如何讓撒哈拉沙漠再變綠洲

四川 蔣建平

主題語境：人與自然 篇幅：394詞 建議用時：6分鐘images/BZ_19_345_1539_378_1572.png

The Sahara is the world's largest hot desert, but parts of it could be made green if massive solar and wind farms set up shops there, a new study finds.These farms could increase rain in the Sahara, especially in the neighboring Sahel region, a semiarid area that lies south of the giant desert. This increase in precipitation, in turn, leads to an increase in vegetation (植被) cover, creating a positive feedback loop.

Researchers already knew that quantities of wind and solar farms can increase the heat and rainfall in the areas around them. But this new study modeled how wind and solar farms would affect the Sahara, while considering how green plants would respond to these changes. “Previous modeling studies have shown that large-scale wind and solar farms can produce significant climate change at continental scales,” the study's co-lead researcher Yan Li said. “But the lack of vegetation feedback could make the modeled climate impacts very different from their actual behavior.”

The model showed that wind farms caused localized air temperatures to warm. The solar farms would also have a positive effect on temperature and rainfall, the researchers noted. “We found that the large-scale installation （安裝） of solar and wind farms can bring more rainfall and promote vegetation growth in these regions,” the study's co-lead researcher Eugenia Kalnay, a distinguished professor at the University of Maryland, said in the statement. “The rainfall increase is a consequence of complex land-atmosphere interactions that occur because solar panels and wind turbines create rougher and darker land surfaces.”

The study's authors also modeled what would happen if wind and solar farms covered more than 3.4 million square miles (9 million square kilometers) of the Sahara. On average, the wind farms would generate about 3 terawatts (太瓦), while the solar farms would generate 79 terawatts of electrical power in one year, they found. That's a lot of energy.One terawatt can power about 10 billion 100-watt light bulbs at the same time. In 2017,the global energy demand was only 18 terawatts, so this is obviously much more energy than is currently needed worldwide.

If this model ever becomes a reality, the increase in rainfall and vegetation, combined with clean electricity as a result of solar and wind energy, could help agriculture,economic development and social well-being in the Sahara, Sahel, Middle East and other nearby regions.

Reading Check

1. What new factor is included in the study by Yan Li?

A. The behavior of researchers.

B. The response of plants to climate change.

C. The number of wind and solar farms.

D. The impacts of wind and solar farms on climate change.

2. What caused the rainfall increase in the model?

A. The improvement to the study.

B. The change in the temperature.

C. The growth of green trees and grass.

D. The interactions between the air and land surfaces.

3. What is paragraph 4 mainly about?

A. An advertisement for the electricity of the Sahara.

B. The potential of the Sahara.

C. Quantities of power from wind and solar farms.

D. The conclusion of a study about the desert.

4. What can we learn about the model from the last paragraph?

A. The main purpose of the model is to save energy.

B. The model is still on the way to becoming true.

C. The running of the model uses clean electricity.

D. The model is speeding up the development of the Sahara.

Language Study

Ⅰ. Difficult sentence in the text

The rainfall increase is a consequence of complex land-atmosphere interactions that occur because solar panels and wind turbines create rougher and darker land surfaces.降雨量的增加是復雜的陸地與大氣相互作用的結果，這是由于太陽能電池板和風力渦輪機造成了更粗糙和更黑暗的陸地表面。

【點石成金】本句是一個主從復合句，The rainfall increase is...是主句，that occur是限制性定語從句，關系代詞that代替先行詞land-atmosphere interactions，在從句中作主語，because solar panels and wind turbines...是原因狀語從句。

Ⅱ. Text-centered chunks

set up 建立；設立；創立

in turn 反過來；依次；輪流

lead to 導致；通向

respond to 對……作出反應

have a positive effect on 對……有積極的影響

on average 平均