Question

Endless treaties to cut carbon emissions and halt global warming have failed to turn the tide of pollution. Now scientists want to reshape our sea and skies to save the world from climate change.

Here are five important geo-engineering ideas that could change the face of the Earth. Realistic or not ? You decide.

Synthetic trees     Living trees absorb carbon dioxide slowly. Scientists are proposing to build synthetic trees, which would not grow of produce leaves，but absorb carbon dioxide. One synthetic tree would remove about 90，000 tons  of carbon dioxide in a year-the output of more than 15,000 cars and a thousand-fold improvement on the natural behavior of a real living tree.     Carbon sequestration(隔離)technology is likely to play a major role in the battle against climate change.  But critics say that engineers could end up using more energy in making the synthetic trees than they would save.

 

Sea grass      Blooms of plankton are the grasslands of the oceans.  They absorb carbon dioxide, die and then sink to the seabed carrying the carbon dioxide they absorbed during their lifetimes. Increase such blooms and you could take out more carbon dioxide from the atmosphere, scientists argue.     The favored method for stimulating plankton growth is to use iron fertilizers. Several groups of US entrepreneurs have begun experiments pumping iron compounds(化合物)into the sea.     But some critics warn that the iron compounds added to the sea might cause serious pollution.

 

Cloud shield     Before reaching the Earth, part of the incoming solar radiation is reflected by the clouds in the sky. As the Earth warms up, scientists plan to spray seawater into the sky to increase cloud cover. It's estimated that in this way cloud cover can increase by 4 percent-enough to shield the Earth from solar radiation.     This plan is cheap and relatively low-tech. But scientists say this could cause other dangers, such as changing weather patterns.

 

Ocean pumps     Cold ocean water contains more life forms than warmer water. Such creatures could help absorb CO2. SO scientists plan t pump cold ocean water from the deep sea up to the surface. The life forms in cold water would absorb CO2, die and then sink to the seabed, storing the carbon away for thousands of years.     Biologists say the scheme could threaten sea life, in particular whales and porpoises（海豚）.

 

Mirrors     Besides making clouds, scientists are trying other ways to block the sun's radiation. One of the most ambitious ideas involves firing giant mirrors into orbit. The special high-tech mirrors would filter infrared radiation.     But such a process would be extremely expensive. To produce a 1 percent cut in solar radiation, scientists would have to install a total mirror surface area of 600,000 square miles.

 

64. The word “shield” underlined in this article is least likely to be replaced by    .

    A. guard    B. protect    C. prevent    D. defend

65. From the above, which statement is not true?

    A. Synthetic trees would not grow or produce leaves

    B. Scientists have been trying to save the world from climate change

    C. The plan of cloud shield is cheap and relatively low-tech

    D. Warmer ocean contains more life forms than cold water

66. From the view of reducing pollution, which is the realistic choice used to save us?

    A. Synthetic trees        B. Ocean pumps

    C. Sea grass               D. Mirrors

67. Of the five idea，which seems more ambitious and absurd from the aspect of cost?

A. Mirrors         B. Cloud shield     C. Sea grass        D. Synthetic trees

Answer 1

CDCA