By John R. Platt
Here at The Revelator, we love a good shark story.
The problem is, there aren't all that many good shark stories. According to recent research, sharks and their relatives represent one of the world's most imperiled groups of species. Of the more than 1,250 known species of sharks, skates, rays and chimeras — collectively known as chondrichthyan fishes — at least a quarter are threatened with extinction.
Speaking of Shark Week:<p><a href="https://therevelator.org/film-fakery-shark-week-conservation/" target="_blank">Film Fakery: Does Shark Week Harm Conservation Efforts?</a></p>
Big Questions:<p><a href="https://therevelator.org/shark-conservation-success/" target="_blank">Are We Ready for Shark Conservation to Succeed?</a></p>
Sharks and Fisheries:<p><a href="https://therevelator.org/protect-sharks-overfishing/" target="_blank">How to Protect Sharks From Overfishing</a></p><p><a href="https://therevelator.org/florida-anglers-endangered-sharks/" target="_blank">Florida Anglers Are Targeting Endangered Sharks</a></p><p><a href="https://therevelator.org/recreational-fishing-environmental-impact/" target="_blank">Fishing for Fun? It Has a Bigger Environmental Impact Than We Thought</a></p><p><a href="https://therevelator.org/fins-protected-sharks-traded/" target="_blank">Fins from Protected Shark Species Still Heavily Traded</a></p><p><a href="https://therevelator.org/essential-unprotected-fish-habitats/" target="_blank">'Essential' But Unprotected: How the United States Fails Its Most Important Fish Habitats</a></p>
Sharks and the Extinction Crisis:<p><a href="https://therevelator.org/lost-shark/" target="_blank">Found But Lost: Newly Discovered Shark May Be Extinct</a></p><p><a href="https://therevelator.org/rhino-rays-cites/" target="_blank">A Chance to Save the 'Rhinos of the Sea'</a></p><p><a href="https://therevelator.org/one-million-extinctions/" target="_blank">What Losing 1 Million Species Means for the Planet — and Humanity</a></p><p><a href="https://therevelator.org/extinction-crisis-keep-feeling-overwhelmed/" target="_blank">The Extinction Crisis is Here. How do We Keep from Feeling Overwhelmed?</a></p>
Broader Ocean and Conservation Issues:<p><a href="https://therevelator.org/ocean-biodiversity-mpa/" target="_blank">The Top 10 Ocean Biodiversity Hotspots to Protect</a></p><p><a href="https://therevelator.org/protect-species-environmental-dna/" target="_blank">How Do You Protect a Species You Can't See?</a></p><p><a href="https://therevelator.org/global-ocean-treaty/" target="_blank">Here's Our Best Opportunity to Save the Oceans — and Ourselves</a></p><p><a href="https://therevelator.org/coral-reef-replanting/" target="_blank">Coral in Crisis: Can Replanting Efforts Halt Reefs' Death Spiral?</a></p><p><a href="https://therevelator.org/oceans-challenges/" target="_blank">What Are the Biggest Challenges for Saving the Oceans?</a></p><p><a href="https://therevelator.org/empowering-communities-save-ocean/" target="_blank">Empowering Communities to Save the Ocean</a></p><p><a href="https://therevelator.org/toxic-plastic-pollution-food-chain/" target="_blank">Something Fishy: Toxic Plastic Pollution Is Traveling Up the Food Chain</a></p><p><a href="https://therevelator.org/trump-offshore-oil-wildlife/" target="_blank">Trump's Offshore Oil Plan: Like Nothing the Country Has Ever Seen</a></p><p><a href="https://therevelator.org/author/john/" target="_blank">John R. Platt</a> <em>is the editor of <em>The Revelator</em>. An award-winning environmental journalist, his work has appeared in <em>Scientific American</em>, <em>Audubon</em>, <em>Motherboard</em>, and numerous other magazines and publications. His "Extinction Countdown" column has run continuously since 2004 and has covered news and science related to more than 1,000 endangered species. He is a member of the Society of Environmental Journalists and the National Association of Science Writers. John lives on the outskirts of Portland, Ore., where he finds himself surrounded by animals and cartoonists.</em></p><p><em>Reposted with permission from <a href="https://therevelator.org/sharks-imperiled/" target="_blank">The Revelator</a>.</em></p>
<div id="7eb49" class="rm-shortcode" data-rm-shortcode-id="83819841e380a7072ec66d3186c160e8"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1291705003984510977" data-partner="rebelmouse"><div style="margin:1em 0">🚨RESPONSE to #Mauritius #OILSpill 🚨 “Once again we see the risks in oil: aggravating the #ClimateCrisis, as well as… https://t.co/PBLioZat6X</div> — Greenpeace Africa (@Greenpeace Africa)<a href="https://twitter.com/Greenpeaceafric/statuses/1291705003984510977">1596801446.0</a></blockquote></div><p>"There is no guaranteed safe way to extract, transport and store fossil fuel products. This oil leak is not a twist of fate, but the choice of our twisted addiction to fossil fuels. We must react by accelerating our withdrawal from fossil fuels," Greenpeace Africa Senior Climate and Energy Campaign Manager Happy Khambule said in a <a href="https://www.greenpeace.org/africa/en/press/11864/greenpeace-africa-response-to-mauritius-oil-spill/?utm_campaign=oil&utm_source=t.co&utm_medium=post&utm_content=single-image&utm_term=mauritius-oil-spill-reactive" target="_blank">statement Friday</a>. "Once again we see the risks in oil: aggravating the <a href="https://www.ecowatch.com/tag/climate-crisis" target="_self">climate crisis</a>, as well as devastating oceans and <a href="https://www.ecowatch.com/tag/biodiversity" target="_self">biodiversity</a> and threatening local livelihoods around some of Africa's most precious lagoons."</p>
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By Zulfikar Abbany
"We don't have a definition of life," says Kevin Peter Hand, one early California morning when we speak via video. "We don't actually know what life is."
Alien Oceans Here and There<p>Europa, Enceladus, and Triton are just three of over 200 moons in our solar system. But they are special moons. They seem to have live, liquid water environments below the surface — also known as subsurface oceans — under an icy shell.</p><p>"These are global liquid oceans covered with ice," says Hand. "And if we go to Europa or Enceladus, these worlds where hydrothermal vents could exist, but where no continents exist, and there's no atmosphere, and if we found life, that would almost certainly point to an origin of life in hydrothermal vents."</p><p>And that may then tell us more about life on Earth. </p><p>Hydrothermal vents are found at extreme depths of around 6,000 kilometers (3,728 miles) in vast trenches below the surface of Earth's own ocean.</p><p>Not so long ago, those trenches were believed to be too dark for any life to exist. But through oceanographic research and commercial prospectors trawling for rare minerals like manganese nodules, we now know that hydrothermal vents are teeming with microbial life. So, the same may be true on a distant moon.</p><p>"That's not to say we'd be able to cross off the potential for the origin of life in tide pools on ancient Earth, but if we found life in hydrothermal vents on these moons, we would at least have another data point," says Hand.</p>
Biology Beyond Earth<p>Biology — or organic life as we know it — is perhaps the final piece in a jigsaw puzzle for space scientists.</p><p>Thanks to Galileo, says Hand, we know that the laws of physics work beyond Earth. So, too, with the principles of chemistry and geology.</p><p>"But we don't know whether this phenomenon called life has happened a second, independent time from life here on Earth. And that's why the question of a second origin of life is so compelling," says Hand.</p>
The Europa Clipper<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="367f258c4634fbd67ad3ce7ef3a73b5f"><iframe lazy-loadable="true" src="https://www.youtube.com/embed/GqTaDCt_F1Y?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>Hand's focus for now is Jupiter's moon, Europa. One of his current projects is the <a href="https://www.jpl.nasa.gov/missions/europa-clipper/" target="_blank">Europa Clipper</a> mission, which will perform about 45 so-called "flybys" of the moon. </p><p>Its launch date has yet to be decided. But the plan is for the Europa Clipper to take hi-resolution images of the moon's surface on a scale of between 50 centimeters per pixel and tens of meters per pixel.</p><p>It will look for organics, like salt.</p><p>It will have an ice penetrating radar onboard, and spectrometers that could "taste" any plumes erupting out of Europa.</p><p>"It will fly through the plumes and capture some of that material so we can analyze it directly. That will be phenomenal, but it won't get us down to the surface," says Hand. So, they are working on another mission that would land on Europa, too.</p>
Trident for Triton<p>Meanwhile, NASA's <a href="https://www.nasa.gov/press-release/nasa-selects-four-possible-missions-to-study-the-secrets-of-the-solar-system" target="_blank">Discovery Program</a> has two further outer solar system moon missions under consideration. One of those missions is called Trident. And if it's selected to move forward, the mission will investigate Neptune's moon, Triton.</p><p>Trident would launch in 2026 for a 12-year journey to Triton. The last spacecraft to study Triton was Voyager 2, which launched in 1977. It got to within 40,000 km of Triton, whereas Trident would get as close as 500 km on two flybys.</p><p>"Voyager gave us pictures that let us see geysers and plumes on Triton and that was 30 years ago — 50 years before Trident," says Yohai Kaspi, a professor of atmospheric dynamics and planetary science at the Weizmann Institute in Israel. "But with today's technology and imaging, we can do much better."</p><p>Kaspi and his colleagues are contributing a special clock to the project, with which they hope to measure the density and temperature of Triton's atmosphere.</p><p>The clock is called an Ultra-Stable Oscillator (USO).</p><p>It's a basically quartz clock, like a quartz wristwatch, but it's kept it at a very stable temperature to protect it from all the temperature variations in space.</p><p>"You hold it in a little oven, literally a tiny oven, with a stable temperature of one milliKelvin," says Kaspi, "and that gives us an accurate time frequency."</p><p>The spacecraft will have a radio link to Earth for the purpose of Kaspi's experiment and for general use, such as navigation. It will be a constant signal.</p><p>But the speed at which that signal travels back to Earth will change as the spacecraft enters and moves through Triton's atmosphere. The atmosphere is almost a filter through which the signal will have to pass. Measuring and comparing the difference in time it takes the signal to travel to Earth will allow scientists to measure thickness of Triton's atmosphere and build a profile of the moon's atmospheric temperature.</p>
How Do Moon Oceans and Their Atmospheres Interact?<p>Kaspi says Triton's atmosphere makes it unique. "Enceladus is too small to have an atmosphere and Europa barely has an atmosphere," he says. "Triton's atmosphere is not as dense as the one on Earth but it's enough of an atmosphere to transport material around. And in addition to that, it's likely that Triton was not even formed in our solar system. So, it's a real opportunity."</p><p>If the mission goes ahead, it may also be an opportunity to understand more about the interaction between subsurface oceans, or the "interior" of such moons, and their atmospheres. Because atmospheres are just as important for maintaining life and water is for originating life.</p><p>"We see these plumes coming from the interior, and they are then transported by the atmosphere. We see these active geysers and then these streaks on the planet, and they're all in the same direction," Kaspi says. "So, you would assume that there is a wind going from one side to the other. Voyager observed that. But that is about as much as we know."</p><p>What we don't know, says Kaspi, is how much of Triton's atmosphere originated from the interior, or whether the subterranean ocean can communicate or interact much with the outside.</p><p>The instruments on Trident are designed to find out how the whole system works together. They may even get us a little closer to that elusive definition of life itself.</p><p>"I hope that maybe 400 years from now our descendants will be able to point to innovations and discoveries that we made and go, 'Wow, can you believe they argued about the importance of searching for life beyond Earth and its application?'" says NASA's Kevin Hand.</p><p>"And perhaps they will be able to laugh about that in the same way that we look at Galileo and say: 'Of course, Galileo's work was pivotal in changing the way we think about the universe' — and everything that cascades from that, right down to the computer conversation that we're having now."</p><p>Message received.</p>
By Gavin Naylor
Sharks elicit outsized fear, even though the risk of a shark bite is infinitesimally small. As a marine biologist and director of the Florida Program for Shark Research, I oversee the International Shark Attack File – a global record of reported shark bites that has been maintained continuously since 1958.
A Big, Diverse Family<p>Not all sharks are the same. Only a dozen or so of the roughly 520 shark species pose any risk to people. Even the three species that account for almost all shark bite fatalities – the <a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharodon-carcharias/" target="_blank">white shark</a> (<em>Carcharodon carcharias</em>), <a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/galeocerdo-cuvier/" target="_blank">tiger shark</a> (<em>Galeocerdo cuvier</em>) and <a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharhinus-leucas/" target="_blank">bull shark</a> (<em>Carcharhinus leucas</em>) – are behaviorally and evolutionarily very different from one another.</p><p>The tiger shark and bull shark are genetically as different from each other as a dog is from a rabbit. And both of these species are about as different from a white shark as a dog is from a kangaroo. The evolutionary lineages leading to the two groups split 170 million years ago, during the age of dinosaurs and before the origin of birds, and <a href="https://www.ck12.org/book/CK-12-Human-Biology/section/7.2/" target="_blank">110 million years before the origin of primates</a>.</p>
White, tiger and bull sharks are distinct species that diverged genetically tens of millions of years ago. Gavin Naylor / CC BY-ND<p>Yet many people assume all sharks are alike and equally likely to bite humans. Consider the term "shark attack," which is scientifically equivalent to "mammal attack." Nobody would equate dog bites with hamster bites, but this is exactly what we do when it comes to sharks.</p><p>So, when a reporter calls me about a fatality caused by a white shark off Cape Cod and asks my advice for beachgoers in North Carolina, it's essentially like asking, "A man was killed by a dog on Cape Cod. What precautions should people take when dealing with kangaroos in North Carolina?"</p>
Know Your Species<p>Understanding local species' behavior and life habits is one of the best ways to stay safe. For example, almost all shark bites that occur off Cape Cod are by white sharks, which are a large, primarily cold-water species that spend most of their time in isolation feeding on fishes. But they also aggregate near seal colonies that provide a reliable food source at certain times of the year.</p><p>Shark bites in the Carolinas are by warm-water species like bull sharks, tiger sharks and <a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharhinus-limbatus/" target="_blank">blacktips</a> (<em>Carcharhinus limbatus</em>). Each species is associated with particular habitats and dietary preferences.</p><p>Blacktips, which we suspect are responsible for most relatively minor bites on humans in the southeastern United States, feed on schooling bait fishes like menhaden. In contrast, bull sharks are equally at home in fresh water and salt water, and are often found near estuaries. Their bites are more severe than those of blacktips, as they are larger, more powerful, bolder and more tenacious. Several fatalities have been ascribed to bull sharks.</p><p>Tiger sharks are also large, and are responsible for a significant fraction of fatalities, particularly off the coast of volcanic islands like Hawaii and Reunion. They are tropical animals that often venture into shallow water frequented by swimmers and surfers.</p>
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="1cfa1c9590e386ecc9455b4762b87518"><iframe lazy-loadable="true" src="https://www.youtube.com/embed/yDqzGOa-adc?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Humans Are Not Targets<p>Sharks do not "hunt" humans. Data from the International Shark Attack File compiled over the past 60 years show a tight association between shark bites and the number of people in the water. In other words, shark bites are a simple function of the probability of encountering a shark.</p><p>This underscores the fact that shark bites are almost always cases of mistaken identity. If sharks actively hunted people, there would be many more bites, since humans make very easy targets when they swim in sharks' natural habitats.</p><p>Local conditions can also affect the risk of an attack. Encounters are more likely when sharks venture closer to shore, into areas where people are swimming. They may do this because they are following bait fishes or seals upon which they prey.</p><p>This means we can use environmental variables such as temperature, tide or weather conditions to better predict movement of bait fish toward the shoreline, which in turn will predict the presence of sharks. Over the next few years, the Florida Program for Shark Research will work with colleagues at other universities to monitor onshore and offshore movements of tagged sharks and their association with environmental variables so that we can improve our understanding of what conditions bring sharks close to shore.</p>
More to Know<p>There still is much to learn about sharks, especially the 500 or so species that have never been implicated in a bite on humans. One example is the tiny <a href="https://www.newsweek.com/one-worlds-rarest-sharks-also-one-most-adorable-325280" target="_blank">deep sea pocket shark</a>, which has a strange pouch behind its pectoral fins.</p><p>Only two specimens of this type of shark have ever been caught – one off the coast of Chile 30 years ago, and another more recently in the Gulf of Mexico. We're not sure about the function of the pouch, but suspect it stores luminous fluid that is released to distract would-be predators – much as its close relative, the <a href="https://sharkdevocean.wordpress.com/2015/04/23/second-ever-pocket-shark-discovered-in-gulf-of-mexico/" target="_blank">tail light shark</a>, releases luminous fluid from a gland on its underside near its vent.</p>
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="5783b39d0838d6e410344a852ed0dcc3"><iframe lazy-loadable="true" src="https://www.youtube.com/embed/UTO5debfmsg?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>Sharks range in form from the bizarre <a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/mitsukurina-owstoni/" target="_blank">goblin shark</a> (<em>Mitsukurina owstoni</em>), most commonly encountered in Japan, to the gentle filter-feeding <a href="https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/rhincodon-typus/" target="_blank">whale shark</a> (<em>Rhincodon typus</em>). Although whale sharks are the largest fishes in the world, we have yet to locate their nursery grounds, which are likely teeming with thousands of <a href="https://www.earthtouchnews.com/oceans/sharks/baby-whale-shark-rescued-from-gillnet-in-india-video/" target="_blank">foot-long pups</a>. Some deepwater sharks are primarily known from submersibles, such as the giant <a href="https://twitter.com/gavinnaylor/status/1146144452681113601" target="_blank">sixgill shark</a>, which feeds mainly on carrion but probably also preys on other animals in the deep sea.</p><p>Sharks seem familiar to almost all of us, but we know precious little about them. Our current understanding of their biology barely scratches the surface. The little we do know suggests they are profoundly different from other vertebrate animals. They've had 400 million years of independent evolution to adapt to their environments, and it's reasonable to expect they may be hiding more than a few tricks up their gills.</p>
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<div id="14b13" class="rm-shortcode" data-rm-shortcode-id="3dabcc399c214226e768937f555a5ebc"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1289943962405318657" data-partner="rebelmouse"><div style="margin:1em 0">Tropical Storm #Isaias no longer expected to restrengthen into a hurricane. 🌀 The vertical wind shear shredder has… https://t.co/kqBsJOS3Tj</div> — Ryan Maue (@Ryan Maue)<a href="https://twitter.com/RyanMaue/statuses/1289943962405318657">1596381581.0</a></blockquote></div>
<div id="dea35" class="rm-shortcode" data-rm-shortcode-id="132c2812ba753aaaf415ad33fb7ff2c0"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1290213982947737600" data-partner="rebelmouse"><div style="margin:1em 0">Here are the 5 am EDT Monday, August 3 Key Messages for Tropical Storm #Isaias. For the full advisory on #Isaias, v… https://t.co/5MbSBJmEhI</div> — National Hurricane Center (@National Hurricane Center)<a href="https://twitter.com/NHC_Atlantic/statuses/1290213982947737600">1596445959.0</a></blockquote></div>
<div id="80487" class="rm-shortcode" data-rm-shortcode-id="dcd38a3bef604d3ff7ef47552482cbe4"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1290216672976986113" data-partner="rebelmouse"><div style="margin:1em 0">There is a moderate risk of flash flooding across portions of the eastern Carolinas and Mid-Atlantic states from… https://t.co/C5Ys46ZetX</div> — National Hurricane Center (@National Hurricane Center)<a href="https://twitter.com/NHC_Atlantic/statuses/1290216672976986113">1596446600.0</a></blockquote></div>
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By Kristen Pope
Melting and crumbling glaciers are largely responsible for rising sea levels, so learning more about how glaciers shrink is vital to those who hope to save coastal cities and preserve wildlife.
Groans, Creaks, Icebergs’ Calving Splashes<p>Oskar Glowacki already knew that melting glacial ice sounds like frying bacon. As ice bubbles burst, anyone nearby can hear crackling and popping, said Glowacki, a postdoctoral scholar at the Scripps Institution of Oceanography. Using hydrophones, he and other scientists now can make more nuanced measurements of how a changing climate sounds underwater, from the groans, creaks and splashes of a calving iceberg to the changes in whale songs as the ocean warms.</p><p>Glowacki recently used a pair of hydrophones to study the underwater world of glaciers, publishing his findings in <a href="https://www.the-cryosphere.net/14/1025/2020/" target="_blank">The Cryosphere</a>. He and co-author Grant B. Deane measured glacier retreat by <a href="https://yaleclimateconnections.org/2020/07/melting-glaciers-sound-like-frying-bacon/" target="_blank">recording the sounds of ice</a> – from small chunks to enormous slabs – falling off the glacier and splashing into the water.</p><p>During the summer of 2016, Glowacki's team placed two hydrophones near Hansbreen Glacier in Hornsund Fjord, Svalbard. For a month and a half, they recorded sounds, also using three time-lapse cameras to collect images – including the "drop height" (how far the ice fell into the water) – so they could compare photos to the recordings. The team created a formula to represent the relationship between the size of a piece of ice falling from a glacier and the sound it makes underwater, also accounting for the pieces of ice falling from varying heights. (Hear an example of the sound an iceberg makes while calving <a href="https://soundcloud.com/user-248456662/iceberg-calving-hansbreen-glacier" target="_blank">here</a>.)</p>
Unlocking Information About Antarctic Ice Shelf<p>Other researchers also are using hydrophones to learn more about crumbling glaciers. Bob Dziak, research oceanographer with the NOAA/Pacific Marine Environmental Laboratory <a href="https://www.pmel.noaa.gov/acoustics" target="_blank">acoustics research group</a>, captured a massive calving event of the Nansen Ice Shelf in Antarctica with a hydrophone. He published the results with colleagues in <a href="https://www.frontiersin.org/articles/10.3389/feart.2019.00183/full" target="_blank">Frontiers in Earth Science</a></p><p>On April 7, 2016, satellite images showed a massive calving event had occurred on the ice shelf. The paper described it as the "first large scale calving event in >30 years."</p><p>However, once Dziak and colleagues delved into the data from three hydrophones deployed 60 kilometers east of the ice shelf, they uncovered a series of "icequakes" from January to early March 2016. He and other researchers believe that much of the ice actually broke free in mid-January to February, but it remained in the same location until an April storm – which their paper described as the "largest low-pressure storm recorded in the previous seven months" – broke the ice free.</p><p>"We suspected that the icebergs broke apart but remained in place – kind of pinned in place – until a major storm with high winds passed through the area and, finally, it was that last push that pushed the icebergs out to sea," Dziak says.</p><p>He and his co-authors wrote that "fortuitous timing and proximity of the hydrophone deployment presented a rare opportunity to study cryogenic signals and ocean ambient sounds of a large-scale ice shelf calving and iceberg formation event."</p>
Listening to Songs of Humpback Whales<p><a href="https://www.mbari.org/" target="_blank">Monterey Bay Aquarium Research Institute</a> studies the ocean, including its acoustics. One of the institute's projects involves examining the soundscape of California's Monterey Bay, including sounds from animals, humans, weather, and geologic processes like earthquakes. The researchers once even recorded an under-sea landslide. They also focus on recording and analyzing the <a href="http://www.mbari.org/humpback-song/" target="_blank">songs of humpback whales</a>. Male humpback whales' songs can be over 15 minutes in length, and they can be repeated for long periods of time – even hours. Listening to these songs and analyzing them can provide unique insights into the lives of these complex animals.</p><p>"Any time we want to study marine mammals, sound gives us a window into their lives because they use sound for all of their essential life activities, really," says institute biological oceanographer John Ryan. "Communication, foraging, reproduction, navigation – depending on the species, of course."</p><p>Previously, scientists had thought singing occurred only during courtship and mating, but now they think whales may also use song while migrating and hunting. They know song has a crucial role in the whales' lives.</p><p>"There's a whole other dimension to humpback whale song," Ryan says. "It is a mode of cultural transmission in this species. They learn songs from each other. They share songs as a population, and when populations mix and mingle, they learn new ideas, they explore with their song, improvise, and it's a real essential part of their culture."</p>
Every day, sharks suffer from different threats. Up to 100 million sharks disappear every year, due to destructive fishing by humans and the impact of climate breakdown. One-third of the world's known shark species have been listed as "threatened" species by the International Union for Conservation of Nature.
This whale shark smiles for the camera in the warm water off the coast of the Philippines. Greenpeace<p>2. Sharks come in all shapes and sizes, from the tiny lantern sharks, which are about the size of your hand, to giant whale sharks, which are about the same size as a bus.</p>
A former fisherman, now a whale shark guide, hand feeds a whale shark as a tourist takes an underwater photo, Tan-awan, Oslob Cebu. Greenpeace<p>3. Greenland sharks, which live in cold polar waters, hold the record as the oldest known vertebrate animals on the planet. Since they are estimated to live as long as 500 years, there could be some alive today that were born in the Middle Ages. For reference, Leonardo Da Vinci painted the <em>Mona Lisa</em> 500 years ago!</p>
An oceanic whitetip shark in Egypt. Greenpeace<p>4. Mako sharks hold the record for being the most athletic sharks, reaching swimming speeds of over 40 miles per hour! They are also known to have jumped as much as 30 feet out of the water.</p>
A whale shark photographed from above in Cenderawasih Bay National Park, Indonesia. Greenpeace<p>5. The world's biggest sharks also have the widest mouths and eat only tiny ocean plankton, just like the largest whales.</p>
A whale shark in the Philippines. Greenpeace<p>6. Carpet sharks live on the ocean floor and have elaborate patterns to blend in with perfect camouflage. The Tasseled Wobbegong shark takes this to the extreme, with a fringe of feathery 'tassels' around its body.</p>
Lemon shark and other fish underwater at Tuamotus, French Polynesian. Greenpeace<p>8. Hammerhead sharks' elongated heads not only give them super-sense when it comes to electromagnetic detection, but they also have almost 360-degree surround vision.</p>
A Blue Shark (Prionace glauca) near the Azores. Greenpeace<p>9. When sharks are turned upside down, they go into a natural suspended state called tonic immobility.</p>
A shark is seen in the Republic of Palau. Greenpeace<p><span style="background-color: initial;">10. It's dark in the deep sea, so tiny lantern sharks have developed their own way to glow in the dark. It's not yet known if this is to find food, find each other, or help avoid being eaten!</span><br></p>
Grey Reef Sharks in Tahiti. Greenpeace<p>In June 2019, the Greenpeace ship Esperanza went to the North Atlantic to confront the overfishing of sharks. At the same time, Greenpeace International issued a report, <a href="https://www.greenpeace.org/international/publication/22700/sharks-under-attack/" target="_blank">Sharks Under Attack: Overfished and under-protected</a>. It proposed a solution: secure a strong Global Ocean Treaty at the UN.</p>
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By Robert McLachlan
Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.
If you have a question you'd like an expert to answer, please send it to email@example.com
Is humanity doomed? If in 2030 we have not reduced emissions in a way that means we stay under say 2℃ (I've frankly given up on 1.5℃), are we doomed then?
<div id="98101" class="rm-shortcode" data-rm-shortcode-id="9c658bbc6292bd7eb49514c454053d13"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1078329950703357952" data-partner="rebelmouse"><div style="margin:1em 0">As I have been pointing out for some time, climate change isn't a cliff we go off at 1.5C or 2C. It's much more lik… https://t.co/tY8NoRq153</div> — Michael E. Mann (@Michael E. Mann)<a href="https://twitter.com/MichaelEMann/statuses/1078329950703357952">1545928869.0</a></blockquote></div>
Good Reasons Not to Give Up Just Yet<p>The <a href="https://www.ipcc.ch/" target="_blank">Intergovernmental Panel on Climate Change</a> described the effects of a 1.5℃ increase in average temperatures in a <a href="https://www.ipcc.ch/sr15/" target="_blank">special report</a> last year. They are also nicely summarized in an article about <a href="https://climate.nasa.gov/news/2865/a-degree-of-concern-why-global-temperatures-matter/" target="_blank">why global temperatures matter</a>, produced by NASA.</p><p>The global average temperature is currently about <a href="https://climate.nasa.gov/vital-signs/global-temperature/" target="_blank">1.2℃</a> higher than what it was at the time of the Industrial Revolution, some 250 years ago. We are already witnessing localized impacts, including the <a href="https://theconversation.com/we-just-spent-two-weeks-surveying-the-great-barrier-reef-what-we-saw-was-an-utter-tragedy-135197" target="_blank">widespread coral bleaching</a> on Australia's Great Barrier Reef.</p>
This graph shows different emission pathways and when the world is expected to reach global average temperatures of 1.5℃ or 2℃ above pre-industrial levels. Global Carbon Project, Author provided
The Pessimist Perspective<p>Now suppose we don't manage that. It's 2030 and emissions have only fallen a little bit. We're staring at 2℃ in the second half of the century.</p><p>At 2℃ of warming, we could expect to lose more than 90% of our coral reefs. Insects and plants would be at higher risk of extinction, and the number of dangerously hot days would increase rapidly.</p><p>The challenges would be exacerbated and we would have new issues to consider. First, under the "<a href="https://news.mongabay.com/2009/06/proving-the-shifting-baselines-theory-how-humans-consistently-misperceive-nature/" target="_blank">shifting baseline</a>" phenomenon — essentially a failure to notice slow change and to value what is already lost — people might discount the damage already done. Continuously worsening conditions might become the new normal.</p><p><span></span>Second, climate impacts such as mass migration could lead to a rise of nationalism and make international cooperation harder. And third, we could begin to pass unpredictable "<a href="https://www.nature.com/articles/d41586-019-03595-0" target="_blank">tipping points</a>" in the Earth system. For example, warming of more than 2°C could set off widespread melting in Antarctica, which in turn would contribute to sea level rise.</p><p>But true doom-mongers tend to assume a worst-case scenario on virtually every area of uncertainty. It is important to remember that such scenarios are not very likely.</p><p><span></span>While bad, this 2030 scenario doesn't add up to doom — and it certainly doesn't change the need to move away from fossil fuels to low-carbon options.</p>
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In 2007, baby oysters began dying by the millions at the Whiskey Creek Shellfish Hatchery on the Oregon coast.
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Ecuador authorities are keeping tabs on a fleet of roughly 260 fishing boats near the Galapagos Islands, a UNESCO World Heritage Site. Ecuadorian boats are patrolling to try to stop the fishing boats from entering the area, according to Reuters.
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