1 . 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.

2 . A new study by researchers at the University of British Columbia (UBC) and the University of Victoria has shown that common levels of traffic pollution can damage human brain function in only a matter of hours.

“For many decades, scientists thought the brain may be protected from the harmful effects of air pollution,” said senior study author Dr. Chris Carlsten. “This study, which is the first of its kind in the world, provides fresh evidence supporting a connection between air pollution and cognition.”

For the study, the researchers briefly exposed 25 healthy adults to diesel exhaust (柴油废气) and filtered air at different times in a laboratory setting. Brain activity was measured before and after each exposure using functional magnetic resonance imaging (fMRI).

The researchers analyzed changes in the brain’s default mode network (DMN), a set of inter-connected brain regions that play an important role in memory and internal thought. The fMRI revealed that participants had decreased functional connectivity in widespread regions of the DMN after exposure to diesel exhaust, compared to filtered air.

“We know that altered functional connectivity in the DMN has been associated with reduced cognitive performance and symptoms of depression, so it’s concerning to see traffic pollution interrupting these same networks,” said Dr. Jodie Gawryluk, a psychology professor at the University of Victoria and the study’s first author. “While more research is needed to fully understand the functional impacts of these changes, it’s possible that they may impair (损害) people’s thinking or ability to work.”

Notably, the changes in the brain were temporary and participants’ connectivity returned to normal after the exposure. Dr. Carlsten assumed that the effects could be long lasting where exposure is continuous. He said that people should be mindful of the air they’re breathing and take appropriate steps to minimize their exposure to potentially harmful air pollutants like car exhaust.

Water pollution

There are various causes of water pollution.

4 . California has been using recycled wastewater for many years. A team has used it to make ice surfaces for the game of hockey(冰球运动). It has been used to make snow for the sport of skiing. And farmers use it to water their crops. But it has not been used directly for drinking water.

Recently, California officials approved new rules to let water agencies recycle wastewater and put it right back into the pipes that carry drinking water to homes, schools, and businesses. It is a big step for California.

California’s new rules would let—but not require—water agencies to take wastewater, treat it, and then put it right back into the drinking water system. That means proving to people that recycled water is not only safe to drink but also not dirty. California would be just the second US state to permit this, following Colorado. It has taken officials more than 10 years to develop these rules, a process that included several studies by independent groups of scientists.

A project in San Diego is aiming to produce nearly half of the city’s water through recycling wastewater by 2035. And the Metropolitan Water District of Southern California aims to produce up to nearly 570 million liters(升)a day for its 19 million people. Adel Hagekhalil is with Metropolitan Water. He said the new rules will permit new projects that have not yet been considered.

California’s new rules require the wastewater be treated for all bacteria and viruses, even if they are not present in the wastewater. In fact, the treatment is so intense that it removes all of the minerals that make fresh drinking water taste good. That means the minerals need to be added back at the end of the process. Polhemus is a director of the drinking water group for the California Water Resources Control Board. “It’s at the same drinking water quality, and probably better in many instances,” he said, adding that it takes time and money to build these treatment centers. So, they will only be available for bigger cities at first.

6 . In the 20th century, conservationists set out to restore the Galapagos giant tortoise (巨型陆龟) on Española — and the island ecosystem. From 1963 to 2020, conservationists reintroduced nearly 2,000 Galapagos giant tortoises to Española. Since then, the tortoises have continued to multiply in the wild, causing the population to blossom to an estimated 3,000. They’ve also seen the ecological transformation of Española.

The tortoises’ return has also helped the critically endangered waved albatross (信天翁) — a species that multiplies only on Española. During the island’s woody times, Maud Quinzin, a conservation geneticist who has previously worked with Galapagos tortoises, says that people had to repeatedly clear the areas the seabirds use as runways to take off and land. Now, if the landing places are getting overgrown, they’ll move tortoises into the area to take care of it for them. The secret to this success is that — much like brown bears and elephants — giant tortoises are ecological architects. As they wander around, they change the landscape. They step on young trees and bushes before they can grow big enough to block the albatrosses’ way.

The giant tortoises likewise have a big impact on the giant species of prickly pear cactuses (仙人掌梨) that call Española home — one of the tortoises’ favorite foods and an essential resource for the island’s other inhabitants. When the tortoises eat the cactus’s fallen leaves, they prevent them from taking root and competing with their parents. And, after they eat the cactus’s fruit, they drop the seeds across the island, offering a protective shell of fertilizer.

The extent of these and other ecological effects of the tortoise are documented in a new study by James Gibbs, a conservation scientist of the giant tortoise restoration program. The results, he says, are a good sign for other rewilding projects that include giant tortoise restoration as a keystone of their efforts, such as those underway on other islands of the Galapagos and the Mascarene Islands in the Indian Ocean.

7 . Yellowstone National Park withdrew more than 10,000 visitors after a flash flood hit the park. Houses, roads and bridges were washed away, and the park’s gateway communities were cut off from roads. Even though scientists and land managers are caught off guard by the flood, unseen in 100 years of recorded history, they recognize the similarities between the situation their data predicted and the flood. They just didn’t expect the flood would occur this year.

While it will take more research to confirm if climate change made this flood event more extreme, the 2021 Greater Yellowstone Climate Assessment predicts significant changes in precipitation (降水), including when it will arrive and what forms it will take. Scientists expect more spring rain and less winter snow. The assessment also predicts increasing annual precipitation in Yellowstone National Park.

Changes have been already documented in the assessment. Since 1950, spring precipitation in the region has increased by 17-23 percent in April and May. Snowfall has dwindled even as overall annual precipitation has increased. That means rather than slowly increasing meltwater flowing to valleys during the summer months, rain tends to combine with melting snow, causing riskier events like the recent flood.

June precipitation this year is now at more than 400 percent above average in the parts of Montana and Wyoming that include Yellowstone National Park. And as temperatures rise, these rain-on-snow events are projected to become more frequent at higher elevations (海拔) in western North America, while lower snowpack will make them less frequent at low elevations.

Bruce Stein, chief scientist of the National Wildlife Federation, said several years ago, when he trained Yellowstone employees for climate planning, they focused on the features that drew visitors to the park — like bison and wolves. Roads, bridges, and houses being washed away was out of their consideration. “I think it’s urgent and necessary for the park to look ahead to plan for different situations that could possibly happen as the climate changes,” said Stein.

9 . Do you know that the oldest tree is a 5, 000-year old bristlecone pine (狐尾松) located in the forests of Nevada? Unfortunately, many of these precious old-growth trees are starting to disappear from our planet. The term old-growth refers to trees that are 150 years or older. This means that many of the trees on the Earth today are younger, smaller, and have shorter lifespans.

As the Earth’s temperature warms up due to climate change, it is having unintended effects on the world’s forests. When temperatures rise, trees close their pores (气孔) to prevent the loss of moisture, and this, in turn, slows down the process of photosynthesis (光合作用). As a result, these trees are shorter and grow slowly, as well as have a high deathrate. Climate change also increases the possibility of droughts and wildfires. After wildfires, it takes a while for the forest ecosystems to recover, and in some cases, the forests are lost permanently. Trees that are stressed are also susceptible (易受影响的) to attacks by bacteria (细菌). Finally, humans have changed the forest landscape through logging (伐木).

There are some who claim that increased greenhouse gas emission is helping trees grow faster because CO₂, is needed for photosynthesis. While some younger trees may benefit from this, we are seeing significantly more loss of forests than gain.

Old-growth forests are a storehouse of carbon, and when they die, the stored CO₂, is released into the air worsening the greenhouse effect. Older forests have higher biodiversity, which is beneficial as each organism has a role to play and there is a wide variety of species. As these forests disappear, species that once called them “home” are forced to relocate, affecting the biodiversity of those ecosystems. Unfortunately, some endangered species are unable to adapt and go extinct.

With trees dying continuously, will future generations miss out on the wonders of forests?