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.（雖然溫室效應(yīng)這個術(shù)語通常是指整個大氣(主要為水蒸汽和云)在維持地球表面溫度方面的作用,但它日益與二氧化碳聯(lián)系起來(目前估計由人為因素造成的溫室效應(yīng),其百分之五十來自于二氧化碳的貢獻(xiàn)值)?但是,由工業(yè)和人們?nèi)粘；顒铀a(chǎn)生的一些其他氣體,譬如:甲烷(CH4)?氟氯碳化物(CFCs)?碳鹵化合物?一氧化二氮(N2O)?臭氧和過氧乙?；跛狨?所謂的溫室氣體),也有助于溫室效應(yīng),導(dǎo)致地表溫度上升?這個全球性問題如圖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.（在溫室效應(yīng)現(xiàn)象中,太陽射線到達(dá)地球后會維持15℃左右的平均溫度?一大部分紅外線在被地球反射后被大氣中的二氧化碳,水和其他(包括CFCs)物質(zhì)吸收,而不能返回太空?溫室效應(yīng)的增強(qiáng)將導(dǎo)致溫度的突然上升,這很可能和人類的一些活動相關(guān),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).

（同時,溫室效應(yīng)的增強(qiáng)會導(dǎo)致以下結(jié)果(Din9er,1992):

·大氣變暖(到2050年估計上升3℃或5℃);

·海洋的水平面上升(到2050年估計達(dá)到20cm);

·氣候變化(干旱?雨水?降雪?高溫?嚴(yán)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.（在過去十年中,CFCs在大氣中的濃度不斷增加,占溫室氣體的24%?然而通過觀察發(fā)現(xiàn),臭氧層的減少與平流層中不斷增加的氯原子(來自于CFCs)有關(guān),這表明在過去的十年中CFCs的冷效應(yīng)趨勢?）

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.

（釋放到大氣中的CFCs對氣候的影響有兩個不同的途徑(Badretal.1990):

·CFCs是極其有害的溫室氣體(相對于二氧化碳來說),因為它們有更高的紅外譜帶強(qiáng)度,更強(qiáng)的吸收特點和更長的大氣壽命?

·CFCs衰減臭氧層會通過兩種方式影響地球表面的溫度:更多的太陽輻射到達(dá)地表更低的對流層,導(dǎo)致氣候變暖;較少的紅外射線到達(dá)地表較低的對流層,導(dǎo)致更低的地表溫度?）

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,最終的影響取決于臭氧層變化的地點?

全球性變暖指數(shù)(GWP)是一個數(shù)字,它是指由某種物質(zhì)引起全球變暖的量?GWP是由某種物質(zhì)引起的變暖量與由同樣質(zhì)量的二氧化碳引起的變暖量的比值?因此,二氧化碳的GWP為1.0,CFC12的GWP為8500,而CFC11的GWP為5000?不同的HCFCs和MFCs的GWPs值從93到12100?水在許多用途中只是代替品,它的GWP為0?GWP代表了在某個時期中,一種給定質(zhì)量的化學(xué)物質(zhì)相當(dāng)于同質(zhì)量的二氧化碳來說對全球變暖的貢獻(xiàn)值?二氧化碳的GWP被定義為1.0?這些值在一百年的時間范圍內(nèi)被計算?MFCs根據(jù)ASHRAE標(biāo)準(zhǔn)34號計劃被編號?表1列出了許多臭氧衰減物質(zhì)以及它們的ODPs?GWPs和CAS數(shù)據(jù)?）

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.（從表1可以看出,全氟化碳不破壞同溫層的臭氧,但是美國環(huán)保署關(guān)注它們對全球變暖的影響?然而,最新科學(xué)研究表明碳鹵化合物的ODPs分別至少為13和4?盡管HBFCs原本未被規(guī)定在“空氣清潔法案”中,但后來的調(diào)整又增加了HBFCs為一類物質(zhì)?雖然HCs為高度易燃物,但它們作為ODS的代替物有其優(yōu)點,因為它們的生產(chǎn)成本低,并且對臭氧沒有破壞,很低的GWP和低毒性?HCFCs的ODPs范圍是從0.01到0.1?ODPs最高的HCFCs在生產(chǎn)中將首先被淘汰,隨后就是其他的HCFCs?所有HFCs的臭氧衰減指數(shù)為0,某些HFCs有較高的GWPs?）