California Condor’s Shocking Recovery
California condors are North America’s largest birds, with wind-length of up to 3 meters. In the 1980s, electrical lines and lead poisoning(铅中毒) nearly drove them to dying out. Now, electric shock training and medical treatment are helping to rescue these big birds.
In the late 1980s, the last few condors were taken from the wild to be bred(繁殖). Since 1992, there have been multiple reintroductions to the wild, and there are now more than 150 flying over California and nearby Arizona, Utah and Baja in Mexico.
Electrical lines have been killing them off. “As they go in to rest for the night, they just don’t see the power lines,” says Bruce Rideout of San Diego Zoo. Their wings can bridge the gap between lines, resulting in electrocution(电死) if they touch two lines at once.
So scientists have come up with a shocking idea. Tall poles, placed in large training areas, teach the birds to stay clear of electrical lines by giving them a painful but undeadly electric shock. Before the training was introduced, 66% of set-freed birds died of electrocution. This has now dropped to 18%.
Lead poisonous has proved more difficult to deal with. When condors eat dead bodies of other animals containing lead, they absorb large quantities of lead. This affects their nervous systems and ability to produce baby birds, and can lead to kidney(肾) failures and death. So condors with high levels of lead are sent to Los Angeles Zoo, where they are treated with calcium EDTA, a chemical that removes lead from the blood over several days. This work is starting to pay off. The annual death rate for adult condors has dropped from 38% in 2000 to 5.4% in 2011.
Rideout’s team thinks that the California condors’ average survival time in the wild is now just under eight years. “Although these measures are not effective forever, they are vital for now,” he says. “They are truly good birds that are worth every effort we put into recovering them. ”
1.California condors attract researchers’ interest because they _________.
A. are active at night
B. had to be bred in the wild
C. are found only in California
D. almost died out in the 1980s
2.Researchers have found electrical lines are _________.
A. blocking condors’ journey home
B. big killers of California condors
C. rest places for condors at night
D. used to keep condors away
3.According to Paragraph 5, lead poisoning _________.
A. makes condors too nervous to fly
B. has little effect on condors’ kidneys
C. can hardly be gotten rid of from condors’ blood
D. makes it difficult for condors to produce baby birds
4.This passage shows that _________.
A. the average survival time of condors is satisfactory
B. Rideout’s research interest lies in electric engineering
C. the efforts to protect condors have brought good results
D. researchers have found the final answers to the problem
Old problem，new approaches
While clean energy is increasingly used in our daily life，global warming will continue for some decades after CO2 emissions (排放) peak. So even if emissions were to begin to decrease today，we would still face the challenge of adapting to climate change. Here I will stress some smarter and more creative examples of climate adaptation.
When it comes to adaptation，it is important to understand that climate change is a process. We are therefore not talking about adapting to a new standard，but to a constantly shifting set of conditions. This is why, in part at least，the US National Climate Assessment says that：“There is no ‘onesize fits all’ adaptation.” Nevertheless，there are some actions that offer much and carry little risk or cost.
Around the world, people are adapting in surprising ways，especially in some poor countries. Floods have become more damaging in Bangladesh in recent decades. Mohammed Rezwan saw opportunity where others saw only disaster. His notforprofit organization runs 100 river boats that serve as floating libraries，schools，and health clinics，and are equipped with solar panels and other communicating facilities. Rezwan is creating floating connectivity(连接) to replace flooded roads and highways. But he is also working at a far more fundamental level：his staff show people how to make floating gardens and fish ponds to prevent starvation during the wet season.
Elsewhere in Asia even more astonishing actions are being taken. Chewang Norphel lives in a mountainous region in India, where he is known as the Ice Man. The loss of glaciers (冰川) there due to global warming represents an enormous threat to agriculture. Without the glaciers, water will arrive in the rivers at times when it can damage crops. Norphel's inspiration came from seeing the waste of water over winter, when it was not needed. He directed the wasted water into shallow basins where it froze, and was stored until the spring. His fields of ice supply perfectly timed irrigation(灌溉) water. Having created nine such ice reserves, Norphel calculates that he has stored about 200，000m3 of water. Climate change is a continuing process, so Norphel's ice reserves will not last forever. Warming will overtake them. But he is providing a few years during which the farmers will, perhaps, be able to find other means of adapting.
Increasing Earth's reflectiveness can cool the planet. In southern Spain the sudden increase of greenhouses (which reflect light back to space) has changed the warming trend locally, and actually cooled the region. While Spain as a whole is heating up quickly, temperatures near the greenhouses have decreased. This example should act as an inspiration for all cities. By painting buildings white, cities may slow down the warming process.
In Peru, local farmers around a mountain with a glacier that has already fallen victim to climate change have begun painting the entire mountain peak white in the hope that the added reflectiveness will restore the lifegiving ice. The outcome is still far from clear. But the World Bank has included the project on its list of “100 ideas to save the planet”．
More ordinary forms of adaptation are happening everywhere. A friend of mine owns an area of land in western Victoria. Over five generations the land has been too wet for cropping. But during the past decade declining rainfall has allowed him to plant highly profitable crops. Farmers in many countries are also adapting like this—either by growing new produce, or by growing the same things differently. This is common sense. But some suggestions for adapting are not. When the polluting industries argue that we've lost the battle to control carbon pollution and have no choice but to adapt, it's a nonsense designed to make the case for business as usual.
Human beings will continue to adapt to the changing climate in both ordinary and astonishing ways. But the most sensible form of adaptation is surely to adapt our energy systems to emit less carbon pollution. After all, if we adapt in that way, we may avoid the need to change in so many others.
1.The underlined part in Paragraph 2 implies ________．
A.adaptation is an everchanging process
B.the cost of adaptation varies with time
C.global warming affects adaptation forms
D.adaptation to climate change is challenging
2.What is special with regard to Rezwan's project?
A.The project receives government support.
B.Different organizations work with each other.
C.His organization makes the best of a bad situation.
D.The project connects flooded roads and highways.
3.What did the Ice Man do to reduce the effect of global warming?
A.Storing ice for future use.
B.Protecting the glaciers from melting.
C.Changing the irrigation time.
D.Postponing the melting of the glaciers.
4.What do we learn from the Peru example?
A.White paint is usually safe for buildings.
B.The global warming trend cannot be stopped.
C.This country is heating up too quickly.
D.Sunlight reflection may relieve global warming.
5.According to the author, polluting industries should ________．
A.adapt to carbon pollution
B.plant highly profitable crops
C.leave carbon emission alone
D.fight against carbon pollution
6.What's the author's preferred solution to global warming?
A.Setting up a new standard.
B.Reducing carbon emission.
C.Adapting to climate change.
D.Monitoring polluting industries.
Plastic-Eating Worms
Humans produce more than 300 million tons of plastic every year. Almost half of that winds up in landfills(垃圾填埋场), and up to 12 million tons pollute the oceans. So far there is no effective way to get rid of it, but a new study suggests an answer may lie in the stomachs of some hungry worms.
Researchers in Spain and England recently found that the worms of the greater wax moth can break down polyethylene, which accounts for 40% of plastics. The team left 100 wax worms on a commercial polyethylene shopping bag for 12 hours, and the worms consumed and broke down about 92 milligrams, or almost 3% of it. To confirm that the worms’ chewing alone was not responsible for the polyethylene breakdown, the researchers made some worms into paste(糊状物) and applied it to plastic films. 14 hours later the films had lost 13% of their mass — apparently broken down by enzymes (酶) from the worms’ stomachs. Their findings were published in Current Biology in 2017.
Federica Bertocchini, co-author of the study, says the worms’ ability to break down their everyday food — beeswax — also allows them to break down plastic. ＂Wax is a complex mixture, but the basic bond in polyethylene, the carbon-carbon bond, is there as well, ＂she explains, ＂The wax worm evolved a method or system to break this bond. ＂
Jennifer DeBruyn, a microbiologist at the University of Tennessee, who was not involved in the study, says it is not surprising that such worms can break down polyethylene. But compared with previous studies, she finds the speed of breaking down in this one exciting. The next step, DeBruyn says, will be to identify the cause of the breakdown. Is it an enzyme produced by the worm itself or by its gut microbes(肠道微生物)?
Bertocchini agrees and hopes her team’s findings might one day help employ the enzyme to break down plastics in landfills. But she expects using the chemical in some kind of industrial process — not simply ＂millions of worms thrown on top of the plastic.＂
1.What can we learn about the worms in the study?
A.They take plastics as their everyday food.
B.They are newly evolved creatures.
C.They can consume plastics.
D.They wind up in landfills.
2.According to Jennifer DeBruyn, the next step of the study is to .
A.identify other means of the breakdown
B.find out the source of the enzyme
C.confirm the research findings
D.increase the breakdown speed
3.It can be inferred from the last paragraph that the chemical might .
A.help to raise worms
B.help make plastic bags
C.be used to clean the oceans
D.be produced in factories in future
4.What is the main purpose of the passage?
A.To explain a study method on worms.
B.To introduce the diet of a special worm.
C.To present a way to break down plastics.
D.To propose new means to keep eco-balance.
How does an ecosystem(生态系统) work? What makes the populations of different species the way they are? Why are there so many flies and so few wolves? To find an answer, scientists have built mathematical models of food webs, noting who eats whom and how much each one eats.
With such models, scientists have found out some key principles operating in food webs. Most food webs, for instance, consist of many weak links rather than a few strong ones. When a predator(掠食动物) always eats huge numbers of a single prey(猎物), the two species are strongly linked; when a predator lives on various species, they are weakly linked. Food webs may be dominated by many weak links because that arrangement is more stable over the long term. If a predator can eat several species, it can survive the extinction(灭绝) of one of them. And if a predator can move on to another species that is easier to find when a prey species becomes rare, the switch allows the original prey to recover. The weak links may thus keep species from driving one another to extinction.
Mathematical models have also revealed that food webs may be unstable, where small changes of top predators can lead to big effects throughout entire ecosystems. In the 1960s, scientists proposed that predators at the top of a food web had a surprising amount of control over the size of populations of other species—including species they did not directly attack.
And unplanned human activities have proved the idea of top-down control by top predators to be true. In the ocean, we fished for top predators such as cod on an industrial scale, while on land, we killed off large predators such as wolves. These actions have greatly affected the ecological balance.
Scientists have built an early-warning system based on mathematical models. Ideally, the system would tell us when to adapt human activities that are pushing an ecosystem toward a breakdown or would even allow us to pull an ecosystem back from the borderline. Prevention is key, scientists say, because once ecosystems pass their tipping point(临界点), it is remarkably difficult for them to return.
1.What have scientists discovered with the help of mathematical models of food webs?
A.The living habits of species in food webs.
B.The rules governing food webs of the ecosystems.
C.The approaches to studying the species in the ecosystems.
D.The differences between weak and strong links in food webs.
2.A strong link is found between two species when a predator ________.
A.has a wide food choice
B.can easily find new prey
C.sticks to one prey species
D.can quickly move to another place
3.What will happen if the populations of top predators in a food web greatly decline?
A.The prey species they directly attack will die out.
B.The species they indirectly attack will turn into top predators.
C.The living environment of other species will remain unchanged.
D.The populations of other species will experience unexpected changes.
4.What conclusion can be drawn from the examples in Paragraph 4?
A.Uncontrolled human activities greatly upset ecosystems.
B.Rapid economic development threatens animal habitats.
C.Species of commercial value dominate other species.
D.Industrial activities help keep food webs stable.
5.How does an early-warning system help us maintain the ecological balance?
A.By getting illegal practices under control.
B.By stopping us from killing large predators.
C.By bringing the broken-down ecosystems back to normal.
D.By signaling the urgent need for taking preventive action.
By the end of the century，if not sooner，the world’s oceans will be bluer and greener thanks to a warming climate，according to a new study.
At the heart of the phenomenon lie tiny marine microorganisms(海洋微生物) called phytoplankton. Because of the way light reflects off the organisms，these phytoplankton create colourful patterns at the ocean surface. Ocean colour varies from green to blue，depending on the type and concentration of phytoplankton. Climate change will fuel the growth of phytoplankton in some areas，while reducing it in other spots，leading to changes in the ocean's appearance.
Phytoplankton live at the ocean surface，where they pull carbon dioxide(二氧化碳) into the ocean while giving off oxygen. When these organisms die，they bury carbon in the deep ocean，an important process that helps to regulate the global climate. But phytoplankton are vulnerable to the ocean's warming trend. Warming changes key characteristics of the ocean and can affect phytoplankton growth，since they need not only sunlight and carbon dioxide to grow，but also nutrients.
Stephanie Dutkiewicz，a scientist in MIT's Center for Global Change Science，built a climate model that projects changes to the oceans throughout the century. In a world that warms up by 3℃，it found that multiple changes to the colour of the oceans would occur. The model projects that currently blue areas with little phytoplankton could become even bluer. But in some waters，such as those of the Arctic，a warming will make conditions riper for phytoplankton，and these areas will turn greener. “Not only are the quantities of phytoplankton in the ocean changing. ”she said，“but the type of phytoplankton is changing. ”
1.What are the first two paragraphs mainly about?
A. The various patterns at the ocean surface.
B. The cause of the changes in ocean colour.
C. The way light reflects off marine organisms.
D. The efforts to fuel the growth of phytoplankton.
2.What does the underlined word “vulnerable” in Paragraph 3 probably mean?
A. Sensitive. B. Beneficial
C. Significant D. Unnoticeable
3.What can we learn from the passage?
A. Phytoplankton play a declining role in the marine ecosystem.
B. Dutkiewicz's model aims to project phytoplankton changes
C. Phytoplankton have been used to control global climate
D. Oceans with more phytoplankton may appear greener.
4.What is the main purpose of the passage？
A. To assess the consequences of ocean colour changes
B. To analyse the composition of the ocean food chain
C. To explain the effects of climate change on oceans
D. To introduce a new method to study phytoplankton
California has lost half its big trees since the 1930s, according to a study to be published Tuesday and climate change seems to be a major factor(因素).
The number of trees larger than two feet across has declined by 50 percent on more than 46, 000 square miles of California forests, the new study finds. No area was spared or unaffected, from the foggy northern coast to the Sierra Nevada Mountains to the San Gabriels above Los Angeles. In the Sierra high country, the number of big trees has fallen by more than 55 percent; in parts of southern California the decline was nearly 75 percent.
Many factors contributed to the decline, said Patrick McIntyre, an ecologist who was the lead author of the study. Woodcutters targeted big trees. Housing development pushed into the woods. Aggressive wildfire control has left California forests crowded with small trees that compete with big trees for resources(资源).
But in comparing a study of California forests done in the 1920s and 1930s with another one between 2001 and 2010, McIntyre and his colleagues documented a widespread death of big trees that was evident even in wildlands protected from woodcutting or development.
The loss of big trees was greatest in areas where trees had suffered the greatest water shortage. The researchers figured out water stress with a computer model that calculated how much water trees were getting in comparison with how much they needed, taking into account such things as rainfall, air temperature, dampness of soil, and the timing of snowmelt(融雪).
Since the 1930s, McIntyre said, the biggest factors driving up water stress in the state have been rising temperatures, which cause trees to lose more water to the air, and earlier snowmelt, which reduces the water supply available to trees during the dry season.
1.What is the second paragraph mainly about?
A.The seriousness of big-tree loss in California.
B.The increasing variety of California big trees.
C.The distribution of big trees in California forests.
D.The influence of farming on big trees in California.
2.Which of the following is well-intentioned but may be bad for big trees?
A.Ecological studies of forests.
B.Banning woodcutting.
C.Limiting housing development.
D.Fire control measures.
3.What is a major cause of the water shortage according to McIntyre?
A.Inadequate snowmelt. B.A longer dry season.
C.A warmer climate. D.Dampness of the air.
4.What can be a suitable title for the text?
A.California’s Forests: Where Have All the Big Trees Gone?
B.Cutting of Big Trees to Be Prohibited in California Soon
C.Why Are the Big Trees Important to California Forests?
D.Patrick McIntyre: Grow More Big Trees in California
