Burning coal to provide energy adds planet-warming carbon dioxide, or CO2, to Earth’s atmosphere. As the planet heats up, experts warn that simply cutting greenhouse gas emissions(排放) will not be enough to avoid possibly disastrous levels of global warming. CO2 must also be obliterated from the atmosphere, they say.
Existing experimental machines that remove CO2 directly from the air are too costly to be widely used. But a new report from the U.S. National Academy of Sciences, Engineering and Medicine says effective carbon-removal technology already exists. It is not costly, or even complex science. It's forests.
The report explains that planting trees and overseeing forests are cost-effective ways to clean the air. They also work well across large areas. Forests used to cover much of the Appalachian Mountains in the eastern United States. In the state of West Virginia, a kind of mining known as strip mining(露天开采) left the land there bare, without trees. Now experts are working to bring back the forests that once covered much of the state.
West Virginia’s Monongahela National Forest is home to a rare group of trees. They are called virgin(原始的) woods; they have never been touched by humans. Shane Jones, a biologist with the U.S. Forest Service, says the trees there were missed by mistake when the surrounding forest was cut down for wood many years ago. That mistake turned out to be a good thing; red spruce(云杉) forests such as those in the Monongahela are extremely effective at taking CO2 out of the atmosphere and locking it into the soil.
Experts say, nature offers powerful tools to fight climate change.
28. What does the underlined word “obliterated” mean in Paragraph 1?
A. Prevented. B. Cleared. C. Produced. D. Stored.
29. What's the advantage of forests compared with the existing experimental machines?
A. They release more oxygen.
B. They clear more CO2.
C. They save more money.
D. They absorb CO2 faster.
30. Why does the author mention West Virginia in Paragraph 3?
A. To prove the place is unsuitable for human survival.
B. To stress planting trees is practical for clean air.
C. To indicate trees are difficult to live on such poor soil.
D. To show people in the state are now living a hard life.
31. What can we know about the red spruce trees?
A. They can only be found in Monongahela National Forest.
B. They were given the name virgin woods for beauty.
C. They were cut down for wood by farmers.
D. They could store carbon dioxide in the soil.