Jökull - 01.12.1969, Blaðsíða 109

I2°C
Fig. 1 Theoretical “worlcl air temperature’’, curve A, as a function of the CO^-content in the
atmosphere, according to Plass (1959). A ± 1% fluctuation around the equilibrium CO^-cont-
ent in the oceans would in Plass’ theory give a corresponding fluctuation in air temperature
as shown by the wavy curve between the extremes Bi and B^.
orders of magnitude larger than the climatic
fluctuations.
This remark applies also to, and excludes,
A-4, a, b, c as primary causes. A-2, a, b are also
dropped for similar reasons. A-2, c and A-4, d
combined leacl to a variant of the COo-hypo-
tlresis which is discussed in some detail. The
amount of COo dissolved in the sea in various
forms is essentially in equilibrium with the
amount in the atmosphere. The former amount
is 55 times larger than the latter and consequ-
ently relatively small variations in the former
will correspond to large variations in the latter.
Fore sake of demonstration the data of Plass
(1959) are used, although these are out of date,
and counteracting atmospheric factors, such as
humidity, are here left out of consideration.
One finds that a fluctuation in the CO2
amount in the ocean by ± 1 percent will give
a 2° rise or a 5° drop in air temperature, or
altogether a fluctuation of 7° C. Causes for
such fluctuations in the sea could be sought in
the process of formation of deep sea water. A
temporary intensification of that process may
pump down CO2. But on account of the clegree
of eddy-conductivity a serious deviation from
the equilibrium of CO2 between air ancl sea
could last at most for a few centuries at a time.
This variant of the CO^-hypothesis would then
come into consideration only if the climatic
curve of a time of glaciation consists in detail
of a series of such short cold spells. But even
so, a different agency is needed to explain why
cold spells were dominant during a glacial time
and not during an interglacial time.
We now consider C-1 and A-4, e together.
An influence of solar corpuscular radiation,
concentrated through the magnetic field near
the auroral belts, on pressure troughs at the
300 mb-level, has been pointed out by Mac-
donald and lioberts (1960), and a reílection of
the sunspot periods (11 years and 80 years) in
climatic fluctuations has often been claimed.
According to one hypothesis the climatic in-
fluence ot' the corpuscular solar radiation may
be sought in the creation of cores of condensa-
tion at levels above about 20 km. If this is so,
a great weakening or disappearance or a great
fluctuation of the axis of the magnetic field,
will imply spreading of the corpuscular radia-
tion over the earth or into equatorial regions
instead of the present concentration in lrigh
latitudes. Whether this effect would sulTice to
increase significantly the average cloud cover
is an open question. But the possibility of a
great change of the magnetic field is no ques-
tion, and Fig. 2 shows correlation.
A combination of A-2, a and A-4, a, b, c
with the addition of the albedo effect of ex-
tensive snow sheets is represented by the hypo-
JÖKULL 19. ÁR 1 05