CO2与气候变化(残狗/待确认)

　　V1

　　2) 是关于气候的，好像挺长的。说是compared to 40million years ago, the climate of the earth, especially the last 12 million years have become warmer and wetter with greater regional differences. (这里我忘了它是说40million以前更潮湿，还是更冷了，貌似是以前更冷，现在更潮湿). 之后说了一些theory to explain this change. One theory was that the carbon in the atmosphere is fast disappearing. When the carbon disappear, they sort of eventually go into the sea and somehow return the atmosphere. however this process will take xx millions of years. 然后最后一个paragraph described a "withering" 的现象(忘了怎么拼) 貌似说的就是最近(last 40 million years)，这个w很严重，所以carbon is disappearing faster. 这个w好像和什么石头有关系，我真的不记得了。。

　　我记得的问题包括：

　　a) what's the climate like before 40 million years ago -> 答案应该是colder with less regional differences

　　b) 好像还有一题是问what's the condition that's needed for the carbon to disappear

　　V2

　　气候变化：文章长，但没有生词，逻辑简单。

　　核心是说：气候变化的原因：是因为大气中的CO2被吸收了。

　　P1：减少现象：40M年前，气候更加wet和温暖，极端天气较少(较多?)。

　　近代气候反倒变冷了(所有情况取反)。

　　原因是大气中的CO2都被吸收了：被吸收到海底sea floor的矿物质里。

　　P2：一个科学家的相关研究，随着大陆地性的变化，一些地底的山脊(uplifting)升了起来。

　　这些山上的岩石进一步吸收空气中间的CO2，这个过程叫做weathering.

　　近代越来越多地底的岩石uplifing，导致更多CO2被岩石吸收。所以气候温度下降。

　　题目：古代的气候是什么：

　　答：更加wet和温暖，极端天气较少。

　　考古：

　　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 effects of oceans. Computer model simulations show that changes in the arrangement of the continents and the size of inland seas can have important effects 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 effect 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

　　【V6】科学家发现最近40million years，地球不再是原来那么warm和wet了(此处有题)，先给出了一个流派的若干解释：随着二氧化碳的增多，大气的降水中融解了二氧化碳，这些水降到海面，被各种过程吸收，然后沉积到海底，虽然到海底这些c最终还是要回到大气中，但是这个过程需要hundreds of millions of years(隐含40百万年对它来说是相对短的过程，此处有题)，另外陆面也对二氧化碳的吸收起到一定作用，而且随着内海的面积逐渐减少，陆面的面积越来越大因而吸收c也越多。第一段的末尾说这个解释不错，但作为唯一的解释未免不让人信服。

　　第二段是讲好像叫M R的人提出一种观点，对第一段的解释起到支持作用，他说地质演变抬高了陆地某些位置，高了之后会有更多的fresh岩石吸收c，而且因为抬高了后这些位置比较陡，降水可以更好的冲走这些吸收了c的岩石。提出的新观点觉得有二个重要原因

　　a. weathering的过程　(即对第一段的解释起到支持作用); b. 岩石陆地的上升strengthen了weathering的过程

　　1.一个题目在第一段，问现在环境跟原来环境有什么区别，选择较Warm, Wet(此题也许是取非题，问现在的环境怎么样，那以前的来取非)

　　2.第二段，这个过程(二氧化碳溶解沉入海底再回到大气这个过程)需要hundreds of millions of years(隐含40百万年对它来说是相对短的过程，此处有题)

　　3.有一个Except题(注意第二段中的机理讨论部分，见版本6的总结)

　　4.然后有一个应该是取非条件的(注意第二段中的机理讨论部分，见版本6的总结)

　　5.R科学家提出，有逻辑题，以下哪项weaken了R的观点，定位于二段后半部分. 注意R的观点有两个部分　a.weathering的过程　(即对第一段的解释起到支持作用); b.岩石陆地的上升strengthen了weathering的过程.这题要削弱的应该是第二个观点

　　6.第二段全划线，机理题

　　【版本一】JJ地球降温那篇。 唔第二段真的是高亮(刷的一下四分之一电脑屏幕亮瞎楼主狗眼的那种亮)。首段：地球越来越冷了。提出一个老的解释：大陆和海洋的变化(一堆比较，不过大意是海水面积减少，陆地面积增加，导致温度降低)指出仅仅这一个原因是不够的。次段提出一个新的观点：是由于CO2的沉积导致了气候变冷。(其实就是温室效应的逆过程) 机制部分解释了Co2运动的方向，从大气中的气体到被裸露的岩石吸收，同时还要有水(这里有题)，的作用下变成H2CO3最后变成碳酸钙沉积于岩石中，导致气候变冷。有考到一题是说什么情况下新的观点才会真正有效?我选的是CO2沉积的速度大于co2释放的速度(不要套用)。

　　【V4】

　　一篇关于global warming的文章，分析为何最近几百万年(记不清了)地球的温度会下降。给出的原因是因为二氧化碳更多的被储存在海底的沉积物中，因此空气中的二氧化碳含量降低，导致了地球温度的下降。第二段集中解释为何大气中二氧化碳含量会下降，主要原因是风化作用(weathering)，使得岩石中的C被转化，逐渐沉积到海底(一个复杂的过程，此处有一道except题，要耐心读)。文中还提到，一个能加快这种变化的原因是地壳的剧烈运动(造山运动)，在这种地方，风化作用更显著。这里应该有一道削弱题，我选的是在过去几百万年前的几百万年，同样有剧烈的地壳运动(A选项)。

　　【V6】

　　地球气候

　　Q4：哪个最能cast doubt on 那个关于weathering的理论?/哪项weaken了R的观点?(削弱题)

　　40 miles years前的什么什么变化并不比40 miles years前来的大。 ---对地，我就选这个

　　定位于二段后半部分，注意R的观点有两个部分，这题削弱的是第二个部分。

　　Q5：根据第二段的理论下面除了哪个都是正确的? ---记不清了

　　选项有：

　　1、化学风化(chemical weathering)需要水

　　2、地势抬高(uplift)是吸收的二氧化碳的主要因素

　　Q7：什么情况下新的观点才会真正有效?

　　我选的是CO2沉积的速度大于CO2释放的速度。----同选这个