I think most scientists are now on board with the idea that we are in the midst of what is being called (not terribly cleverly) the "Sixth Extinction" - this being the sixth time in Earth's history that 75% or more of extant species are expected to go extinct - to disappear forever. The causes are myriad but have one thing in common - humans - which is why scientists have gone even further and now argue that we have entered an entirely new geologic era, dubbed (again, not terribly cleverly), the Anthropocene - literally, the Era of Humans.
Having said that, there's nothing new about the argument that's been raging for decades over the consequences of extinction. Naturalists tend to argue that the extinction of any species is a potential disaster as (they rightly point out) all organisms within an ecosystem are interdependent, which means that when something happens to any one organism, all the rest are impacted. Think of this as a version of Ray Bradbury's "Butterfly Effect" - in an interdependent system, even the minutest factors can profoundly impact the operation of the systems to which they belong. Others dispute this, however, pointing out that extinction serves a critical natural function - to "weed out" species that are not well adapted to survive - an argument with solid Darwinian roots. They point out, for instance, that if it hadn't been for the mass extinction event that eliminated the dinosaurs, then mammals (including ourselves) might never have had a chance to emerge from their holes and assume dominance over the world.
I'm not sure where I fall on the spectrum, but as an environmental scientist I can tell you that not all extinctions are equal. Some endangered species appear to have slipped into extinction without creating a noticeable ripple. Other endangered species, however, such as the species noted below, seem at risk of causing not just ripples at their passing, but potential tsunamis. We may not be able to reverse this coming Sixth Extinction, but I would argue that if we don't actively work to preserve the following 10 organisms, we foolishly risk placing ourselves on the endangered list.
- Bees. Yes, they ruin BBQs and cause thousands of hospital admissions every year, but here's why we need to be very, very, very scared about recent reports of declining bee populations: without bees, many of the crops we depend on as food sources would be at huge risk of extinction. Bees don't just pollinate random flowers - they are also the primary pollinator of crops including: apples, mangoes, squash, cantaloupe, watermelon, cashew, cucumber, avocados, apricots, cherries, plums, almonds, peaches, pears, raspberries, blackberries, blueberries. Bees are, hands down, the most efficient method ever invented for transferring pollen between plants, which is necessary to ensure the production of fruit and seeds. Without bees, farmers would have to invent new systems to perform this task which - guaranteed - would be hugely less efficient and hugely more expensive. What's killing the bees? Well, scientists aren't 100% sure, but certain chemicals in fertilizers such as neonicotinoids appear to act as neurotoxins, gradually poisoning the hunters/gatherers. Pathogens and global warming may also play a role. Whatever the cause, this is one effect we can't afford to allow - not unless we're okay with the prospect of sky-high food prices and mass starvation among those who can't afford those prices.
- Bats. Speaking of pollinators, can we take a moment to talk about another animal that gets a bad rap? Not only are bats second only to bees in importance as pollinators (see above if you don't think that's a worthy enough purpose in life), but the ones that don't feast on flower sap typically feast on insects, a favorite of which happens to be mosquitoes. Want to guess the identity of the most deadly creature on earth - the creature that's responsible for the most human deaths? It's not sharks, or bears, or even fleas - it's mosquitoes. Malaria, dog heartworm, dengue fever, yellow fever, encephalitis, West Nile virus, and now Zika are all carried by these biting nuisance. So, you have to ask yourself: can we really afford to stand by and allow bat populations to plummet due to an untreated fungus (white nose syndrome), just because they look like rats with wings and we're all totally creeped out that they might get tangled in our hair or possibly suck our blood?
- Wolves (also other top predators, such as sharks and bears). There's a common theme to many of the organisms on this list - animals with bad reputations. Which is not entirely coincidental - one could argue that it's easier to stand aside and allow an animal we loath to go extinct vs. species that are harmless and cuddly - like, say, panda bears. Farmers hate wolves because they eat lambs, calves, and chickens, which can hurt a farmer's bottom line. But here's why we need top predators likes wolves, bears, and sharks on this earth: because they transfigure the ecosystems to which they belong in profound ways that we are only beginning to understand. Doubters need only consult what happened when wolves were removed from Yellowstone Park and then, decades later, restored: biodiversity increased (rather than decreased, as was uniformly predicted), grasslands were transformed into forests, whole rivers changed their courses, When we mess with top predators, we impact every food chain they belong to, every ecosystems they interact with, every ecosystems that interacts with THOSE ecosystems. And now, let's consider the past record of outcomes when humans mess with nature - almost universally disastrous. Should we really be messing with natural systems on this scale when we comprehend so humiliatingly little about the potential impacts?
- Prairie dogs (also pika). Another so-called "pest" species that farmers have managed to hunt almost to extinction, in the belief that these tunneling creatures denature critical grazing land by eating all the grasses. Except, guess what? Once the population of these species began to plummet, weird things started to happen. Instead of recovering their health, grasslands actually became even LESS healthy. Why? Turns out their tunnels were providing an essential function: draining floodwater from the flat grasslands which - otherwise - just sits there, drowning the grass. Oh, and their tunnels also facilitate the return of nutrients back into the soil, improving both the rate and abundance of plant growth. Cattlemen may not like that cows and sheep eventually step into the holes, but the number of injured animals pales in comparison to the number of animals that will perish from hunger if we don't quickly restore the prairie dogs and pika to some semblence of their previous abundance.
- Tuna. Fun fact: did you know tuna can reach up to 15ft long and 1500lbs? Fishermen would have to kill, like, 500 mackerel just to produce as much food. Want to guess how long the mackerel are going to be around if tuna go extinct and suddenly we're turning to mackeral to make up the difference? This may be fudging the facts a little (substitute other species for mackeral) - but the lesson learned remains the same: humans require feeding, and if you kill off the large species that provide lots of food, we're going to turn to smaller species - except that we're going to need to kill A LOT MORE of them. Think a chain of dominoes, except that each domino is a different species driven to extinction, all because we made the short-sighted mistake of tipping over that one domino at the top of the chain.
- Cod. At one time, there were so many cod in the Atlantic Ocean that the challenge for fishermen wasn't catching them, but restraining themselves from catching so many that their boats sank. As a result, cod has become our go-to fish for just about everything. Almost all breaded fish (as in "fish & chips," the staple of all British pubs) is made from cod; cod liver oil is also a fairly critical nutritional supplement. However, you can probably guess the rest of the story - cod have now been so overfished that survival of the entire species is in peril. I for one REALLY don't want to be the one to tell my British friends that their days of fish & chips are numbered.
- Shellfish. Fond of oysters, scallops, clams? Then I've got some bad news for you, because all these species are at risk of extinction thanks to the same man-made factors that are bringing us climate change - too much CO2 (carbon dioxide) in the atmosphere. You see, when you mix seawater with carbon dioxide (which settles into the water from the atmosphere and is then mixed into the water by wave action), you get carbonic acid, H2DO3, which is just as acidy as it sounds. Acidy enough to gradually dissolve away the protective shells of the shellfish noted above, as well as sea urchins and - SO much more scary - certain microscopic plankton that provide energy for practically every food chain in the ocean. Seriously, Washington and Oregon, which used to provide up to 25% of the U.S. oyster supply, have had to shutter their entire oyster industry because the water off those shores has become so acidic, baby oysters no longer survive seeding. And while doing without seafood may seem like little more than an inconvenience in a country like the U.S., where we have plenty of cows and pigs to make up any protein deficits, I assure you that this is a HUGE deal in island nations such as Japan, Indonesia and the Phillipines, that rely on seafood to feed their populations.
- Chestnut trees. I'm using chestnut trees as a placeholder for all the tree species at risk of extinction, because it's hard to think of a single tree species that we humans aren't exploiting for some purpose - as wood, as charcoal, as a source of food, as a source of medicinal compounds. The causes of extinction are multitudinous - invasive species, climate change, deforestation - but the results are universal: less food for humans and animals, less biodiversity (think of biodiversity as insurance against extreme natural disasters), and fewer resources to create jobs and fulfill basic needs. Also, do we really want to live in a world where "chestnuts roasting on an open fire" is no longer a "thing"?
- Dolphins & porpoises (also gorillas & monkeys). In most of the above cases, the argument for saving the organism has been food-based - either they themselves are an important food source, or they facilitate the survival of a food source. In this instance, however, I'm going to go just a little bit PETA on y'all and argue that allowing the extinction of one of the few other sentient species on earth is morally wrong: akin, one might argue, to genocide. Though scientists may not yet fully comprehend the extent of their intelligence, few doubts remain that these species have achieved consciousness (look it up), which philosophers have long identified as the true measure of "human-ness." For instance, scientists may quibble over whether Koko the gorilla truly understands 1000 words in ALS, but few now dispute that she demonstrates consciousness and language use equivalent to a small human child. Seriously - for her last birthday, she requested (and received) a kitten to keep as a pet; tell me that's not adorable. Now think of that as farmers and fishermen continue to slaughter these creatures for meat, or simply for convenience. Or, as my notably more blunt husband would undoubtedly shout if he knew I was typing this, repeat after me: "Soylent Green is People! Soylent Green is People!"
- Coral reefs. In this case I'll be appealing to your stomach, your conscience, and your aesthetic sense. Because, seriously, is there anything more wonderous in nature than a thriving coral reef? The colors, the biodiversity (25% of all ocean species live in reefs), the intricately linked chains of interdependence! (Also, Nemo & Dory live there!) Alas, climate change has already bleached 100s of miles of coral reef, with no end in sight. Turns out coral are fragile creatures who can't handle even tiny changes in ocean pH (being caused by ocean acidification) or temperature (being caused by global warming). A recent ABC News report cited estimates that 25% of coral reefs are already dead, and predicts that the rest could be gone within the next 20 years. Grim news for the millions of people on earth who rely on coral reefs for food, who rely on reef tourism to generate money for food, or who's bucket lists include "dive the Great Barrier Reef."