LP3 间冰期是否温和稳定
★★★☆
这篇题目都不难，就看考场上时间够不够。
时间就要从填空和短文章里省了~
题型优先级判定：
1.The passage is primarily concerned with 主旨目的，首段+各段首句，可以先做
2.Which of the following describes research that is most clearly analogous to the testing done by GRIP scientists? 不同层不同组成体现某个趋势变化，找到testing就做
3.According to the passage, which of the following is the most accurate statement of what scientists believed, prior to the GRIP findings, about Earth’s climate? 直接细节信息，定位第一句，注意审题。
4.The passage suggests that which of the following is most likely to have been true of the oxygen-16 and oxygen-18 isotopes found in the lower sections of the GRIP core? 看似考细节，就看盯不盯得住文章主旨了，需要知道第四段研究结论
文章分析：
para 1:
Based on evidence from tree rings, pollen samples and other records, scientists have for a long time assumed that interglacials—warm interludes between ice ages—were as mild and uniform as the Holocene, the present interglacial, has been for all of its 8,000 to 10,000 years. But new research in Greenland has put this assumption into question.
para 1: 观点点评，新研究质疑老观点；
这时候什么题都没法做。
继续读各段首句。
para 2:
Researchers on two teams, the Greenland Ice-Core Project (GRIP) and the Greenland Ice Sheet Project 2 (GISP2), have analyzed two different cylinders of ice, each about two miles in depth, pulled up from the Greenland ice sheet. 做研究
para 3:
Findings from the upper sections of the cores have confirmed what scientists already knew:climate during the last ice age fluctuated rapidly. 得结果
para 4:
Researchers’ clues to the Eemian climate come from measurements of the ratios of two slightly different types of oxygen, isotopes oxygen-16 and oxygen-18, preserved in theGRIP core. 讲原理
para 5:
However, finds from the lower section of GISP 2 do not confirm those of GRIP. 有转折，两组实验有不一致。
这时候可以尝试解第1题主旨题。
1.The passage is primarily concerned with 主旨目的，考结构，先看首段+各段首句
A.refuting certain scientific theories about Earth’s climatic history 看完选项可以作为备选
（关于refute，如果以这个主旨倒回去写一篇文章，呈现出来的就不是这篇文章的本来样子了）没有证据
B. outlining new findings concerning Earth’s climate during ice ages 说明文
C. discussing new research that may challenge a long-held scientific assumption about Earth’s climatic history 符合
D.describing the climatic changes that occurred when Earth moved from an ice age into an interglacial period 无关，说明文
E.reconciling conflicting evidence concerning climatic changes. 无关/没有证据
继续。
para 2:
Researchers on two teams, the Greenland Ice-Core Project (GRIP) and the Greenland Ice Sheet Project 2 (GISP2), have analyzed two different cylinders of ice, each about two miles in depth, pulled up from the Greenland ice sheet. Such ice cores trap gases, bits of dust, and other chemicals that were present in the snow that fell over Greenland for thousands of years and then became compressed into ice. By studying these components, scientists have obtained a detailed archive of many aspects of climate, including air temperatures, snowfall, and concentrations of greenhouses gases in the atmosphere.
para 2: 介绍新研究内容；
有两题可做。
2.Which of the following describes research that is most clearly analogous to the testing done by GRIP scientists? 不同层不同组成体现某个趋势变化
A.Scientists studying the formation of the Sahara desert measure the rate oftopsoil erosion in the region 没有不同组成
B.Scientists seeking to determine the age of a particular fossil measure thepercentage of its carbon atoms that have decayed 没有不同组成
C.Scientists researching vision in flies measure and compare the amounts ofvitamin A found in the retinas of several fly species. （视网膜）没有不同组成
D.Scientists investigating the development of life on Earth measure and comparethe amount of oxygen used by various organisms along the evolutionary scale. 没有不同组成
E. Scientists plotting the fluctuationsin rainfall in the early rain forests measure the presence of certain gasestrapped in tree rings of older trees.
3.According to the passage, which of the following is the most accurate statementof what scientists believed, prior to the GRIP findings, about Earth’s climate? 这一段实验做完了。实验之前的想法也就出来了。直接细节信息，定位全文第一句，注意审题。
A.Over the course of Earth’s history, interglacials have become progressively milder没有证据
B.Earth’s overall climate has been generally mild since the planet’s formation 没有证据
C.During both interglacials and ice ages, Earth’s climate has fluctuated violently. 相反
D. During ice ages, Earth’s climate has been highly variable, whereas during interglacials it has been mild and stable.
E.During interglacials, Earth’s climate has been highly variable, whereas during ice ages it has been uniformly cold and icy. 相反/没有证据
还有一题。
专注找O16 O18就好了。
para 3:
Findings from the upper sections of the cores have confirmed what scientists already knew:climate during the last ice age fluctuated rapidly. But scientists wereastonished by findings from the lower sections of the GRIP core, which provideda close look at an interglacial period other than our own, the Eemian interglacial, a period that lasted from 135,000 to 115,000 years ago. Data from GRIP seem to indicate that the Eemian climate swung at least as wildly as theclimate of ice age periods.
para 4:
①Researchers’ clues to the Eemian climate come from measurements of the ratios of two slightly different types of oxygen, isotopes oxygen-16 and oxygen-18, preserved in the GRIP core. ②These ratios register the fluctuations of air temperatures over the seasons and years. ③When the air was warm, vapor containing the heavier isotope, oxygen-18, condensed and formed precipitation, in the form of snow, more readily than did vapor containing oxygen-16. ④Thus, snow that fell during warmer periods contains proportionally more oxygen-18 than snow deposited during cold spells. ⑤Evidence of rapid climate shifts was also drawn from other sources, such as measurements of amounts of dust and calcium ions in the ice layers during cold periods: winds were strong, causing calcium-rich dust from loess deposits,which are composed of loose surface sediment, to blow across the ice sheet.Thus, differing amounts of dust in the layers also indicate changing climatic conditions.
para 5:
However, finds from the lower section of GISP 2 do not confirm those of GRIP. The wild climates wings shown by GRIP in the last interglacial are not seen in the GISP2 core. According to a GISP 2 scientist, the weight of flowing glacial ice above has stressed the lower sections of both cores. This may have deformed the lower ice, disrupting its annual layers and thereby causing the discrepancy between the records. Still, some climatologists believe GRIP’s record may be the more reliable of the two. It was drilled closer to a location called the ice divide, where stresses would have been lower, they say.
4.The passage suggeststhat which of the following is most likely to have been true of the oxygen-16 and oxygen-18 isotopes found in the lower sections of the GRIP core? 看似考细节，就看盯不盯得住文章主旨了，需要知道第四段研究结论
A.There was significantly more isotope oxygen-18 than isotope oxygen-16 in theice layers. 无证据
B.There was significantly more isotope oxygen-16 than isotope oxygen-18 in theice layers. 无证据
C. Ratios of isotopes oxygen-18 and oxygen-16 varied in the ice layers.
D.Layers containing isotope oxygen-18 placed stress on the layers containing isotope oxygen-16, possibly distorting them. 无证据
E.Isotope oxygen-16, being lighter, was located mainly in the upper layers, whereas oxygen-18 had settled into the lower layers. 无证据
背景拓展：
Holocene 全新世
全新世是地质时代最新阶段，第四纪二分的第二个世，开始于12000～10000年前持续至今。这一时期形成的地层称全新统，它覆盖于所有地层之上。全新世是1850年由哲尔瓦（P.Gervais）提出的，并为1885年国际地质大会正式通过。
全新世时间短，沉积物厚度小，但分布范围广。由于距今时代短，可应用几种有效的年代测定方法，因此，其地层划分比较详细、精确。全新世与更新世的界限，以第四纪冰期一次亚冰期结束、气候转暖为标志，因此又称为冰后期。全新世气候有轻微波动。海面变化与气候相一致，冰后期海面迅速上升，到距今11000年上升到－60米位置。距今6000年海面已接近现今位置，其后仅有轻微的变化。全新世时，人类已进入现代人阶段。
全新世的气候变化与人类社会的发展有密切的关系，因此详细研究全新世的气候和环境变化至关重要。研究全新时气候变化的主要材料包括高纬度和高海拔冰芯，湖泊沉积物纪录，树轮，石笋及其他洞穴沉积物，高沉积速率的深海沉积物等。
格陵兰岛的冰芯记录提供了年纪分辨率的气候变化，它显示了自新仙女木事件（见passage 60）以后全新世气温很稳定。但这种稳定的气温变化受到越来越多的挑战，有很多研究表明全新世的气候变化同样很明显，并且呈现一定的周期性。
The Greenland Ice Core Project (GRIP) was a multinational European research project, organized through the European Science Foundation. Funding came from 8 nations (Belgium, Denmark, France, Germany, Iceland, Italy, Switzerland, and United Kingdom), and from the European Union.
The project ran from 1989 to 1995, with drilling seasons from 1990 to 1992. GRIP successfully drilled a 3029-metre ice core to the bed of the Greenland ice sheet at Summit, Central Greenland from 1989 to 1992 at 72°34.74′N 37°33.92′W.
Studies of isotopes and various atmospheric constituents in the core have revealed a detailed record of climate variability reaching more than 100,000 years back in time. The results indicate that Holocene climate has been remarkably stable and have confirmed the occurrence of rapid climatic variation during the last ice age (the Wisconsin). Delta-O-18 variations observed in the core part believed to date from the Eemian Stage have not been confirmed by other records including the NGRIP core and are now believed not to represent climate events: the interglacial climate of Eemian Stage appears to have been as stable as the Holocene.
