4 . Internet users worldwide are planting trees — nearly 65 million of them to date — just by browsing the internet. That’s because instead of relying on Google or Yahoo to conduct their online searches, they are using Ecosia.

Like other search engines, Ecosia makes money through advertising — every time someone clicks on one of the ads located next to search results, Ecosia makes several cents. The Berlin-based start-up invests 80 percent of its profits in tree planting.

Currently, 8 million users are funding 20 tree-planting projects in 15 countries. For example, Ecosia is planting mangrove trees along the Madagascar coast, nut trees in Ghana, and acacia trees in Ethiopian valley.

To make sure the trees actually stay in the ground, the search engine employs a chief tree-planting officer, who reviews projects and regularly visits tree-planting sites. The company also relies on satellite imaging to help ensure millions of trees it funds aren’t subject to logging.

The majority of Ecosia users are located in France, Germany, and the UK, but the search engine is rapidly expanding in US. “We’re seeing real growth in the US as people find out they can plant trees while searching the internet,” founder Christian Kroll said, “which means we are on track to plant more than 100 million trees by next year.”

When it comes to being a force for social good, Ecosia seems to walk the walk. As the climate movement worldwide grows, the internet has not escaped scrutiny for its carbon footprint — and for good reason. In early August, the company announced that with the completion of its second solar plant, it is returning enough renewable energy to the grid to offset more than 100 percent of the energy used by Microsoft to power Ecosia searches. Given that trees suck up carbon dioxide from the atmosphere, the start-up claims that each Ecosia internet search actually removes 1kg of CO₂ from the atmosphere.

6 . A smoke bomb from a party started a major blaze (火焰) near Los Angeles in September,just one of many recent wildfires ignited (引燃) by people. Now, an analysis of satellite data shows human-caused blazes spread much faster and kill more trees than ones ignited by lightning.

Fire has always been a part of California’s natural history. But several centuries of human settlement have created new conditions that promote its spread.Studies have shown human ignition is to blame for 84% of all wildfires in the United States,and 97% of all those that threaten homes.

Human-caused fires always seemed more extreme, says Stijn Hantson,a fire ecologist at the University of California,Irvine,who led the new research. But measurements of how fast they spread and their impacts on ecosystems (生态系统) in California had not been explored, he notes.

To examine those differences, Hantson and his colleagues analyzed satellite data for 214 wildfires in California between 2012 and 2018.Human-caused fires typically spread about 1.83 kilometers per day, more than twice as fast as lightning-ignited burns,the team reports.The faster spreading fires also burned more violently and killed “double or triple” the trees as lightning-caused ones.

However, there is no fundamental difference in the chemistry of a human-caused blaze. “A fire is a fire” Hantson says. “It’s the surrounding things that matter.” Causes of fires ranging from improperly thrown cigarettes to sparking (冒火花) power lines could ignite a blaze on any given day, he says, while lightning strikes and dry thunderstorms only happen seasonally.

The researchers tracked meteorological data and found that human-caused fires were more likely to start on days with extreme weather conditions,and were more associated with drier,less-forested landscapes. This adds to scientists’ understanding of how humans are extending the fire season, says Nathan Mietkiewicz, an ecologist with the National Ecological Observation Network.

9 . 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.