| In 2008 and 2009 I published two articles researching a lull (停歇)in solar activity. At the time, there appeared to be some disagreement among scientists as to what effect this might have on humancaused global warming. Now climate scientists agree a less active sun won't have much of an effect. According to the reports from the IPCC, global climate is expected to warm between 4 and 10 degrees Fahrenheit by the year 2100. On the other hand, scientists show that the reduction in radioactive forcing due to low solar activity would reduce world temperature half a degree F if the lull in solar activity lasted until the end of the 21 century. It is highly unlikely the current lull in solar activity would have such a long period. "It is more likely that a new lull in solar activity would reduce the global temperature average of 0.2 Celsius by the end of 2100," commented Professor Stefan Rahmstorf, who was responsible for a study of a lull in solar activity effects on climate at the Institute for Research on the Impacts of Climate Change in Potsdam. In short, this small forcing is likely to have little, if any, observable effect on humancaused global warming,at most reducing the temperature increase to between 3.5 and 9.5 degrees F. The reason for the small effect on temperature is due to the fact that the difference between solar activity highs and lows changes solar output by less than one half of one percent. So the difference in the amount of energy coming out of the sun between solar highs and lows isn't very large. The result is that the human forcing on climate is many times larger than that caused by any natural difference in the sun. Generally if humancaused climate_change isn't controlled it can't be stopped by natural changes in the sun. |
| 1. What once caused the argument among scientists? |
| A. The reduction in world temperature. B. That humans are responsible for global warming. C. That humans are stronger than nature. D. Whether the lull in solar activity has effect on humancaused global warming. |
| 2. According to scientists, world temperature would fall a little if ________. |
| A. less CO2 is given off B. more trees are planted C. redioactive forcing becomes strong D. the lull in solar activity lasts a long period |
| 3. What can we learn from the passage? |
| A. The author is expert at writing science fiction. B. The current lull in solar activity will last very long. C. The power of humans is stronger than the sun on global warming. D. The IPCC reported that world temperature would fall greatly. |
| 4. What do the underlined words "climate change" refer to? |
| A. The flood. B. Global warming. C. The earthquake. D. Global environmental change. |
| 5. What does the passage mainly talk about? |
| A. The effect of global warming. B. An argument among scientists. C. That humans are a cause of global warming. D. That a less active sun cannot stop global warming. |
| 6. 用30词左右概括文章大意 |
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