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absolutely crucial to life on our planet since only due to their ability to efficiently absorb terrestrial radiation the average surface temperature of the
earth is increased by 33°C or from -18°C to +15°C. The most common
gases of our atmosphere, oxygen and nitrogen, which take up more than
99% of the total volume, are almost completely transparent to both the
radiation from the sun and the terrestrial radiation. The first attempt to
estimate the effect of atmospheric greenhouse gases on climate was made
by the Swedish physicist Arrhenius (1896). Arrhenius undertook a careful
examination of available measurements concerning the absorption of terrestrial radiation in the atmosphere and was able, on the basis of these
measurements, to correctly quantify the role of carbon dioxide and water
vapour. By making use of a simple energy balance model he also calculated
the change in the surface temperature which would result in an increase
respectively a decrease in the atmospheric concentration of CO2 including
the feedback from water vapour. Based on available data for surface albedo
and cloud distribution, Arrhenius calculated that a doubling of CO2 from
300 ppm to 600 ppm would result in a warming of about 5°C. A similar reduction in the concentration to 150 ppm would give a corresponding
cooling. Arrhenius himself did not believe that man-made release of carbon dioxide into the atmosphere could have any effect, due to the very
small amounts offossil coal burning at the time (500 Mtons annually), on
the concentration of carbon dioxide in the atmosphere because the amount
was such a tiny part compared to the natural exchange between the atmosphere, the oceans and the land surface. Today the situation is different
with a 20-fold increase in the burning of fossil fuels. With the exception of
some interesting papers by Callendar (1938, 1949), who indeed was the first
to raise the issue whether the anthropogenic production could influence climate, and pioneering work thereafter e.g. by Bolin and Eriksson (1959),
Moller (1963), Manabe (1971), Manabe and Wetherald (1975), it was not
until the 1980ies that the issue started to attract world-wide scientific as
well as public interest.
2
Basic energy processes of the climate system
The concept of climate, as will be considered here, will be defined as the
totality of weather conditions which are experienced during a given time
interval. These weather conditions are quantified by different meteorological variables such as surface pressure, wind, temperature, humidity,
absolutely crucial to life on our planet since only due to their ability to efficiently absorb terrestrial radiation the average surface temperature of the
earth is increased by 33°C or from -18°C to +15°C. The most common
gases of our atmosphere, oxygen and nitrogen, which take up more than
99% of the total volume, are almost completely transparent to both the
radiation from the sun and the terrestrial radiation. The first attempt to
estimate the effect of atmospheric greenhouse gases on climate was made
by the Swedish physicist Arrhenius (1896). Arrhenius undertook a careful
examination of available measurements concerning the absorption of terrestrial radiation in the atmosphere and was able, on the basis of these
measurements, to correctly quantify the role of carbon dioxide and water
vapour. By making use of a simple energy balance model he also calculated
the change in the surface temperature which would result in an increase
respectively a decrease in the atmospheric concentration of CO2 including
the feedback from water vapour. Based on available data for surface albedo
and cloud distribution, Arrhenius calculated that a doubling of CO2 from
300 ppm to 600 ppm would result in a warming of about 5°C. A similar reduction in the concentration to 150 ppm would give a corresponding
cooling. Arrhenius himself did not believe that man-made release of carbon dioxide into the atmosphere could have any effect, due to the very
small amounts offossil coal burning at the time (500 Mtons annually), on
the concentration of carbon dioxide in the atmosphere because the amount
was such a tiny part compared to the natural exchange between the atmosphere, the oceans and the land surface. Today the situation is different
with a 20-fold increase in the burning of fossil fuels. With the exception of
some interesting papers by Callendar (1938, 1949), who indeed was the first
to raise the issue whether the anthropogenic production could influence climate, and pioneering work thereafter e.g. by Bolin and Eriksson (1959),
Moller (1963), Manabe (1971), Manabe and Wetherald (1975), it was not
until the 1980ies that the issue started to attract world-wide scientific as
well as public interest.
2
Basic energy processes of the climate system
The concept of climate, as will be considered here, will be defined as the
totality of weather conditions which are experienced during a given time
interval. These weather conditions are quantified by different meteorological variables such as surface pressure, wind, temperature, humidity,