Why Walmart is eliminating single-use bags in some states but not others

You might be surprised to learn just how much of our world is shaped by animals doing unremarkable things like scratching, digging, eating, and pooping. Especially pooping. These activities are the first in a chain of events that result in highly complex, biodiverse ecosystems.

Certain species, because of their unique skills, food choices, or even size, are ecosystem linchpins—remove them from the equation, and an ecosystem collapses. Without mussels, you might not have clean drinking water. Without forest elephants, atmospheric carbon dioxide would skyrocket. And if you think an otter's appetite for sea urchin doesn't impact your life, think again.

In a world where nature works in concert to stay balanced, human-driven climate change is like a counterweight dropped from the top of a building, threatening more than 1 million species around the world. Humans are responsible for altering nearly 100% of Earth's land-based ecosystems, according to a 2021 study published in Frontiers in Forests and Global Change.

These changes are detrimental to ecosystems on which humankind relies. Now, animals like the beaver, which are all too easy to write off as unexceptional or unimportant from our own perspective, may be among our best hope for climate salvation.

Stacker compiled a list of 10 animals from diverse environments, outlining how each helps sustain its ecosystem.

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Beavers are revered as nature's civil engineers, a species capable of altering entire ecosystems with the dams they build. Beavers dam up moving water to create a pond where they take up residence. Upon meeting the obstruction, running water on the opposite side of the dam is diverted to the surrounding land, creating wetlands and attracting new flora and fauna to that ecosystem. While some people, especially farmers, might understandably view this freelance construction as a nuisance, it can be lifesaving in drought-prone areas.

Dams prevent water sources from running too thin and drying up completely. Wetlands created by the overflow quench dry lands that would otherwise be at risk of wildfires. They are so effective at climate-driven drought mitigation that the California Department of Fish and Wildlife has earmarked $3 million for North American beaver habitat restoration so that they may, in turn, cause more good trouble.

Freshwater mussels act as tiny water treatment plants filtering out pollutants like algae and bacteria from rivers and streams. A mussel bed the size of two football fields can filter up to 10 million gallons of water daily—and research in Alaska demonstrates that they do, in fact, get that big. This service keeps their freshwater cohabitants healthy. Mussels themselves can also serve as aquatic ecosystems. When embedded together on the floor of rivers, streams, or lakes, they create a physical structure where good algae can flourish, and fish can feed. As water temperatures rise due to climate change, 70% of all mussels in the U.S. are at serious risk of extinction. Without freshwater mussels, humans and animals would face river pollution and significant changes to freshwater ecosystems.

Sea otters are so much more than cute faces and clownish dispositions. They are essential to protecting coastal kelp forests. Adult sea otters eat up to 30% of their body weight (or 25 pounds) each day, feasting on abalone, crabs, clams, and, most importantly, sea urchins. Without sea otters to keep their population in check, urchins can decimate kelp forests, eliminating an underwater ecosystem that is an essential store of carbon dioxide where many other marine species thrive. Coastal ecosystems such as kelp forests remove carbon dioxide from the atmosphere through photosynthesis and store roughly 20 times more carbon per acre than terrestrial forests. Without sea otters, there would be no kelp; without kelp, carbon sequestration would plummet.

Armadillos perform a variety of important ecological functions such as pest control, seed dispersal, and even protection for other species. Like the beaver, the giant armadillo of South America is an ecosystem engineer. The extensive burrows they dig for refuge and bug hunting are utilized by dozens of other species for warmth, foraging, and protection from predators. Even the piles of sand and dirt displaced by armadillos in their burrow excavations are put to use by other species as places to rest or sunbathe. These smaller ecosystems and the biodiversity they bring are integral to the overall health of the larger one in which they exist.

Hornbills are frugivores, a species with a diet composed almost exclusively of raw fruit. Some species of hornbills grow to have a 6-foot wingspan. Their size relative to other fruit-eating birds makes them the perfect propagator of plants that bear large fruit. Without the hornbill, orchards of Canarium and Phoebe would not exist. They spread undamaged seeds through their excrement over vast distances as they fly, earning them the moniker of "farmer of the forest." A study published in the Journal of Avian Biology found that hornbill populations can disperse nearly 13,000 seeds per day over an area the size of 184 football fields. Their dispersal fosters ecological prosperity and diversity in tropical forests.

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These giant forest dwellers protect their environment by destroying it—to a degree. As these massive creatures move through dense rainforests, they trample and graze on small trees and thin the vegetation that competes for resources like sunlight and water. Field researchers in the Congo Basin discovered that where forest elephants existed, trees were larger and denser. These kinds of trees are critical to the environment because they store large amounts of carbon. If forest elephants were to vanish tomorrow, 3 billion tons of carbon dioxide would be released—the equivalent output of more than 646,000 gas-powered vehicles over one year, or over 7 trillion miles driven by such vehicles. Forest elephants also help to disperse seeds throughout the forest through their excrement.

Bison are essential to maintaining the biodiversity of America's grasslands; they do this primarily by eating. Bison create the opportunity for new flora to grow by feeding almost exclusively on grasses that outcompete most other plants for space. Their presence on grasslands doubles plant diversity, according to Konza Prairie Biological Station data. The biodiversity of plant species makes ecosystems more resistant to drought. These regions are rebounding after the species was hunted nearly to extinction by the late 1800s, slaughtered for profit, sport, and as a means to inflict harm on Native Americans who depended on bison. Bison parts could be transformed into 150 different items—including food, clothing, tools, and weapons—that were essential to Native American survival on the Great Plains.

They also shape their environment by scratching. Yes, scratching. Fully-grown male bison can weigh up to 2,000 pounds; adult females can weigh up to 1,200 pounds. When they wallow, or roll on the ground to scratch an itch, their powerful bodies create depressions in the earth. These depressions create a buffer—a bunker of sorts—from the wide open plain where plant and animal species are more guarded from threats.

As climate change shortens the length and intensity of winter, gray wolves are mitigating the impacts on scavenger species like bears, coyotes, and certain large birds by increasing their food supply. Milder winters mean an increased survival rate for prey like elk due to lower metabolic exertion and fewer winter stressors, according to findings from a University of California at Berkeley study. Less snow means they won't perish from exhaustion and earlier melt means easier access to food sources. Wolves provide balance by hunting elk and leaving their remains for scavenger species to feed upon.

The world's only scaly mammal, pangolins are integral to maintaining healthy forests by dining on termites. While termites actually help maintain a healthy ecosystem by consuming dead wood and turning it into nutrient-rich organic matter called humus, an unchecked population can overrun a forest. A single pangolin can protect about 31 football fields' worth of forest from termite damage. Pangolins also keep soil healthy and aerated by digging burrows, which aids in decomposition and vegetative regrowth.

Pangolins have been hunted nearly to extinction due to myths about the medicinal and magical properties of their blood and scales, which are made of material similar to our hair and fingernails and bear no benefit to humans. In some regions of Asia, pangolin meat is a delicacy; in Africa, it is sold as bushmeat. These creatures faced additional persecution when they were erroneously named as a possible source of COVID-19. 

Like other heroes on this list, tapirs are frugivores. Seeds from food sources move through their digestive tract and are eventually discarded along the forest floor in their nutrient-rich waste. In this way, frugivores are essential to restoring degraded environments and increasing carbon storage. Tapirs actually prefer to feed in these degraded settings. So, by simply performing everyday functions like eating and defecating, the tapir is helping to seed and restore large swaths of its South American rainforest habitats that have been disturbed by fires and deforestation.

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Plastics are convenient for packaging, but can have detrimental effects on the environment and human health. In 2021, an estimated 583 billion plastic bottles were produced, totaling 100 billion more than in 2017. The practice of reusing items can have a positive impact on the environment because it helps to reduce air, land, and water pollution.

Plastic was first created in the 1800s and proved beneficial to manufacturers in various aspects including medicine and design solutions, and was more affordable than other materials. After World War II, the U.S. introduced the mass production of plastic. The 1950s to 1970s saw small amounts of the material being used in packaging or shopping bags, so plastic debris was more manageable during those times. From the 1970s to the 1990s, plastic waste tripled. By 1985, 75% of supermarkets provided plastic bags to their customers. By the early 2000s, even more plastic was produced.

Since the emergence of the COVID-19 pandemic, single-use plastics have increased globally due to takeout food orders. Even with recent efforts to combat these concerning trends, plastics by the millions of tons are finding their way into oceans. The Mississippi River—where plastic waste is carried to the ocean—serves as the drainage system for 40% of the U.S. A large amount of global waste is disposed of in landfills, streams, and oceans—which also negatively affects aquatic animals.

There's been varied discussions on whether reusable is "better" than the single-use alternatives. Factors such as how often an item is reused, as well as how it's refilled and cleaned all play a role in the environmental impact.

The Rounds compiled facts and statistics from environmental groups, government agencies, and news sources to understand how adopting different reusable products can impact consumers and the environment.

In 2018, close to a million plastic bottles were purchased every minute. For non-sparkling, one-time-use bottled water, it costs costs $1.17 on average. Switching to a refillable bottle would eliminate the use of 62 plastic bottles annually for each person worldwide, saving them $72 every year, and also cut down on the 40 billion plastic bottles used around the world each month.

The practice of using a refillable water bottle (not plastic) helps to reduce plastic accumulation in landfills, oceans, and streams. Plastic water bottles also contain a synthetic chemical, Bisphenol A (BPA), which has been linked to reproductive issues, as it mimics the hormone estrogen. This can change genes in the body, hormone concentration, and the function of the body's enzymes.

Based on data gathered from straw manufacturers across the country, environmentalist Milo Cress reported in his research that Americans use 500 million drinking straws daily. The Be Straw Free Campaign further expanded on the research and found that 1.6 straws per person are used daily in the country.

One way to contribute to reducing the adverse effects plastic has on the environment is opting for metal straws instead. As with many reusable items, consistently using them over time is key to offset the amount of energy it took to make and wash them. Metal straws do not rust and are simple to clean, while plastic straws are usually used once and then discarded. Over time, the costs accumulate for the person using the straws and also for governments who spend a lot of money on landfills.

A common assumption is that reusing the same container is safer for the environment, but here's the real consensus: It depends on how often it gets reused. In addition to cleaning them after each use, reusable containers can require more materials and energy—and can also increase the container's carbon footprint. It's difficult to quantify the amount of plastic that would be saved by switching to reusable food containers, but one survey estimates that about 116 million people bought disposable food storage containers in one month in 2020, so the figure is certainly high. 

Research published in the February 2019 edition of the Journal of Cleaner Production shows that reusable containers have to be used a certain number of times before being considered "eco-friendly." In other words, it's not just about having reusable containers, but remembering to use them on a regular basis.

Americans spend $5.7 billion on paper towels annually. Paper towels tend to be more convenient when it comes to cleaning, because you can use them and throw them away. But the end result is more waste in landfills.

Cloth towels are reusable and more eco-friendly if made from fabrics such as cotton and linen. Microfiber cleaning cloths work well for cleaning but contribute to microplastic pollution, which can have adverse effects on the environment and animals.

According to National Geographic, in 2018, 5.8 billion tampons were purchased in the U.S. alone. In a lifetime, a person who menstruates can use an estimated 5,000 to 15,000 pads and tampons and throw away 400 pounds of menstrual product packaging. The reality is the packaging for many of these products accumulates exorbitant amounts of waste annually and takes several hundred years to decompose.

After facing consumer skepticism about the safety of tampons due to many being produced from chemically bleached cotton, more companies are creating reusable and more eco-friendly menstrual products. In recent years, menstruation products such as reusable period underwear and menstrual cups have emerged in advertisements. For people who use these reusable products, the reasoning is to help reduce waste and cut costs as the products last longer.

Reusable products such as period underwear can cost $35 on average and last a couple of years. Single-use products such as pads and tampons however can cost $159 or more each year. Some concerns about reusable menstrual products have been how to use them correctly and how sanitary they can remain when worn for longer periods.

This story originally appeared on The Rounds and was produced and distributed in partnership with Stacker Studio.