Beavers (河狸) are famous for building impressive dams in streams. They have a rare ability to transform the landscapes they live in. This is primarily because beavers need to use their dams to hide from predators (捕食者) like bears, wolves, and river otters. Beavers live in dome-shaped constructions within the ponds that can only be accessed by underwater entrances. Inside, they are safe from threats. Besides, they can also store food inside and keep warm in winter.

Beavers build dams up to 5 meters high, and the largest one, in Alberta, Canada, is 850 meters long. Most dams are built from pieces of wood, with stones at the base and a sealing layer of mud and plants on the upstream side. The dams are thicker at the bottom with a shallow slope on the upstream side, meaning that the weight of the water pushes down on the dam, keeping it in place and allowing it to hold back large volumes of water. Their engineering work is so effective that beaver dams can last for decades.

Beaver dams can promote the creation and development of stable wetland ecosystems, one of the most productive ecosystems in the world, which serve as the home of rare and endangered species. In addition, the dams can help water flow to the newly created ponds, thus, preventing flooding in areas downstream of the rivers where these dams are built. They also protect the land from soil erosion (侵蚀, 腐蚀) and block pollutants in the water flow downstream into major water bodies.

However, Ph. D. student Robert Needham, from the International Centre for Ecohydraulics Research at Southampton, expressed a great deal of his concern about the possibility of beaver dams blocking the upstream and downstream migration (迁移) of Atlantic salmon (鲑鱼) and trout during their reproduction seasons, as well as affecting habitat (栖息地) quality. Thus, people should control the construction of beaver dams, especially in human-inhabited areas, near agricultural fields and pasture lands.

Humans eat an astonishing amount of meat every year — some 800 billion pounds of it, enough flesh to fill roughly 28 million dump trucks. Our desire for meat, particularly in industrialized countries like the United States, is one reason why the planet is warming as fast as it is. Raising animals consumes a lot of land that could otherwise absorb carbon. Cows, sheep and goats give out heat-trapping methane (甲烷). And to grow the corn, soy and other plants that those animals eat, farmers use fertilizer (肥料) that gives off nitrous oxide, another planet-warming gas.

Cutting out meat sounds like an effective approach. But what would happen if everyone actually stopped eating meat tomorrow? Such a quick shift probably wouldn’t cause the sort of turmoil that would come if the planet immediately abandoned fossil fuels. But still, the consequence could be quite a mess, causing different problems.

Researchers say the economic damage caused by the sudden disappearance of meat would fall mainly on low-income countries with farming economies, like Niger or Kenya, where farming and raising livestock (家禽) are important sources of income. Getting rid of livestock overnight would not only deprive many people of essential nutrients, but also threaten food security, especially in regions like South Asia and sub-Saharan Africa. Besides, there’s the issue of cultural damage. Taking away meat, according to Wilson Warren, a history professor at Western Michigan University, would do more than just deprive Americans of hot dogs and hamburgers and Italians of salami.

Rejecting meat entirely, let alone immediately, isn’t an ideal solution to the climate crisis. Dutkiewicz, a political economist at the Pratt Institute, suggested using guidelines established by the EAT-Lancet Commission, an international group of scientists who have designed a diet intended to give people the nutrients they need without destroying the planet.

About 12% of the total global energy demand comes from heating and cooling homes and businesses. A new study suggests that using underground water to maintain comfortable temperatures could reduce consumption of natural gas and electricity in this section by 40% in the US. The approach is called ATES, short for aquifer thermal energy storage (含水层热能储存).

“We need storage to absorb energy from the sun and wind. It’s crucial to creating affordable, reliable, and deeply environmental-friendly electricity systems. Most people are interested in batteries and other kinds of electrical storage. But we were wondering whether there was any opportunity to use geothermal (地热的) energy storage,” said first author A.T.D Perera. “With ATES, energy can be stored for a long period of time, without adding an additional burden to the grid (输电网).”

ATES is a pleasantly simple concept that takes advantage of the heat-absorbing property of water and the natural geological features of the planet. You simply pull existing underground water up and heat it at the surface in the summer with environmental heat or energy. Then you send it back down. It stays fairly hot because the Earth is a good insulator (绝热体).

“Unlike above-ground tank-based water or ice storage systems, ATES will not need space. It’s also more efficient and can support larger communities in cooling or heating than traditional geothermal heat pump systems that rely on heat moving with the underground soil,” added co-author Hong Tianzhen.

A major beneft of ATES is that it will become more efficient as weather becomes more extreme in the coming years due to climate change. The hotter summers and severer winters could increase the amount of free thermal energy that can be stored with ATES. “It’s very much a realistic thing to do and this work is really about showing its value,” said Perera. “This technology is ready to go, so to speak. We just need to do it.”