1 . Overlooking the Davis—Gant Varsity Soccer Field, a bed of overturned soil waits for further development. In a few years, this area will become a natural habitat and a playground for animals and residents. This peaceful area didn’t appear naturally, but through planning and action taken by Catlin Gabel’s Tiny Forest project launched by teacher Patrick Walsh.

Forests typically take hundreds of years to mature, with four stages of growth. “Tiny forests flatten out time through the planting of all four layers (层),” Walsh explained. The end result is a fast-growing, native forest in about 20 years. Over 600 plants from 43 species will be planted in the tiny forest, the first one in Oregon.

Walsh was inspired to build a tiny forest after hearing about this idea, which emerged in Japan and has taken hold in North America. He shared his vision with seniors in his class. The seniors researched tiny forests and made a proposal resulting in Clean Water Services donating 60 trees and $5,000 from the National Oceanic and Atmospheric Administration. Armed with these resources, Walsh and the students started working. “Something I didn’t really expect was the outpouring of students’ enthusiasm. Seeing students from all grades volunteered to contribute to the ‘dirty work’ really blew me away,” Walsh said.

Senior Megan Cover has been at the school since the first grade. “I’ll graduate after working on this project, which is surely sad, but it’s really rewarding and great to be a part of this project and to do my bit. We’re creating this educational space for many young kids,” Cover said.

Walsh summed up his goal of the project, which is to build a place where students can enjoy and learn about nature. “The forest will obviously not solve climate change, but it will deserve the efforts if the kids think about climate change and remember the importance of reforestation and trees when they look outside at the forest.”

6 . A blue hole is a special kind of underwater cave found inland or in the sea, which forms when the earth above a cave falls in and water fills the space.

An inland blue hole’s water is very still and has different layers. A layer of fresh rainwater floats on top of salt water; the fresh water keeps oxygen from the atmosphere from reaching the salt water; brightly colored bacteria live where the two layers meet.

Diving into blue holes is very dangerous. Near the top of the blue hole, there is a layer of toxic gas, which causes itching, headache, and—in large amounts—death. Divers must also be fast. They have to get in and out of a cave before their oxygen runs out. Additionally, divers have to follow a guideline as they swim through a blue hole because it is very dark inside. Without the guideline, they may get lost.

If blue holes are so dangerous, why do explorers and scientists risk their lives to explore them? The reason is that these underwater caves can provide valuable scientific information. They provide clues about geology, archaeology, and biology. For example, some blue hole creatures probably haven’t changed for millions of years.

The blue holes could even provide clues about astrobiology. For example, divers have found bacteria there that can live without oxygen. Astrobiologist Kevin Hand says the bacteria may be similar to forms of life that might exist on Jupiter’s fourth largest moon, Europa. “Our study of life’s extremes on Earth,” he says, can help increase “our understanding of habitable environments off Earth.”

In addition, the oxygen-free environment of the blue holes preserves bones of humans and animals that fell into the caves long ago. By studying blue holes, we can understand what life was like in prehistoric times. As cave diver Kenny Broad says, “I can think of no other environment on Earth that is so challenging to explore and gives us back so much scientifically.”

7 . In habitats across the planet, animals periodically drop everything to walk, fly or swim to a new place. Some animals such as whales and geese learn migration paths by following their parents. Others, including small songbirds, gain the distance and direction of their migration within their genetic code. And some animals use a combination of genetics and culture to guide their migration.

Another group of migrators does not quite fit either model, and researchers have only recently started to figure out how they find their way. The Cory’s shearwater is an oceangoing seabird that migrates over the Atlantic every year. The young do not migrate with their parents, so culture cannot explain their journeys. And the exact paths vary wildly from individual to individual, making genetics equally unlikely.

Cory’s shearwaters are long-lived, rarely producing young successfully before age nine. This leaves an opening for learning and practice to develop their migration patterns. Researchers call this the “exploration-refinement”, and until now it has been hypothetical (假设的) because of difficulties in tracking migratory animals’ movements.

But a team of researchers has done that by attaching small geolocators to more than 150 of the birds aged four to nine. They found that younger birds traveled longer distances, for longer periods, and had more diverse paths than older birds. “We finally have evidence of the ‘exploration-refinement’ for migratory birds,” says Letizia Campioni, who led the study. Younger Cory’s shearwaters are able to fly just as fast as the adults——but they do not, suggesting that the young do more exploring, which gradually fades as they mature and settle into a preferred course.

“Although it may seem less efficient than other strategies, exploration refinement could be beneficial to birds and other organisms in a rapidly changing world due to unpredictable man-made changes,” says Barbara Frei. “It might be safer to repeat a behavior that was recently successful than to rely on patterns that were perfected long ago but might no longer be safe.”

8 . Endangered polar bears are breeding (繁殖) with grizzly bears (灰熊), creating “pizzly” bears, which is being driven by climate change, scientists say.

As the world warms and Arctic sea ice thins, starving polar bears are being forced ever further south, where they meet grizzlies, whose ranges are expanding northwards. And with that growing contact between the two come increasing hybrids (杂交种).

With characteristics that could give the hybrids an advantage in warming northern habitats, some scientists guess that they could be here to stay. “Usually, hybrids aren’t better suited to their environments than their parents, but these hybrids are able to search for a broader range of food sources,” Larisa DeSantis, an associate professor of biological sciences at Vanderbilt University, told Live Science.

The rise of “pizzly” bears appears with polar bears’ decline: their numbers are estimated to decrease by more than 30% in the next 30 years. This sudden fall is linked partly to “pizzly” bears taking up polar bears’ ranges, where they outcompete them, but also to polar bears’ highly specialized diets.

“Polar bears mainly consumed soft foods even during the Medieval Warm Period, a previous period of rapid warming,” DeSantis said, referring to fat meals such as seals. “Although all of these starving polar bears are trying to find alternative food sources, like seabird eggs, it could be a tipping point for their survival.” Actually, the calories they gain from these sources do not balance out those they burn from searching for them. This could result in a habitat ready for the hybrids to move in and take over, leading to a loss in biodiversity if polar bears are replaced.

“We’re having massive impacts with climate change on species,” DeSantis said. “The polar bear is telling us how bad things are. In some sense, “pizzly” bears could be a sad but necessary compromise given current warming trends.”

10 . A five-­year-­old dog named Kelsey has been praised as a hero for helping to save the life of her owner who slipped in the snow and broke his neck.

The man, Bob, was alone when he left his farmhouse on New Year’s Eve to collect firewood.Expecting a journey of only several meters, Bob was wearing just long johns (衬裤), a shirt and slippers when he went outside, although the temperature was around －4℃.

After the accident, he was unable to move in the snow. Fortunately, Kelsey came to his assistance.

“I was shouting for help, but my nearest neighbor is about 400 meters away, and it was 10:30 p. m.,” Bob explained. “By the next morning, my voice was gone and I couldn’t yell for help, but Kelsey didn’t stop barking.”

Kelsey’s companion kept him warm by lying on top of him. She licked his face and hands to keep him awake. “Kelsey kept barking but never left my side,” Bob recalled. “I knew I couldn’t give up and that it was my choice to stay alive.”

Bob spent 20 hours in the freezing cold. When he finally lost consciousness, his dog kept barking. Finally, hearing the barking, Bob’s neighbor discovered him at 6:30 p. m. on New Year’s Day and called the emergency services at once. When Bob arrived in hospital, his body temperature was below 21℃. However, doctors were surprised to find that he didn’t have any frostbite (冻疮). They believed it was because of Kelsey’s determination to keep him warm. Dr. Chaim Colen, the doctor who treated Bob, said, “His dog really saved him.He was very fortunate.”

Bob said he was very grateful to both Dr. Colen and his Kelsey. “They saved my life. They are truly heroes!”