首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Dr Corell heads a team of some 300 scientists who have spent the past four years investigating the matter in a process known as
Dr Corell heads a team of some 300 scientists who have spent the past four years investigating the matter in a process known as
admin
2013-06-12
47
问题
Dr Corell heads a team of some 300 scientists who have spent the past four years investigating the matter in a process known as the Arctic Climate Impact Assessment (ACIA). The group, drawn from the eight countries with territories inside the Arctic Circle, has just issued a report called "Impacts of a Warming Arctic", a lengthy summary of the principal scientific findings.
Scientists have long suspected that several factors lead to greater temperature swings at the poles than elsewhere on the planet. One is albedo (反照率)-the posh scientific name for how much sunlight is reflected by a planet’s surface, and how much is reflected. Most of the polar regions are covered in snow and ice, which are much more reflective than soil or ocean. If that snow melts, the exposure of dark earth (which absorbs heat) acts as a feedback loop that accelerates warming. A second factor that makes the poles special is that the atmosphere is thinner there than at the equator, and so less energy is required to warm it up. A third factor is that less solar energy is lost in evaporation at the frigid poles than in the steamy tropics.
Arctic warming may influence the global climate in several ways. One is that huge amounts of methane, a particularly potent greenhouse gas, are stored in the permafrost of the tundra. Although a thaw would allow forests to invade the tundra, which would tend to ameliorate any global warming that is going on (since trees capture carbon dioxide, the greenhouse gas most talked about in the context of climate change), a melting of the permafrost might also lead to a lot of trapped methane being released into the atmosphere, more than offsetting the cooling effects of the new forests.
Another worry is that Arctic warming will influence ocean circulation in ways that are not fully understood. One link in the chain is the salinity of sea water, which is decreasing in the north Atlantic thanks to an increase in glacial meltwaters. Because fresh water and salt water have different densities, this "freshening" of the ocean could change circulation patterns. The most celebrated risk is to the mid-Atlantic Conveyor Belt, a current which brings warm water from the tropics to north-western Europe, and which is responsible for that region’s unusually mild winters. Some of the ACIA’s experts are fretting over evidence of reduced density and salinity in waters near the Arctic that could adversely affect this current.
The biggest popular worry, though, is that melting Arctic ice could lead to a dramatic rise in sea level. Here, a few caveats are needed. For a start, much of the ice in the Arctic is floating in the sea already. Archimedes’s principle shows that the melting of this ice will make no immediate difference to the sea’s level, although it would change its albedo. Second, if land ice, such as that covering Greenland, does melt in large quantities, the process will take centuries. And third, although the experts are indeed worried that global warming might cause the oceans to rise, the main way they believe this will happen is by thermal expansion of the water itself.
Nevertheless, there is some cause for nervousness. As the ACIA researchers document, there are signs that the massive Greenland ice sheet might be melting more rapidly than was thought a few years ago. Cracks in the sheet appear to be allowing melt water to trickle to its base, explains Michael Oppenheimer, a climatologist at Princeton University who was not one of the report’s authors. That water may act as a lubricant, speeding up the sheet’s movement into the sea. If the entire sheet melted, the sea might rise by 6-7 metres. While acknowledging that disintegration this century is still an unlikely outcome, Dr Oppenheimer argues that the evidence of the past few years suggests it is more likely to happen over the next few centuries if the world does not reduce emissions of greenhouse gases. He worries that an accelerating Arctic warming trend may yet push the ice melt beyond an "irreversible on/off switch".
Not everybody wants to hear a story like that. But what people truly believe is happening can be seen in their actions better than in their words. One of the report’s most confident predictions is that the break-up of Arctic ice will open the region to long-distance shipping and, ironically, to drilling for oil and gas. It is surely no coincidence, then, that the Danish government, which controls Greenland, has just declared its intention to claim the mineral rights under the North Pole. It, at least, clearly believes that the Arctic ocean may soon be ice-free.
What does the word "caveat" in line 2, paragraph 5 most probably mean?
选项
A、A warning.
B、A qualification.
C、A explanation.
D、A formal notice filed by an interested party with a court or officer, requesting the postponement of a proceeding until the filer is heard.
答案
C
解析
第五段“caveat.”一词最有可能是什么意思?从下文中可以推断出是指“为防止误解而作出的解释”。
转载请注明原文地址:https://kaotiyun.com/show/Ew4O777K
0
专业英语八级
相关试题推荐
HistorybuffsstillwaxpoeticaboutthebrutalpatentbattlesacenturyagobetweentheWrightbrothersandGlennCurtis,anoth
Stratford-on-Avon,asweallknow,hasonlyoneindustry—WilliamShakespeare—.Buttherearetwodistinctlyseparateandin
AllofthefollowingworksarewrittenbyJamesJoyceEXCEPT
______meansthatlanguagecanbeusedtorefertothecontextsthatareremovedfromtheimmediatesituationofthespeaker,esp
StagesofSecondLanguageAcquisitionStageⅠ:【1】Period:1)inthisstage,moststudentsunderstand【2】thantheycanpro
Bynow,itshouldcomeasnosurprisewhenscientistsdiscoveryetanothercaseofexperiencechangingthebrain.Fromthesenso
InNorthernIreland______makeupthedominantgroup.
Severalyearsago,webeganconstructiononanewchurchbuilding.Inthebeginning,theworkmendugabigpitintheground
JohnSteinbeckwasawardedboththeNobelPrizeforLiteratureandthePulitzerPrizeforhismasterpiece______.
随机试题
设z=(x-2y)y,则.
A.血培养B.骨髓培养C.尿培养D.粪便培养E.胆汁培养
下列体现了五行相克规律的治法为
据《全国主体功能区规划》,全国主体功能区规划开发原则中,要按照建设环境友好型社会的要求,根据国土空间的不同特点,以保护自然生态为前提、以()为基础进行有度有序开发,走人与自然和谐的发展道路。
名镇和名村保护规划成果的组成包括()
自2007年10月9日到2008年6月12日,某期货公司允许邵某等9名客户在保证金不足的情况下继续进行期货交易,累计透支交易6000笔,累计透支金额约2亿元,期货公司累计收取手续费9000元。在上述交易期间,即2007年11月17日和2008年4月18日开
读书指导法
计算曲面积分,其中S是曲面x2+y2=R2及两平面z=R,z=一R(R>0)所围成立体表面的外侧。
在软件的生命周期中,通常分为【 】阶段、开发阶段和运行阶段3大阶段。
ThewritercametoLondonfrom______.Thewriter______.
最新回复
(
0
)