2 . THE GLOBAL WASTE TRADE IS ESSENTIALLY BROKEN

Cut into hillside in northern Malaysia stands a large, open-air warehouse. This is a recycling factory, which opened last November. On a very hot afternoon in January, Shahid Ali was working his very first week on the job. He stood knee-deep in soggy, white bits of plastic. Around him, more bits floated of the conveyor belt and fell to the ground like snowflakes.

Hour after hour, Ali sorts through the plastic jumble moving down the belt, picking out pieces that look off-color or soiled-rejects (废品) in the recycling process. Though it looks like backbreaking work, Ali says it is a great improvement over his previous job, folding bed-sheets in a nearby textile factory, for much lower pay. Now, if he eats simply, he can save money from his wages of just over $l an hour and send $250 a month to his parents and six brothers and sisters in Peshawar, Pakistan, 2,700 miles away, “As soon as I heard about this work, I asked for a job,” says Ali, 24, a bearded man with glasses and an easy smile. Still, he’s working 12 hours a day, seven days a week. “If I take a day off, I lose a day’s wages,” he says.

In the warehouse, hundreds of bags are stacked more than 60 feet high-each stuffed with plastic wrappers and bags thrown away weeks earlier by their original users in California. The fact that the waste has traveled to this distant corner of the planet in the first place shows how badly the global recycling economy has failed to keep pace with humanity’s plastics addiction. This is an ecosystem that is deeply dysfunctional, if not on the point of collapse: About 90% of the millions of tons of plastic the world produces every year will eventually end up not recycled, but burned, buried, or dumped.

Plastic recycling enjoys ever-wider support among consumers: Putting yogurt containers and juice bottles in a blue bin is an eco-friendly act of faith in millions of households. But faith goes only so far. The tidal wave of plastic items that enters the recycling stream each year is increasingly likely to fall right back out again, casualties of a broken market. Many products that consumers believe (and industries claim) are “recyclable" are in reality not, because of hard economics. With oil and gas prices near 20-year lows, so-called virgin plastic, a product of petroleum feed-stocks, is now far cheaper and easier to obtain than recycled material. That unforeseen shift has yanked the financial rug out from under what was until recently a practical recycling industry. “The global waste trade is essentially broken,” says the head of the global plastics campaign at Greenpeace. “We are sitting on vast amounts of plastic with nowhere to send it and nothing to do with it.”

4 . Urban agriculture, the practice of farming within the restrictions of a city, is becoming increasingly popular and is viewed as a sustainable alternative to big industrial farms. By some estimates, between 20% and 30% of the global urban population engages in some form of urban agriculture. But until recently, its carbon footprint remains understudied.

Using data from 73 low-tech city farms, community gardens and personal plots of land, Newell and his team compared the average carbon emissions of food produced at low-tech urban agriculture sites to those of conventionally grown crops. The team found that because of urban gardens’ relatively low yields, along with the energy used in constructing the planting beds, big-city spuds (马铃薯) were significantly more carbon-intensive than commercially grown ones. This held true even when the researchers factored in emissions from transporting commercially grown produce to often distant grocery stores. That doesn’t mean that growing vegetables in big cities is totally bad, however. “Urban farming is great, ” if imperfect, says Carola Grebitus, a food choice expert. It can be a powerful tool for job creation and education, she says, and a good way to introduce fresh produce to urban “food deserts” where healthy fruits and vegetables are hard to come by. Community gardens can also provide a place to connect with nature, and the added green space can reduce the risks of heat and flooding.

Conscious of these benefits, Newell’s team highlighted several ways to make urban agriculture more sustainable. One option is to be selective about what crops are grown. For instance, tomatoes grown in the soil of open-air urban plots had a lower carbon intensity than tomatoes grown in conventional greenhouses. Another strategy is to rely on existing constructions. Include old structures into a new garden’s design instead of taking down old buildings. Finally, take the local climate, water quality and soil into account. Growing plants that are ill-suited to an area requires more water, energy and pesticides (杀虫剂), all of which affect the environment.

5 . Common water plant could provide a green energy source. Scientists have figured out how to get large amounts of oil from duckweed, one of nature’s fastest-growing water plants. Transferring such plant oil into biodiesel (生物柴油) for transportation and heating could be a big part of a more sustainable future.

For a new study, researchers genetically engineered duckweed plants to produce seven times more oil per acre than soybeans. John Shanklin, a biochemist says further research could double the engineered duckweed’s oil output in the next few years.

Unlike fossil fuels, which form underground, biofuels can be refreshed faster than they are used. Fuels made from new and used vegetable oils, animal fat and seaweed can have a lower carbon footprint than fossil fuels do, but there has been a recent negative view against them. This is partly because so many crops now go into energy production rather than food; biofuels take up more than 100 million acres of the world’s agricultural land.

Duckweed, common on every continent but Antarctica, is among the world’s most productive plants, and the researchers suggest it could be a game-changing renewable energy source for three key reasons. First, it grows readily in water, so it wouldn’t compete with food crops for agricultural land. Second, duckweed can grow fast in agricultural pollution released into the water. Third, Shanklin and his team found a way to avoid a major biotechnological barrier: For the new study, Shanklin says, the researchers added an oil-producing gene, “turning it on like a light switch”by introducing a particular molecule (分子) only when the plant had finished growing. Shanklin says, “If it replicates (复制) in other species-and there’s no reason to think that it would not — this can solve one of our biggest issues, which is how we can make more oil in more plants without negatively affecting growth.”

To expand production to industrial levels, scientists will need to design and produce large-scale bases for growing engineered plants and obtaining oil — a challenge, Shanklin says, because duckweed is a non-mainstream crop without much existing infrastructure (基础设施).

10 . The Yurok people have lived along the Klamath River, which flows from the Cascades in Oregon southwest through Northern California, for thousands of years, protecting the region and river from which they — and others — draw sustenance (生计).

But as development and pollution continue to reduce the number of fish in the river and the quantity and quality of its waters, the Yurok Tribe is legalizing (合法化) the tribe’s longstanding care by granting the Rights of Personhood to the Klamath, the first river in North America to have such rights declared.

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