全球气候变暖

1、全球气候变暖,制作人：夏海金,定义,全球变暖是指在一段时间中陆地，海洋和大气因温室效应而造成的温度上升的气候变化现象。全球变暖的主要原因是人类在近一个世纪以来大量使用矿物燃料，排放大量温室气体。全球变暖会导致全球气候变化，使全球降水量重新分配，冰川，冻土消融和海平面上升，既危害自然生态系统的平衡，也威胁人类的食物供应和居住环境。,基本概述,全球变暖指的是在一段时间中，地球大气和海洋温度上升的现象，主要是指人为因素造成的温度上升。目前世界范围内认为主要原因很可能是由于温室气体（二氧化碳）排放过多所造成的。,历史文化,全球变暖是指全球气温升高。近100多年来，全球平均气温经历了冷暖冷暖两次波动，总

2、的看为上 升趋势。进入八十年代后，全球气温明显上升。 19811990年全球平均气温比100年前上升了0.48。导致全球变暖的主要原因是人类在近一个世纪以来大量使用矿物燃料（如煤、石油等），排放出大量的CO2等多种温室气体。由于这些温室气体对来自太阳辐射的可见光,（3.8-7.6nm，波长较短）具有高度的穿透性，而对地球反射出来的长波辐射（如红外线）具有高度的吸收性，也就是常说的“温室效应”，导致全球气候变暖。 出现全球变暖趋势的具体原因是，人们焚烧化石矿物以生成能量或砍伐森林并将其焚烧时产生的二氧化碳进入了地球的大气层。政府间气候变化问题小组根据气候模型预测，到2100年为止，全球气温估计将

3、上升大约1.4-5.8(2.5-10.4华氏度)。根据这一预测，全球气温将出现过去10,000年中从未有过的巨大,变化，从而给全球环境带来潜在的重大影响。 为了阻止全球变暖趋势，1992年联合国专门制订了联合国气候变化框架公约，该公约于同年在巴西城市里约热内卢签署生效。依据该公约，发达国家同意在2000年之前将他们释放到大气层的二氧化碳及其它“温室气体”的排放量降至1990年时的水平。另外，这些每年的二氧化碳合计排放量占到全球二氧化碳总排放量60%的国家还同意将相关技,术和信息转让给发展中国家。发达国家转让给发展中国家的这些技术和信息有助于后者积极应对气候变化带来的各种挑战。截止2004年5月

4、，已有189个国家正式批准了上述公约。 毫无疑问我们这个星球正在升温，在上个世纪全世界的平均温度大约攀升了0.6 摄氏度。北半球春天的冰雪解冻期比150年前提前了9天，而秋天的霜冻开始时间却晚了10天左右。 20世纪90年代是自19世纪中期开始温度记录工作以来最温暖的十年，在记录上最热的几年依次是：1998年，2002年，2003年，2001年和1997年。,气候变暖降水量减少致奥地利冰川继续萎缩,2011年奥地利境内97%的冰川都出现不同程度的萎缩，其中后退距离超过30米的冰川有15个，比前一年增加近一倍，后退距离最远的甚至达到64.5米。而且这一年，奥地利境内没有一座冰川生长。 菲舍尔说，

5、奥地利的著名冰川也没能逃过萎缩的命运。大钟山的巴斯特泽冰川继前年后退25米后，去年又后退了40米，而且这条冰川中部还首次出现了崩塌。 菲舍尔认为，2011年初夏过暖的气温是奥地利冰川融化加快的重要原因之一。此外，这一年相对偏少的降水也使山区的积雪没能得到充足的补充。,Are we about to get an ice-free Arctic?,Only yesterday, NASA released an image of the White Marble - an image from space showing our snow-and-ice-capped planet from a

6、bove the North Pole.,昨天 NASA 才发布了一张从太空传回的“白色大理石”图像，展示了从北极上空看到的冰雪覆盖着的地球。,Today, a new NASA release of pictures shows an alarming decrease in the amount of ice-locked water on the Arctics floating ice cap - revealing that the oldest and thickest Arctic sea ice is disappearing at an extremely fast rate

7、.,今天，NASA 又公布了一批图片，对北极浮动冰盖中冻成冰的水量减少提出警告。这批图片说明，时间最久最厚的北极海冰正以极快的速度消失。,As the pictures below dramatically make clear, the size of the Arctics floating ice cap has diminished massively over the last 30 years, lending evidence to the theory we are in a period of global warming.,从图片中可以非常明显地看出，北极浮动冰盖的面积在过

8、去 30 年间大规模减小，这也证明了我们正处在全球变暖的过程中。,The thicker ice, known as multi-year ice, survives through the cyclical summer melt season, when young ice that has formed over winter just as quickly melts again. The rapid disappearance of older ice makes Arctic sea ice even more vulnerable to further decline in th

9、e summer, said Joey Comiso, senior scientist at NASA Goddard Space Flight Center.,被称作多年冰的较厚冰层熬过了循环夏季融化期，在此期间上个冬天刚形成的初期冰则再次迅速地融化了。 NASA 戈德达航天中心资深科学家 Joey Comiso 说，形成时间较长的冰在快速消失，这令北极海冰在夏季更容易减少,。,Sign of the times in 2012: The ice covering has dramatically shrunk, with research showing the cap is losin

10、g around 15-20% of its mass per decade The new research takes a closer look at how multi-year ice, ice that has made it through at least two summers, has diminished with each passing winter over the last three decades. Multi-year ice extent - which includes all areas of the Arctic Ocean where multi-

11、year ice covers at least 15 percent of the ocean surface - is diminishing at a rate of -15.1 percent per decade, the study found.,2012 年最新趋势：北极冰盖面积已经显著缩小，研究显示冰盖正不断缩小，其速度为每十年约 15% 至 20%。 人们进行了更加仔细的研究，希望发现在过去三十年间每个冬天都是转瞬即逝的情况下，至少需要两个夏天才能形成的多年冰是如何减少的。 研究发现，多年冰的“范围”（包括北冰洋的所有海域，多年冰覆盖了洋面的至少 15%）正在缩小，每十年减少

12、 15.1%。,Theres another measurement that allows researchers to analyse how the ice cap evolves: multi-year ice area, which discards areas of open water among ice floes and focuses exclusively on the regions of the Arctic Ocean that are completely covered by multi-year ice. Sea ice area is always smal

13、ler than sea ice extent, and it gives scientists the information needed to estimate the total volume of ice in the Arctic Ocean.,研究人员还采取了另一种方法来分析冰盖是如何形成多年冰“区域”，也就是浮冰间的无冰水域以外完全被多年冰覆盖的北冰洋区域。 海冰区域总是小于海冰范围，这给了科学家测量北冰洋里冰块总体积的所需信息。,Comiso found that multi-year ice area is shrinking even faster than multi-

14、year ice extent, by -17.2 percent per decade. The average thickness of the Arctic sea ice cover is declining because it is rapidly losing its thick component, the multi-year ice.,Comino 发现多年冰区域比多年冰范围减少的速度更快，达到了每十年缩小 17.2 % 北极海冰盖的平均厚度在降低，原因在于冰盖较厚的部分也就是多年冰在迅速减少。,At the same time, the surface temperatu

15、re in the Arctic is going up, which results in a shorter ice-forming season, Comiso said. It would take a persistent cold spell for most multi-year sea ice and other ice types to grow thick enough in the winter to survive the summer melt season and reverse the trend.,Comiso说：“与此同时，北极表面温度在升高，于是冰块形成的周

16、期变得更短。” “大多数多年海冰和其他类型的冰要经过很长的寒冷期才能在冬季发展到一定厚度，以便度过夏季融化期并扭转此趋势。”,Scientists differentiate multi-year ice from both seasonal ice, which comes and goes each year, and perennial ice, defined as all ice that has survived at least one summer. In other words: all multi-year ice is perennial ice, but not all

17、 perennial ice is multi-year ice (it can also be second-year ice).,科学家将多年冰与季节冰和长年冰区分开来，季节冰每年形成后又消失，长年冰则是指所有度过了至少一个夏季的冰块。换句话说：所有多年冰都是长年冰，但不是所有长年冰都是多年冰（它也可能是隔年冰）。,England from the North Pole: This is a very special version of the Blue Marble image - Earth captured on its entirety from an altitude of 5

18、12 miles (824 kilometers) over the North Pole Comiso found that perennial ice extent is shrinking at a rate of -12.2 percent per decade, while its area is declining at a rate of -13.5 percent per decade. These numbers indicate that the thickest ice, multi-year-ice, is declining faster than the other

19、 perennial ice that surrounds it.,从北极上空看到的英格兰：这是蓝色大理石图像的特别版从北极上空 512 英里（824 千米）的高度抓拍的地球全景。 Comiso 发现长年冰范围正在以每十年减少 12.2 % 的速度缩小，而长年冰面积缩小的速度则是每十年减少 13.5 % 。这些数据说明，最厚的冰即多年冰减少的速度快于周围的其他长年冰。,As perennial ice retreated in the last three decades, it opened up new areas of the Arctic Ocean that could then b

20、e covered by seasonal ice in the winter. A larger volume of younger ice meant that a larger portion of it made it through the summer and was available to form second-year ice. This is likely the reason why the perennial ice cover, which includes second year ice, is not declining as rapidly as the mu

21、ltiyear ice cover, Comiso said.,在过去的三十年里长年冰消退了，于是北冰洋上出现了可在冬季被季节冰覆盖的新区域。 Comiso 说，形成时间较短的冰体积较大，这意味着其中的大部分都可以安然度过夏季，形成隔年冰。这可能就是为什么包括隔年冰在内的长年冰会比多年冰盖减少的速度慢。,Multi-year sea ice hit its record minimum extent in the winter of 2008. That is when it was reduced to about 55 percent of its average extent since

22、 the late 1970s, when satellite measurements of the ice cap began. Multi-year sea ice then recovered slightly in the three following years, ultimately reaching an extent 34 percent larger than in 2008, but it dipped again in winter of 2012, to its second lowest extent ever.,多年海冰区域在 200 8 年创下了历史最小值。当

23、时多年海冰范围缩小到了自 1970 年代开始冰盖卫星测量以来平均数的大约 55%。之后三年里多年海冰稍稍增多了，最终比 2008 年增加了 34%。但在 2012 年冬季多年海冰范围再次缩小，达到历史上第二低。,For this study, Comiso created a time series of multi-year ice using 32 years of passive microwave data from NASAs Nimbus-7 satellite and the U.S. Department of Defenses Defense Meteorological S

24、atellite Program, taken during the winter months from 1978 to 2011. This is the most robust and longest satellite dataset of Arctic sea ice extent data to date, Comiso said.,Comiso 为这次研究制作了一份多年冰时间序列，其中使用了来自 NASA Nimbus-7 卫星和美国国防部国防气象卫星计划的数据，这些数据历时 32 年（从 1978 年冬季至 2011 年 冬季）。Comiso 说这是迄今为止最强大也耗时最久的北

25、极海冰范围数据集。,Younger ice, made from recently frozen ocean waters, is saltier than multi-year ice, which has had more time to drain its salts. The salt content in first- and second-year ice gives them different electrical properties than multi-year ice: In winter, when the surface of the sea ice is cold

26、 and dry, the microwave emissivity of multiyear ice is distinctly different from that of first- and second-year ice.,形成时间较短的冰是由最近冻住的海水形成的，比多年冰更咸，因为多年冰有更多时间将所含盐分沥除。首年冰和隔年冰的含盐量使它们的电性能与多年冰不同：冬季当海冰表面又冷又干时，多年冰的微波发射率明显不同于首年冰及隔年冰。,Microwave radiometers on satellites pick up these differences in emissivity,

27、 which are observed as variations in brightness temperature for the different types of ice. The brightness data are used in an algorithm to discriminate multiyear ice from other types of ice. Comiso compared the evolution of the extent and area of multi-year ice over time, and confirmed that its decline has accelerated during the last decade, in part because of the dramatic decreases of 2008 and 2012.,卫星的微波辐射计接收到这些不同的发射率，将其作为不同类型冰块亮温度的变体。计算“亮度”数据可以将多年冰同其他类型的冰作出区分。 Comiso 将多年冰范围和区域随时间变化的过程进行比较，随后确定在过去十年内多年冰加速减少，部分原因在于 2008 和2012 年多年冰数量的急剧下降。,He also detected a periodic nine-year