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
Human beings have little direct control over the volume of water in the atmosphere. But we produce other greenhouse gases that i
Human beings have little direct control over the volume of water in the atmosphere. But we produce other greenhouse gases that i
admin
2009-06-15
38
问题
Human beings have little direct control over the volume of water in the atmosphere. But we produce other greenhouse gases that intensify the effect. The IPCC estimates that rising CO2 emissions, mostly from burning fossil fuels, account for about 60 percent of the warming observed since 1850, Carbon dioxide concentration has been increasing by about 0.3 percent a year, and it is now about 30 percent higher than it was before the industrial revolution.
2. The relentless accumulation of greenhouse gases has led the IPCC to project that in the next hundred years average global temperatures will rise by 1 to 3.5 degrees C. That may not
seem like much. Yet the "little ice age," an anomalous cold snap that peaked from 1570 to 1730 and forced European farmers to abandon their fields, was caused by a change of only half a degree.
3. The compeer models used to project greenhouse effects far into the future are still being improved to accommodate a rapidly growing font of knowledge. And it is remarkably difficult to detect a definitive "signature" of human activity in the world’s widely fluctuating climate record. To project future climate patterns, scientists use computer simulations of the interactions among land, air, water, ice and sunlight. These general circulation models, or GCMs, consist of equations representing the known laws of atmospheric physics and ocean circulation. For each section of the planet, they calculate the effect of such factors as air temperature, the Earth’s rotation, surface friction at sea level, rainfall, and other climatic conditions. A perfect model, if given enough information about conditions on Earth several hundred years ago, could provide an exact description of today’s climate. Only very recently have models been developed that are capable of realistically depicting the present global climate without a lot of tinkering— adjustments often called "fudge factors."
4. In part, this is because only the most powerful computers are fast enough to handle the job, and in part because some aspects of climate change are still mysterious. Even avid proponents caution that GCMs are not yet trustworthy for predicting detailed effects in individual regions: Models divide the world’s surface into grids that are typically about 200 miles on a side, but ocean eddies, storms and cloud activity take place on far smaller scales. The modelers, therefore, have to compensate with approximations. According to Kevin Trenberth, chief climate analyst at the National Center for Atmospheric Research in Boulder, Colorado, all GCMs project global warming, but they can provide only a range of projected temperature change.
5. The role of clouds and airborne suspended particles called aerosols is no easier to factor into models. Clouds shade the Earth’s surface, promoting cooling. But, depending on their altitude, density, and other conditions, they can also trap outgoing heat, promoting warming. Aerosols are also equally tricky. Some encourage water vapor in the air to condense into tiny droplets. The resulting clouds are dense and shiny, shading the surface for weeks. Thus, ironically, our own pollution, mainly from combustion of sulfur-bearing coal and oil, may temporarily have spared us some effects of global warming.
6. Yet the warming could be part of the natural roller coaster of average global air temperatures, which have varied by as much as 6 degrees C during the past 150,000 years. Climate fluctuates over thousands of years owing to periodic changes in the sun’s energy output and in the Earth’s orbit and tilt, both of which influence the amount and intensity of sunlight reaching the surface. Proof of these climate shifts comes from variations in the composition of ice extracted in cores from the depths of ancient glaciers in Greenland and Antarctica and from differences among marine organisms in sediment cores taken from the seafloor. It is possible that around 1860, when scientists first began keeping dependable temperature records, the planet was still recovering from the "little ice age." The present warming might be a continuation of that rebound, and enhanced greenhouse warming may be superimposed on, and camouflaged by, that trend.
选项
答案
E
解析
句意:电脑模型的研发。
转载请注明原文地址:https://kaotiyun.com/show/xCLd777K
本试题收录于:
职称英语理工类A级题库职称英语分类
0
职称英语理工类A级
职称英语
相关试题推荐
Nervesignalsmaytravelthroughnerveormusclefibersatspeedsashighastwohundredmilesperhour.
BeAlerttoAntimicrobial(抗微生物的)ResistanceTheabilityofmicro-organismsto.findwaystoavoidtheactionofthedrugs
AreYoungGirlsOutofControlToday?Imagesonfashionmagazinesandtelevisionareconstantlypromotingsexintheiradver
HighStressMayDamageMemoryAccordingtoareportissuedinMay1998,elderlypeoplewhohaveconsistentlyhighbloodleve
FalseFearofBigFishManypeoplebelievesharks(鲨鱼)aredangerousandwillalwaystrytohurtorevenkillhumans.46
Therearenoticestothecontrary,agreatdealoftechnicalwritingisatbestawkwardandatworstactuallyunclear.
WhatistheresearchatJohnsHopkinsUniversityabout?Howdidtheresearcherscarryouttheirstudy?
ManyOlderDoctorsPlantoPhaseoutTheirPracticeTheresultsofanewsurveyindicatethat48percentofphysiciansbetween5
ScientistsDevelopWaysofDetectingHeartAttackGermanresearchershavecomeupwithanewgenerationofdefibrillators(除颤
Itisverydifficultforachildtoadheretorules.
随机试题
文学形象与非文学形象的区别在于,文学形象具有【】
StudentsmajoringinEnglish______bythatamusingteacheratthattime.
男,18岁,大学一年级学生,近2个月来行为怪异:尽管家境富裕却经常捡吃垃圾,解释是要“励志”;上课时常突然旁若无人地发笑,有时举手提问一些与课堂内容无关的奇怪问题,如“老师的孩子有4只眼睛吧?因为你和爱人各有2只眼睛”。几次从澡堂里赤身裸体出来,解释是“要
一个估价项目完成后,应保存的档案资料包括()。
2014年3月5日,机床生产商甲公司向乙公司出售机床20台,每台20万元。乙公司因资金周转困难,欲向丙银行贷款400万元,并与甲公司约定:“仅在乙公司的400万元银行借款于2014年6月2日前到账时,机床买卖合同始生效。”2014年4月2日,乙公
高中体育一个模块由18学时组成,学完一个模块并考核合格后获得1个学分,高中生应修满()。
上课前,语文老师故意把一个扫把横倒在教室的门口。第一个学生过去了,第二个、第三个……已经过去54个学生了,只剩一位平时表现不尽如人意的同学没进来了。坐下来的同学终于注意到那把扫帚了,而最后一个同学也终于走过来了,“万众瞩目”下,这位同学也走过去了,但是一段
YouaretheadministratorofaSQLServer2000computer.Yourcompanyusestheservertostoreservicecontractinformationfor
A、 B、 C、 D、 B
以下叙述中正确的是
最新回复
(
0
)