People have harnessed energy from moving water for thousands of years. Greeks used various types of water wheels to grind grain in mills more than 2,000 years ago. In the late 1800s, people figured out how to harness the power to produce electricity. Throughout the 20th century and into the 21st, hydropower has expanded, producing about 17 percent of the world's electricity by 2014 and about 85 percent of renewable energy—and it shows no signs of slowing.
According to the online magazine WaterWorld, "An expected 3,700 major dams may more than double the total electricity capacity of hydropower to 1,700 GW within the next two decades,"—including in my home province of BC, where the government has started a third dam on the Peace River at Site C. "Hydropower is the most important and widely-used renewable source of energy," the U.S. Geological Survey said.
But how "green" is hydropower and how viable is it in a warming world with increasing water fluctuations and shortages? To some extent, it depends on the type of facility.
The Center for Climate and Energy Solutions notes some large dams are used mainly for water storage or flood control with power generation an additional function, while some are used primarily to generate electricity. Small hydro such as run-of-river is installed on running water and doesn't use water stored in reservoirs. Pumped storage facilities don't generate additional energy, but store energy by pumping water from a lower reservoir to a higher one when demand and price are low, sometimes using renewable energy and release water through turbines when price and demand are high. All have varying environmental impacts.
One of the biggest trade-offs with large-scale hydro facilities is that building them often means flooding land used for farming and human communities. Damming rivers also impedes fish—even with technologies like fish ladders—and can harm wildlife habitat and alter river temperatures, dissolved oxygen levels and flows. And while hydropower creates fewer pollution and climate problems than fossil fuel power, it isn't entirely clean. Clearing vegetation to build a dam and flood land can release greenhouse gases. And as vegetation decays and water levels fluctuate, methane—a greenhouse gas far more potent than carbon dioxide—can build up and escape from reservoirs.
The #Hydropower #Methane Bomb No One Wants to Talk About http://t.co/wgO4JwY3yu @Waterkeeper @GaryWockner @patagonia http://t.co/LkEwzu8MLL— EcoWatch (@EcoWatch)1444150709.0
Ironically, although hydropower is seen as an energy source that helps slow global warming, in many areas its viability is threatened by climate change. Rising greenhouse gas emissions and a warming world affect the entire hydrological cycle—surface and ground water, glaciers, precipitation, runoff and evaporation. Shifting precipitation patterns and increased droughts are changing water levels in rivers and behind hydro dams.
The massive Hoover Dam on the Colorado River is operating at 30 percent capacity and new turbines have to be installed at lower elevation because of low precipitation and drought. In Nepal, "low water levels rendered a brand-new dam project ineffective and cut off the water supply farther downstream," said John Matthews, director of fresh water and adaptation at Conservation International, in Scientific American.
Matthews and co-authors of a study in the journal PLoS Biology wrote that climate change puts 40 percent of hydro development investments at risk. They recommend an approach to dams and hydro that takes climate change into account, by building projects in stages so adjustments can be made as more is known about climate patterns or by "building with nature" rather than on top of it.
Meanwhile, as more environmentally benign power technologies become increasingly cost-effective and viable, the U.S. is removing older dams, many of which don't have fish ladders, because costs to maintain and repair them are too high, as are environmental impacts.
Hydropower will remain part of the clean-energy equation, but we need to find the least disruptive, most efficient methods. Scientist Peter Gleick, president and cofounder of California's Pacific Institute, says the key to supplying energy to growing populations in a warming world will be to use a diversity of power sources. "We need to design our energy systems to be resilient in the face of growing uncertainty about technology and climate and national security and all of the factors that affect energy," Gleick told online magazine Slate.
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The Washington Redskins will retire their controversial name and logo, the National Football League (NFL) team announced Monday.
By Alyssa Murdoch, Chrystal Mantyka-Pringle and Sapna Sharma
Summer has finally arrived in the northern reaches of Canada and Alaska, liberating hundreds of thousands of northern stream fish from their wintering habitats.
A Good News Story?<p>On the surface, the <a href="https://doi.org/10.1111/fwb.13569" target="_blank">results from our study</a> appear to provide a "good news" story. Warming temperatures were linked to higher numbers of fish, more species overall and, therefore, potentially more fishing opportunities for northerners.</p><p>Initially, we were surprised to learn that warming was increasing the distribution of cold-adapted fish. We reasoned that modest amounts of warming could lead to benefits such as increased food and winter habitat availability without reaching stressful levels for many species.</p>
Photo of Arctic grayling (left) and Dolly Varden trout (right). Alyssa Murdoch / Lilian Tran / Nunavik Research Centre and Tracey Loewen / Fisheries and Oceans Canada<p>Yet, not all fish species fared equally well. Ecologically unique northern species — those that have evolved in colder, more nutrient-poor environments, such as Arctic grayling and Dolly Varden trout — were showing declines with warming.</p>
Fish Strandings and Buried Eggs<p>Recent news headlines run the gamut for Pacific salmon — from their increased escapades <a href="https://nunatsiaq.com/stories/article/more-pacific-salmon-showing-up-in-western-arctic-waters/" target="_blank">into the Arctic</a> to <a href="https://www.juneauempire.com/news/warm-waters-across-alaska-cause-salmon-die-offs/" target="_blank">massive pre-spawning die-offs</a> in central Alaska. Similarly, results from our study revealed different outcomes for fish depending on local climatic conditions, including Pacific salmon.</p><p>We found that warmer spring and fall temperatures may be helping juvenile salmon by providing a longer and more plentiful growing season, and by supporting early egg development in northern regions that were previously too cold for survival.</p><p>In contrast, salmon declined in regions that were experiencing wetter fall conditions, pointing to an increased risk of flooding and sedimentation that could bury or dislodge incubating eggs.</p>
Headwaters of the Wind River within the largely intact Peel River watershed in northern Canada. Don Reid / Wildlife Conservation Society Canada / Author provided<p>Interestingly, we found that certain climatic combinations, such as warmer summer water temperatures with decreased summer rainfall, were important in determining where Pacific salmon could survive. Summer warming in drier watersheds led to declines, suggesting that lowered streamflows may have increased the risk of fish becoming stranded in subpar habitats that were too warm and crowded.</p>
The Fate of Northern Fisheries<p>The promise of a warmer and more accessible Arctic has attracted mounting interest in new economic opportunities, <a href="https://doi.org/10.1016/j.marpol.2019.103637" target="_blank">including fisheries</a>. As warming rates at higher latitudes are already <a href="https://www.ipcc.ch/sr15/" target="_blank">two to three times global levels</a>, it seems probable that northern biodiversity will experience dramatic shifts in the coming decades.</p><p>Despite the many unknowns surrounding the future of Pacific salmon, many fisheries are currently <a href="https://doi.org/10.1080/03632415.2017.1374251" target="_blank">thriving following warmer and more productive northern oceans</a>, and some <a href="https://doi.org/10.14430/arctic68876" target="_blank">Arctic Indigenous communities are developing new salmon fisheries</a>.</p><p>As warming continues, the commercial salmon fishing industry is poised to expand northwards, but its success will largely depend on extenuating factors such as <a href="https://www.eenews.net/stories/1060023067" target="_blank">changes to marine habitat and food sources</a> and <a href="https://www.yukon-news.com/news/promising-chinook-salmon-run-failed-to-materialize-in-the-yukon-river-panel-hears/" target="_blank">how many fish are caught during the freshwater stages of their journey</a>.</p><p>Even with the potential for increased northern biodiversity, it is important to recognize that some northern communities may be unable to adapt or may <a href="https://thenarwhal.ca/searching-for-the-yukon-rivers-missing-chinook/" target="_blank">lose individual species that are associated with important cultural values</a>.</p>
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By Joni Sweet
If you get a call from a number you don't recognize, don't hit decline — it might be a contact tracer calling to let you know that someone you've been near has tested positive for the coronavirus.
Interviews With Contact Tracers<p>Contact tracing is a public health strategy that involves identifying everyone who may have been in contact with a person who has the coronavirus. Contact tracers collect information and provide guidance to help contain the transmission of disease.</p><p>It's been used during outbreaks of sexually transmitted infections (STIs), Ebola, measles, and now the coronavirus that causes COVID-19.</p><p>It starts when the local department of health gets a report of a confirmed case of the coronavirus in its community and gives that person a call. The contact tracer usually provides information on how to isolate and when to get treatment, then tries to figure out who else the person may have exposed.</p><p>"We ask who they've been in contact with in the 48 hours prior to symptom onset, or 2 days before the date of their positive test if they don't have symptoms," said <a href="https://case.edu/medicine/healthintegration/people/heidi-gullett" target="_blank">Dr. Heidi Gullett</a>, associate director of the Center for Community Health Integration at the Case Western Reserve University School of Medicine and medical director of the Cuyahoga County Board of Health in Ohio.</p>
“You’ve Been Exposed”<p>After the case interview, contact tracers will get to work calling the folks who may have been exposed to the coronavirus by the person who tested positive.</p><p>"We give them recommendations about quarantining or isolating, getting tested, and what to do if they become sick. If they're not already sick, we still want them to self-quarantine so that they don't spread the disease to anyone else if they were to become sick," said Labus.</p><p>Generally, the contact tracer won't ask for additional contacts unless they happen to call someone who is sick or has a confirmed case of the virus. They will help ensure the contact has the resources they need to isolate themselves, if necessary. The contact tracer may continue to stay in touch with that person over the next 14 days.</p><p>"We follow the percentage of people that were contacts, then converted into being actual cases of the virus. It's an important marker to help us understand what kind of transmission happens in our community and how to control the virus," said Gullett.</p>
Why You Should Participate (and What Happens If You Don’t)<p>A <a href="https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30457-6/fulltext" target="_blank">Lancet study</a> from June 16, which looked at data from more than 40,000 people, found that COVID-19 transmission could be reduced by 64 percent through isolating those who have the coronavirus, quarantining their household, and contacting the people they may have exposed.</p><p>The combination strategy was significantly more effective than mass random testing or just isolating the sick person and members of their household.</p><p>However, contact tracing is only as effective as people's willingness to participate, and a small number of people who've contracted the coronavirus or were potentially exposed are reluctant to talk.</p><p>"Contact tracers have all been hung up on, cussed at, yelled at," said Gullet.</p><p>The hesitation to talk to contact tracers often stems from concerns over privacy — a serious issue in healthcare.</p>
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