2 . The streets, sidewalks and roofs of cities all absorb heat during the day, making some urban areas across the United States up to 6 degrees Fahrenheit hotter than rural ones during the day—and 22 degrees F hotter at night. These “urban heat islands”   can also develop underground as the city heat spreads downward, beneath the surface. And basements, subway tunnels and other underground infrastructure also constantly bleed heat into the surrounding earth, creating hotspots. Now the underground heat is building up as the planet warms.

According to a new study of downtown Chicago, underground hotspots may threaten the very same structures that emit the heat in the first place. Such temperature changes make the ground around them expand and contract (收缩) enough to cause potential damage. “Without anyone realizing it, the city of Chicago’s downtown was deforming,” says the study’s author Alessandro F. Rotta Loria, a civil and environmental engineer at Northwestern University.

The findings, published in Communications Engineering, expose a “silent hazard (危险)” to civil infrastructure in cities with soft er ground — especially those near water — Rotta Loria says. “There might have been structural issues caused by this underground climate change that happened, and we didn’t even realize,” he adds. While not an immediate or direct danger to human lives, this previously unknown effect highlights the impacts of a lesser-known component of climate change.

Similar to climate change above the surface, these underground changes occur over long periods of time. “These effects took decades, a century, to develop,” Rotta Loria says, adding that elevated underground temperatures would likewise take a long time to dissipate (逐渐消失) on their own.

But other researchers interviewed for this story all say this wasted energy could also be recycled, presenting an opportunity to both cool the subsurface and save on energy costs. Subway tunnels and basements could be updated with technologies to recapture the heat. For example, water pipes could be installed to run through underground hotspots and pick up some of the heat energy.

3 . Warmer oceans can cause coral (珊瑚) bleaching. Bleaching happens when the coral, colonies of tiny animals called polyps, lose colored algae (藻类) living in their bodies and turn completely white. Without the algae, the coral loses its main food source and can die.

In 2021, the United Nations reported a 14 percent loss of corals across the world largely from rising sea temperatures in the previous 13 years. Australia declared mass bleaching events in 2022 across large parts of the Great Barrier Reef, the fourth since 2016.

Reefs in Hawaii, Florida, and the Caribbean were all severely affected, but thankfully some coral areas were not. Scientists looked into the characteristics of these corals and their ecosystems to see how others could be protected. Warm water reefs in the tropics are the worst affected by bleaching, but they also contain corals with better heat resistance.

Research is focused on finding genes for heat tolerance so that they can be passed on to future generations. Biologists mix corals that are more resilient to higher temperatures with those that are not and the resulting hybrid generation has a better chance of survival.

Researchers in Florida’s reefs have been using ocean nurseries to replant coral with batches that contain genes resistant to heat, acidification, and disease. Those areas have recovered within a year.

Other projects like Revive and Restore are using methods like preserving older coral populations’ sperm and eggs (biobanking) and using corals with better adaptability characteristics in breeding. The project also believes that boosting biodiversity by restoring (恢复) seabirds to islands, and ridding them of invasive species like rats, helps coral reefs thrive.

Ultimately, scientists say that without a serious reduction in greenhouse gas emissions, 99 percent of the world’s coral reefs will be gone by the end of the century. There is a limit to how quickly coral can adapt, especially given the rate of climate change. Computer simulations have shown that mild or moderate warming allows coral to adapt, but if temperatures rise rapidly then extinction is certain.

4 . How to prepare for a wildfire

Before you can effectively prepare, it’s very important to understand how wildfires operate. Many think wildfires destroy homes because a wall of flames(火焰)moves across the landscape.     1    . Now that you know what a wildfire is, here’s how you can protect your home and your family.

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Creating a defensible space around your home acts as a barrier against wildfire flames. Home hardening involves constructing with fire-resistant materials. Investing $10,000 to $20,000 in these measures significantly reduces the chance of a home being ravaged by a wildfire, lowering risk by 75%.

Similar to dry or bagged leaves, dead tree branches are dry, which means they, too, can catch fire quickly. If you have any hanging from trees or laying in your yard, remove them ASAP. The same rule applies when removing dead tree branches:     3    .

Families should go over an evacuation plan and practice it well before an emergency actually occurs. Knowing when to leave and being able to go quickly is crucial during an evacuation scenario.     4    . Then plan your primary and alternative evacuation route, and assemble emergency supplies and store them where you can get to them quickly.

    5    . Fix metal gutter covers to reduce leaf litter and windblown debris. This will ensure that things don’t burn in them and spread fire to your home. Don’t pressure-wash gutters; it can damage them or pull them off your house.

6 . A species of iguana (鬣蜥) that went extinct nearly 200 years ago on one of the Galápagos Islands appears to be making a comeback, with some help from a team of conservationists. The last person to spot a Galápagos land iguana on Santiago Island in Ecuador was Charles Darwin in 1835. When an expedition team from California arrived in 1906, the iguanas were nowhere to be found. And though this kind of iguana can still be found on the other Galápagos Islands, it’s believed to have been extinct on Santiago for the past 187 years—until now.

A team of scientists and park guardians discovered new lizards (蜥蜴) of various ages while walking the island in late July, which suggests the species has been successfully reintroduced. And according to Jorge Carrión, director of conservation of the Galápagos Conservancy, the ecosystem is thriving as a result. The evidence is in the details, he explained. Seeing lizards of different ages and coming across unmarked specimens means the iguanas are breeding (繁殖) in their natural environment.

Before joining the Galápagos Conservancy, Carrión worked for the Galápagos National Park Directorate, the caretakers of the islands’ ecosystems and resources. The GNPD is also the authority spearheading the iguana reintroduction project, with funding and assistance coming from the Conservancy. He said the collaborative has released more than 3,000 land iguanas on the island since January 2019.

Conservationists decided to reintroduce the land iguana after carefully considering how a return of the species would affect the ecosystem. These lizards are what’s known as an engineering species, like the Galápagos giant tortoise, in that they play a key role in keeping a healthy balance in an ecosystem.

“This kind of species are key for ecosystem in general,” Carrión said. “In this case it was the justification for the reintroduction of land iguanas, to return the natural dynamic to Santiago Island. When engineer species are not present, many imbalances occur in the ecosystem.”

8 . The world has been troubled by COVID-19 for over a year. Masks (口罩) are really important to everybody during the pandemic (疫情). We all wear masks every day.     1    . This could become a big environmental problem.

In a study, scientists from the US and Denmark said that people around the world are now using 129 billion face masks every month.    2    . What a large number it is!

According to Elvis Genbo Xu from the University of Southern Denmark, disposable (一次性的) masks are plastic products.     3    . People think that they are a new kind of pollution.

    4    . But we can’t recycle masks. Scientists have called for setting up mask-only trash cans (垃圾箱) to deal with mask waste.     5    . We believe that we can solve this problem in the near future though there is still a lot of work to do.