T H E Q U E S T I O N O F I N C R E A S E O F A T M O S P H E R I C CO,
Table
Decade
I.
CO, added to atmosphere by consumption of fossil fuels
Average amount added per
decade
Measured
1o18 gms
1%
I
Atm CO,
1870-79
1880-89
1890-99
0.0054
0.0085
0.0128
0.0185
0.23
0.36
0.54
0.79
190--09
0.0299
1.27
1g10-1g
1.72
0.0405
0.0470
2.00
2.11
0.0497
0.0696
2.71
Forecast
I860-69
192-29
193-39
194-49
Cumulative total added
10l8
gms
0.0054
0.0139
0.0267
0.0452
0.0751
0.1156
0.1626
0.2123
0.2759
yo Atm CO,
0.091
1960-69
0.128
197-79
1980-89
1990-99
0.176
0.247
0.340
0.472
2000--09
3.9
5.4
7.5
10.5
14.5
20.0
0.367
0.495
0.671
0.918
1.258
I .730
1o18 gms
1%
Atm CO,
$
~
0.23
0.59 '
1.13
I.92/
3.19
4.91
6.91
9.02
'1.73
4ssuming fossil fuels are used t o meet future requirements
of fuel and power as estimated by UN (1955)
195-59
I9
15.6
21.0
28.5
39.0
53.5
73.5
~
~
at estimated 1955 rate
0.367
0.458
0.549
0.640
0.731
0.822
15.6
19.5
23.4
27.2
31.1
35.0
atmospheric CO, (SLOCUM,
1955; FONSELIUS combustion of fossil fuels will continue to
et al. 1956). Most of the excess CO, from fuel increase, if the fuel and power requirements of
combustion may have been transferred to the our world-wide industrial cidization continue
ocean, a possibility suggested by S. ARRHENIUSto rise exponentially, and if these needs are met
(1903). Second, a few percent increase in the only to a limited degree by development of
CO, content of the air, even if it has occurred, atomic power. Estimates by the UN (1955)
might not produce an observable increase in indicate that during the first decade of the 21st
average air temperature near the ground in the century fossil fuel combustion could produce
face of fluctuations due to other causes. So an amount of carbon dioxide equal to 20 %
little is known about the thermodynamics of of that now in the atmosphere (Table 1).1
the atmosphere that it is not certain whether
robably two orders of magnitude
or how a change in infrared back radiation greater
This is t an the usual rate of carbon dioxide
from the upper air would affect the temperature production from volcanoes, which on the
near the surface. Calculations by PLASS(1956) average must be equal to the rate at which
indicate that a 10 % increase in atmospheric silicates are weathered to carbonates (Table 2).
carbon dioxide would increase the average Thus human beings are now carrying out a
tem erature by 0.36" C. But, amplifying or large scale geo hysical experiment of a kind
feehlback processes may exist such that a that could not ?
ave
l happened in the past nor
slight change in the character of the back be reproduced in the future. Within a few
radiation might have a more pronounced effect. centuries we are returning to the atmosphere
Possible examples are a decrease in albedo of and Oceans the concentrated organic carbon
the earth due to melting of ice caps or a rise stored in sedimentary rocks over hundreds of
in water vapor content of the atmosphere millions of years. T h s experiment, ifadequately
(with accompanying increased infrared absorpWorld production of COa from the use of limetion near the surface) due to increased evaporastone for cement, fluxing stone and in other ways was
tion with rising temperature.
about I % of the total from fossil fuel combustion
During the next few decades the rate of in 19.50.
i
Tellus
IX
(1957). 1
~
r