With their long tusks, elephants look elegant and strong. However, this unique feature is also the reason for     1     the animal is endangered. It has long been a problem worldwide that people kill elephants     2     their tusks.     3     laws have been introduced to ban the selling of tusks, they have not been enough to save the elephants.

The balance between humans and nature is crucial for the sustainability (可持续发展) of our planet. As humans, we are a part of nature and rely on it for our survival. However, in recent years, our action s have caused a significant disruption (扰乱) to this balance.

4 . As biologist Nicola Foster and her colleagues guided a remote-controlled monitor through the coral reefs (珊瑚礁) of the Indian Ocean’s Chagos Archipelago, they saw corals full of color near the surface. But nearly 300 feet below, in the darker and colder waters of what oceanographers call the “twilight zone,” some corals had turned terrible white, leaving them vulnerable (脆弱的) to disease and death.

“It wasn’t something we were expecting to see,” says Foster, who studies deeperwater coral ecosystems called mesophotic reefs. Mesophotic reefs would seem to be protected from rising sea-surface temperatures that white n higher-up corals. But this team’s 2019 observations show the deepest instance of bleaching (变白) ever recorded — suggesting similar reefs are more vulnerable than previously believed.

Bleaching often happens when warming water boosts corals to remove the colorful algae (水藻) that live in their tissues and help to sustain them. Although surface waters weren’t typically warm when Foster and her team took their measurements, the twilight zone waters neared 84 degrees Fahrenheit (华氏度) — far above the 68-to 75-degree range in which mesophotic corals are used to.

The researchers realized that bleaching is related to the timing of the Indian Ocean Dipole. This phenomenon shifts the region’s surface winds and ocean currents, says study co-author Phil Hosegood. Wind and waves shake the upper ocean, keeping it relatively warm and uniform in temperature. But the 2019 dipole deepened this well-mixed upper layer; the thermocline (the slice of ocean that separates warm upper waters from the cold depths) had become deeper than normal. Then, those corals were exposed to temperatures that are normally found at the surface.

This observation suggests mesophotic reefs elsewhere could also be bleaching. Fortunately, the corals in this study had largely recovered their color by 2022, Foster notes. But each bleaching stresses the corals and, if extended, can starve them. Future Indian Ocean Dipole patterns are likely to be more severe, Hosegood says, noting that data suggest “that these natural cycles are becoming increased with climate change.”

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5 . Around the world, coral reefs (珊瑚礁) are in danger. Now, let’s check out a few ways conservationists are protecting these habitats.

Seaweed Smackdown

Hot ocean temperatures can supercharge seaweed growth — and that’s not good for a reef. So, in Hawaii, scientists have used an underwater vacuum (真空吸器) to suck up lots of seaweed into the device’s long tube. In Australia, scientists are studying a low-tech solution: pulling seaweed by hand.

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Some polyps (珊瑚虫) are harmed by heat waves and pollution. Scientists cut parts of coral from a healthy reef. Then these polyps are taken to a nursery, which could be in shallow protected areas underwater. After about a year, the healthy coral parts are attached to damaged reefs. The nursery-grown corals can bring new life to a struggling habitat.

Sound Saver

Healthy reefs are noisy. Fish make different sounds, and thousands of shrimp create and pop bubbles with their claws to create a sound. The biologists play sounds of healthy reefs through underwater speakers. They found that six weeks of broadcasting healthy reef sounds doubled the amount of fish in the area.

Bleaching Killer

One of the biggest threats to coral reefs is bleaching. Here’s how it works.

Biologists have discovered that many corals in the Red Sea have a species of algae in their tissue that’s found nowhere else, so they can survive heat waves. Biologists hope their work will inspire governments and environmental groups to protect these corals.

6 . A shopkeeper’s son breaks a window, causing a crowd to gather. They tell the shopkeeper not to be angry: actually, the broken window is a reason to celebrate, since it will create work for the glazier (装玻璃的工人). In the story, written by a 19th-century economist, the crowd envisions the work involved in repairing the window, but not that   involved in everything else on which the shopkeeper could have spent his money — unseen possibilities that would have brought him greater happiness.

If that window were to be broken these days, people might have a different reaction, especially if they were NIMBYs (Not In My Back Yard) who oppose any local construction that affects their quality of life. Their concern might be with the “embodied carbon”. The production of a piece of glass would carry a sizeable carbon cost. Similarly, the bricks and concrete in a building are relics of past emissions. They are, the logic goes, embodied carbon.

Conserving what already exists, rather than adding to the building stock, will avoid increasing these embodied emissions — or so NIMBYs often suggest. At its worst, this idea is based on a warped logic. Greenhouse gases released by the construction of an existing building will heat the planet whether the building is repaired or knocked down. The emissions have been taken out of the world’s “carbon budget”, so treating them as anew debit means double counting. The right question to ask is whether it is worth using the remaining carbon budget to repair a building or it is better to knock it down.

Choosing between these possibilities requires thinking about the unseen. It used to be said that construction emitted two types of emissions. Besides the embodied sort, there were operational ones from cooling, heating and providing electricity to residents. Around the world, buildings account for 39% of annual emissions, according to the World Green Building Council, of which 28% come from operational carbon.

These two types of emissions might be enough for the architects designing an individual building. But when it comes to broader questions, economists ought also to consider how the placement of buildings affects the manner in which people work, shop and travel. Density (密度) lowers the per-person cost of public transport, and this reduces car use. Research by Green Alliance, a pressure group, suggests that in Britain a policy of “demolish (拆除) and densify” — replacing semi-detached housing near public transport with blocks of flats — would save substantial emissions. Without such demolition, potential residents would typically have to move to the suburbs instead, saving money on rent but consuming more energy.

Targeted subsidies (补贴), especially for research and development into construction materials, could speed up the pace at which the built environment decarbonises. What will never work, however, is allowing the loudest voices to decide how to use land and ignoring the carbon emissions of their would-be neighbours once they are out of sight.

9 . Time is one of humanity’s greatest blind spots. We experience it as days, months or years. But nature functions on much grander scales, measured in centuries, and even longer phases often grouped as “deep time.” Humanity’s shortsightedness around time creates major limits on modern conservation. As the climate and biodiversity crises accelerate, we are urgently working to protect and regenerate ecosystems without understanding how they functioned when they were truly doing well. A deep time perspective can help change that.

Take forest management. For decades, our practices called for all-out prevention of even the mildest forest fires, believing that fire was bad for both people and nonhuman nature. Until recently we ignored the forest management strategies indigenous (土著的) communities had successfully used for centuries, in particular the application of small-scale controlled burns. Fire, it turns out, has always been an integral ingredient in healthy forest ecosystems, promoting new growth by thinning the understory. Today, we’re beginning to see widespread application of indigenous knowledge to forest management, tapping into this ancient wisdom.

But how can we know what an ecosystem looked like centuries ago? One pathway is through modern mathematical modeling. We have married it with streams of long-term data and discovered a possible way to preserve the ecosystem of California’s kelp forest. By examining how North Pacific kelp forests existed long before the 19th century, we found that we’ve ignored the presence of a keystone species—the Steller’s sea cow, and its role in maintaining the harmony of this ecosystem.

Our model described the interactions between giant kelp and understory algae competing for light and space on the seafloor. Then we ran the model again, but this time with the Steller’s sea cow added in. These mammals fed on the leaves from the upper kelp layers. This allowed light to reach the sea bottom, which in turn stimulated the growth of not only the kelp but other kinds of organisms. In re-creating that vanished historical system that included the Steller’s sea cow, we could see a more diverse forestwhere the understory competed better with kelp

In short, what we assume we know about an ecosystem based on the recent past may impede our ability to fully understand and protect it. To ensure that our boldest conservation efforts are successful, we must begin looking at time as an essential tool.

The first pairs of jeans were designed for blue-collar workers. Over the course of the 20th century, the working-class pants have transformed into fashion icons and become popular around the world. However, each new pair you buy has a much higher cost than you might think.

Every pair of jeans takes about 0.7 kilograms of cotton. Growing this much cotton requires roughly 10,000 liters of water, not to mention various herbicides and pesticides, which can pollute groundwater. Typically, plastic fibers are mixed with cotton threads to increase comfort and flexibility. In order to dye the cloth, chemical sprays and several cycles of acid-washing are adopted, discharging toxic pollutants into rivers and even turn them into indigo-blue. Also, there are the zippers, buttons, and rivets made of copper and other metals, whose mining is yet another source of environmental degradation. All in all, the manufacturing (制造) process for a single pair of jeans emits over 33 kilograms of carbon — the equivalent of driving over 110 kilometers.

Like many globally produced products, jeans are made in poor countries and bought in rich ones. Much of the world’s cotton is grown in developing countries, with poor labor practices and few protections for workers. Cotton here is often picked by children or forced labor. And their health may be threatened by poisonous chemicals during production. Because of the fast-paced and rough manufacturing with unnatural materials, today, most pairs last no longer than a year. Like most waste, discarded jeans end up in landfills, where their decomposition releases greenhouse gas. Some governments are pursuing policies to make companies more responsible for worker pay and welfare, but unsustainable practices still run crazy throughout the fashion industry.