Although the term greenhouse effect has generally been used for the role of the whole atmosphere (mainly water vapor and clouds) in keeping the surface of the earth warm, it has been increasingly associated with the contribution of CO2 (currently, it is estimated that CO2 contributes about 50% to the anthropogenic greenhouse effect).However,several other gases such as CH4,CFCs,halons,N2O,ozone and peroxyacetylnitrate (so-called greenhouse gases) produced by the industrial and domestic activities can also contribute to this effect, resulting in a rise in the earth's temperature.A schematic representation of this global problem is illustrated in Figure 1.（虽然温室效应这个术语通常是指整个大气(主要为水蒸汽和云)在维持地球表面温度方面的作用,但它日益与二氧化碳联系起来(目前估计由人为因素造成的温室效应,其百分之五十来自于二氧化碳的贡献值)｡但是,由工业和人们日常活动所产生的一些其他气体,譬如:甲烷(CH4)､氟氯碳化物(CFCs)､碳卤化合物､一氧化二氮(N2O)､臭氧和过氧乙酰基硝酸酯(所谓的温室气体),也有助于温室效应,导致地表温度上升｡这个全球性问题如图1所示｡）
In the greenhouse effect phenomenon, the rays of the sun reach the earth and maintain an average temperature level of around +15℃.A large part of the infrared rays reflected off the earth are caught by CO2, H2O, and other substances (including CFCs) present in the atmosphere and kept from going back out into space. The increase in the greenhouse effect would result in a sudden rise in temperature, and it is very likely linked with human activity, in particular the emissions from fossil fuel consumption.（在温室效应现象中,太阳射线到达地球后会维持15℃左右的平均温度｡一大部分红外线在被地球反射后被大气中的二氧化碳,水和其他(包括CFCs)物质吸收,而不能返回太空｡温室效应的增强将导致温度的突然上升,这很可能和人类的一些活动相关,尤其是化石燃料消耗的排放｡）
Also,increasing the greenhouse effect may result in the following (Din9er,1992):
*an intermediate warming of the atmosphere(estimated as 3℃ to 5℃ by 2050),
*a rise in the level of the oceans(estimated as 20cm by 2050),and
*climatic effects(increases in drought，rain，snow，warming，and cooling).
（同时,温室效应的增强会导致以下结果(Din9er,1992):
·大气变暖(到2050年估计上升3℃或5℃);
·海洋的水平面上升(到2050年估计达到20cm);
·气候变化(干旱､雨水､降雪､高温､严寒的增加)｡）
Increasing atmospheric concentrations of CFCs have accounted for about 24% of the direct increase in the radiative heating from greenhouse gases over the last decade. However, an observed decrease in stratospheric ozone, thought to be connected to increasing stratospheric chlorine from CFCs, suggests a negative radiative heating or cooling tendency over the last decade.（在过去十年中,CFCs在大气中的浓度不断增加,占温室气体的24%｡然而通过观察发现,臭氧层的减少与平流层中不断增加的氯原子(来自于CFCs)有关,这表明在过去的十年中CFCs的冷效应趋势｡）
The release of CFCs into the atmosphere affects climate in two different ways (Badr et al.,1990):
CFCs are highly harmful greenhouse gases (relative to CO2), due to their stronger IR band intensities,stronger absorption features and longer atmospheric lifetimes.
CFCs deplete the stratospheric ozone layer which affects earth surface temperature in two ways: more solar radiation reaching the surface lower troposphere system, resulting in a warmer climate and leading to lower stratospheric temperatures and, therefore, less IR radiation being passed to the earth's surface-lower troposphere system, resulting in lower ground-level temperatures.
（释放到大气中的CFCs对气候的影响有两个不同的途径(Badretal.1990):
·CFCs是极其有害的温室气体(相对于二氧化碳来说),因为它们有更高的红外谱带强度,更强的吸收特点和更长的大气寿命｡
·CFCs衰减臭氧层会通过两种方式影响地球表面的温度:更多的太阳辐射到达地表更低的对流层,导致气候变暖;较少的红外射线到达地表较低的对流层,导致更低的地表温度｡）
Therefore,the net effect is dependent on the altitudes where the ozone change take splace.
The global warming potential (GWP) is a number that refers to the amount of global warming caused by a substance.The GWP is the ratio of the warming caused by a substance to the warming caused by a similar mass of CO2.Thus,the GWP of CO2 is defined to be 1.0.CFC12 has a GWP of 8500, while CFC11 has a GWP of 5,000. Various HCFCs and MFCs have GWPs ranging from 93 to 12100. Water, a substitute in numerous end-uses, has a GWP of 0. GWP represents how much a given mass of a chemical contributes to global warming,over a given time period, compared to the same mass of CO2. CO2's GWP is defined as 1.0. These values are calculated over a 100-year time horizon.MFCs are numbered according to the ASHRAES tandard 34 scheme.Table 1 lists many ozone depleting substances showing their ODPs,GWPs,and CAS numbers.（因此,最终的影响取决于臭氧层变化的地点｡
全球性变暖指数(GWP)是一个数字,它是指由某种物质引起全球变暖的量｡GWP是由某种物质引起的变暖量与由同样质量的二氧化碳引起的变暖量的比值｡因此,二氧化碳的GWP为1.0,CFC12的GWP为8500,而CFC11的GWP为5000｡不同的HCFCs和MFCs的GWPs值从93到12100｡水在许多用途中只是代替品,它的GWP为0｡GWP代表了在某个时期中,一种给定质量的化学物质相当于同质量的二氧化碳来说对全球变暖的贡献值｡二氧化碳的GWP被定义为1.0｡这些值在一百年的时间范围内被计算｡MFCs根据ASHRAE标准34号计划被编号｡表1列出了许多臭氧衰减物质以及它们的ODPs､GWPs和CAS数据｡）
As can be seen in Table 1,perfluorocarbons do not deplete stratospheric ozone,but the US Environmental Protection Agency is concerned about their impact on global warming. Recent scientific studies, however, indicate that the ODPs for Halons are at least 13 and 4, respectively.Although HBFCs were not originally regulated under the 'Clean Air Act', subsequent regulation added HBFCs to the list of class I substances.Although HCs are highly flammable,they may offer advantages as ODS substitutes because they are inexpensive to produce and they have zero ozone depletion potential,very low GWP,and low toxicity.HCFCs have ODPs ranging from 0.01 to 0.1.Production of HCFCs with the highest ODPs will be phased out first, followed by other HCFCs.All HFCs have an ozone depletion potential of 0.Some HFCs have high GWPs.（从表1可以看出,全氟化碳不破坏同温层的臭氧,但是美国环保署关注它们对全球变暖的影响｡然而,最新科学研究表明碳卤化合物的ODPs分别至少为13和4｡尽管HBFCs原本未被规定在“空气清洁法案”中,但后来的调整又增加了HBFCs为一类物质｡虽然HCs为高度易燃物,但它们作为ODS的代替物有其优点,因为它们的生产成本低,并且对臭氧没有破坏,很低的GWP和低毒性｡HCFCs的ODPs范围是从0.01到0.1｡ODPs最高的HCFCs在生产中将首先被淘汰,随后就是其他的HCFCs｡所有HFCs的臭氧衰减指数为0,某些HFCs有较高的GWPs｡）
