which methyl tags get taken on or off as you proceed through generations."</p><p>The researchers said the study should prompt future toxics testing to consider impacts on future generations.</p><p>"The results … throw a wrench in the current approach to regulating chemicals, where it's often short-term testing looking at simple things like growth, survival, and maybe gene expression," Brander said.</p><p>"These findings are telling us we really at least need to consider" the next two generations, she added.</p>
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Poor eating habits, lack of exercise, genetics, and a bunch of other things are known to be behind excessive weight gain. But, did you know that how much sleep you get each night can also determine how much weight you gain or lose?
By Laura Beil
Consumers have long turned to vitamins and herbs to try to protect themselves from disease. This pandemic is no different — especially with headlines that scream "This supplement could save you from coronavirus."
Vitamin D<p><strong>What it is: </strong>Called "the sunshine vitamin" because the body makes it naturally in the presence of ultraviolet light, <a href="https://www.sciencenews.org/article/vitamin-d-supplements-lose-luster" target="_blank">Vitamin D is one of the most heavily studied</a> supplements (<em>SN: 1/27/19</em>). <a href="https://health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/appendix-12/" target="_blank">Certain foods</a>, including fish and fortified milk products, are also high in the vitamin.</p><p><strong>Why it might help: </strong>Vitamin D is a hormone building block that helps strengthen the immune system.</p><p><strong>How it works for other infections:</strong> In 2017, the <em>British Medical Journal</em> published a meta-analysis that suggested a daily vitamin D supplement <a href="https://www.bmj.com/content/356/bmj.i6583" target="_blank">might help prevent respiratory infections</a>, particularly in people who are deficient in the vitamin.</p><p>But one key word here is <em>deficient. </em>That risk is highest during dark winters at high latitudes and among people with more color in their skin (melanin, a pigment that's higher in darker skin, inhibits the production of vitamin D).</p><p>"If you have enough vitamin D in your body, the evidence doesn't stack up to say that giving you more will make a real difference," says Susan Lanham-New, head of the Nutritional Sciences Department at the University of Surrey in England.</p><p>And taking too much can create new health problems, stressing certain internal organs and leading to a dangerously high calcium buildup in the blood. The recommended daily allowance for adults is 600 to 800 International Units per day, and the upper limit is considered to be 4,000 IUs per day.</p><p><strong>What we know about Vitamin D and COVID-19:</strong> Few studies have looked directly at whether vitamin D makes a difference in COVID.</p>
Zinc<p><strong>What it is: </strong>Zinc, a mineral found in cells all over the body, is found naturally in certain meats, beans and oysters.</p><p><strong>Why it might help: </strong>It plays several supportive roles in the immune system, which is why zinc lozenges are always hot sellers in cold and flu season. Zinc also helps with cell division and growth.</p><p><strong>How it works for other infections: </strong><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6457799/" target="_blank" rel="noopener noreferrer">Studies of using zinc for colds</a> — which are frequently caused by coronaviruses — suggest that using a supplement right after symptoms start might make them go away quicker. That said, a clinical trial from researchers in Finland and the United Kingdom, published in January in <em>BMJ Open</em> <a href="https://bmjopen.bmj.com/content/10/1/e031662" target="_blank" rel="noopener noreferrer">did not find any value for zinc lozenges</a> for the treatment of colds. Some researchers have theorized that inconsistencies in data for colds may be explained by varying amounts of zinc released in different lozenges.</p><p><strong>What we know about zinc and COVID-19:</strong> The mineral is promising enough that it was added to some early studies of hydroxychloroquine, a drug tested early in the pandemic. (Studies have since shown that <a href="https://www.sciencenews.org/article/covid-19-coronavirus-hydroxychloroquine-no-evidence-treatment" target="_blank">hydroxychloroquine can't prevent or treat COVID-19</a> (<em>SN: 8/2/20</em>).)</p>
Vitamin C<p><strong>What it is: </strong>Also called L-ascorbic acid, vitamin C has a long list of roles in the body. It's found naturally in fruits and vegetables, especially citrus, peppers and tomatoes.</p><p><strong>Why it might help:</strong> It's a potent antioxidant that's important for a healthy immune system and preventing inflammation.</p><p><strong>How it works for other infections: </strong>Thomas cautions that the data on vitamin C are often contradictory. One review from Chinese researchers, published in February in the <em>Journal of Medical Virolog</em>y, looked at <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/jmv.25707" target="_blank">what is already known about vitamin C</a> and other supplements that might have a role in COVID-19 treatment. Among other encouraging signs, human studies find a lower incidence of pneumonia among people taking vitamin C, "suggesting that vitamin C might prevent the susceptibility to lower respiratory tract infections under certain conditions."</p><p>But for preventing colds, a 2013 Cochrane review of 29 studies <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD000980.pub4/full" target="_blank" rel="noopener noreferrer">didn't support the idea</a> that vitamin C supplements could help in the general population. However, the authors wrote, given that vitamin C is cheap and safe, "it may be worthwhile for common cold patients to test on an individual basis whether therapeutic vitamin C is beneficial."</p><p><strong>What we know about Vitamin C and COVID-19: </strong>About a dozen studies are under way or planned to examine whether vitamin C added to coronavirus treatment helps with symptoms or survival, including Thomas' study at the Cleveland Clinic.</p><p>In a review published online in July in <em>Nutrition</em>, researchers from KU Leuven in Belgium concluded that the <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD000980.pub4/full" target="_blank" rel="noopener noreferrer">vitamin may help prevent infection</a> and tamp down the dangerous inflammatory reaction that can cause severe symptoms, based on what is known about how the nutrient works in the body.</p><p>Melissa Badowski, a pharmacist who specializes in viral infections at the University of Illinois at Chicago College of Pharmacy and colleague Sarah Michienzi published an extensive look at all supplements that might be useful in the coronavirus epidemic. There's <a href="https://www.drugsincontext.com/can-vitamins-and-or-supplements-provide-hope-against-coronavirus/" target="_blank" rel="noopener noreferrer">still not enough evidence to know whether they are helpful</a>, the pair concluded in July in <em>Drugs in Context</em>. "It's not really clear if it's going to benefit patients," Badowski says.</p><p>And while supplements are generally safe, she adds that nothing is risk free. The best way to avoid infection, she says, is still to follow the advice of epidemiologists and public health experts: "Wash your hands, wear a mask, stay six feet apart."</p>
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By Elliot Douglas
In early October, Britain's Prince William teamed up with conservationist David Attenborough to launch the Earthshot Prize, a new award for environmentalist innovation. The Earthshot brands itself the "most prestigious global environment prize in history."
The world-famous wildlife broadcaster and his royal sidekick appear to have played an active role in the prize's inception, and media coverage has focused largely on them as the faces of the campaign.
“Rather than a Moonshot 🌕, we need Earthshots 🌍 for this decade.” Watch Prince William’s @Tedtalks talk in full:… https://t.co/m5NCj6TQzH— The Duke and Duchess of Cambridge (@The Duke and Duchess of Cambridge)1602408749.0
But the pair are only the frontmen of a much larger movement which has been in development for several years. In addition to a panel of experts who will decide on the winners, the prize's formation took advice from the World Wildlife Fund, Greenpeace and the Jack Ma Foundation.
With more and more global attention on the climate crisis, celebrity endorsement of environmental causes has become more common. But why do environmental causes recruit famous faces for their campaigns? And what difference can it make?
'Count Me In'
"We need celebrities to reach those people who we cannot reach ourselves," says Sarah Marchildon from the United Nations Climate Change secretariat (UNFCCC) in Bonn, Germany.
Marchildon is a proponent of the use of celebrities to raise awareness of environmental causes. In addition to promoting a selection of climate ambassadors who represent the UN on sustainability issues, Marchildon's team has produced videos with well-known narrators from the entertainment world: among them, Morgan Freeman and Mark Ruffalo.
"We choose celebrities who have a lifestyle where they are already talking about these issues," Marchildon explains.
"Sometimes they reach out to us themselves, as David Attenborough did recently. And then they can promote the videos on their own social channels which reach more people than we do — for example, if they have 20 million followers and we have 750,000."
Environmental groups focused on their own domestic markets are also taking this approach. One Germany-based organization that uses celebrities in campaigns is the German Zero NGO. Set up in 2019, it advocates for a climate-neutral Germany by 2035.
German Zero produced a video in March 2020 introducing the campaign with "66 celebrities" that supported the campaign, among them Deutschland 83 actor Jonas Nay and former professional footballer Andre Schürrle. They solicit support as well as financial contributions from viewers.
"Count me in," they say, pointing toward the camera. "You too?"
"We are incredibly grateful for the VIPs in our videos," says German Zero spokeswoman Eva-Maria McCormack.
Assessing Success Is Complex
But quantifying the effectiveness of celebrity endorsement of campaigns is not a straightforward process.
"In order to measure effectiveness, first of all you need to define what is meant by success," says Alegria Olmedo, a researcher at the Zoology Department at the University of Oxford.
Olmedo is the author of a study looking at a range of campaigns concerning pangolin consumption, fronted by local and Western celebrities, in Vietnam and China. But she says her biggest stumbling block was knowing how to measure a campaign's success.
"You need a clear theory of change," explains Olmedo. "Have the celebrities actually helped in achieving the campaign's goals? And how do you quantify these goals? Maybe it is increased donations or higher engagement with a cause."
A popular campaign in China in recent years saw famous chefs Zhao Danian and Shu Yi pledge to abstain from cooking endangered wildlife. While the pledge achieved widespread recognition, both Olmedo and Marchildon say it's difficult to know whether it made any difference to people's actions.
"In life we see a thousand messages every day, and it is very hard to pinpoint whether one campaign has actually made a difference in people's behavior," she explains.
Awareness Is Not Enough
Many campaigns that feature celebrities focus on raising awareness rather than on concrete action — which, for researcher Olmedo, raises a further problem in identifying effectiveness.
"Reach should never be a success outcome," she says. "Many campaigns say they reached a certain number of people on social media. But there has been a lot of research that shows that simply giving people information does not mean they are actually going to remember it or act upon it."
But anecdotal evidence from campaigns may suggest reach can make an active difference.
"Our VIP video is by far the most watched on our social media channels," McCormack from German Zero says. "People respond to it very directly. A lot of volunteers of all ages heard about us through that video."
However, some marketing studies have shown that celebrity endorsement of a cause or product can distract from the issue itself, as people only remember the person, not the content of what they were saying.
Choosing the Right Celebrity
Celebrity choice is also very important. Campaigns that use famous faces are often aiming to appeal to members of the public who do not necessarily follow green issues.
For certain campaigns with clear target audiences, choosing a climate scientist or well-known environmentalist rather than a celebrity could be more appealing — Attenborough is a classic example. For others, images and videos involving cute animals may be more likely to get a message heard than attaching a famous face.
"We choose celebrities who have a lifestyle where they are already talking about these issues," says Marchildon from the UN. "You need figures with credibility."
McCormack cites the example of Katharine Hayhoe, an environmental scientist who is also an evangelical Christian. In the southern United States, Hayhoe has become a celebrity in her own right, appealing to an audience that might not normally be interested in the messages of climate scientists.
But as soon as you get a celebrity involved, campaigns also put themselves at risk of the whims of that celebrity. Prince William and younger members of the royal family have come under fire in recent years for alleged hypocrisy for their backing of environmental campaigns while simultaneously using private jets to fly around the world.
But Does It Really Work?
While environmental campaigns hope that endorsement from well-known figures can boost a campaign, there is little research to back this up.
"The biggest finding [from my study] was that we were unable to produce any evidence that shows that celebrity endorsement of environmental causes makes any difference," says Olmedo.
This will come as a blow to many campaigns that have invested time and effort into relationships with celebrity ambassadors. But for many, the personal message that many celebrities offer in videos like that produced by German Zero and campaigns like the Earthshot Prize are what counts.
The research may not prove this conclusively — but if the public believes a person they respect deeply personally cares about an important issue, they are perhaps more likely to care too.
"I personally believe in the power this can have," says Marchildon. "And if having a celebrity involved can get a single 16-year-old future leader thinking about environmentalist issues — that is enough."
Reposted with permission from DW.
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