1 . In the world of water, 2021 was another year for the record books. Parts of Western Europe suffered from deadly floods while large areas of the southwestern United States remained locked in a massive drought.

One might think that our impressive water management would safeguard society from such catastrophic events. Yet when it comes to water, the past is no longer a good guide for the future and most of the water engineering is unprepared for consequences of increasingly occurring extreme weather. One of the most alarming wake-up calls came from the city of Cape Town, where the water taps of 4 million residents were nearly forced to be shut off after severe drought dried up its reservoir (水库).

Appealing as it might be, the solution is not to further build bigger and higher dams (水坝) that often result in more disastrous flooding. Rather, it is to work more with natural processes.

The Netherlands avoided major damage from the historic floods in July 2021 thanks to its recently completed project, which gives river room to spread out by redirecting floodwaters into wetlands, lowering parts of the stormy river by more than a foot. Agricultural practices offer another strategy. Scientists have found that boosting organic matter in the soil by 1% can increase the soil’s water-holding capacity by up to 18,000 gallons per acre, creating flexibility to both intense rains and dry periods. This means farmland practices such as the planting of cover crops can not only raise output but improve water management.

Solutions don’t come easily, but they are key to a livable future. While it’s too late to avoid the impacts of climate change, we can avoid the worst of those impacts by investing more in such nature-based water solutions.

2 . From tiny hummingbirds (蜂鸟) to giant whooping cranes, roughly half of the world’s more than 10,000 bird species migrate (迁徙). Longer wings and powerful flying muscles often help these birds cross vast expanses of air. But a study of nearly all bird species suggests many migrators share another unexpected flight aid: lighter-colored feathers.

Being a bit more lightly colored than non-migrating birds may help these long-distance fliers stay cool as they work hard under the hot sun to fly, researchers report December 6 in Current Biology.

It’s known that color can help birds hide from predators (捕食者) by blending in, or attract mates by standing out. But color has subtle effects too, including regulating temperature by absorbing or reflecting light, says Kaspar Delhey, an expert at the Max Planck Institute for Ornithology in Germany. For example, bird eggs laid in colder climates tend to be darker, which may help keep them warm. 

Migrating birds push their bodies to the physiological limit, which creates much heat. Some species cope by rising to cooler air during daytime. “If overheating is a problem in migratory birds, another way of dealing with that would be to evolve lighter colors that absorb less heat,” Delhey says.

Delhey and his colleagues analyzed over 20,000 illustrations of 10,618 bird species, ranking feather lightness for each species and comparing that with how far the birds fly. On average, lightness slightly increased with migratory distance, the team found. The longest-distance migrators were about 4 percent lighter than non-migrators, an effect that wasn’t explained by size, climate or habitat type for different species.

“It’s not a big difference,” Delhey says, noting that many migrators are darkly colored, perhaps for reasons unrelated to flight. But the trend was remarkably consistent.“Very different groups with very different biologies show this pattern,” Delhey says.“That surprised us.”

3 . Although there are plenty of flightless bird species on Earth, the parlor roller pigeon(鸽子) is believed to be the only one selectively bred(养殖) by humans until it lost its capacity to take to the skies and developed a completely new and strange means of getting around—backflips(后空翻).

Seeing a parlor roller pigeon roll on the ground, you would think it might go crazy, but in reality, the bird is rolling on the ground because it comes naturally to it. No one knows exactly how or when the breed was created, but experts and enthusiasts assume that its origin can be traced back to the mid-19th century when someone probably encountered a specimen with a slight tendency to roll on the ground and decided it was worth emphasizing via selective breeding. It is believed that over years of selective breeding, pigeons that rolled over long distances were obtained.

The parlor roller is a common-looking pigeon that weighs about between 200 and 280 grams and comes in a variety of colors. What sets it apart from any other pigeon breed is its inability to fly, and its tendency to continuously do backflips on the ground, especially when encouraged. Interestingly, parlor rollers are physically equipped to fly and are not heavier than other pigeon breeds. Some believe they have some shortcomings in the balance centers of the brain that cause them to roll on the ground instead of flying.

Doing backflips is what these pigeons are good at and what they are bred for. Fanciers will roll them on the ground like bowling balls, just to get them started. The birds will then continue to roll for up to a few hundred feet. The current record for the longest roll sits at 662 feet.

Although parlor roller pigeons are very popular among fanciers, animal lovers consider it cruel to strengthen what they consider a disability.

Throughout history, people have fought bitter wars over political ideology, national sovereignty and religious expression. How much more     1     will these conflicts be when people fight over the Earth’s most indispensable resource water? We may find out in the not-too-distant future if projections about the     2     of water in the Middle East and other regions prove correct.

Less than three percent of the planet’s     3     is fresh water, and almost two-thirds of this amount is     4     in ice caps, glaciers, and underground aquifers too deep or too remote to access. In her book, Pillars of Sand-Can the Irrigation Miracle Last, Sandra Postel outlines three forces that     5     tension and conflict over freshwater. Using up the water “resource pie”. In India, the world’s second-most populous nation, with over 1 billion inhabitants, the rate of groundwater     6     is twice that of recharge, a deficit higher than in any other country. Although water is a renewable resource, it is not a(n)     7     one. The freshwater available today for more than 6 billion people is no greater than it was 2,000 years ago, when global population was approximately 200 million. (The current U.S. population is 287 million.)

Global     8     accounts for about 70% of all freshwater use. In five of the world’s most water-stressed, controversial areas the Aral Sea region, the Ganges, the Jordan, the Nileland and Tigris-Euphrates population increases of up to 75% are projected by 2025. With the fastest rate of growth in the world, the population of Palestinian territory will more than     9     over the next generation. Most experts agree that, because of geography, population     10     and politics, water wars are most likely to break out in the Middle East, a region where the amount of available freshwater per capita will decrease by about 50% over the next generation.

6 . The grass swung gently above a crack in the limestone (石灰岩) and Ludvik Husu realized he had found what he was searching for: a new cave in Slovenia’s dramatic Karst (喀斯特) region.

The cave enthusiast, with more than 50 years of experience, told AFP that “the conditions were perfect ... all the signs pointed to something beneath” as he felt the air current push up from below.

The 63-year-old had come across a new, 60-meter-deep limestone cave, a discovery that made the headlines this summer in a country that prides itself on its 14,000 underground caves.

The tiny Alpine nation is unusually rich in caves, which are a major tourist attraction. Perhaps the best known is the Postojna cave system, the longest in Europe, discovered by another amateur enthusiast two centuries ago. It extends for 24 kilometers and has offered up valuable finds for biologists.

Stanislav Glazar, a Postojna cave guide, told AFP that more than 150 species have been discovered in the system.

Glazar said Postojna is one of the richest caves in the world “in limestone formations.” The cave, located about 50 kilometers south of the capital Ljubljana, was also home to the world’s first cave tourist train, which began transporting visitors in 1872.

Elsewhere in the Karst region, the cave systems are of historical, cultural and even extraterrestrial interest. For instance, the UNESCO-listed Skocjan system was where the European Space Agency sent some astronauts to prepare for life in space.

“Astronauts know that the Karst world is exceptional, in a similar way to the environment in space: you don’t know what to expect at your next step,” said Skocjan Caves director Tomaz Zorman.

But for Husu, it’s the exploration that proves most rewarding. Once he knows there is something beneath, he digs around the crack to widen it and alerts fellow cavers to help gain access. He then uses ropes and a lamp to go down to what are vertical entrances in most caves. But doesn’t he feel scared to enter such unexplored depths?

“You enter a cave out of curiosity — there is no fear! Those who feel fear should stay home,” he said.

Caring for the Environment Starts from Ourselves

10 . Mount Tai, located just north of Tai’an city in East China’s Shandong Province, is a mountain of historical and cultural_________, with impressive views and beautiful natural scenery.

Among the Five Sacred Mountains (the other four are Heng Mountain of Hunan Province, Hua Mountain of Shaanxi Province, Song Mountain of Henan Province and Heng Mountain of Shanxi Province), Mount Tai is only the third highest. Why is it seen as the _________of the Five Sacred Mountains?

In absolute terms, Mount Tai cannot be considered as the highest of China’s mountains, but because it is_________ to the sea and rivers and rises abruptly from the relatively low hills and plains, its _________height is quite impressive, with a (an)_________ of over 1, 300 meters. _________, in Chinese culture east is regarded as a sacred direction, since it is where the sun and the moon rise. Therefore, Mount Tai is often regarded as the first of the Five Sacred Mountains. It is associated with sunrise, birth and_________,

Many Chinese emperors climbed to the top for enthronement (登基) or other significant ceremonies in ancient China, for they considered it to be a _________ of Chinese power given by master of nature. The earliest activities could _________to Xia Dynasty and Shang Dynasty, so it __________a good many of cultural relics and historic sites. Famous writers, poets and celebrities were attracted here and thousands of poems and __________ about Mount Tai are best-known nowadays.

Mount Tai is famous for its various stone inscriptions, which are the works of either ancient emperors or celebrities. The stone inscriptions__________ different bodies of calligraphy, and most of them are inscribed with beautiful diction, elegant writing style and __________ design. Besides historic relics, Mount Tai also boasts unique natural scenery, and it is well known for its__________. Overlapping mountains, gigantic rocks, centuries-old pines and cypresses (柏树), ever-changing clouds make Mount Tai __________with brightness and peaceful with miracle. As a result, it attracts lots of tourists from the whole world.