1 . The streets and roofs of cities all absorb heat, making some urban areas hotter than rural ones. These “urban heat islands” can also develop underground as city heat spreads downward, and subway tracks and other subsurface infrastructure(基础设施) also constantly radiate warmth into the surrounding earth.

A new study of downtown Chicago shows underground hotspots may threaten the very same structures that give off the heat in the first place. “Without anyone realizing it, the city of Chicago’s downtown was deforming,” says study author Rotta Loria, an environmental engineer.

Humans aren’t the only potentially affected. “For a lot of things in the subsurface, it’s kind of ‘out of sight, out of mind’,” says Grant Ferguson, a geologist. But the underground world is full of creatures that have adapted to subsurface existence such as insects and snails. As the temperature rises because of climate change and underground urban development, scientists are keeping eyes on the potential implications for underground ecosystems.

But the question of how underground hotspots could affect infrastructure has gone largely unstudied. Because materials expand and contract with temperature change, Rotta suspected that heat coming from underground could be contributing to wear and tear on various structures. To understand how underground temperature difference has affected the ground’s physical properties, he used a computer model to simulate(模拟) the underground environment from the 1950s to now—and then to 2050. He found that by the middle of this century, some areas may lift upward by as much as 0.50 inch or settle by as much as 0.32 inch, depending on the soil makeup of the area involved. Though these may sound like small displacements, Rotta says they could cause cracks in the foundations of some buildings, causing buildings to fall.

Kathrin Menberg, a geoscientist in Germany, says these displacement predictions are far beyond her guesses and could be linked to the soft, clay-heavy soils. “Clay material is particularly sensitive,” she says, “It would be a big issue in all cities worldwide that are built on such material.”

Like climate change above the surface, underground changes occur gradually. “These effects took decades to develop,” Ferguson says, adding that increased underground temperatures would likewise take a long time to dissipate on their own. “We could basically turn everything off, and it’s going to remain there, the temperature signal, for quite a while.”

But Ferguson says this wasted heat energy could also be reused, presenting an opportunity to both cool the subsurface and save on energy costs. Still, this assumption could fail as aboveground climate change continues to boost underground warming. However slowly, this heat will gather beneath our feet. “It’s like climate change,” Rotta Loria says. “Maybe we don’t see it always, but it’s happening.”

3 . How can a large city find water for 10 million people if it is in the desert? Fog-catching nets on hills around the city of Lima, the capital of Peru, could solve the city’s water shortages for good. A twenty-meter high net tower will soon be displayed in the city as a solution to the problem.

Peru’s capital city has just one inch of rain a year. The city sees high annual temperatures and water consumption rates. Located in a desert, the city’s temperatures are higher than world averages. However, a unique feature of Lima’s weather offers a way of meeting some of this demand. Located on the coast, Lima’s surrounding hills are constantly bathed in waves of fog coming off the Pacific Ocean, and the moisture (湿气) taken in by plants ensures they stay green year-round.

Inspired by fog nets placed by rural communities across the continent, Alberto Fernandez, a Chilean architect currently studying for a Ph.D. from University College London, has designed a series of towers and fog-catching nets. They can collect as much as 1,000 liters of water per day, amounting to 3.6 million liters per year, if enough are put into use. Their towering structure allows them to get into the clouds, collecting more vital water vapor (蒸气), and their unique shape means that no matter the direction of the wind, the moisture-rich fog will strike some part of the structure directly.

The water will largely be used for agriculture — as the water would require filtering (过滤) before consumption — helping free up resources for city residents. Cheaper than filtering water from the Rimac River, these towers and nets, which Fernandez says could be built up to 200 meters high, are part of a series of designs for the Lima 2035 project. It aims to change current desertification and create a new place for sustainable and human-centered food systems that promote healthy diets and improve incomes in the driest city on Earth.

4 . Issues such as global warming and sustainability have become passionate concerns for many of the concert industry’s fans and increasingly for the musicians. Coldplay, a pop band whose members scored their first big hit in 2000 with a song called Yellow, announced in November that it wouldn’t go on tour to promote its latest album, Everyday Life, until it could find a way to make concerts more sustainable and greener to the environment.

It’s not always easy to walk the talk. A growing number of artists, including Peggy Gou, have environmental demands built into their contracts when they tour, such as bans on plastic tableware. But there’s almost no way of avoiding carbon emissions produced by a tour, which involves moving hundreds of people and tons of equipment across large distances.

Lisa Pomerantz, who books travel for acts says that real change will require action by venue owners, concert promoters, and the fans. Major acts like Coldplay can afford to stop touring while figuring out how to lessen their environmental impact. But lesser-known artists can’t stay off the road, since streaming earnings haven’t been able to compensate (弥补) for the collapse in CD and downloaded music sales. Even when concerts are aggressive about being more sustainable, the impact of audience travel can easily swamp (淹没) their efforts. For bigger acts, this can represent as much as 80% of the carbon footprint, according to a 2015 study. Another analysis showed that roughly a third of the tour’s carbon footprint came from a venue’s power consumption.

Still, even the most green-conscious bands must balance their desire to be more sustainable against the financial necessity of touring. “I absolutely think you can go on tour and have a concern about the environment. It’s a matter of just keeping our carbon footprint as low as possible,” says Flavian Graber, lead singer of We Invented Paris.

5 . Last summer on the Hawaiian Island of Kauai, Tina Taniguchi worked close to the ground. Her coconut leaf hat covered most of her thick brown hair. Wet soil had gotten on her clothes and her smiling face.

Taniguchi smiles a lot while working on the Hanapepe salt land on the west side of Kauai. It is a piece of land about half a hectare in size with pools of salty water. The salt becomes crystals (晶体)as the water dries.

“The work is tiring, but for me it’s also play,” Taniguchi said with a laugh. Taniguchi’s family is one of 22 families who make salt, following a cultural and spiritual tradition. Hanapepe is one of the last remaining salt lands in Hawaii. Its salt can be traded or given away but must never be sold. Hawaiians use it in cooking, healing, and as protection.

Over the past 10 years, there have been several threats to this field. They encompass development, pollution from a neighboring airfield, damage to the sand from vehicle traffic and waste left by visitors to the nearby beach. In addition, rising sea levels and weather might stop the practice.

The process of turning sea water into salt can be slow. The season begins once the rain stops and water starts to disappear from the salt beds. Ocean water travels underground and enters the wells. Each family has their own well. As water enters the well, so do tiny, red brine shrimp. These small ocean animals give Hanapepe salt its unusual, sweet taste.

The families first clean the salt beds and line them with black clay (陶土). Then they move water from the wells into the beds. There, salt crystals form. The top level, or layer, is the whitest. It is used for table salt. The middle layer is pinkish and is used in cooking, while the bottom layer, which is a deep red color, is used in blessings.

8 . Campaigners opposing the building of new wind farms often point to the possibility that the blades of wind turbines (涡轮机) can cut careless birds to bits. No one doubts that wind turbines kill some birds. But a new analysis of American data, published in Environmental Science & Technology, suggests the numbers have little impact on bird populations.

Wind power has expanded dramatically in America over the past 20 years. Many studies have analysed the effects in specific locations or on specific bird species. But few have looked at the effects on wildlife at the population level. Dr. Katovich, an economist at the University of Geneva, used the Christmas Bird Count, a citizen-science project. Volunteers count birds they spot over Christmas, and the society edits the numbers. Its records stretch back over a century.

Dr. Katovich assumed, reasonably, that if wind turbines harmed bird populations, then the numbers seen in the Christmas Bird Count would drop in places where new turbines had been built. He combined bird population and species maps with the locations and construction dates of all wind turbines in America, with the exceptions of Alaska and Hawaii, between 2000 and 2020. He found that building turbines had no obvious effect on bird populations. That reassuring finding held even when he looked specifically at large birds that many people believe are particularly easy to be struck.

Dr. Katovich didn’t limit his analysis to wind power alone. He also examined oil-and-gas extraction (提取). Like wind power, this has boomed in America over the past decades. Comparing bird populations to the locations of new gas wells revealed an average 15% drop in bird numbers when new wells were drilled, probably due to a combination of noise, air pollution and the disturbance of rivers and ponds that many birds rely upon. When drilling happened in places designated by experts as “important bird areas”, bird numbers instead dropped by 25%. Such places are typically migration hubs, feeding grounds or breeding locations.

Wind power, in other words, not only produces far less planet-heating gas than fossil fuels. It appears to be significantly less damaging to wildlife, too. Wind turbines might look dramatic, but their effect on birds isn’t.

9 . When this year’s all-woman team arrived on Antarctica’s Goudier Island to run the world’s most remote post office, it was shovels they needed rather than stamps.

They’d traveled some 8,000 miles from the UK, by plane and boat, and Britain’s Royal Navy had helped them dig out their new home at the Port Lockroy scientific base, which was buried up to four meters deep under several tonnes of December snow.

It wasn’t just the frozen wastes that first struck postmaster Clare Ballantyne, who at 23 years old was the baby of the four-woman group. It was that “there’s penguins everywhere.”

More than a thousand Gentoo penguins live on this tiny island on the western side of the Antarctic peninsula (半岛), around the size of a soccer field. Since 1944, when the UK’s first permanent Antarctic base was established here, it’s also become a shelter for explorers, scientists and — in recent years — tourists.

Each year, a team is selected to run and maintain the site from November to March, or summertime in the southern hemisphere. Around 4,000 people applied for this job, but just four made the cut: Ballantyne, base leader Lucy Bruzzone, wildlife monitor Mairi Hilton and shop manager Natalie Corbett.

The job also involves counting penguins: The scientific data they gather on the Gentoos’ breeding patterns is part of a decades-long study of the colony.

When it comes to choosing candidates, “there is no recipe we can follow,” says Ballantyne. “It’s about your ability to work together as a team. Cheeriness goes a long way, being able to see the light in life and resolve problems quickly.”

Ballantyne notes that there has been “a bit of a decline in recent years in the breeding success” of the Gentoo penguins, but says “the causal connect ion is the tricky bit.” While climate change is probably “the biggest driver,” they also need to carefully examine if there’s a “human element” as well. In her opinion, Antarctica tourism has boomed significantly in the past couple of decades, but there aren’t legally enforced limits on tourism, which hopes to be a regulated industry.