THE HISTORY OF CO2 IN THE GLOBAL
ATMOSPHERE
It is an undisputed fact that all life on Earth is carbon based
and that the source of this carbon is CO2, which cycles
through the global atmosphere. The original source of CO2 in
the atmosphere is thought to be massive volcanic eruptions
during the Earth’s early history, the extreme heat of which
caused the oxidation of carbon in the Earth’s interior to form
CO2.
3 Today, as a minor gas at 0.04 per cent, CO2 permeates
the entire atmosphere and has been absorbed by the oceans
and other water bodies (the hydrosphere), where it provides
the food for photosynthetic species such a phytoplankton
and kelp. If there were no CO2 or an insufficient level of CO2
in the atmosphere and hydrosphere, there would be no life as
we know it on our planet.
On a relatively short-term basis (years to hundreds of
years), the carbon cycle is a complex series of exchanges
among the atmosphere, the hydrosphere, living species
and decomposing organic matter in soils and sediments.
Over the long term (millions to billions of years), the majority
of the carbon that has been absorbed from the atmosphere
by plants has been lost to the cycle into deep deposits of
fossil fuels and carbonaceous rock (minerals) such as
chalk, limestone, marble and dolomite. By far the majority of
the carbon sequestered over the long term is in the form of
carbonaceous rock.
We do not have a good estimate of the total amount of CO2
that has been emitted from volcanic activity into the global
atmosphere. We do not know the total amount of carbon
that has been lost to long-term sequestration in fossil fuels
and carbonaceous rock, but we do have order-of-magnitude
estimates. We do have quantitative estimates of the level of
CO2 in the atmosphere going back more than 600 million
years, i.e., the net result of additions from volcanic events,
losses to deep deposition in carbonaceous rocks and
fossil fuels, the biomass of living species and decomposing
organic matter. These estimates become more accurate
the closer they are to the present. This paper will focus on
the past 540 million years and in particular the past 140
million years.
The best estimate of CO2 concentration in the global
atmosphere 540 million years ago is 7,000 ppm, with a wide
margin of error. (See Figure 1). For the sake of discussion,
we will accept that number, which indicates a mass of more
than 13,000 billion tonnes (Gt) of carbon in the atmosphere,
17 times the present level, during the Cambrian Explosion,
when multicellular life evolved. This is considered the
advent of modern life, when both plant and animal species
diversified rapidly in warm seas and later colonized the land
during a warm terrestrial climate.4 Prior to this, for more than
three billion years, life was largely unicellular, microscopic
and confined to the sea.
Figure 1. Graph of global temperature and atmospheric CO2 concentration over the past 600 million years. Note both temperature and CO2 are lower
today than they have been during most of the era of modern life on Earth since the Cambrian Period. Also, note that this does not indicate a lock-step
cause-effect relationship between the two parameters.5
[8]
FRONTIER CENTRE FOR PUBLIC POLICY
The Rise of Terrestrial Woody Plants
One of the most significant developments during the
establishment of terrestrial plant species was the
evolution of wood, a complex of cellulose and lignin that
provided a rigid stem. This allowed plants to place their
photosynthetic structures higher toward the sun, thus
providing a competitive advantage. The evolution of lignin
also provided protection against attack from bacteria
and fungi, as no species had yet evolved enzymes that
could digest lignin. There followed in the Devonian Period
the spread of vast forests of tree ferns, trees and shrubs,
resulting in a massive increase in living biomass compared
with the low-lying vegetation prior to the woody era. This
orders-of-magnitude increase in biomass came with an
inevitable drawing down of CO2 from the atmosphere, as
wood is almost 50 per cent carbon. From that time until the
present day, the biomass of trees and other woody plants
far surpasses the sum of all other species combined.6
It could be expected that once living biomass had reached a
much higher but relatively stable state that the net withdrawal
of CO2 would end and would level off at a concentration
somewhat lower than the approximately 4,000 ppm (7,600
Gt of carbon) in the mid-Devonian. However, this was not the
case. CO2 levels continued to drop, with minor fluctuations
perhaps caused by volcanic activity, for the next 80 million
to 100 million years into the mid-Carboniferous Period until
they reached a level of about 400 ppm (760 Gt of carbon),
similar to present-day levels. Therefore, during this era, the
level of CO2 in the atmosphere was reduced by about 90
per cent. Many of the massive coal deposits we are mining
today were formed during this period.
There are two competing hypotheses regarding the
formation of coal during these ancient times. One hypothesis
postulates that coal deposits came about as trees died and
fell into vast swamps where they were preserved, eventually
buried by deep sediments, and over time transformed into
coal by heat and pressure.7 An alternative explanation
is that the decomposer species of bacteria, fungi and
insects had not yet developed the complex set of digestive
enzymes necessary to digest wood. Therefore, the dead
trees in forests simply piled up on top of one another and
new trees grew upon an ever-deepening layer of dead trees
until eventually they were buried, and heat and pressure
converted them into coal.8
The end of the Carboniferous and the beginning of the
Permian marked a reversal of the downward trend in CO2,
and over the next 125 million years, CO2 rose to about 2,500
ppm in the Jurassic Period. During this period, species of
Figure 2. The graph of CO2 and temperature shown in Figure 1 with the trend in CO2 concentration in the global atmosphere represented by the green arrow.
Note the uptick at the far right of the graph representing the reversal of the 600 million-year downward trend due primarily to emissions of CO2 from the use
of fossil fuels for energy. Note that even today, at 400 ppm, CO2 is still far lower than it has been during the most of this 600 million history.
[9]
FRONTIER CENTRE FOR PUBLIC POLICY
fungi developed enzymes that could digest the lignin in
wood.9 It is plausible that these species consumed vast
stores of dead wood near the surface, with the attendant
release of CO2 into the atmosphere. Coincident with the
development of decomposers that could digest lignin was
a significant reduction of coal formation. Volcanic activity
and outgassing of CO2 from the oceans may also have
played a role in bringing CO2 levels higher.
Regardless of which coal-forming hypothesis one favours,
and a combination of the two is plausible, if fungi and other
species had not evolved to produce the enzymes necessary
to digest lignin, it is likely that atmospheric CO2 would have
continued to decline until it reached the 150 ppm threshold
for the survival of plant life. At that point, species of plants
would begin to die for lack of CO2, and as more carbon was
sequestered as wood and as calcium carbonate in marine
deposits, living biomass would begin to shrink steadily until
most or all of it died. It was therefore most fortuitous that
white rot fungi and other species evolved the enzymes to
digest lignin, or the history of life on Earth would have been
considerably shorter.
The Second Long Decline of CO2
With this historical background, we will now focus on the
period from 140 million years ago to the present. Having
recovered to approximately 2,500 ppm, CO2 concentrations
gradually and steadily fell to what is likely the lowest level it
has been in the history of the Earth. The ice cores drilled
at Vostok Station in Antarctica indicate that at the height
of the last major glaciation event, 18,000 years ago, CO2
dropped to roughly 180 ppm (See Figure 3).10 This is only
30 ppm above the level of starvation for most plant species,
which is 150 ppm.11
One hundred and forty million years ago at 2,500 ppm, the
atmosphere held 4,750 Gt of carbon as CO2. At 180 ppm,
the atmosphere held 342 Gt of carbon as CO2, which over
the 140-million-year period represented a loss of 4,530 Gt
of carbon or 92.8 per cent of atmospheric CO2. While we do
not have accurate estimates of volcanic emissions of CO2
or of deep ocean sequestration of CO2 over this period,
we do have a very good representation of the net effect
on atmospheric levels of CO2. Because of this decline, on
a number of occasions during the present Pleistocene
Ice Age, CO2 has dropped during major glaciations to
dangerously low levels relative to the requirements of plants
for their growth and survival. At 180 ppm, there is no doubt
that the growth of many plant species was substantially
curtailed.12
The solubility pump and the biological pump continuously
remove carbon dioxide from the atmosphere.13 The
Figure 3. Graph of temperature and CO2 concentration from the Vostok ice cores in Antarctica showing that atmospheric CO2 concentration descended
close to 180 ppm at 18,000 YBP (years before present). Note that CO2 levels tend to lag behind changes in temperature.14
[10]
FRONTIER CENTRE FOR PUBLIC POLICY
solubility pump refers to the high solubility of CO2 in cold
ocean water at higher latitudes where sinking cold seawater
carries it into the depths of the ocean. The biological pump
refers to the sequestration of carbon from biomass and
calcium carbonate (CaCO3) from planktonic shells, corals
and shellfish into the deep ocean sediments. During the
past 140 million years, these processes have removed
more than 90 per cent of the CO2 in the atmosphere.
The steady reduction of CO2 in the atmosphere over the
past 140 million years from 2,500 ppm to 180 ppm, prior
to the Holocene interglacial period and prior to significant
human emissions of CO2, amounts to a net loss from the
global atmosphere of 32 thousand tonnes (Kt) of carbon
every year. We can reasonably surmise that the primary
cause of this downward trend was CaCO3 deposition from
plankton and coral reefs in marine sediments.15 During the
major glaciations, cooling oceans may also have absorbed
additional CO2.
CO2 Rises from the Brink
After the most recent major glaciation peaked 18,000 years
ago, CO2 levels began to rise in the atmosphere, reaching
260 ppm 10,000 years ago and 280 ppm prior to the
Industrial Revolution when fossil fuels became dominant for
energy production. The most plausible explanation for the
majority of this rise is outgassing of CO2 from the oceans as
they warmed with a warming climate.16 Since then, human
emissions of CO2 have contributed to raising the level to
about 400 ppm, a level perhaps not experienced during the
past 10 million to 20 million years. Since the onset of the
Industrial Age, CO2 has risen by 120 ppm or approximately
230 Gt of carbon in a little more than 100 years, whereas
the lesser “natural” increase from 180 ppm to 280 ppm took
about 15,000 years. The increase during the Industrial Age
is likely due to a combination of fossil fuel combustion, landuse
change, cement production and possibly outgassing
of CO2 from the oceans due to rising global temperature.
This latter point is the subject of much discussion and
contention but is not of principal concern in the context of
this paper.
[11]
FRONTIER CENTRE FOR PUBLIC POLICY
THE DISTRIBUTION OF CARBON TODAY
The global atmosphere today, at about 400 ppm CO2,
contains approximately 850 Gt of carbon compared with
the oceans, which contain approximately 38,000 Gt of
carbon, most of which was initially absorbed as CO2 from
the atmosphere. (See Figure 4) Therefore, the emission or
absorption of 1 per cent of CO2 from or into the oceans
would make a 45 per cent change to the CO2 level in the
atmosphere at the present concentration of CO2.
The truly astounding figure is the estimate of 100,000,000
Gt (one hundred million billion tons, also known as 100
quadrillion tons) of carbon in carbonaceous rocks, all or
most of which originated from CO2 in the global atmosphere.
If all that CO2 had remained in the atmosphere, it would
represent approximately 70 current global atmospheres
by weight at 100 per cent CO2. This highlights the fact that
during the Earth’s early times, vast quantities of CO2 were
outgassed from volcanism. During the past 3.5 billion years,
the vast majority (about 99.5 per cent) of the carbon in that
CO2 has been sequestered in carbonaceous rocks and to a
much lesser extent, fossil fuels.
It is interesting to note that our closest neighbouring planets,
Venus and Mars, have atmospheres that are dominated by
CO2, likely from early volcanic eruptions. Neither of them
evolved life that could convert the CO2 to CaCO3 to be
buried in marine sediments.
CO2 in the Oceans
The solubility of CO2 in the oceans is dependent on
the salinity and temperature of the oceans and on CO2
concentration in the atmosphere. Salinity varies among
oceans between 30 parts per thousand and 38 parts per
thousand and is relatively constant over time. The oceans
have warmed since the height of the Little Ice Age, so it is
likely there has been a net outgassing from them during the
past 300 years, at least until human-caused emissions of
CO2 began in earnest. From the literature, it appears that
we do not have definitive quantitative data for the fate
Figure 4. Depiction of the global carbon budget in Gt of carbon. Values in blue are stocks of carbon while values in red are annual flows. Note that the ocean
contains nearly 50 times as much carbon as the atmosphere does, and the ocean and atmosphere are in constant flux.17
[12]
FRONTIER CENTRE FOR PUBLIC POLICY
of the current 10 Gt of carbon emitted annually due to
human activities. We can measure the increase in the CO2
concentration in the atmosphere, but some of this may be
due to outgassing from the warming oceans rather than
from human-caused emissions. Many scholars conclude
that the oceans are absorbing roughly 25 per cent of the
human CO2 emissions, therefore negating the possibility
of a net outgassing of CO2. It is generally recognized that
global plant biomass is increasing because of increased
CO2 in the atmosphere, but quantifying this accurately
is difficult. One recent paper concluded that most of the
short-term CO2 uptake is by terrestrial plants and that very
little, if any, is absorbed by the oceans.18
In recent years there has been an outpouring of papers
warning that if CO2 emissions continue, and CO2 levels in
the atmosphere continue to rise, that a phenomenon called
“ocean acidification” will occur that will threaten the entire
marine food chain. Some postulate that the decrease in the pH
of the oceans will render it impossible for calcifying species
such as corals, shellfish, and calcifying species of plankton
such as coccolithophores and foraminifera to produce their
shells from CaCO3. The author has recently published an
in-depth paper on this subject. The paper concludes that
“ocean acidification” is a fabrication and provides five key
factors that make such an outcome impossible.19
CO2 in the Modern Era
The most important question facing a species on Earth
today is how long would it have been in the absence of
human-caused CO2 emissions until the gradual depletion of
CO2 in the atmosphere fell to levels that began to decrease
biomass due to starvation, thus signaling the beginning of
the end of life on Earth?
It is commonly believed that volcanic activity results in
massive emissions of CO2 comparable to or greater than
human-caused emissions. This is not the case. Whereas
the original atmospheric CO2 was the result of massive
outgassing from the Earth’s interior, there is no evidence that
large volumes of new CO2 were added to the atmosphere
during the 140-million-year decline leading to the present
era. The eruption of Mount Pinatubo, the largest in recent
history, is estimated to have released the equivalent of
2 per cent of the annual human-caused CO2 emissions.
Therefore, in the absence of human-caused emissions, it
could reasonably be presumed that CO2 levels would have
continued to fall as they had done for the previous 140
million years.20
Judging by the timing of the many glacial and interglacial
periods during the Pleistocene Ice Age, the next major
glaciation period could begin any time. Interglacial periods
have generally been of 10,000 years’ duration, and this
Holocene interglacial period began nearly 12,000 years
ago. In the absence of human-caused CO2 emissions and
other environmental impacts, there is no reason to doubt
that another major glaciation would have occurred, following
the pattern that has been established for at least the past
800,000 years, as established by the European Project for Ice
Coring in Antarctica (EPICA),21 and presumably for the past
2.5 million years of the Pletstocene Ice Age. These glaciations
have coincided with the Milankovitch cycles.22 (See Figure
5) The Milankovitch cycles are determined by oscillations in
the Earth’s orbit and by cycles of the tilt of the Earth toward
the sun. The strong correlation between the onset of major
periods of glaciation during the past 800,000 years and the
Milankovitch cycles has led the majority of earth scientists
and climatologists to accept the hypothesis that the major
glaciations are tied to the Milankovitch cycles in a causeeffect
relationship.
For 90 million years from the late Jurassic Period to the
Early Tertiary Period, global temperature rose considerably
while CO2 levels steadily declined.
Then after the Paleocene-Eocene Thermal Maximum, there
began a 50-million-year cooling trend in global temperature
to the current era. (See Figure 6) The Paleocene-Eocene
Thermal Maximum saw an average global temperature
[13]
FRONTIER CENTRE FOR PUBLIC POLICY
as much as 16°C higher than the temperature today. Yet,
the ancestors of every species living today must have
survived through this period, as they had also survived
through previous much colder climates. It is instructive
to note that despite the numerous periods of extreme
climatic conditions and cataclysmic events, every species
alive today is descended from species that survived those
conditions. This leads one to question the predictions
of mass species extinction and the collapse of human
civilization if the average global temperature exceeds a rise
of 2°C above today’s level.25
It may seem surprising that the average global temperature
could have been 16°C higher in previous ages, as this
Figure 5. Graph showing the atmospheric CO2 concentration and temperature from Antarctica for the most recent four interglacial periods, closely tied to
the Milankovitch cycles of 100,000 years. This graph is based on data from the 420,000 year record obtained from the Vostok ice cores drilled by Russian
scientists.23 Note the gradual nature of the onset of colder temperatures and the rapid warming at the end of the cycle. Note that the peak warming during
the most recent interglacial period (the Holocene) is lower than during the previous three interglacial periods.24
Figure 6. Global surface temperature from 65 million YBP showing the major cooling trend over the past 50 million years. While the poles were considerably
warmer than they are today, there was much less warming in the tropics, which remained habitable throughout. The Earth is in one of the coldest periods
during the past 600 million years.26
[14]
FRONTIER CENTRE FOR PUBLIC POLICY
would appear to render parts of the Earth that are warm
today virtually uninhabitable. The key to understanding this
is that when the Earth warms, it does so disproportionally,
depending on the latitude. While the Arctic and Antarctic
experience considerable warming, there is much less
warming in the tropics. Thus, the tropical regions remain
habitable while the high latitudes shift from polar to
temperate, and during the warmest ages, they shift to a
tropical climate.
It is clear from the 800,000-year Antarctic ice core record
that the coldest periods during major glaciations coincide
with the lowest levels of CO2 in the atmosphere. (see Figure
5) The correlation is certainly strong enough during this
period to suggest a causal relationship between CO2 and
temperature. However, there is disagreement in the literature
about which is the cause and which is the effect. Those who
ascribe the warming over the past century to greenhouse
gas emissions, CO2 in particular, also tend to agree with the
position set forth in Al Gore’s An Inconvenient Truth: The
Planetary Emergency of Global Warming and What We Can
Do about It, that the warming during the interglacial periods
is caused by rising CO2 levels.27 However, it is problematic
to postulate how the Milankovitch cycles could cause an
increase or decrease in atmospheric CO2 levels, whereas
it is plausible that the Milankovitch cycles could cause a
fluctuation in global temperature due to changes in solar
radiation, which in turn could cause either CO2 outgassing
from or absorption into the oceans. Indeed, both sets of ice
core data from Antarctica show that changes in temperature
usually precede changes in CO2 levels, suggesting that
temperature change is the cause of change in the level of
CO2.
28 Some have suggested that although the onset of
warming after a glaciation is caused by the Milankovitch
cycles, the subsequent outgassing of CO2 from the ocean
then becomes the predominant driver of further warming.29
Presumably, it would also be postulated that the cooling
leading to glaciation is triggered by the Milankovitch cycle
and then driven by reduced CO2 levels due to ocean
absorption. This hypothesis is not proven.
It is extremely unlikely or perhaps impossible to imagine how
CO2 could have increased from a pre-industrial 280 ppm
to 400 ppm in the absence of human-caused emissions.
No other species, existing or imagined in the near future,
is capable of digging and drilling into the massive deposits
of fossil fuels and then burning them so as to release CO2
back into the atmosphere from where it had come in the first
place. Many scientists think this increase in atmospheric
CO2 is the dominant cause of the slight warming (0.5C) of
the atmosphere over the past 65 years. Only time will tell
if this is the case. Since the Little Ice Age peaked around
1700, the climate has been warming in fits and starts for
about 300 years. It is possible that the most recent warming
is a continuation of the longer period of warming that had
already begun long before human-caused CO2 emissions
could have been a factor.
[15]
FRONTIER CENTRE FOR PUBLIC POLICY
HIGHER CO2 CONCENTRATIONS WILL
INCREASE PLANT GROWTH AND
BIOMASS
It has been well demonstrated that the increase in CO2 in
the atmosphere is responsible for increased plant growth
on a global scale. Many studies suggest that nearly 25 per
cent of human-caused CO2 emissions, or 2.5 Gt of carbon
annually, are absorbed by plants, thus increasing global
plant biomass. A recent study postulates that up to 50 per
cent of human CO2 emissions are absorbed by increased
plant growth.30 This has been described as a “greening
of the Earth” as CO2 reaches concentrations well above
the near-starvation levels experienced during the major
glaciations of the Pleistocene.31 The most prestigious
Australian science body, the Commonwealth Scientific
and Industrial Research Organisation (CSIRO), has shown
that CO2 particularly benefits plants that are adapted to dry
climates. In higher CO2 environments, they become more
efficient at photosynthesis, growing faster without using
more water.32
One of the most impressive records comes from an
experimental forest in Germany where there is a continuous
Figure 8. Change in net primary productivity of vegetation 1982 to 2010. The driest regions, such as Western Australia, sub-Saharan Africa, western India
and the Great Plains of North America, show the greatest increase in plant growth.36
Figure 7. Craig Idso,expert on CO2 and author of the CO2Science website34 demonstrating the growth-rate of pine trees under ambient conditions versus
the addition of 150 ppm, 300 ppm and 450 ppm CO2. In a higher CO2 world there will be a great increase in the growth of food crops, forests, and wild
landscapes around the world. Studies also demonstrate that higher CO2 levels in the oceans will result in increased growth of phytoplankton and other
marine plants.35
[16]
FRONTIER CENTRE FOR PUBLIC POLICY
record of forest growth since 1870. Since 1960, as CO2
emissions began to rise rapidly, the growth rate of individual
trees has increased by 32 per cent to 77 per cent. While
some of this may be due to the slight increase in temperature
since 1960, the much higher growth rate is consistent with
laboratory and field studies on the effect of increased CO2
levels on plants.33
It is not widely known that greenhouse operators worldwide
inject additional CO2 into their greenhouses in order to increase
the growth and yield of their crops. Among horticulturalists, it
is well known that this practice can increase growth by 40 per
cent or more. This is because the optimum level of CO2 for
plant growth is between 1,000 ppm and 3,000 ppm in air, much
higher than the 400 ppm in the global atmosphere today.37
Every species on Earth, including our own, is descended from
ancestors that thrived in climates with much higher levels of
CO2 than are present today.
Discussion
The debate about climate change has one side insisting
that the “science is settled.” Yet, there is no scientific proof
that increased CO2 will result in disaster, as CO2 has been
higher during most of the history of life on Earth than it is
today. On the other hand, it can be stated without a doubt
that if CO2 once again falls to the level it was only 18,000
years ago, or lower, there would be a catastrophe unlike any
known in human history. We are advised by many scientists
that we should be worried about CO2 levels climbing higher
when, in fact, we should actually be worried about CO2
levels sinking lower.
Atmospheric CO2 Concentrations in
the Future
If humans had not begun to use fossil fuels for energy, it is
reasonable to assume that atmospheric CO2 concentration
would have continued to drop as it has done for the past
140 million years. It is also reasonable to assume that
the Earth’s climate would continue to fluctuate between
relatively long periods of glaciation and relatively short
periods of interglacial climate similar to the present climate.
Given continued withdrawal of carbon from the atmosphere
into the ocean sediments, it would only be a matter of time
before CO2 dropped to 150 ppm or lower during a period
of glaciation. At the average rate of 32 Kt of carbon lost
annually, this would occur in less than two million years from
now. In other words, the beginning of the end of most life
on planet Earth would begin in fewer years into the future
than our genus of primates, Homo, has existed as a distinct
taxonomic unit.
It is instructive to note that our species is a tropical species
that evolved at the equator in ecosystems as warm or
warmer than today’s. We were only able to leave the warmth
of the tropical climate due to harnessing fire, wearing
clothing and building shelters. This allowed us to settle in
temperate climes and even Arctic conditions by the sea
where domesticated dogs as well as marine mammals made
life possible for a very small population. However, we cannot
grow food crops in abundance on glaciers or in frozen soil.
Moreover, we would not be able to grow much of anything
anywhere if the level of CO2 went below 150 ppm. There is a
distinct possibility that no amount of additional CO2 will shift
the climate out of the next major period of glaciation. This
is not a reason to abandon hope but rather to marvel at the
fact that we can actually put some of the CO2 needed for life
back into the atmosphere while at the same time enjoying
abundant, reasonably priced energy from fossil fuels.
There has been a gradual net loss of CO2 from the
atmosphere during the past 550 million years from
approximately 14,000 Gt to approximately 370 Gt at the
lowest level during the height of the last glaciation. This
is a reduction of nearly 98 per cent of one of the most
essential nutrients for life on Earth. In the absence of
human CO2 emissions over the past century, it is difficult
to imagine how this process of continuous removal of CO2
would be interrupted. Massive volcanism on a scale not
seen for more than 200 million years would be required to
[17]
FRONTIER CENTRE FOR PUBLIC POLICY
bring about a reversal in the long-term CO2 trend that has
now been achieved by human CO2 emissions. There is no
doubt the Earth’s interior has cooled substantially over
its roughly 4.6-billion-year existence. This makes massive
volcanism an ever-decreasing likelihood. There is no other
plausible natural mechanism to return carbon to the global
atmosphere in the form of CO2.
The present Holocene interglacial has already endured
longer than some previous interglacial periods. The
Holocene is also somewhat cooler than previous
interglacial periods. Of more urgent concern than the
possible starvation of life two million years from now is what
would happen at the onset of the next glaciation, possibly a
relatively short time from now. In the absence of human CO2
emissions, both temperature and CO2 would have dropped
to levels that would result in a continuous reduction in plant
growth, bringing in climatic conditions similar to or perhaps
even more severe than those that occurred in previous
glaciations. This would certainly lead to widespread famine
and likely the eventual collapse of human civilization. This
scenario would not require two million years but possibly
only a few thousand. Even if the conditions of the Little
Ice Age reoccurred in the next hundreds of years with a
human population of nine billion or more, we can be sure
the population would not be nine billion for long.
There is a strong argument to be made that the Earth is
already in a cooling trend that is descending into the next
100,000-year cycle of major glaciation. See Figure 5 and
note that in the three preceding interglacial periods, there
was a sharp peak followed by a steady downward trend
in temperature. The peak temperature in this Holocene
interglacial period was during the Holocene Optimum
between 5,000 and 9,000 years ago. Since then, the
warming peaks have been diminishing, and the cool periods
have been colder. The Little Ice Age, which peaked about
300 years ago, was possibly the coldest period of climate
since the Holocene Optimum.39
A Paradigm Shift in the Perception
of CO2
Independent scientist James Lovelock provides an
interesting example of both these contrasting predictions
of future catastrophe versus salvation regarding CO2
Figure 9. Reconstructed Greenland mean temperature anomalies (top) and Antarctic CO2 concentration (bottom). Halving the temperature anomalies to
allow for polar amplification gives a reasonable approximation of global temperature change in the Holocene. Since the Holocene Optimum began about
9,000 years before present (ka BP), global temperature has fallen by ~1°C, though CO2 concentration rose throughout.38
[18]
This abrupt reversal of Lovelock’s interpretation of CO2 is
precisely what is required universally to avoid the tragedy
of depriving billions of people of reasonably priced, reliable
energy, especially those with a need to lift themselves
out of poverty. There must be a total paradigm shift from
demonizing fossil fuels and fearing CO2 as a toxic pollutant
to celebrating CO2 as the giver of life that it is while
continuing to use fossil fuels ever-more efficiently. Like
Lovelock, we should be hopeful that CO2 will prove to be
the moderate warming influence that it is predicted to be in
theory. A somewhat warmer world with a higher level of CO2
in the atmosphere would result in a greener world with more
plant biomass, higher yields of food crops and trees, a more
hospitable climate in high northern latitudes and a possible
reduction in the likelihood of another major glaciation.
It is highly probable, and ironic, that the existence of life itself
may have predetermined its own eventual demise due mainly
to the development of CaCO3 as armour plating in marine
organisms.45 The fact that humans appear able to reverse
this fate temporarily due to our recycling of CO2 back into
the atmosphere by burning fossil fuels for energy verges on
the miraculous. Nevertheless, there is only so much fossil
fuel, and once burned, it is not renewable in the short to
medium term. The vast bulk of carbon is sequestered into
carbonaceous rocks, mainly as CaCO3. Today, about 5 per
cent of human CO2 emissions are derived from converting
CaCO3 with heat into CO2 and CaO (lime) to manufacture
cement. Therefore, when fossil fuels become scarce in
future centuries, and if CO2 again begins to dwindle, we will
have the option of producing additional CO2 by burning
limestone with nuclear or solar energy, with lime for cement
as a useful by-product. This has the potential to extend
the existence of a highly productive living Earth into the far
distant future.
It is clear from the preceding discussion that rather than
bringing on a catastrophic climate condition, human CO2
emissions are serving to reinstate a balance to the global
carbon cycle. By reversing the 140-million-year decline in
atmospheric CO2, we are helping to ensure the continuation
of carbon-based life on Earth.
[19]
FRONTIER CENTRE FOR PUBLIC POLICY
CONCLUSION
CO2 is essential for life, and twice in the history of modern
life there have been periods of steep decline in the
concentration of CO2 in the global atmosphere. If this decline
were to have continued at the same rate into the future, CO2
would eventually fall to levels insufficient to support plant
life, possibly in less than two million years. More worrisome
is the possibility in the nearer future that during a future
glaciation, CO2 may fall to 180 ppm or lower, thus greatly
reducing the growth of food crops and other plants. Human
CO2 emissions have staved off this possibility so that at least
during a period of glaciation, CO2 would be high enough to
maintain a productive agricultural industry.
A 140 million year decline in CO2 to levels that came close
to threatening the survival of life on Earth can hardly be
described as “the balance of nature”. To that extent human
emissions are restoring a balance to the global carbon cycle
by returning some of the CO2 back to the atmosphere that
was drawn down by photosynthesis and CaCO3 production
and subsequently lost to deep sediments. This extremely
positive aspect of human CO2 emissions must surely be
weighed against the unproven hypothesis that human CO2
emissions are mainly responsible for the slight warming
of the climate in recent years and will cause catastrophic
warming over the coming decades. The fact that the current
warming began about 300 years ago during the Little Ice
Age indicates that it may at least in part be the continuation
of the same natural forces that have caused the climate to
change through the ages.
Despite a great deal of evidence to the contrary, much
of Western society has been convinced that a global
warming and a climate change crisis is upon us. The idea
of catastrophic climate change is a powerful one, as it
encompasses everything and everywhere on Earth. There
is nowhere to hide from “carbon pollution.” There is also the
combination of fear and guilt: we are fearful that driving our
cars will kill our grandchildren, and we feel guilty for doing so.
A powerful convergence of interests among key elites
supports and drives the climate catastrophe narrative.
Environmentalists spread fear and raise donations;
politicians appear to be saving the Earth from doom; the
media has a field day with sensation and conflict; scientists
and science institutions raise billions in public grants, create
whole new institutions, and engage in a feeding frenzy of
scary scenarios; businesses want to look green and receive
huge public subsidies for projects that would otherwise be
economic losers, such as large wind farms and solar arrays.
Even the Pope of the Catholic Church has weighed in with
a religious angle.
Lost in all these machinations is the indisputable fact that
the most important thing about CO2 is that it is essential
for all life on Earth and that before humans began to burn
fossil fuels, the atmospheric concentration of CO2 was
heading in a very dangerous direction for a very long time.
Surely, the most “dangerous” change in climate in the short
term would be to one that would not support sufficient food
production to feed our own population. The current “pause”
in global warming recorded by two satellites and thousands
of weather balloons, now nearly two decades on, does give
pause to the hypothesis that higher CO2 will inevitably lead
to higher temperatures.46 During this period of no significant
warming, about one-third of all human CO2 emissions since
the beginning of the Industrial Age has been emitted into
the atmosphere. The best outcome would be that CO2 does
cause some measure of warming, but somewhat lower than
that suggested by extreme predictions.47
We should ask those who predict catastrophic climate
change, including the UN’s Intergovernmental Panel on
Climate Change, some pressing questions regarding the
outcome if humans had not intervened in the carbon cycle.
• What evidence or argument is there that the global
climate would not revert to another glacial period in
keeping with the Milankovitch cycles as it has done
repeatedly during at least the past 800,000 years?
[20]
FRONTIER CENTRE FOR PUBLIC POLICY
• What evidence is there that we are not already
past the maximum global temperature during this
Holocene interglacial period?
• How can we be certain that in the absence of
human emissions the next cooling period would
not be more severe than the recent Little Ice Age?
• Given that the optimum CO2 level for plant growth
is above 1,000 ppm and that CO2 has been above
that level for most of the history of life, what sense
does it make to call for a reduction in the level of
CO2 in the absence of evidence of catastrophic
climate change?
• Is there any plausible scenario, in the absence
of human emissions, that would end the gradual
depletion of CO2 in the atmosphere until it reaches
the starvation level for plants, hence for life on earth?
These and many other questions about CO2, climate and
plant growth require our serious consideration if we are to
avoid making some very costly mistakes.
.
