2 . In Denmark, bicycling is one of the primary forms of transportation. In sunshine, rain and snow, you will see cyclists on their way to work, to the grocery store, or to social events. The bike is a Dane’s best friend.

Danish cycling culture is as old as the bicycle itself. Bikes were first introduced to the country in the 1880s, and during the 1920s and 1930s, the bicycle became a widespread symbol of equality and freedom. People of all social classes began biking side by side — in the cities on their way to work and in the countryside on their days off.

The increased prosperity of the late 1950s saw some Danes replacing bikes with motorcycles and automobiles. Just like their colleagues around the world, Danish urban planners believed the future belonged to cars, trucks, and ever-wider highways. In the early 1970s, however, the Mideast oil crisis terminated that development. “Car Free Sundays” were introduced in Copenhagen, and protests demanding Copenhagen to become car-free took place. Over time, concerns about air pollution, climate change, and the need for people to get enough exercise have helped bicycles make a big comeback. Denmark’s heavy taxes on petrol and automobiles are a factor, too.

Today, cycling is an inseparable part of Danish culture. Newcomers who do not know how to cycle are encouraged to learn as soon as they arrive. Danish children usually learn to bike before they begin school at the age of six — and often much earlier. In school, children learn about traffic rules, road safety, and the importance of wearing a helmet as well as good cycling habits. Another alternative for families with children is the cargo bike — a sort of oversized tricycle with a large wooden box on the front. It’s estimated that a quarter of all Copenhagen families with two or more children own one of these cargo bikes for transporting kids, groceries, and other necessities. Danish cargo bikes have also won design awards and become a Danish export success.

Commuting by bike is the fastest, easiest and most environmentally friendly way to get around the cities of Denmark. And the numbers speak for themselves: Residents who cycle in Copenhagen request 1.1 million fewer sick days. Cyclists reduce CO2 emissions by 20, 000 tonnes a year on average.

In a small community located at a suburb of Exeter, a disheartening issue had been troubling the neighborhood for years. The once pleasant surroundings were ruined by piles of waste that seemed to multiply with each passing day. Residents were growing tired of the worsening environment, leading many to abandon their homes in search of cleaner neighborhoods. It was in this terrible situation that two young students, Emma and Mia, decided to take matters into their own hands.

Emma and Mia were classmates and best friends from Phillips Exeter Academy, both passionate about environmental preservation and deeply concerned about the pollution crisis their community was facing. Witnessing more and more neighbors’ leaving, they knew they couldn’t stand by any longer. Determined to bring about a change, they undertook a mission that would soon catch the attention of the entire community.

Their journey began with thorough research and planning. The two girls searched carefully on the Internet for information on environmental initiatives and connected with local environmentalists. They organized meetings with residents to understand the issues at hand, collecting data on the types of waste, the sources, and the areas most affected. Armed with this knowledge, Emma and Mia worked out a comprehensive plan and announced it to ask for opinions from the residents. Surprisingly it was strongly supported.

Their strategy was twofold. First, they initiated a waste classification and recycling program. They distributed recycling bins(回收箱) to every household and educated the community about the importance of responsible waste management. Soon, the streets began to show signs of improvement as the volume of garbage inappropriately thrown away decreased gradually.

The second part of their plan was more ambitious. Emma and Mia gathered volunteers from their school and the neighborhood to take part in a massive clean-up campaign. Armed with gloves and trash(垃圾)bags, they began systematically clearing the waste from the streets, parks, and even the local bodies of water. Their firm commitment and hard work inspired others to join the cause.

Half a year later, the changes were significant.

Emma and Mia received recognition and honors for their work.

5 . For years, scientists have debated whether humans or the climate have caused the population of large mammals to decline dramatically over the past several thousand years. A new study from Aarhus University confirms that climate cannot be the explanation.

About 100,000 years ago, the first modern humans migrated out of Africa in large numbers. They were very good at adapting to new habitats, and they settled in almost every kind of landscape — from deserts to jungles to the icy taiga in the far north.

Part of the success was human’s ability to hunt large animals. With clever hunting techniques and specially built weapons, they perfected the art of killing even the most dangerous mammals.

But unfortunately, the great success of our ancestors came at the expense of the other large mammals.

It is well-known that numerous large species went extinct during the time of worldwide colonization by modern humans. Now, new research from Aarhus University reveals that those large mammals that survived also experienced a dramatic decline.

By studying the DNA of 139 living species of large mammals, scientists have been able to show that the abundances of almost all species fell dramatically about 50,000 years ago. This is according to Jens-Christian Svenning, a professor and head of the Danish National Research Foundation’s Center for Ecological Dynamics in a Novel Biosphere (ECONOVO) at Aarhus University and the initiator of the study.

“We’ve studied the evolution of large mammalian populations over the past 750,000 years. For the first 700,000 years, the populations were fairly stable. But 50,000 years ago, the populations fell dramatically and never recovered,” he says, and continues: “For the past 800,000 years, the globe has fluctuated (波动) between ice ages and interglacial periods about every 100,000 years. If the climate was the cause, we should see greater fluctuations when the climate changed 50,000 years earlier.But we don’t. Humans are, therefore, the most likely explanation.”

8 . In 2014, Xu Yitang, a Beijing native who had been studying Peking Opera since childhood, went with friends for a birthday celebration to Beijing Zoo. Little did he know that a chance encounter at the aquarium there would excite a lifelong passion. As Xu Yitang stared at corals bathed in tank’s light, a sense of wonder crowded into his mind. Lost in the beauty and mystery of the creatures, he spent the entire afternoon in front of it. After that, he began to frequent the local market to learn about coral farming from merchants who sell ornamental plants, fish and corals. He also searched for information on relevant forums online. Before long, he had set up a small fish tank at home and started cultivating a coral.

Nowadays, Xu Yitang who has moved to the tropical island of South China’s Hainan province, works for a Sanya-based tropical biological laboratory belonging to the Chinese Academy of Sciences. Each day, he spends several hours diving deep under the waves to observe and document the growth and development of the creatures that captured his heart all those years ago. Nicknamed “coral man”, he is actively engaged on such social media platforms as Sina Weibo, where he regularly shares visually beautiful photos and entertaining videos of corals. He aims to encourage individuals to take action in protecting coral reefs and the oceans as a whole from the destructive impact of climate change and human activities.

Unfortunately, with the strengthening of the greenhouse effect, rising sea temperatures have led to coral bleaching (白化) and decay. A coral reef’s beautiful colors come from the symbiotic algae (共生藻类) zooxanthellae that provide more than 90 percent of the energy through photosynthesis (光合作用). Coral bleaching occurs when coral expels the algae and dies due to the lack of nutrients.

In the laboratory, he would film educational videos to raise awareness and knowledge about corals, so that people can learn how to protect them effectively.