[填空题]

The science of climate change is easy. We burn millions of tons of fossil fuels(矿物燃料) a year, sending millions of carbon dioxide into the atmosphere. The gas acts like the windows of a greenhouse, retaining heat that would otherwise radiate(散发)away. Result: The world is warmer—half a degree or so in the past 100 years.
Think it doesn’t matter Your grandchildren will disagree. In the near term, this warning contributes to accidental weather. More storms here; more drought (干旱) there. Over time, the disastrous consequences may include melted ice caps and higher sea levels. No more icebergs, No more Miami.
With 4 96 of the world population, the United States produces 22 % of all greenhouse gas. Clearly, we bear some responsibility. Which is why, combined with the threat to future Americans, the White House this week outlined a new plan to reduce greenhouse gas emissions(排放).
The plan is painfully modest. It delays hard limits for

[单项选择] In the United States the science of climate change still remains a controversial issue. Part of the problems is that it is complex and hard to isolate its parts. We do know how vital it is to life. The atmosphere forms a gaseous, protective envelope around earth protecting the earth from the cold of space, from harmful ultraviolet light, and from all but the largest meteors. After traveling over 93 million miles, solar energy strikes the atmosphere and earth’’s surface, warming the planet and creating what is known as the "bio sphere" which is the region of earth capable of sustaining life. Atmospheric circulation is one important reason that life on earth can exist at higher latitudes because equatorial heat is transported poleward, moderating the climate. The atmosphere is not just a protector but also a great transporter. The transport of water vapor in the atmosphere is an important mechanism by which heat energy is redistributed poleward. Heat energy absorbed at the equator
A. sheltering effect
B. reviving effect
C. invigorating effect
D. cleansing effect

[填空题]When we are trying to change our diet, we usually will be anxious because we are nervous about ______.