As environmentalists convene in Rio de Janeiro this week to ponder the global climate of thefuture, earth scientists are in the midst of a revolution in understanding how climate haschanged in the past-and how those changes have transformed human existence. Researchershave begun to piece together an illuminating picture of the powerful geological andastronomical forces that have combined to change the planet's environment from hot tocold, wet to dry and back again over a time period stretching back hundreds of millions of years.

　　Most important. scientists are beginning to realize that the climatic changes have bad a majorimpact on the evolution of the human species. New research now suggests that climate shiftshave played a key role in nearly every significant turning point in human evolution: from thedawn of primates(靈長目動物) some 65 million years ago to human ancestors rising up to walkon two legs. from the huge expansion of the human brain to the rise of agriculture. Indeed,the human history has not been merely touched by global climate change, some scientistsargue, it has in some instances been driven by it.

　　The new research has profound implications for the environment summit in Rio. Amongother things, the findings demonstrate that dramatic climate change is nothing new forplanet Earth. The benign(宜人的) global environment that has existed over the past 10,000years-during which agriculture. writing, cities and most other features of civilization appeared-isa mere bright spot in a much larger pattern of widely varying climate over the ages. In fact, thepattern of climate change in the past reveals that Earth's climate will almost certainly gothrough dramatic changes in the future-even without the influence of human activity.

　　當全球變暖終于變成現實的時候，一切都顯得異乎尋常。在一些地區，氣溫在不到一百年的時間里上升了好幾度。海平面上升了近400英尺，海水淹沒了住在海邊的人家，并迫使人們搬往內地。因為北美、歐洲扣亞洲植被急劇變化，所以沙漠在全球肆虐。[1]人類在將其周圍的許多種動物通向瀕臨滅絕的境地之后，也被迫放棄他們已導致饑荒、疾病的舊有生活方式而選擇全新的求生策略。這種策略就是農業：造成這種求生策略的改變的全球變暖現象在10000年前就發生過。

　　正當本周環境保護主義者在里約熱內盧召開會議思考全球氣候前景之際，地球科學家們在對過去氣候的變化以及這些變化怎樣改變了人類存在等問題的認識上正經歷著革命性轉變。[2]研究者已經開始拼湊出一幅富有啟發意義的演示地質和天體巨大力量的圖畫：在已往的數億年期間，這兩種力量結合起來改變了地球環境，使之從熱到冷，從濕到干，然后在一段時間之后又如此反復，循環不止。

　　[3]最重要的是，科學家開始意識到氣候對人類進化曾產生重要影響。新的研究表明氣候變化幾乎在人類進化的每個重要轉折點都起到關鍵作用：從6500萬年前的初期靈長目動物到用雙腿直立走路的人類始祖，從人類腦容量的急劇擴充到農業的興起。的確，一些科學家爭論說，人類歷史不僅受到全球氣候變化的影響，人類歷史在某種程度上說也是全球氣候變化所推動的結果。

　　新研究對于里約熱內盧的環境峰會具有深刻的啟示。研究成果之一就是它表明巨大的氣候變化對于地球這顆行星來說并不是新鮮事。在過去的1萬年里氣候宜人的全球環境——在此期間，農業、城市以及其他文明的標志紛紛出現——只不過是在漫長歲月中千差萬別的種種氣候模式里的一小塊亮點而已。[4]/[5]事實上，以往的氣候變化模式顯示地球氣候幾乎注定要在將來發生巨大的變化——哪怕它并沒有受到人類活動的影響。

　　1.Farming emerged as a survival strategy because man had been obliged__________.

　　A) to give up his former way of life

　　B) to leave the coastal areas

　　C) to follow the ever-shifting vegetation

　　D) to abandon his original settlement

　　2. Earth scientists have come to understand that climate____________.

　　A)is going through a fundamental change

　　B)has been getting warmer for 10,000 years

　　C) will eventually change from hot to cold

　　D) has gone through periodical changes

　　3.Scientists believe that human evolution________.

　　A) has seldom been accompanied by climatic changes

　　B) has exerted little influence on climatic changes

　　C) has largely been affected by climatic changes

　　D) has had a major impact on climatic changes

　　4.Evidence of past climatic changes indicates that__________.

　　A) human activities have accelerated changes of Earth's environment

　　B) Earth’s environment will remain mild despite human interference

　　C) Earth's climate is bound to change significantly in the future

　　D) Earth's climate is unlikely to undergo substantial changes in the future

　　5.The message the author wishes to convey in the passage is that______________.

　　A) human civilization remains glorious though it is affected by climatic changes

　　B) mankind is virtually helpless in the face of the dramatic changes of climate

　　C) man bas to limit his activities to slow down the global warming process

　　D) human civilization will continue io develop in spite of the changes of nature