1 . People have come to understand the enormous impacts-beneficial as well as harmful- plastics have on human lives and the environment. As polymer (聚合物) scientists committed to inventing sustainable solutions for real-world problems, we set out to tackle the issue of plastic waste by rethinking the way polymers are designed so we could make plastics with recyclability built right in.

Everyday items including milk jug, grocery bags, and takeout containers are made from a class of polymers called polyolefins. These plastics are really durable (耐用的) because the chemical bonds in those polymers are extremely stable. In a world set up for disposable (一次性的) items, durability is no longer a design feature but rather a design drawback. Imagine if half the plastics used today were recyclable through twice as many processes as they are now. Also conventional recycling requires careful sorting of all the collected materials, which can be challenging with so many different plastics. For example, separating paper from metal doesn’t require complex technology, but sorting a container from a milk jug of a different polyolefin is difficult to do without the occasional mistake.

In a study published in Science in October 2023, we described a series of polymers with only two building blocks-one soft polymer and one hard polymer-that behave like polyolefins but could be chemically recycled. Connecting two different polymers multiple times until they form a single, long molecule (分子) creates what’s called a multiblock polymer. By changing how much of each polymer type goes into the multiblock polymer, our team produced a wide range of materials with properties that covered all polyolefin types.

Using the same strategy but by adding hydrogen, we could disconnect the polymers back into their building blocks and easily separate them to use again. When we made new polymers out of these recycled plastics, they performed just as well as the original materials even after several rounds of chemical recycling. So we were able to create materials with similar properties of the plastics the world relies on. We believe this work is a step toward more sustainable plastics.

2 . Tima Abudhi is a 55-year-old mother of five. When growing up, she remembers watching her neighbors _________ at the mangrove forests (红树林) around her village on Pate Island, on Kenya’s east coast, to build houses or to sell as wood.

As the mangroves _________, so did the fish that live among their roots --- a _________ for the fishing village of Kizingitini. The threat to their livelihoods and homes _________ Abudhi and other women to start replanting the mangroves, often spending all day at the _________, taking time away from caring for their families and _________ their small businesses. Protecting the mangroves over the past few decades has _________ their incomes, but they felt it was a matter of urgency, Abudhi said.

“Replanting the mangroves is not _________. We have to go early in the morning to get the seedlings (幼苗) and then come to the beach and plant them until evening, just before the tides _________ again. We couldn't make __________ time for our businesses,” she said.

Today, the women of Kizingitini no longer have to __________ to both make a living and conserve the mangroves, thanks to a loan scheme that helps them keep food on the table so they can __________ to continue planting. “This has led to increased __________ of women in conservation and community development, as well as reduced __________ inequality,” said Abudhi.

Mangrove forests can __________ flooding and are considered key to controlling climate change and protecting people against warming-linked disasters.

3 . Every year, as the surface water temperature off the United States mid-Atlantic coast rises steadily from late spring through the summer, a pocket of uncharacteristically cool and crisp water gets trapped at the bottom of the ocean. Packed with nutrients this thick band of cold water, known as the mid-Atlantic cold pool, is a vital home for shellfish species. Extending at its seasonal peak from Nantucket, Massachusetts, to Cape Hatteras, North Carolina, the cold poll creates a diverse ecosystem ranging from algae(海藻)to fish — and some of the most valuable shellfish fisheries in the United States.

Now, however, two pressures have scientists worrying about whether the cold pool will last. The first is no surprise: climate change. Over the past five decades, climates change has destabilized the cold pool, causing it to warm and shrink. Compared with 1968, the cold pool is now 13℃ warmer and has lost more than one-third of its area.

The second concern is 1ess certain. In 2023, the US federal government approved plans to install(安装)98 wind turbines(涡轮机)off the New Jersey coast, covering an area of more than 300 square kilometers. Yet putting so many turbines to the seafloor could have unexpected consequences for the cold pool. That’s why Travis Miles, a researcher at New Jersey’s Rutgers University, and his colleagues are investigating. So far, Miles and his colleagues can’t definitively say what will happen to the cold pool, saying more research is needed to assess how climate change and offshore wind, together, could affect the cold pool. However, their initial analyses suggest the cold pool should be fine — at least in normal conditions.

New Jersey’s offshore wind plans are strongly opposed mainly by fossil fuel-industry funded efforts. Miles worries that an overabundance of caution or fear of potential impacts, including on the cold pool, might slow down the development of renewable energy. “...it’s quite clear that climate change is far more damaging than installing wind farms,” he says. “I don’t think any scientist would argue with that.”

4 . Like many of the Indigenous (土著的) communities across the Australian continent, the remote communities in north-west New South Wales are struggling. Many of the 300 or so residents rely on welfare. Higher electricity bills—up to $3,000 a quarter for some households—further worsen the poverty. They’re always at the end of the power line, so the service that is there is quite extraordinary in terms of cost. It’s a real problem that needs to be fixed.

To that end, Anderson and other Indigenous leaders have formed the First Nations Renewable Energy Alliance (FREA) to push for renewable energy in Indigenous communities. They partner with private enterprise to support Indigenous communities looking to switch to renewable energy.

“We can build a power station where the community exists,” Anderson says, “so people are able to successfully live in the environment the way they want to live and have access to power which enables them to better determine their economic future.”

Only a handful of Indigenous communities have set up renewable energy projects in Australia. The Indigenous-owned and -operated company AllGrid Energy, for instance, has installed solar panels and battery storage systems to replace diesel (柴油) generators in the communities of Ngurrara and Kurnturlpara in the Northern Territory’s Barkly Tableland. Within two months of the system being installed in May 2016, people were moving back to their homelands, the communities growing from just two permanent residents to about 40.

But FREA will go one step further, working with community leaders and acting as a conduit (纽带) between the communities and the businesses they are dealing with. This is essential, says Anderson, to avoid predatory (吞并) practices they have seen in the past, with companies “playing on the psychology of poverty” to gain advantage. The FREA has drafted terms of agreements that will guide how companies engage with Indigenous communities for renewable energy projects.

One of the next steps for FREA will be to identify a community that can act as a test case for a renewables project. “Our experience is that if we can make it work for one community, it will work in every other community,” Anderson says.

5 . Whenever I order food for delivery, I play a little game to guess how many sets of tableware(餐具)the restaurant will provide with my meal. Sometimes restaurants will throw in two, three or four sets for just one order. But I rarely need any tableware at all, and the waste goes into the trash or collects dust in a kitchen drawer.

Researchers working with Chinese technology group Alibaba tried a simple approach to this problem. Instead of just wastefully doling out tableware, the company required food-delivery customers in some cities in China to pick how many sets of tableware they wanted to receive.The default (默认设置)was set at zero. The result, published today in the journal Science, was a 638% increase in the share of no-tableware orders. If applied across China, researchers found, the approach would save nearly 22 billion sets of plastic tableware. The study doesn’t cover carbon emissions, but it’s safe to say that the impact would be significant. It struck me as a useful reminder of the many low-hanging fruits across the economy that can cut waste, and emissions.

Nudging its customers cost Alibaba nothing more than a few hours of software engineering time and the impact it brought was immense. The concept of nudging comes from the field of behavioral economics known as nudge theory. It suggests that a slight action can encourage good human behavior without the need for policies that limit choice or economic punishment that raises the cost of bad behavior. To nudge customers to eat better, for example, a restaurant might organize its menu by listing healthy options first and bury unhealthy ones at the bottom. More recently, some big companies like Google have also begun to use nudges to advance climate objectives.

Behavioral economics broadly, and nudges more specifically, aren’t without controversy. Some might think it assigns consumers responsibility for addressing environmental challenges. But there is another way to look at it. In the absence of necessary policy—and policy is needed一companies can help encourage a widespread shift of consumer behavior.

And all of that behavioral change can add up. The International Energy Agency found in 2021 that small behavioral changes in energy consumption such as walking instead of driving and adjusting the thermostat could in total shave off 4% of global emissions. The more that companies can do to facilitate such changes, the better.

7 . In the rich countries of the West, the electric vehicle revolution is well underway. Climate-conscious consumers drive Teslas or Polestars for reasons of morality and fashion. Poorer countries are also experiencing a wave of electrified trend. In Bangladesh, electric three-wheeler taxis, known as tuk-tuks, are rapidly replacing gas-powered ones on the streets. Such electric vehicles are climate friendly, cost effective, and help reduce air pollution.

Yet a glance under the hood (引擎盖) of these vehicles reveals a poisonous secret: each tuk-tuk runs on five massive lead-acid batteries, containing almost 300 pounds of lead in total. Every year and a half or so, when those batteries need to be replaced and recycled, about 60 pounds of lead leak into the environment. Battery recycling, often at small-scale unregulated factories, is a highly profitable but deadly business.

Lead is dangerous, and any exposure to it is harmful to human health. Lead that has entered the environment hurts people on an extraordinary scale. The numerous ways lead enters air, water, soil, and homes across the developing world — and the enormous damage it does to human health, wealth, and welfare — causes one of the biggest environmental crises in the world yet receives little attention.

The World Bank estimates that lead kills 5. 5 million people per year, which would make it a bigger global killer than AIDS, malaria, diabetes, and road traffic deaths combined. On top of the shocking deaths, the social burden of lead poisoning is extraordinary, as is its contribution to global inequality — our research on the cognitive effects of lead poisoning suggests that it may explain about one-fifth of the educational achievement gap between rich and poor countries.

But unlike many challenges faced by developing countries, lead poisoning is a problem that is fixable with some attention and a relatively modest financial investment. Better monitoring, research, and rules can help protect children all over the world from the dreadful effects of lead poisoning and reduce the massive global costs it brings.

8 . Watford and her family have lived in Curtis Bay, Baltimore for generations. Her community has faced environmental injustice. Heavy industries continued to move in her community. As a result, her neighbors have had to live with serious respiratory (呼吸的) problems.

When she knew a plan to build the nation’s largest trash-burning incinerator (焚化炉) less than a mile away from her high school, she realized she had to take action. The incinerator was being sold wrongly as clean, renewable energy equipment but actually it would be a source of brain-damaging chemicals and would release 200 million tons of greenhouse gases per year, both worse than coal burning. Watford felt she had a responsibility to warn her community to work together to shut this plant down.

She co-founded Free Your Voice (FYV), a 10-person student organization devoted to community rights and social justice. Together, they decided to start a campaign to take down Energy Answers, the incinerator’s developer. They went door-to-door talking to neighbors and organizing protests.

When it was discovered that Baltimore City Public Schools (BCPS) was going to be a customer of Energy Answers, the organization fought with the board and presented their case, urging BCPS to withdraw from the project. BCPS was convinced to cancel their contract, which in turn inspired 22 other customers to do the same. Without any financial gain, Energy Answers had no market to move forward with its plan.

Watford continues to work with Curtis Bay residents toward fair development. They have a vision for the future which includes building a zero-waste movement, a solar farm, and green jobs. She wants the entire human family to join the fight for environmental justice because survival as a species depends on our ability to take action.