Earth has existed for some 4,600 million years. This condensed history sets the current concerns about the level of atmospheric CO2 and the recent possible impact of any extra Man-made CO2 affecting global temperature in context.
CO2 in the atmosphere
To understand the context of current concerns about the increase of CO2 in the atmosphere from the Man-made activities, it is useful to review the long-term history of the Earth’s atmosphere
- as far as the development of life on Earth was concerned the first 4,000 million years were comparatively uneventful. Although photosynthesis first occurred ~ 3,000 million years ago, it took evolution all that time to make any advances beyond single cell/algal organisms.
- in those earlier times, ~3,300 million years ago atmospheric CO2 had reached its maximum level of about 35%, 350,000 ppmv: atmospheric CO2 concentration has progressively diminished ever since.
- it was only when photosynthesis took hold about 2,000 million years ago, that the level of atmospheric Oxygen could start to rise to its current level of ~22% of the atmosphere.
- over the same period CO2 concentrations diminished as Plant Photosynthesis used the sun’s energy to convert atmospheric CO2 to sugars and thus to generate all the other types of organic molecules associated with life.
- CO2 has progressively reduced in the atmosphere by both being absorbed by the Oceans to be sequestered by Ocean life as limestones or later converted into fossil fuels from luxuriant Plant growth.
- as a result, atmospheric CO2 has reduced by some thousand-fold from its high point of 35%, 350,000ppmv to arrive at the current levels around 400+ppmv.
The Phanerozoic Eon: the most recent 600 million years
It is only in last 600 million years, the Phanerozoic Eon, (meaning “visible life”), that Life on earth developed and advanced radically. The following observations arise from the Scotese – Berner representation of the Phanerozoic Eon:
- throughout much of this period global temperatures were fairly stable. In the main they were significantly higher at ~25°C some 10°C higher than at present.
- until ~600 million years ago life only existed in the Oceans and atmospheric CO2 levels were high at 5000 – 7000 ppmv more than 12 – 15 times current levels.
- about 500 million years ago Plants evolved to populate the land with CO2 levels still at 4000 – 5000 ppmv.
- so, Plant evolution took place with CO2 levels at or more than 10 times higher than at present.
- by 400 million years ago, Plant life on land had become very successful and productive worldwide at a CO2 level, (~3000 – 4000ppmv).
- that abundant Plant life, enabled by Solar energy, was progressively laying down Coal formations and other fossil fuels.
- this abundant period was followed by an extended ice age 320 – 280 million years ago when CO2 levels fell to close to current modern levels, (~500ppmv).
- with higher temperatures again reaching to ~25°C CO2 levels advanced to a maximum of ~ 2500ppmv, ~170 million years ago.
- this was the time of the dinosaurs lasting some 160 million years from 230 – 65 million years ago.
- following a Global catastrophe, probably the Chixulub asteroid impact, when the dinosaurs became extinct 65 million years ago the Earth was gradually repopulated by mammals, who progressively filled the environmental niches vacated by the dinosaurs.
- from a high CO2 level of ~2200ppmv some 165m years ago, CO2 concentration has declined consistently down to the current levels ranging from 180 – 410 ppmv.
- likewise, temperatures have also declined from about 25°C to about 15°C or lower.
The Quaternary Era
About 2,600,000 years ago the World again descended into a true Ice Age, with the establishment of permanent ice sheets at both poles. The world is now living in that continuing Ice Age. There is no indication of how long Planet Earth may remain in its current state of long-term glaciation.
These long-term ice-age conditions have generally maintained global temperatures as much as 8°C lower than during our present Interglacial, resulting in massive Ice sheets covering much of the currently inhabited portion of the land mass of the Northern Hemisphere.
During those ~100,000 year-long glacial periods CO2 levels have always fallen significantly. This is a result of colder oceans being again capable of re-absorbing CO2 from the atmosphere. Once transferred to the Oceans, CO2 is lost permanently from the atmosphere, as it is sequestered by marine life forming their protective shells: these eventually sink and progressively form limestone rocks.
Variations in the planetary and orbital geometry within the Solar system have meant that this state of glaciation has been punctuated fairly regularly, at roughly ~100,000 year intervals by interglacial periods, when temperatures have risen.
Interglacial warming episodes cause an enormous, positive but temporary change in the habitability of Planet Earth.
These warmer interglacial periods have always been very productive for the biosphere and most recently for the developmental success of Man-kind for the last 10,000 years.
As Oceans warm during Interglacials, they can no longer retain as much dissolved CO2 and as a result they slowly out-gas CO2. Accordingly atmospheric CO2 increases following any temperature increase, the process of out-gassing is delayed by about 800 years.
Interglacial periods generally last 10,000 – 15,000 years. The rate of temperature change from full glacial conditions to the benign environment of an interglacial can be very sudden on the geological timescale. This level of rapid change was seen at the end of the Eemian interglacial ~120,000 years ago and in the rapid temperature recovery at the beginning of our own benign Holocene Epoch.
Across the 110,000 years of the last interglacial, there were many sudden warming and cooling excursions unaffected by any Man-made intervention. These rapid changes have exceeded the rate of the recent, warming at the end of the 20th century, which is asserted were artificially induced solely by Man-made CO2 emissions.
Most Interglacial periods have been warmer than the present Holocene: in the previous Eemian interglacial Hippopotami thrived in the Rhine delta some 120,000 years ago.
Our Holocene Epoch
Our current Holocene epoch is just the most recent of these periodic, warmer, geologically short interglacial intervals. The current warmish Holocene interglacial has been entirely beneficial to the Biosphere and Man-kind World-wide.
The Holocene Epoch has been the enabler of Man-kind’s civilisation for the last 10,000 years. The congenial climate of the Holocene epoch spans from Man-kind’s earliest farming to the scientific and technological advances of the last 200 years. The temperature profile of the Holocene interglacial is remarkable, when compared to the previous interglacial periods: the temperatures have been lower, the profile apparently flattened and somewhat prolonged.
It is useful to look at climate change from a longer term, century by century and even on a millennial perspective, when considering the scale of temperature changes that “Climate Alarmists” predict arising from Man-made CO2 induced Global Warming and their view of the disastrous effects of additional Man-made Carbon Dioxide emissions in the later part of the last century. The temperature excursions shown by the Greenland Ice core records across the Holocene can be seen to be minor in comparison to the future modelled temperature assertions of Climate Alarmists.
From the record of past interglacials in the Quaternary era, our Holocene interglacial is now likely to be short lived on a geological timescale: although as the Earth’s current orbit is less elliptical than in the past this Holocene interglacial may well be extended somewhat.
The Northern Hemisphere Ice Core records from Greenland show:
- for its first 7-8000 years the early Holocene, including its high point, known as “the Holocene Climate Optimum”, had virtually flat temperatures, an average drop of only ~0.007 °C per millennium.
- but the more recent Holocene, since a “tipping point” at ~1000BC, has seen a temperature diminution at more than 20 times that earlier rate at about 0.14 °C per millennium.
- each of the notable high points in the Holocene temperature record:
- Holocene Climate Optimum.
have been progressively colder than each previous high point.
- the last millennium 1000AD – 2000AD, encompassing the “Little Ice Age”, has been the coldest millennium of the entire Holocene interglacial.
- the Holocene interglacial is already 10 – 11,000 years old and judging from the length of previous interglacial intervals the Holocene epoch could well be drawing to its close: in this century, the next century or this millennium.
- the beneficial recent warming, recovering from the Little Ice Age since the 1850s, occurred with two particular 20th century bursts to a Modern high.
- only the latter of these 20th century temperature increases from ~1975 onwards till 2000 could have been influenced by any CO2 emissions derived from Man-kind’s fossil fuel use.
this temperature increase has been “rebranded” as the:
- “Great Man-made Global Warming Alarm”.
- “Catastrophic Man-made Climate Change”.
- “the Climate Emergency”.
- however, Climate Alarmists seem to expect that because of the brief increase of temperature over the last quarter of the last century, that the warming recovery from the Little Ice Age will continue inexorably upwards.
- meaning that in their Alarmist view that there will be an immediate, exaggerated and precipitous reversal of the long-term temperature trend of the last 3000 years, resulting from Man-made CO2 emissions.
- eventually this late 20th century 25 year temperature blip may come to be seen as just noise in the system in the longer-term progress of comparatively rapid cooling over the past 3000+ years.
- all published Greenland Ice Core records corroborate this finding. They exhibit the same pattern of a prolonged relatively stable early Holocene period followed by a subsequent much more rapid decline in the more recent, (3000 year), past.
- however, it would seem more likely than not that the Earth’s temperature will continue its downward course of the past 3000 years, unless it suddenly falls precipitously, just as temperatures have fallen rapidly at the termination of previous interglacials.
Note that the much vaunted and much feared political “fatal” tipping point of +2°C would only bring Global temperatures back to the level of the very congenial climate of “the Roman warm period” 2000 years ago. Were possible to reach the “horrendous” level of +4°C, postulated by Alarmists, that extreme level of warming would still only bring temperatures to about the level of the previous Eemian maximum, a warm and abundant epoch, when hippopotami thrived in the Rhine delta. For a more comprehensive views of the decline of the Holocene see:
Climate and Human Civilization over the last 18,000 years
The effect of future CO2 growth
As well as the out-gassing of CO2 from warmer oceans, atmospheric CO2 concentration has also seen a contribution of Man-made CO2 emissions from the use of fossil fuels over the past 200 years as the industrial revolution has advanced and Global population has increased. The records show that at present atmospheric CO2 is increasing from both these sources in combination is at about 2ppmv / year. About half of any extra CO2 emissions are absorbed virtually immediately by the Oceans and/or processed by more abundant plant growth within the Biosphere.
As life has thrived and as plants evolved with CO2 levels at more than 10 times this level, any recent comparatively minor increase of atmospheric CO2 is not of any real concern:
- nonetheless, even at its current low level, ~400ppmv, all Life on Earth is still entirely dependent on the CO2 in the atmosphere: CO2 is used by plants via photosynthesis to release oxygen and to thus generate all other organic compounds.
- if atmospheric CO2 concentration were to fall to 150 ppmv in some future glaciation, photosynthesis would stop thus plant-life and all Life on Earth would be extinguished.
- it is only ~30,000 years ago, in the depths of the last glaciation, all Life on Earth came close to that total annihilation, when atmospheric CO2 concentration fell to 180 ppmv, only a few percent above the terminal CO2 value of 150 ppmv when all photosynthesis would cease:
- this atmospheric CO2 reduction process is inexorably driven by colder Oceans absorbing more atmospheric CO2.
- in colder oceans atmospheric CO2 can be progressively sequestered over the millennia by marine life and eventually deposited as limestones.
- as far as plant life is concerned even at ~420+ ppmv the World is still in a state of CO2 starvation.
- from the point of view of Plant life, at least 1200ppmv or more would be preferable: this is well understood by horticulturalists, who add CO2 to about this level to increase crop productivity in their warmed greenhouses.
- in the recent past, (the last 12,000 years,) as the present Holocene interglacial epoch has advanced, the Earth warmed, so warmer Oceans out-gassed CO2 to approach a pre-industrial level of ~300ppmv.
- but when plants evolved on land, atmospheric CO2 levels were very much higher, (3000 – 4000 ppmv), ten-fold current values and although temperatures were generally higher no runaway Global warming resulted.
- there was very luxuriant plant growth in the Silurian and Devonian eras leading to the laying down of massive Coal deposits.
- in the course of some future glaciation, natural processes with the cold Oceans absorbing atmospheric more and more CO2 are likely to finally extinguish all Life on Earth due to the starvation of Plant life from insufficient CO2 in the atmosphere.
- thus, the interference of Man-kind, emitting extra previously sequestered CO2 into the atmosphere from the use of fossil fuels has the potential to slow these processes and thus probably extend the viability of all Life on Earth by several millennia.
- slow and deferred CO2 out-gassing process from warming Oceans is continuing and has been supplemented by Man-made CO2 emissions since the 1850s from the burning of fossil fuels.
- with these two CO2 sources in combination, CO2 level has now reached ~420ppmv
- plant productivity has already improved radically with increasing atmospheric CO2 and NASA has already reported ~+15% more green growth worldwide.
- globally over the last 50 years, enhanced agricultural productivity has enabled the growth in food supply for a growing World human population.
- plant productivity is hampered in colder weather: any cooling can immediately lead to agricultural losses, this has already been seen in the last two growing seasons, 2020-2021, at the present Solar minimum.
- with cooling, weather will inevitably get worse: the temperature difference between the tropics and the poles would increase and with that greater potential energy differential weather deteriorates.
- the only way that atmospheric CO2 levels will ever be reduced is by the cooling of the Oceans: as they cool, they will once again be able to re-absorb CO2 from the atmosphere, that can only occur in some coming major ~100,000+ year glacial period.
The impact of future Man-made CO2 emissions
Climate Sensitivity is defined as the temperature effect of doubling atmospheric CO2 concentration. This is the value assessed by Climate Modellers as their definitive result on which to base international climate policy.
A simplified estimate of the potency of CO2 as a Greenhouse gas is that its effectiveness diminishes logarithmically as concentration increases. A simple, “back of the envelope calculation”, can thus show the likely temperature effect of doubling of atmospheric CO2 concentration from the current 410ppmv up to a future 820ppmv. That calculation takes no account of any possible water vapour and cloud feedbacks, which might enhance but which are equally likely to reduce the temperature effect of any added CO2.
The assumptions behind the calculations and graphic below are as follows:
- the Earth’s Greenhouse effect sustains Global temperature by about +33°C.
- water vapour and clouds are responsible for approximately 90% of the total Greenhouse effect: the net overall effect is correct but the actual effectiveness of water vapour and clouds is bound to be very variable according to latitude and local environmental conditions.
- CO2 and the other minor Greenhouse gases are responsible for roughly 10% of the total effect of about +~3.3°C.
- the other Greenhouse gases, (O3, N2O and CH4), although in absolute terms can give rise to more effective warming than CO2, they are at such low concentrations that they are unable to make any significant contribution to the Greenhouse effect. In addition, it should be noted that N2O and CH4 react rapidly in the atmosphere and are thus quickly dissipated after their release.
- logarithmic diminution operates for CO2 doubling concentration across the full range of CO2 concentration values: the CO2 warming effect diminishes as its concentration increases.
- so, in effect CO2 is a comparatively insignificant “Greenhouse Gas”, and it is only in trace amounts at ~420 parts per million by volume, (ppmv).
- the present ~420ppmv concentration of CO2 is an order of magnitude lower than the CO2 concentration levels existing when Plants evolved on land some 500 million years ago.
- if Plants had the vote, they would much prefer higher CO2 levels and they could thrive even more.
The diagram above shows how:
- there is no direct, straight-line relationship between atmospheric CO2 concentration and its influence on temperature.
- the “Greenhouse” warming effectiveness of CO2 diminishes logarithmically as its concentration increases, indicated in the following diagram:
- the warming capability of CO2 is now so close to saturation because of the logarithmic diminution effect, that doubling concentration from 410ppmv to 820 ppmv results in a temperature effect of only about +0.35°C.
- at the current rate CO2 of emissions growth, ~2.5ppmv/year, the transition to double the present CO2 concentration could take up to ~160 years.
- thus, the minor temperature increase that might be attained from further Man-made CO2 emissions is both miniscule, beneficial and far in the future.
Recent paper by W. A. van Wijngaarden and W. Happer. 2020
“Dependence of Earth’s Thermal Radiation on Five Most Abundant Greenhouse Gases”
This paper shows detailed results for all greenhouse Gases and their combined effect on the thermal radiation to space and thus their influence on Earth’s surface temperatures according to ~300,000 frequency bands. It also assesses the the difference in radiation to space of differing concentrations of CO2 from 400 – 800 ppmv.
The atmospheric temperatures and concentrations of Earth’s five most important, greenhouse gases, H2O, CO2, O3, N2O and CH4 control the cloud-free, thermal radiative flux from the Earth to outer space. Over 1/3 million lines having strengths as low as 10−27 cm of the HITRAN database were used to evaluate the dependence of the forcing on the gas concentrations. For a hypothetical, optically thin atmosphere, where there is negligible saturation of the absorption bands, or interference of one type of greenhouse gas with others, the per-molecule forcings are of order 10−22 W for H2O, CO2, O3, N2O and CH4. For current atmospheric concentrations, the per-molecule forcings of the abundant greenhouse gases H2O and CO2 are suppressed by four orders of magnitude. The forcings of the less abundant greenhouse gases, O3, N2O and CH4, are also suppressed, but much less so. For current concentrations, the per-molecule forcings are two to three orders of magnitude greater for O3, N2O and CH4, than those of H2O or CO2. Doubling the current concentrations of CO2, N2O or CH4 increases the forcings by a few per cent. These forcing results are close to previously published values even though the calculations did not utilize either a CO2 or H2O continuum. The change in surface temperature due to CO2 doubling is estimated taking into account radiative-convective equilibrium of the atmosphere as well as water feedback for the cases of fixed absolute and relative humidities as well as the effect of using a pseudoadiabatic lapse rate to model the troposphere temperature. Satellite spectral measurements at various latitudes are in excellent quantitative agreement with modelled intensities.
The graphic below summarises those results at temperate latitudes. The effect of added CO2 up to 800ppmv is the difference in area between the red and black curves in other words just ~3 Watts / square meter. That amounts to a 1% reduction of the radiation to space and confirms that as an overall estimate of logarithmic diminution of CO2 warming effectiveness is reasonable.
Further graphs can represent differing environments, at different latitudes with differing climates at differing cloudiness and humidity across the world: nonetheless they all show the same fundamental picture. Other natural feedbacks may on occasions change the parameters nonetheless the basic result remains. At a maximum the value for Equilibrium Climate Sensitivity can not be greater than +0.75°C.
As Will Happer said in a recent lecture
“The important point here is the red line on this chart. It shows what would happen if the concentration of CO2 was doubled. The gap between the black line and the red line shows the extent of the effect of doubling CO2. So, you can see that doubling CO2 now makes virtually no difference.
On the basis of this miniscule difference, we are supposed to give up our liberties, give up the gasoline engines in our automobiles, give up all the benefits of Western Industrial society and submit to dictatorial Government controls”.
“The message I want you to understand is: don’t let anyone convince you that is a good bargain: it is in fact a terrible bargain.”
If the limited future temperature effect of additional atmospheric CO2 is anywhere close to reality this result means that:
- there is no immediate and catastrophic overheating problem arising from the further Man-made emissions of CO2 nor from the continued burning of fossil fuels releasing CO2 into the atmosphere.
- at the current rates of growth of CO2 concentrations, it will take about 150 years for the effect of doubling CO2 to ~820 ppmv to materialise.
- any Man-made increase in atmospheric CO2 can only beneficial for the Biosphere and for Man-kind.
- more CO2 emitted to the atmosphere is likely to extend the viability of all life on Earth through future glacial periods.
- the whole Global Warming / Climate Change agenda is a fabrication supported only by quasi-religious unscientific beliefs in the evils of Western industrial society and a political agenda intended to undermine Western capitalism.
- as the undeveloped world advances, seeking the lifestyle advantages of Western civilisations, atmospheric CO2 levels will continue to increase from their CO2 emissions with cheap coal-firing for electricity generation, improving their greater general wellbeing, for their greater personal mobility and eventually leading to a reduction of the pressure for Global Population growth.
- so, any CO2 emissions reductions made in the Western World with their resulting economic sacrifices of wellbeing will be overtaken and soon further exceeded by the activities of the Developing and Eastern worlds.
- it should be realised that climate change policies in the West are being enacted not on valid scientific evidence showing minor temperature effect for further Man-made CO2 emissions but on the basis of quasi-religious emotions and active government propaganda.
- so, all efforts in the West at CO2 emissions reduction are futile, just inducing massive economic self-harm to Western Nations.