The Sixth Extinction (灭绝)

Extinctions, where entire species are wiped out, are not unusual in our Earth’s history. In fact, over 90 percent of all species that ever lived are now extinct. In the last 500 million years, there have been five times when life on Earth has almost ended. These include the third mass extinction, known as the “Great Dying”, which killed 90% to 96% of all species. And the fifth event, which occurred 66 million years ago, caused the death of the dinosaurs. The reasons for extinctions are varied. According to scientists, they include volcanic eruptions, asteroids (小行星) hitting the Earth from space, changes in sea levels, the decrease of the oxygen content of the sea and global warming. Many scientists say we are now entering the Earth’s sixth mass extinction. This time, human activity will be to blame.

Although it is not unusual for species to die out naturally, the rate at which this is now happening is cause for concern. A 2015 study by scientists who were based at Brown University and Duke University in the US, looked at how quickly species die out due to natural causes, that is, the “background extinction rate”. They found that human activity is causing species to die out 1, 000 times faster than normal. There is a long list of reasons why so many species are dying out: air and water pollution, forests being destroyed, factory farming and overfishing. It is clear that human activity has negatively affected all other species on Earth, including animals and plants.

If a sixth mass extinction occurs, scientists who have studied the issue believe that up to three quarters of all species on Earth could die out. Of course, as we humans depend on so many species for our survival, we would also be at risk of dying out. Our world and our lives depend on the balance in nature between animals and plants. Without forests, we would have no air to breathe and without clean water we would be unable to survive.

Can a sixth extinction be avoided? Experts say that it is not yet too late, if we take action now. If we want to survive, we need to stop destroying the planet that we live on and start to protect it.

Calling for the protection of our environment

World Environment Day, falling on the fifth, June, is around the corner.

7 . You don’t need to travel long distances to find pleasure in nature

The Greek historian Herodotus is said to have made one of the earliest lists of seven wonders of the world. These were man-made structures, including the still mysterious feat of ancient horticulture known as the Hanging Gardens of Babylon. More recent times saw natural alternatives to these marvels of classical architecture proposed: waterfalls, mountains, canyons, reefs.     1    

As environmental consciousness has risen in the west, attitudes to such sightseeing have changed. Yes, it is thrilling to visit remote forests or spot rare species. But travelling to far-flung destinations is carbon-intensive when flights or long road journeys are involved, and conservation can be made more difficult as well as assisted by sightseers. There is a balance to be struck, and ethical governments and businesses around the world try to maximize the benefits while minimizing the harms.     2    

Most of us, in the rich countries where people take most holidays, understand better than ever that there are costs as well as benefits associated with exploring. One of the six pledges proposed by an environmental campaign launched last month, The Jump, is to “holiday local”, taking short-haul flights once every three years and long-haul flights very rarely. Fortunately, the UK’s 15 national parks, 86 areas of outstanding natural beauty （known in Scotland as national scenic areas）, and countless other landscapes that are without formal status, but beloved nonetheless, mean that there is no shortage of special places for domestic nature tourists to visit—while a host of European beauty spots are accessible by rail.

One recent survey found that Windsor Great Park and Kew have become Britain’s most popular attractions, while Covid has created difficulties for indoor spaces which do not apply to outdoor ones.     3     Some companies that formerly ran foreign trips have adapted to the pandemic by taking people to watch dolphins and other marine life off British coasts instead.

    4     Sewage outflows are out of control due to failed water industry regulation. The owners of a popular rewilded estate in West Sussex—Knepp—have warned that plans to build 3,500 homes next to their land would be catastrophic for the species that live there. But as we confront an environmental emergency that grows ever more dangerous, it is essential to cultivate appreciation for the nature that surrounds us. In a small way, holiday outings to watch dragonflies, kingfishers or seals, or be surrounded by trees that are coming into leaf, could help us to focus on what matters.

9 . The rechargeable lithium-ion (锂离子) battery market is worth more than ＄50 billion. Lithium-ion batteries, whose demand continues to go up day by day, are used in a wide range of electronic devices. They are made of four main components, and cathode (阴极) is one of them. The cathode’s active material type is what determines the capacity of a battery.

A recent study, led by Wang Yan, a material scientist of Worcester Polytechnic Institute, finds that lithium-ion batteries made with recycled cathodes work better than those with new cathodes.

“The battery industry is expected to grow sharply in the next decade. This high demand has led companies to go to extremes, like increasing deep-sea mining, to gain access to the minerals used in lithium-ion batteries,” Wang said. “Mining minerals will have environmental impacts. Recycling spent lithium-ion batteries offers a way out.”

But until now, the prospect of using recycled materials in lithium-ion batteries has some manufacturers (制造商) worrying that it could impact performance. Thus, lithium-ion batteries are still not widely recycled. Aware of decreasing resources and environmental impact, Wang and other researchers set out to find a way to make recycling lithium-ion batteries economically practical. Through experiments, they could recover more than 90% of the key metals from spent batteries. These recovered metals became the basis of the new recycled battery’s cathode’s active material.

In tests between Wang’s team’s recycled batteries and brand-new batteries of the same composition, the recycled batteries outperform the new ones in their ability to maintain capacity. It took 11,600 charge cycles for recycled cathode batteries to lose 30 percent of their original capacity. That was about 50 percent better than the 7,600 observed cycles for new cathode batteries, the team reported. Those thousands of extra cycles could translate into years of better battery performance, even after repeated use and recharging.

10 . Concerns about microplastics are not new. They’ve been growing for more than a decade. Over the past two years, however, many creative solutions have emerged to address the problem on a local level. Still, experts say there’s a need for a huge effort if we want to curb (控制) the global issue.

The term microplastics was coined in 2004 by marine ecologist Richard Thompson after he discovered tiny bits of plastic littering British beaches. Since then, scientists have found microplastics nearly everywhere. Even inside us. According to a 2021 study in Environmental Toxicology and Chemistry, the physical presence of plastic inside the body poses a potential problem. Plastic’s chemical additives might also affect different species’ tissues and organs. However, there is disagreement as to how much microplastics harm species, including humans.

For a global view of this vast issue, Duke University scientists created a public database to track plastic removal innovations. For instance, the Hoola One is a vacuum that internally separates microplastics from organic materials. In Amsterdam, scientists have introduced the Bubble Barrier in canals, a device that creates a wall of bubbles to send submerged plastic to the surface. Hong Kong Polytechnic University researchers presented a unique idea — a bacteria biofilm that could attract and trap microplastics before they flow into rivers and oceans.

But “if you have a technology that would capture microplastics before they enter our waterways, that would be ideal,” says Zoie Diana, who added 40 new inventions this year. That’s where Alain Marty, chief scientist at the biochemistry start-up Carbios, comes into the picture. In a 2020 Nature article, Marty and colleagues describe how they engineered an enzyme (酶) to break down plastic efficiently. “Industries could employ that in their manufacturing processes so that nearly all of their material could be reused to create products. Marty’s discovery is a breakthrough in the right direction, though preventing microplastics by reducing our plastic use also matters,” says Diana. “We really want to turn off the tap.”