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(zhǎng)目動(dòng)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(dāng)全球變暖終于變成現(xiàn)實(shí)的時(shí)候，一切都顯得異乎尋常。在一些地區(qū)，氣溫在不到一百年的時(shí)間里上升了好幾度。海平面上升了近400英尺，海水淹沒(méi)了住在海邊的人家，并迫使人們搬往內(nèi)地。因?yàn)楸泵馈W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(dòng)物通向?yàn)l臨滅絕的境地之后，也被迫放棄他們已導(dǎo)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(nóng)業(yè)：造成這種求生策略的改變的全球變暖現(xiàn)象在10000年前就發(fā)生過(guò)。

　　正當(dāng)本周環(huán)境保護(hù)主義者在里約熱內(nèi)盧召開會(huì)議思考全球氣候前景之際，地球科學(xué)家們?cè)趯?duì)過(guò)去氣候的變化以及這些變化怎樣改變了人類存在等問(wèn)題的認(rèn)識(shí)上正經(jīng)歷著革命性轉(zhuǎn)變。[2]研究者已經(jīng)開始拼湊出一幅富有啟發(fā)意義的演示地質(zhì)和天體巨大力量的圖畫：在已往的數(shù)億年期間，這兩種力量結(jié)合起來(lái)改變了地球環(huán)境，使之從熱到冷，從濕到干，然后在一段時(shí)間之后又如此反復(fù)，循環(huán)不止。

　　[3]最重要的是，科學(xué)家開始意識(shí)到氣候?qū)θ祟愡M(jìn)化曾產(chǎn)生重要影響。新的研究表明氣候變化幾乎在人類進(jìn)化的每個(gè)重要轉(zhuǎn)折點(diǎn)都起到關(guān)鍵作用：從6500萬(wàn)年前的初期靈長(zhǎng)目動(dòng)物到用雙腿直立走路的人類始祖，從人類腦容量的急劇擴(kuò)充到農(nóng)業(yè)的興起。的確，一些科學(xué)家爭(zhēng)論說(shuō)，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(shuō)也是全球氣候變化所推動(dòng)的結(jié)果。

　　新研究對(duì)于里約熱內(nèi)盧的環(huán)境峰會(huì)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(duì)于地球這顆行星來(lái)說(shuō)并不是新鮮事。在過(guò)去的1萬(wàn)年里氣候宜人的全球環(huán)境——在此期間，農(nóng)業(yè)、城市以及其他文明的標(biāo)志紛紛出現(xiàn)——只不過(guò)是在漫長(zhǎng)歲月中千差萬(wàn)別的種種氣候模式里的一小塊亮點(diǎn)而已。[4]/[5]事實(shí)上，以往的氣候變化模式顯示地球氣候幾乎注定要在將來(lái)發(fā)生巨大的變化——哪怕它并沒(méi)有受到人類活動(dòng)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