12月GMAT閱讀機(jī)經(jīng)：地球降溫.

　　窩在被子里的你看著外面的呼嘯大風(fēng)是否不禁打了個(gè)寒顫呢?澳際小編就在這寒冬中為大家吹來(lái)一股GMAT機(jī)經(jīng)的暖風(fēng)，為大家分享關(guān)于地球降溫的機(jī)經(jīng)，希望大家能感受到這股暖意，并把它化為能量，在GMAT考試的道路上勇往直前。

　　V1：BY uclasdsu

　　另一個(gè)是CO2導(dǎo)致4000萬(wàn)年前地球變冷，是因?yàn)榕c水生成H2CO3, 腐蝕巖石。

　　對(duì)理科背景的，都很簡(jiǎn)單

　　V2: 還有一篇說(shuō)什么地球變暖。。。。第一段先說(shuō)什么一個(gè)假說(shuō)，說(shuō)是因?yàn)榈貧み\(yùn)動(dòng)。和板塊移動(dòng)什么的。。(太扯淡了)

　　第二段又說(shuō)了另外一種假說(shuō)，說(shuō)是天上什么的下來(lái)，下來(lái)之后不馬上回天上。。又去了海里。。。。

　　真心忘了，記得不好，待補(bǔ)充。。。。免得誤導(dǎo)大家。。。。。但我遇到的題基本都是第二段的。。。。

　　挺長(zhǎng)的。。。。不過(guò)難度一般。。。

　　V3：遇到地球降溫，CO2的影響的那一題。 建議可以直接看第二段，第一段貌似沒(méi)有出題點(diǎn)。 然后第二段真的是全文高亮。。

　　V4：JJ地球降溫那篇。 唔第二段真的是高亮(刷的一下四分之一電腦屏幕亮瞎樓主狗眼的那種亮)。首段：地球越來(lái)越冷了。提出一個(gè)老的解釋：大陸和海洋的變化(一堆比較，不過(guò)大意是海水面積減少，陸地面積增加，導(dǎo)致溫度降低)指出僅僅這一個(gè)原因是不夠的。次段提出一個(gè)新的觀點(diǎn)：是由于CO2的沉積導(dǎo)致了氣候變冷。(其實(shí)就是溫室效應(yīng)的逆過(guò)程) 機(jī)制部分解釋了Co2運(yùn)動(dòng)的方向，從大氣中的氣體到被裸露的巖石吸收，同時(shí)還要有水(這里有題)，的作用下變成H2CO3最后變成碳酸鈣沉積于巖石中，導(dǎo)致氣候變冷。有考到一題是說(shuō)什么情況下新的觀點(diǎn)才會(huì)真正有效?我選的是CO2沉積的速度大于co2釋放的速度(不要套用)。

　　考古(求確認(rèn))

　　2.2.1.★地球降溫**

　　V1Scarlettma

　　現(xiàn)在的climate越來(lái)越冷了，因?yàn)?種原因。第一段列出的是因?yàn)榇箨懓鍓K海洋的變化引起的，第二段就說(shuō)是因?yàn)榇髿鈱佣趸家鸬?，就說(shuō)二氧化碳到了海里面，然后被海洋生物還是什么吸收，然后又被排出，留在seabed上面，再影響氣候……好像是這意思，就說(shuō)這個(gè)周期是很長(zhǎng)很長(zhǎng)的。

　　1iamcrystal710題目考到什么削弱第二段里的觀點(diǎn)，有第二段可以推出什么結(jié)論，總之就是大多在第二段里找，注意下hundreds of million years，還有4000million years都是些細(xì)節(jié)定位的地方，在中間和靠后的都有信息要找。

　　2 200702061710：果然看見了傳說(shuō)中的整段HIGHLIGHT啊。那叫一個(gè)壯觀，屏幕都變黃色了。

　　3 gitarrelieber730 V37下面的陳述中除了哪個(gè)都支持了第二段中那個(gè)學(xué)派的觀點(diǎn)：A- 新的石頭(fresh rock)可以吸收更多的二氧化碳/B- 大陸和海洋的相對(duì)移動(dòng)造成地球降溫

　　4 gitarrelieber730 V37根據(jù)第二段的理論下面除了哪個(gè)都是正確的：A- chemical weathering 需要水/B- Uplift是吸收的二氧化碳的主要因素

　　文言文nowwsy "CO2和氣候變冷"前后類似, 只差確認(rèn)

　　V1 (綜合版)

　　兩段長(zhǎng)篇

　　科學(xué)家發(fā)現(xiàn)最近40million years，地球不再是原來(lái)那么warm和wet了(此處有題)，先給出了一個(gè)流派的若干解釋：隨著二氧化碳的增多，大氣的降水中融解了二氧化碳，這些水降到海面，被各種過(guò)程吸收，然后沉積到海底，雖然到海底這些c最終還是要回到大氣中，但是這個(gè)過(guò)程需要hundreds of millions of years(隱含40百萬(wàn)年對(duì)它來(lái)說(shuō)是相對(duì)短的過(guò)程，此處有題)，另外陸面也對(duì)二氧化碳的吸收起到一定作用，而且隨著內(nèi)海的面積逐漸減少，陸面的面積越來(lái)越大因而吸收c也越多。第一段的末尾說(shuō)這個(gè)解釋不錯(cuò)，但作為唯一的解釋未免不讓人信服。

　　第二段是講好像叫M R的人提出一種觀點(diǎn)，對(duì)第一段的解釋起到支持作用，他說(shuō)地質(zhì)演變抬高了陸地某些位置，高了之后會(huì)有更多的fresh巖石吸收c，而且因?yàn)樘Ц吡撕筮@些位置比較陡，降水可以更好的沖走這些吸收了c的巖石。提出的新觀點(diǎn)覺(jué)得有二個(gè)重要原因

　　a. weathering的過(guò)程　(即對(duì)第一段的解釋起到支持作用); b. 巖石陸地的上升strengthen了weathering的過(guò)程

　　1.一個(gè)題目在第一段，問(wèn)現(xiàn)在環(huán)境跟原來(lái)環(huán)境有什么區(qū)別，選擇較Warm, Wet(此題也許是取非題，問(wèn)現(xiàn)在的環(huán)境怎么樣，那以前的來(lái)取非)

　　2.第二段，這個(gè)過(guò)程(二氧化碳溶解沉入海底再回到大氣這個(gè)過(guò)程)需要hundreds of millions of years(隱含40百萬(wàn)年對(duì)它來(lái)說(shuō)是相對(duì)短的過(guò)程，此處有題)

　　3.有一個(gè)Except題(注意第二段中的機(jī)理討論部分，見版本6的總結(jié))

　　4.然后有一個(gè)應(yīng)該是取非條件的(注意第二段中的機(jī)理討論部分，見版本6的總結(jié))

　　5.R科學(xué)家提出，有邏輯題，以下哪項(xiàng)weaken了R的觀點(diǎn)，定位于二段后半部分. 注意R的觀點(diǎn)有兩個(gè)部分　a.weathering的過(guò)程　(即對(duì)第一段的解釋起到支持作用); b.巖石陸地的上升strengthen了weathering的過(guò)程.這題要削弱的應(yīng)該是第二個(gè)觀點(diǎn)

　　6.第二段全劃線，機(jī)理題

　　(疑似)原文未刪減gitarrelieber730 V37考后感：很有幫助，基本上和考試文章一致

　　節(jié)選自Plateau Uplift and Climate Change (Scientific American Magazine @ March 1991)

　　Author：William F. Ruddiman and John E. Kutzbach

　　During the past 40 million years, and particularly during the past 15 million years, this warm, wet climate largely disappeared. Colder climates and much greater regional extremes of precipitation have developed. What caused this cooling and diversification of climate and vegetation into a complex mosaic of many regionally distinctive types?

　　One school of thought focuses on the changing positions of the earth’s continents and oceans. The Atlantic Ocean has expanded at the expense of the Pacific Ocean, whereas an ancient equatorial sea that extended across much of Eurasia (called the Tethys Sea) has shrunk to become the modern, much smaller Mediterranean Sea. In addition, the fraction of continents flooded by shallow inland seas has slowly decreased, exposing large amounts of land and creating climates less moderated by the temperature-stabilizing fects of oceans. Computer model simulations show that changes in the arrangement of the continents and the size of inland seas can have important fects on global climate over very long intervals of geologic time. But they are significantly less convincing as sole explanations for the dramatic changes of the past 40 million years.

　　Another possibility is a long-term decline in the concentration of carbon dioxide in the atmosphere, which would lessen the amount of heat trapped by the atmosphere and lead to “greenhouse cooling.” The amount of carbon dioxide in the earth’s atmosphere over million-year timescales is controlled by two major processes. Chemical weathering of continental rocks removes carbon dioxide from the atmosphere and carries it in dissolved chemical from to the ocean, where it is taken in by marine biota and deposited in sediments on the seafloor. Tectonic activity eventually frees this trapped carbon dioxide, in the earth’s lithospheric plates transports the seafloor to ocean trenches, where subduction carries old crust and sediments down toward the earth’s hot interior. At great depths, the sediments melt, releasing carbon dioxide, which emerges from the volcanic islands that overlie the buried curst and rejoins the atmosphere, completing the cycle.

　　If the pace of seafloor spreading (and hence of subduction) slowed significantly, less carbon dioxide would be vented to the atmosphere, the atmosphere would become relatively depleted of carbon dioxide and temperatures would fall. In fact, globally averaged seafloor spreading rates slow little or no net change in the past 40 million years. Subduction and volcanism eventually return the carbon dioxide to the atmosphere, but this process requires a long time (tens to hundreds of millions of years) to complete.

　　Plateau uplift may alter climate by increasing chemical weathering of rocks, thereby reducing atmospheric carbon dioxide concentrations. Carbon dioxide combines with rainwater and ground water to form carbonic acid, which reacts with silicate minerals in rocks during weathering. The resulting bicarbonate ions drain into the oceans, where they are taken up by marine animals such as plankton and corals and eventually deposited on the seafloor. The net fect is that chemical weathering removes carbon dioxide from the atmosphere and locks it away at the bottom of the oceans.

　　Maureen Raymo proposed that uplift of plateaus and mountain ranges has increased the rate of chemical erosion of continental rock on the globally averaged basis. Uplift could enhance chemical weathering in several ways. Heavy monsoons, which develop at the margins of plateaus, unleash particularly intense rainfall. In these regions, uplift-related faulting and folding also expose fresh rock to the weathering process. Moreover, the steeper slopes created by plateau uplift cause faster runoff, which removes erosion products and intensifies the chemical attack on the rock. Raymo suggests that long-term uplift in Tibet and other regions may have increased the rate at which carbon dioxide is removed from the atmosphere. In this way, concentrations would have fallen even though the amount of carbon dioxide exhaled by volcanoes (as inferred from seafloor spreading rates) remained nearly constant. Falling carbon dioxide levels would reduce the ability of the atmosphere to retain heat, thereby amplifying the global cooling.

　　以上就是關(guān)于GMAT機(jī)經(jīng)的全部?jī)?nèi)容，考生朋友可以有選擇的看看，最后需要提醒各位的是，GMAT機(jī)經(jīng)雖然會(huì)對(duì)我們解題有所幫助，但是在考場(chǎng)中即使題目很像也要避免秒選，最后祝大家都能考出好成績(jī)。