Page 251 - Materials Chemistry, Second Edition

4.5 Impact Categories, Impact Indicators and Characterisation Factors 235

most important factor is probably the last: the prestige of the IPCC working on
behalf of the UN. The IPCC was awarded the Nobel Peace Prize in 2007.
4.5.2.2.1 ‘Greenhouse Effect’ Within the climate discussion and the LCIA, the
term Greenhouse effect designates an additional, anthropogenic greenhouse effect.
Life on earth (as we know it and being a part of it) 169) is only made possible by the
natural greenhouse effect, which is induced by the gases, water vapour and carbon
dioxide, in their pre-industrial concentration; without it the average temperature
◦
◦
on the surface of the earth would be around −18 C instead of +15 C as at present.
The natural greenhouse effect was already known in the nineteenth century as
exemplified by the quotation of John Tyndall (1873, loc. cit.): at least water vapour
as natural GHG was already known before 1870.
The additional, anthropogenic greenhouse effect which has already led to an
◦
increase of the average surface temperature by about 1 C is caused by an increased
concentration of some trace gases in the troposphere (GHGs) partly identical to
‘natural’ GHG 170) , see also Table 4.10:
• carbon dioxide (CO )
2
• watervapour(H O)
2
• methane (CH )
4
• dinitrogen oxide (N O)
2
• ozone (O , tropospheric)
3
• synthetic, persistent chemicals (mostly highly halogenated, for example, CF ,
4
SF ,NF ).
6 3
Relevant gaseous emissions listed in the inventory as mass per fU have their origin
in a multitude of human activities, for example:
• Incineration of fossil fuels or materials produced from fossil raw materials (CO )
2
• calcination of minerals (CO )
2
• agriculture (CH ,N O)
4 2
• losses during extraction and transport of fossil fuels (CH )
4
• industrial processes (halogenated solvents, CF ,SF ,N O)
4 6 2
• private use (chlorinated solvents, refrigerants: freon substitutes)
• landfilling, waste deposit (CH ,CO ).
4 2
Often non-listed in LCI are CO emissions due to incineration or aerobic biodegra-
2
dation of renewable raw materials or fuels that originated only a relatively short
time ago (there is controversy about the period of time discussed, mostly between
20 and 100 a) by assimilation of atmospheric CO . This often so-called CO neu-
2 2
trality does not make any sense for the anaerobic degradation under formation of
CH , for example, in waste deposits, even if it originates from renewable sources:
4
this GHG has a much higher GWP than carbon dioxide into which methane
finally transforms by incineration, aerobic biochemical oxidation or atmospheric
169) It seems that lower forms of life survived periods of low temperatures on earth.
170) Br¨ uhl and Crutzen (1988), Deutscher Bundestag (1988, 1992) and IPCC (1990, 1992, 1995a,b,c,
1996a,b, 2001, 2007).