2 . 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.”

6 . Time is one of humanity’s greatest blind spots. We experience it as days, months or years. But nature functions on much grander scales, measured in centuries, and even longer phases often grouped as “deep time.” Humanity’s shortsightedness around time creates major limits on modern conservation. As the climate and biodiversity crises accelerate, we are urgently working to protect and regenerate ecosystems without understanding how they functioned when they were truly doing well. A deep time perspective can help change that.

Take forest management. For decades, our practices called for all-out prevention of even the mildest forest fires, believing that fire was bad for both people and nonhuman nature. Until recently we ignored the forest management strategies indigenous (土著的) communities had successfully used for centuries, in particular the application of small-scale controlled burns. Fire, it turns out, has always been an integral ingredient in healthy forest ecosystems, promoting new growth by thinning the understory. Today, we’re beginning to see widespread application of indigenous knowledge to forest management, tapping into this ancient wisdom.

But how can we know what an ecosystem looked like centuries ago? One pathway is through modern mathematical modeling. We have married it with streams of long-term data and discovered a possible way to preserve the ecosystem of California’s kelp forest. By examining how North Pacific kelp forests existed long before the 19th century, we found that we’ve ignored the presence of a keystone species—the Steller’s sea cow, and its role in maintaining the harmony of this ecosystem.

Our model described the interactions between giant kelp and understory algae competing for light and space on the seafloor. Then we ran the model again, but this time with the Steller’s sea cow added in. These mammals fed on the leaves from the upper kelp layers. This allowed light to reach the sea bottom, which in turn stimulated the growth of not only the kelp but other kinds of organisms. In re-creating that vanished historical system that included the Steller’s sea cow, we could see a more diverse forestwhere the understory competed better with kelp

In short, what we assume we know about an ecosystem based on the recent past may impede our ability to fully understand and protect it. To ensure that our boldest conservation efforts are successful, we must begin looking at time as an essential tool.

    1     the night of July 28, 1976, one of the greatest earthquakes in the twentieth century hit Tangshan, Hebei. Strange things were happening, but people thought little of the       2     (warn). Then, at 3:42 a. m., the earth shook

Nearly a       3     (three) of China felt it. In less than one minute Tangshan was in ruins and more than 400,000 people were killed or injured. In the afternoon came another quake. Even more building     4     (fall) down. People began to wonder if the disaster would end.

The first pairs of jeans were designed for blue-collar workers. Over the course of the 20th century, the working-class pants have transformed into fashion icons and become popular around the world. However, each new pair you buy has a much higher cost than you might think.

Every pair of jeans takes about 0.7 kilograms of cotton. Growing this much cotton requires roughly 10,000 liters of water, not to mention various herbicides and pesticides, which can pollute groundwater. Typically, plastic fibers are mixed with cotton threads to increase comfort and flexibility. In order to dye the cloth, chemical sprays and several cycles of acid-washing are adopted, discharging toxic pollutants into rivers and even turn them into indigo-blue. Also, there are the zippers, buttons, and rivets made of copper and other metals, whose mining is yet another source of environmental degradation. All in all, the manufacturing (制造) process for a single pair of jeans emits over 33 kilograms of carbon — the equivalent of driving over 110 kilometers.

Like many globally produced products, jeans are made in poor countries and bought in rich ones. Much of the world’s cotton is grown in developing countries, with poor labor practices and few protections for workers. Cotton here is often picked by children or forced labor. And their health may be threatened by poisonous chemicals during production. Because of the fast-paced and rough manufacturing with unnatural materials, today, most pairs last no longer than a year. Like most waste, discarded jeans end up in landfills, where their decomposition releases greenhouse gas. Some governments are pursuing policies to make companies more responsible for worker pay and welfare, but unsustainable practices still run crazy throughout the fashion industry.