Global temperatures, CO2 concentrations and oceans

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Global temperatures, CO2 concentrations and oceans
Abstract
During the last 170 years, global temperature and atmospheric CO2 concentration have increased.
The greenhouse effect of CO2 is supposed to increase temperatures. Published data on global
temperature, CO2 data, and data on sea ice in Arctic have been investigated. It is seen that support
for human activities to cause the observed increases is weak. Rather, it is found that rate of change
in the CO2 concentration is controlled by global temperature rather than vice versa. The trend in
correlation between temperature and growth of CO2 concentration indicates that to stop the
concentration from growing, the temperature has first to be decreased to 1 K below the mean value
during 1981-2010. This makes it questionable if attempts by humans to modify global temperature,
or concentration of CO2 in the atmosphere will give any noticeable result. Furthermore, correlation
is found between seasonal variations of CO2 concentrations and Arctic sea ice quantities.
Introduction
It is well known that during the last 170 years, global mean temperature as well as atmospheric
concentration of CO2 have increased dramatically. Since 1958, atmospheric CO2 concentrations
have been measured at Mauna Loa (https://scrippsco2.ucsd.edu/). Also, since 1978, detailed
information on global and regional temperatures have been measured by polar orbiting satellites
(https://www.nesdis.noaa.gov/current-satellite-missions/history-of-noaa-satellites). The CO2
concentrations undergo seasonal variations layered upon the general monotonic increase in
concentration. The pattern of global temperature is much more irregular, but there also are seasonal
variations caused by the uneven distribution of land and water across the globe. Such variations can
be cancelled out by making use of gliding twelve months mean values. It is obvious that since at
least 1978, global mean temperature, as well as CO2 concentration have increased. The same trend
has been observed during more than 100 years, although the earlier measurements have been less
systematic.
The common view is that burning of fuels, particularly, fossil fuels are causing the concentration of
CO2 to increase. Due to the the ability of CO2 to absorb certain bands in the IR spectrum, heat could
be trapped in the atmosphere, and consequently it is supposed that the increase in global
temperature is caused by increasing concentration of CO2. Twelve months mean values from 1981
and 2019 indicate that the temperature has increased 0.506 K and CO2 concentration 71.6 ppm
during 38 years (figure 1). If the temperature is controlled by CO2, 100 ppm could increase global
temperature 0.71 K. This common view has been challenged by several authors (Jones and Cox,
2005, Ahlbeck, 2009, Humlum et al., 2013, Curry, 2014, Koutsoyiannis et al., 2022).
Problems
There are some problems with the common view. In figure 1, it is seen that while the CO2
concentration is increasing monotonically, the global temperature fluctuates considerably. The
curves in the figure are 12 months mean values that have been calculated from data published by
NOAA. (https://www.nsstc.uah.edu/data/msu/v6.0/tlt/uahncdc_lt_6.0.txt) and
https://www.co2.earth/weekly-co2. Reference temperature is the mean value for the period 1981-
2010.

Figure 1. 12 months mean values of global temperature deviation (solid) measured with satellites
and CO2 concentrations (dashed) measured at Mauna Loa.
Before 1978, data on global temperature as well as carbon CO2 concentrations are less detailed and
accurate. But the general pattern is similar. CO2 measurements 1850-2018 show a steady increase in
concentration. In figure 2, data from HADCRUT and NOAA have been combined to calculate mean
values for 11 years. This period has been chosen to reduce possible effects of solar cycles.
(https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-
carbon-dioxide) and (https://www.metoffice.gov.uk/hadobs/hadcrut4/data/current/download.html)
Figure 2. 170 years of global temperatures combined from HADCRUT and NASA (solid) and CO2
concentrations (dashed).

The development of temperature looks more or less like stairs. While CO2-concentrations have
increased monotonically, this suggests that something else than increasing CO2 concentration could
be the real cause for global temperature to increase. During the 170 years, there have been four
periods with increasing, and three with decreasing temperature. Their lengths do not look random.
There have been 17 years up, 31 down, 34 up, 29 down, 31 up, 7 down, and 7 years up. Why are
the lengths so similar? Coincidence?
Figure 3. Increase of CO2 in the atmosphere since 1750 (solid), and the quantities released from
from burning of fuels (dashed).
There is a similar problem with the assumption that increasing CO2 concentrations are caused by
burning (fossil) fuels. There has been an increase in concentration of atmospheric CO2 ever since
the measurements started during the eighteenth century (Lindsay, 2022). In figure 3, the quantities
of CO2 added to the atmosphere since then, have been calculated from the increase in CO2
concentration. One has also tried to calculate the quantities released from burning of fuels.
(https://ourworldindata.org/co2-and-other-greenhouse-gas-emissions#how-have-global-co2-
emissions-changed-over-time) Although the old values may be uncertain, at least until 1850, it is
clearly seen that until 1965, more CO2 had been added to the atmosphere, than released by burning
of fuels.
Similarly, after 1965, much more CO2 has been released by burning, than has been added to the
atmosphere. Some mechanism other than burning fuels controls the increase in atmospheric CO2
concentrations. Since around the year 1800, both curves show an essentially exponential growth,
but with different growth constants. If the increase in atmospheric CO2 where controlled by burning
of fuels, one should expect the same constant for both curves.
Temperature and rate of change in CO2 concentration
As seen in figure 1, there was a peak in global temperature during 1998. A close look at the CO2
curve shows a small disturbance during the same year. It looks like the CO2 concentration increases
a little faster. And this is not a coincidence. Monthly, 12 months mean values of global temperature
and CO2 concentrations have been calculated and from them slopes of CO2 concentrations. They
have been plotted in figure 4. The correlation between global temperatures and growth rate of CO2

concentration is obvious.
Possible mechanisms causing total concentration of CO2 to control global temperature are known.
But no known mechanism causes small changes in the growth rate of CO2 concentration to give
major changes in global temperature, such as seen in figure 4. An example of this can be seen at the
1998 peak. As stated above, 100 ppm change in CO2 concentration should increase the global
temperature 0.71 K. Then, an increase of 2.7 ppm could not cause the temperature to raise 0.5 K.
Also, a few months later, the temperature decreases by the same amount, while the increase in CO2
concentration continues (although slower). This shows that the rate of change in CO2 concentration
is controlled, not by emissions, but by the global temperature. As the total concentration is the sum
of all changes in the past, temperature controls CO2 concentration rather than vice versa.
Figure 4. Global temperature (solid) and change rate of CO2 concentrations (dashed). Monthly
values of both.
Changes in rate for CO2 growth sometimes appear first, followed by changes in temperature. At
other times the changes occur in opposite order. Air is transparent to incoming sunlight, while
ground and sea absorb most of it. So changes in temperature have to start in sea or on ground, and
after that be transferred to the air. The exchange of CO2 between sea and air, on the other hand, is
determined by the temperature of the water, and not of that in the air above. Wind directions also
are important. Winds reaching Mauna Loa at a certain time may originate from net sources or net
sinks of CO2. This influences the timing considerably.
502 monthly values of growth rate for CO2 concentration versus global ΔT have been plotted in
figure 5. In the figure, a straight line has been calculated by linear regression. The equation of the
line is
Δ[CO2]/Δt = 2.13 ΔT + 2.04 (1)
In (1), the left hand side is the rate for increase in CO2 concentration (ppm/year), and ΔT is the

deviation of global temperature (in K) with respect to the mean value during 1981-2010.
Figure 5. Rate of CO2 concentration changes vs global temperature. The line shows linear
regression according to eqn (1).
The linear relationship tells that CO2 in the atmosphere is not in equilibrium, or even in steady state
with respect to sources and sinks. Equilibrium is not possible, but steady state is. So even if all
burning of fuels everywhere in the world could be stopped, and the temperature could be kept
constant, the concentration of CO2 would continue to grow until a steady state is reached. According
to (1), the CO2 concentration will stop increasing if the global temperature is lowered to about 1 K
below the mean value during 1981-2010. This explains why the quantities of CO2 in the atmosphere
have increased much more than could be explained by combustion during the 18th and 19th centuries
(figure 3). Then, ΔT was never was below -1 K compared to the reference temperature.
Ice, sea water and CO2
The atmospheric CO2 concentration is controlled by temperature rather than vice versa. As 70
percent of the Earth is covered by water, one probably finds the major sources and sinks for CO2 in
the in oceans rather than in vegetation. In warm areas, CO2 is released, and in colder it is absorbed.
The quantity of CO2 and carbonates in the oceans is about 50 times that in the atmosphere (Haynes
et al., 2017). The overall rate is determined by the degree of disequilibrium, but also by other
factors, like the rate at which carbonates are transported to or from the surface, reaction rates of CO2
in the water, and the sizes of areas in which absorption and release take place. In water CO2 reacts
as:
CO2(g) ↔ CO2(aq) (2)
CO2(aq) + H2O ↔ H2CO3(3)
H2CO3 ↔ HCO3- + H+(4)
HCO3- ↔ CO3-2 + H+(5)
The equilibrium (2), and possibly even (3) can be described by Henry's law (Daniels and Alberty,
1966). But (3) and (4) causes much more to be absorbed than stated by Henry's law. They are

described by coupled equations of chemical equilibrium. As an example, the equilibrium equation
for reaction (4) is
{
HCO
3
−
1
}{
H
+
1
}
{
H
2
CO
3
}{
H
2
O
}
=
K
(6)
In (6), {} means activity of the species. K is the equilibrium constant. As the water activity often is
close to one, it is sometimes included into K. Reactions (1)-(4) are most important directly, but (5)
is important in an indirect way, as CO3-2 is important for formation of complexes and other species
like NaCO3- or CaCO3(aq).
The seasonal variations of CO2 concentrations are supposed to be caused by the uneven distribution
of vegetation across the globe. But if CO2 is controlled by oceans, one could expect them to cause
seasonal variations as well.
Figure 6. Seasonal variations of Arctic sea ice and atmospheric CO2-concentration. Arctic sea ice
(solid) and changes of atmospheric CO2 concentration (hatched)
The quantities of sea ice in Arctis is calculated daily by the Danish Meteorological Institute.
(http://ocean.dmi.dk/arctic/icethickness/thk.uk.php) There is a remarkable similarity (figure 6)
between seasonal variations of CO2 concentration and quantity of sea ice in Arctis, with a delay of a
few weeks. Each curve shows mean values for the years 2015-2021 (six seasons), with long time
trends subtracted.
CO2 cannot be dissolved in ice, so when the ice melts, about 16000 km3 of water without CO2 is
formed. The decrease in atmospheric CO2 is about 7.3 ppm, that is 58 Gtons. This is far more than
the water from molten ice is able to absorb. But the melting ice consumes enough heat to decrease
the temperature by one K in about 1.3 million km3 of sea water. Values of the equilibrium constants
change with temperature according to Gibbs-Helmholtz equation (Daniels and Alberty, 1966).
dln
(
K
)
d
(
1
/
T
)=
ΔH
0
(7)

T is the temperature, R the gas constant, and ΔH0 is the enthalpy change of the reaction when
reactants and products are in their standard states. Reactions (2,3) as well as (4) have positive ΔH0
values, so the capacity of sea water to dissolve CO2 increases considerably with decreasing
temperature. As an example, as the freezing point of sea water is below zero, measurements of the
Henry constant for CO2 in NaCl solutions at such temperatures (Baileya et al. 2018) show that the
constant increases 6.8 percent for each K the temperature is lowered. Due to positive ΔH0 for (4) too
and the high pH value of sea water (pH=8.1) this means a large increase in absorption capacity
even for moderate changes in the temperature. Furthermore, new surface areas of absorbing water
are exposed when the ice melts. Thus, there is enough extra capacity to absorb the accumulated
CO2.
Discussion and Conclusion
The observed correlation between global temperature and rate of growth in atmospheric CO2
concentration shows that the global warming is not caused by increased CO2 concentration. Rather
the increase in CO2 concentration is caused by the global warming. This in turn means that neither
the increase in CO2 concentration nor global warming can be stopped by reducing combustion. All
such attempts will have negligible effect. The CO2 concentration will continue to grow anyway, as
long as the global temperature is high enough, or a steady state is approached.
There is an apparent paradox in the findings here. On one hand, higher temperature causes the rate
of CO2 concentration changes to increase (figure 5). On the other hand, lower temperature means
more ice in the arctic sea, and that causes the CO2 concentration to increase. The reason is that the
oceans both absorb and release CO2. In a belt around the equator, release takes place, while in
colder waters, CO2 is absorbed. The rates depend upon surface temperature distribution across the
oceans. A higher global temperature widens the areas releasing CO2. On the other hand, the more of
the absorbing surface that is covered with ice, the more the absorption rate decreases. So in short
term (seasonal), lower temperature causes net release, while higher temperature makes more
absorbing surface active, and thus the CO2 concentration decreases. Sometimes it is mentioned that
if the climate becomes warm enough, it will reach a “tipping point”, after wich there will be an
unstoppable increase of atmospheric CO2 concentration. The results here, in particular what is
shown in figure 1 and 5, indicate that a “tipping point” occurred already some 200 years ago.
With the results presented here, some important questions remain unanswered: Why has the CO2
concentration increased more than can be explained by combustion during 1750-1965? Why is the
concentration now higher than it appears to have been during earlier interglacial periods (Petit et al.
1999)? It is known that the volcano Krafla on Iceland had a huge eruption lasting from 1724 until
1729. (h.settps://earthice.hi.is/krafla_eruption_history) Volcanos generally are located where
continents are diverging. Generally, such zones are located at the bottom of oceans (Kious and
Tilling, 1996). Something that needs to be investigated is to what extent there were an unusually
high number of large volcanic eruptions at the ocean floors during the eighteenth century.
Another question that remains to answer is what has caused the changes in global temperature, and
why are there decades of increasing and decreasing global temperature? Why does it look like a
period with decreasing temperature is followed by an equally long period of rising temperature?
Could this be caused by variations in the Earth orbit due to influences from other planets? Or is it
merely coincidences?
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Keywords
climate, global temperature, carbon dioxide, arctic ice, fossil fuel, carbon dioxide derivative,
seasonal variation, sea water, carbonate, Henry's law, climate crisis, tipping point