We know that the earth has become warmer over the last century. The Intergovernmental Panel on Climate Change (IPCC), a group established by the World Meteorological Organization and the United Nations Environment Program, reports that the average surface temperature of the earth has increased during the twentieth century by 0.6°+ 0.2°C.(The + 0.2°C means that the increase might be as small as 0.4°C or as great as 0.8°C). This may seem like a small shift, but although regional and short—term temperatures do fluctuate(变动) over a wide range, global temperatures are generally quite stable. In fact, the difference between today’s average global temperature and the average global temperature during the last Ice Age is only about 5 degrees C. Indeed, it’s warmer today around the world than at any time during the past 1,000years, and the warmest years of the previous century have occurred within the past decade.
We also know that human activities—primarily the burning of fossil fuels—have increased the greenhouse gas content of the earth’s atmosphere significantly over the same period. Carbon dioxide is one of the most important greenhouse gases, which trap heat near the planet’s surface.
The vast majority of climate researchers agree with these overall findings. The scientific disagreements that do still exist primarily concern detailed aspects of the processes that make up these largely accepted general themes.
You can think of this website as a window into the world of scientific research. In this primer, you’ll find a general discussion of the physical processes underlying the earth’s climate, an outline of the kinds of data that may shed light on how the climate is changing—and the role of human activity in these changes—and a description a some of the questions and uncertainties that researchers continue to explore. This primer is organized into four interconnected sections: the Atmosphere; the Hydrosphere(水圈); the Cryosphere(低温层); and the Biosphere(生物层).
We know from the text that “IPCC”___.

A．engages in the climate and changes about the earth.

B．is a group by scientists who like to walk around the moon

C．works in the World Meteorological Organization

D．often greets the passers-by from the outer space

We know from the text that carbon dioxide ___.

A．is one of the most important greenhouse gases

B．has fossil fuels

C．traps cold near the planet’s surface

D．exist in human activities

From the text, we know when we say the temperature of something has increased by about 0.7+ 0.2°C, the + 0.2°C means___.

A．the increase might by as small as 0.3°C or as great as 0.7°C

B．the increase might by as small as 0.5°C or as great as 0.8°C

C．the increase might by as small as 0.5°C or as great as 0.9°C

D．the increase might by as small as 0.4 C or as great as 0.8°C

What would be the best title for this text?

A．What Are the Scientific Disagreements

B．You Can Think of This Website

C．What Do We Know about Global Climate Change?

D．The Vast Majority of Climate Researchers