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Climate Change : The Long Reach

1 . Earth is warming. Sea levels are rising. There ‘s more carbon in the air, and Arctic ice　is melting faster than at any time in recorded history. Scientists who study the environment to　better gauge (評估) .Earth’s future climate now argue that these changes may not reverse for a very long time .

2 . People burn fossil fuels like coal and oil for energy. That burning releases carbon dioxide, a colorless gas . In the air , this gas traps heat at Earth’s surface . And the more carbon dioxide　released , the more the planet warms . If current consumption of fossil fuels doesn’t slow ,　the long-term climate impacts could last thousands of years-and be more severe than scientists had been expecting. Climatologist Richard Zeebe of the University of Hawaii at Manoa offers this conclusion in a new paper.

3. Most climate-change studies look at what’s going to happen in the next century or so .　During that time, changes in the planet’s environment could nudge(推動) global warming　even higher. For example: Snow and ice reflect sunlight back into space. But as these melt,　sunlight can now reach-- and warm –the exposed ground . This extra heat raises the air　temperature even more, causing even more snow to melt. This type of rapid exaggeration　of impacts is called a ‘fast feedback’.

4. Zeebe says it’s important to look at fast feedbacks. However, he adds, they’ re limited.　From a climate change perspective, ‘This century is the most important time for the next　few generations’, he told Science News “But the world is not ending in 2100”. For his new　study. Zeebe how focuses on “slow feedbacks”. While fast feedback events unfold over decades or centuries, slow feedbacks can take thousands of years. Melting of continental ice sheets and the migration of plant life --- as they relocate to more comfortable areas --- are two examples of　slow feedbacks.

5. Zeebe gathered information from previously published studies investigating how such processes played out over thousands of years during past dramatic changes in climate. Then　he came up with a forecast for the future that accounts for both slow and fast feedback processes. Climate forecasts that use only fast feedbacks predict a 4.5 degree Celsius (8.1 degree　Fahrenheit) change by the year 3000. But slow feedbacks added another 1.5 ℃ --　for a 6 total increase, Zeebe reports. He also found that slow feedback events will cause global warming to persist for thousands of years after　people run out of fossil fuels to burn.

23. Paragraph 2 ________ 答案：B

24. Paragraph 3 ________ 答案：C

25. Paragraph 4 ________ 答案：F

26. Paragraph 5 ________ 答案：A

A. A prediction of future climate change

B. Impact of burning fossil fuels

C. Fast feedbacks

D. Unpredictability of feedback processes

E. Rising of sea levels

F. Slow feedbacks

27. Arctic ice has never been melting so fast in _______ 答案：F

28. Melting of snow and ice enables sunlight to reach ________ 答案：E

29. Zeebe came up with his future climate prediction by analyzing ________ 答案：D

30. After fossil fuels are used up, global warming will continue for ________ 答案：B

A. rapid exaggeration of impacts

B. a very long time

C. the extra heat

D. previously published studies

E. the exposed ground

F. recorded history

（責(zé)任編輯：vstara）

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