In 2007, the African Union announced an ambitious project—to plant the Great Green Wall (GGW), a band of trees that would stretch the length of the Sahel.

The GGW is an ecological restoration project designed by African people for African people. Heavy rains, droughts, wildfires and landslides have all become common throughout the world. But nowhere is quite like the Sahel. In this huge African region, climate change has materialized in a dramatic manner. In some cases, the severe conditions have left people with no option other than to migrate elsewhere to survive. It was with all of this in mind that the extraordinary, but heavily debated project was first put forward.

Fourteen years have passed since the initiative formally kicked off. The stated goal was to create a 15-kilometre-wide, 8, 000-kilometre-long green belt of trees and other plants that, by 2030, would span（跨越）the entire width of the Sahel, from Senegal to Djibouti. Overall, 100 million hectares（公顷）of land would be restored by 2030. Once completed, it was announced, the wall could end up capturing（俘获）250 million tonnes of carbon dioxide, while its creation and upkeep could create ten million jobs in rural areas.

Looking at the project as a whole, there’s still a long way to go. According to a status report by the UN Convention to Combat Desertification, about four million hectares of degraded land have been restored. This means that progress towards the 100 million hectares target stands at just four per cent.

“When we started restoring the soil, we realized the area at risk was much wider than we initially thought,” explains Elvis Paul Tangem, the African Union’s GGW coordinator. “We had few funds to push the initiative as much as we wanted to. There was skepticism among investors, who didn’t understand the project, but also among the African states themselves, which needed time to figure out if the GGW was a priority.”

【小题1】 “Green” is more than just a color. It also means taking special steps to protect the environment—the water, the land, and the air we breathe. Why green? Plants are green, and without them the earth wouldn't be such a lovely home for us human beings.

Sometimes people call ours a “throwaway society”. That means we are always throwing away old things and buying new ones. 【小题2】 For example, if your brother is old enough not to play with his plastic bike, why not give it to another family who has a little kid so that they don't need to buy one? And one less large plastic toy doesn't need to be produced.

【小题3】 Many organizations will pick it up right in front of your house and some towns even require(要求) it. Make sure you encourage everyone in your house to think whether things can be reused or recycled before they're thrown away.

Almost everyone likes traveling. But next time before you travel around the world, take a look at your own backyard. Is there a place where you could plant a tree or put in a little fruit or vegetable garden? If so, get there and get your hands dirty. Then you can watch with pride as your tree takes root, and your garden plants grow into big plants full of ripe, red tomatoes or tiny-juicy blueberries. 【小题4】.

Heavy traffic doesn’t stop big mammals like bears from crossing highways — nor does it keep smaller creatures from being squished (压扁) by cars. In just two years along one highway in Utah, more than 100 animals were killed in traffic accidents. In the United States, there are 21 endangered species whose survival is threatened by traffic accidents.

However, there’s one way to reduce crashes between cars and animals crossing the road: wildlife under and overpasses. Looking much like a regular overpass for cars, but decorated with native plants, they aren’t particularly noticeable unless you know what you’re looking for. The drivers may not be able to see the under crossings. But they’re helping countless species to pass the highways, from gold monkeys in Brazil to water voles in London.

Washington State is one of the latest to join in. Building its first wildlife bridge began in 2015 over Interstate 90(1-90), which runs from Seattle to Boston. Though it’s just a bare set of arches now, with native plants to be planted next year, deer and wolves are already using it. Along with six underpasses built since 2013, these crossings are the first in a set of 20 along a 15-mile stretch of highway on I-90. These passes will allow black bears and mountain lions to pass through what was once an impenetrable road.

These wildlife crossings aren’t just about saving individual animals —they’re about species survival, too. I-90 is an economically important east-west lifeline in the state. But many of the animals mostly want to move from north to south. Those animals on the south of the highway got trapped in an island. Inbreeding (近亲繁殖) became a potential problem. Localized extinction happens if they don’t have genetic variability (变化). The Snoqualmie overpass helps reconnect these isolated (隔绝的) populations. I-90’s underpasses are important in connecting waterways and species.