Peter Clack writes on X:
A common climate myth is that modern CO₂ is rising faster than anything in 800,000 years.
The truth is, no one can ever know. And this is where the science rubber really hits the road. There’s no way to measure the speed of previous warming episodes. This means no one can say modern warming is ‘unprecedented’.
The truth comes from science, the laws of physics and ice core studies for more than a century. Before snow turns into solid ice, it exists in what is known as the ‘firn’. This refers to the porous, packed layer of snow that eventually settles into glacial ice. But this doesn’t happen overnight.
These ice bubbles are not sealed from the surrounding air. So the air moves freely through this layer for decades or even centuries before the weight of new snow finally crushes the pores shut. This gas-age/ice-age difference is why a single slice of ice contains air that is significantly younger than the ice surrounding it.
Because the air can circulate during those 50 to 200 years (depending on the site’s snowfall rate), a single bubble doesn’t represent a year. It can represent a rolling average of a century.
If a massive CO₂ spike occurred 10,000 years ago but only lasted 40 years, the ice core would smooth it out. The spike would be averaged into the surrounding centuries of lower data, making it appear as a tiny, invisible bump.
Comparing a 20-year satellite trend to a 200-year ice core average is like comparing a high-definition photograph to a smudge of charcoal.
Been saying this for quite a while.
The ice core record does not register large shorter term sun/ocean induced variations in atmospheric CO2.
The entire farrago is a result of that stupid error.
why geologists are never asked about climate change
For “global” (average) CO2 levels to rise or fall requires adding or removing CO2 in precisely calculable quanties:
1 PgC (≡GtC) = 3.6642 ±0.0003 Gt CO2 = 0.46962 ±0.00007 ppmv CO2.
1 ppmv CO2 = 7.8024 ±0.0005 Gt CO2 = 2.1294 ±0.0003 PgC
where “ppmv” is shorthand for “µmol/mol of dry atmosphere.”
So 427 ppmv = 3332 Gt CO2, which is 909 GtC.
Since 1958, when precise direct measurements of CO2 levels began, they’ve risen from 315 ppmv (which was a little bit higher than the highest ice core levels in the last 800K years), to 427 ppmv in 2025. That’s +112 ppmv in just 68 years.
(112 ppmv) × (7.8024 Gt CO2 / ppmv) = 874 Gt CO2
That’s an enormous amount, equal to about 35.5% of the TOTAL amount of CO2 that was in the atmosphere in 1958.
There’s no plausible mechanism which could cause comparable quantities of CO2 to be added to the atmosphere and then disappear from it on such short timescales that they would not be visible in the ice core records, because of “smearing” (averaging over time). “A massive CO2 spike… 10,000 years ago [which] only lasted 40 years” is not possible.
For comparison, total human “fossil CO2” emissions totaled only about 38.6 ±4 Gt CO2 in 2024.
The evidence is conclusive that CO2 levels are currently rising much, much faster than they’ve risen at any time in the last 800K years.
Unfortunately, there are not enough recoverable fossil fuels on Earth to ever raise CO2 levels to anywhere near a level that is optimum for agriculture and natural ecosystems. We’ve managed to rase CO2 levels by nearly 150 ppmv since the start of the industrial revolution. But commercial greenhouse operators typically use “CO2 generators” to raise daytime CO2 levels in their greenhouses by another 1000 ppmv or more, because that makes the plants much healthier, faster-growing, and more productive.
Here’s a valuable study:
Taylor, C & Schlenker, W (2021, 2025). Environmental Drivers of Agricultural Productivity Growth: CO2 Fertilization of US Field Crops. National Bureau of Economic Research, no. w29320. https://doi.org/10.3386/w29320
It reports that a +1 ppmv CO2 increase “equates to yield increases of 0.17%, 0.20%, and 0.55% for corn, soybeans, and winter wheat, respectively…”
That’s HUGE!
Given that human CO2 emissions have raised CO2 levels by about 147 ppmv, +0.4% per ppmv = 1.004^147 = +80%. That’s a massive improvement, and it is one of the main reasons that humanity is no longer threatened by catastrophic famines (usually caused by droughts), for the first time in human history.
That’s a very, Very BIG DEAL. In 1876-78, with CO2 levels down around 289 ppmv, a drought and famine which devastated three continents killed an estimated 3.7% of the entire human race. For comparison, Covid-19 killed about 0.1%.
Atmospheric CO2 levels are rising solely because of human CO2 emissions, they are rising much faster than at any time in the last 800K years, and that is good news, and they would be falling were it not for human CO2 emissions.
What mass of the atmosphere did you use for your calculations?
At the MLO in Hawaii, the concentration of CO2 in dry air is 429 ppm at STP. I calculate the mass of CO2 in a cubic meter of air as follows where 429 ppm = 429 cc = 429 ml:
mass CO2 = 429 ml /22.4 ml/mmole x 44 mg CO2/mmole = 843 mg
or 0.843 g.
Is this calculation correct? Note how little CO2 there is in the air and therefore it can’t cause any warming of air.
I live in Canada. The consumer carbon tax on fossil fuels of $80 per tonne of CO2 eq. has been ended. However, the commercial carbon tax of fossil fuels will rise to $130 per tonne of CO2 eg. on April 1. This will greatly increase the cost of transportation fuels in particular diesel. This will impact the cost of food. We need to convince the Canadian government that CO2 does not cause warming of air and there is no need for carbon taxes.
Harold asked, “What mass of the atmosphere did you use for your calculations?”
Sorry, I should have linked to this little webpage, which has all the details, including the answer to that question:
https://sealevel.info/PgC_vs_Gt_CO2.html
Harold wrote, “At the MLO in Hawaii, the concentration of CO2 in dry air is 429 ppm at STP.”
Oh my goodness, I didn’t realize that there are so many definitions of “Standard Temperature and Pressure” (STP)! I asked Grok; here’s its answer:
https://grok.com/share/c2hhcmQtNQ_fd63c86e-4d93-4a97-8f4d-8e0fd7c4acbe
Grok says that according to the two most common standards the density of dry air at STP is either 1.2754 kg/m³ (IUPAC, 0°C, 1 bar) or 1.2041 kg/m³ (NIST, 20°C, 1 atm).
The average molecular weight of dry air is variously given as 28.965 g/mol or 28.966 g/mol. So:
429 ppmv (µmol/mol) = 429 × ((44.00940 ±0.00174) / (28.9655 ±0.0010)) = 651.8 ±0.1 ppmm.
NIST: ((651.8 ±0.1) / 1,000,000) × 1.2041 kg = 0.7848 ±0.0001 g
IUPAC: ((651.8 ±0.1) / 1,000,000) × 1.2754 kg = 0.8313 ±0.0001 g (which matches your result)
However, the fact that there’s less than a gram of CO2 in a cubic meter of air absolutely does not mean that it can’t cause warming of the air. In fact, it causes a great deal of warming.
Additional CO2 causes only a little additional warming, but that’s not because there’s so little CO2, it’s because there’s already so much of it!
CO2, water vapor and other GHGs are colorants. They tint the atmosphere, though in the far infrared, rather than visible part of the spectrum. They absorb radiation which otherwise would’ve escaped to space.
It doesn’t take much colorant to tint the air. To inform your intuition, drop a single drop of food coloring into a liter of water. One drop is about 0.05 ml, so that’s only about 50 ppmv, yet it noticeably tints the water.
Now, consider the fact that the Earth’s atmosphere has about the mass of a layer of water about 10 meters deep! Looking through atmosphere with a 50 ppmv concentration of a colorant is like looking through a 10 meter (33 foot) thickness of water with that 50 ppmv colorant.
Now, consider that CO2 is at about 429 ppmv, rather than just 50 ppmv.
CO2 in the air absorbs IR radiation at wavelengths near the peak of the Planck curve for typical surface temperatures. CO2 causes the big notch in Earth’s emission spectrum, which I’ve marked in green, here:
Absorbing radiation makes whatever absorbed it (the air, in this case) warmer than it otherwise would have been.
In the case of CO2, there’s already so much of it in the air that additional CO2 does not much change the percentage of radiation from the ground which manages to pass through the atmosphere without being absorbed. It’s like adding more dye to a liquid which is already strongly colored by that same dye; the addition has little effect on the color. There’s already so much CO2 in the air that within CO2’s absorption/emission band nearly all of the emissions that escape to space are from within the atmosphere, not the Earth’s surface.
But additional CO2 does still have a modest warming effect, at fringe wavelengths, where CO2 absorbs only weakly, by raising the “emission height,” from those emissions that escape to space. At the fringes, the emission height is down in the troposphere, so raising the emission height reduces the temperature at the emission height, which reduces the amount of radiation emitted. Since emitting radiation to space cools the air which emits it, reducing the emitted radiation reduces the cooling, which raises the average temperature of the air.
The warming effect is modest and benign, but it isn’t zero.
The results of this experiment says you are incorrect.
Did this experiment use gas in jars? If so, it has no relevance to atmospheric gases, which are always in large scale churn. Frankly, I can’t see the numerous calculations of gaseous components of the atmosphere as anything other than academic exercises that have little, if anything at all, to do with climate.
Do you have a link tot the experiment itself, to know what they exactly have done?
Dave, the argument assumes that all the energy transferred by CO2 goes directly into kinetic energy and stays there. I.e., nothing else changes.
But the added K.E. may increase the rate of convection and can find its way to water vapor.
If the hydrological rate of energy emission to space is not saturated, one can imagine a slight rate increase of the hydrological cycle will cause the extra K.E. to be radiated off to space without any discernible warming.
EM radiation does not convert to KE in CO2.
The notch is the result of scattering.
Scattering is when the electron released the quantum of EM energy it creates a spherical EM wavefront with a minimal amount in the save vector of the EM wavefront that excited the electron.
Furthermore, there are 360x360x360 orientations (given 1 degree resolution of x, y, z axis orientation) of a gas molecule.
So, if it is literally a photon pellet emitted (it isn’t) there is 1 out of 46,656,000 CO2 molecules (2.16E-10 %) aligned such that those photon pellets are emitted on the original EM wavefront vector.
So at the 14.99 micron CO2 IR notch, it is not surprising a lookdown satellite does not register much IR at that frequency.
How does KE radiate EM energy?
Sorry, but this makes no sense at all…
Ice cores gas contents have quite different resolutions, depending of the local snow accumulation: between less than a decade for the 1.2 meter “ice equivalent” snow per year at Law Dome and some 560 and 600 years, for the few mm/year snowfall at Vostok and Dome C ice cores.
The Law Dome ice core even has an overlap of some 20 years (1958-1978) with direct measurements at the South Pole, within 1.2 ppmv (1 sigma).
The drawback of high accumulation is that bedrock is reached fast with less layers: only 150 years of average gas age of the past for Law Dome at the summit, but some 1,000 years more downslope, up to 800,000 years for Dome C.
The interesting point is that all these ice cores, with extreme differences in snow accumulation, local temperature and resolution all are within a few ppmv CO2 of each other for the same average gas age of the enclosed air bubbles. Overlapping time periods from the last 150 years to 800,000 years back in time, here for the past 10,000 years:
If one looks at the current peak of ~130 ppmv in 170 years time, if that happened 800,000 years ago, that would have been noticed as an “not normal” peak of at least 30 ppmv in the low resolution ice core of Dome C, if we may assume that the descent of the peak would be as fast (or slow) as the increase.until now was.
Moreover, the current increase has a very interesting “fingerprint”: a steep decline in 13C/12C ratio, not seen in any ice core of the past 800,000 years,
That means that even the 80-100 ppmv CO2 difference between glacial and interglacial periods was dominated by the ocean CO2 levels: these maintained the atmospheric 13C/12C ratio at -6.5 +/- 0.4 per mil δ13C until about 1850, when a steep descent started, both in the ocean waters (as seen in coralline sponges) as in ice cores – firn – atmosphere:
Only recent and fossil CO2 have a much lower 13C/12C ratio than the oceans or atmosphere, but as the biosphere is a net sink for CO2 (the earth is greening…) only human FF CO2 can be the cause of the recent drop in ratio.
That is about the CO2 levels.
The resolution of temperature is even much better: one can deduce the temperatures of the past by looking at the 18O/16O ratio or the H/D (hydrogen/deuterium) ratio in the ice, layer by layer, if the layers are sufficiently thick enough.
That mainly reflects the local temperatures of where the snow was formed, thus near Antarctica, even with a yearly resolution for 10,000’s of years, up to 130,000 years in time for e.g. the Greenland ice core for Arctic temperatures…
That showed that the temperatures of the previous interglacial, the Eemian, were higher than today, with at a much lower CO2 level (~300 ppmv): about 1/3 of all Greenland ice was melted…
Ferdinand,
I agree with your comment that the modern ~130 ppm rise would be preserved in Dome C (EDC) as about a 30 ppm rise. I digitized all the gas age distribution curves I could find for both EDC and WAIS. Of course they vary by different accumulation rates during interglacials and glacials. I suppressed the modern rise of 427 ppm (MLO and Law Dome combined) using these curves. EDC ensemble mean is ~330 ppm and WAIS is ~380 ppm.
Ice core samples have the same scientific rigor as tea leaves and Ouija boards.
The instant thousands of years & tons of pressure are released the gas composition is compromised.
Indeed. At some stage people start trying to extract more information than there is in the source. And motivated reasoning prevents them from seeing that line being crossed.
And then there are tree rings being used as proxy thermometers.
ISTR reading something about traces of combustion byproducts from jet fuel being found in ice cores pulled up from depths that should predate dawn of the jet airliner. Ice is not a hermetically sealed time capsule for air bubbles.
Sorry, there isn’t any proof that the air bubbles in the ice at any depth are “released” and air or CO2 migrates spread in the neighborhood to other layers or some 2.000 meters up to the atmosphere. To the contrary:
There is a very nice correlation between temperature and CO2 levels over the past 800,000 years over all glacial-interglacial transitions of about 8 ppmv/°C (for Antarctic temperatures, double that for global temperatures). If there was the slightest migration, that correlation would fade out the longer in the past, but that is not the case…
The proxy temperature at the time of precipitation is deduced from the ice 18O/16O ratio and D/H ratio. The ice does “flow” from higher points to lower points and ultimately to the oceans, but in general, the layers remain intact with depth.
Slight modification, showing approximate current temperature.
Indeed, CO2 increased from about 285 ppmv to currently around 425 ppmv, while the temperature hardly increased and still is far below the temperature of the previous interglacial: when trees did grow up to the Ice Sea in Alaska and about 1/3 of the Greenland inland ice was melted…
That points – again – to a low influence of CO2 on temperature…
Therefore it wonders me again and again why some skeptics have such a resistance to accept that our FF emissions are that cause of the CO2 increase: it has many benefits and until now only catastrophic effects in failed computer models…
Anthony, just because you have never taken the time to learn does not mean others have not or can not. Don’t be afraid to learn
We can all be absolutely certain that AW knows far more about climate, and anything to do with climate, than you will ever be capable of learing.
Just because you can string words together into a sentence doesn’t mean that you know what you’re talking about. Don’t be afraid to learn.
Says the man who just assumed they won the argument by typing a motivational refrigerator magnet.
Anthony did not write this post; he just posted it so we, (including you) could learn from it.
An Australian ‘writer’ with no education in science. What could go wrong?
An obscure commenter, who hasn’t bothered to examine the argument he disagrees with and the ice core data that supports the argument, shooting his mouth off from ignorance. What could go wrong? He could look, well, ignorant.
Here’s the data you were too lazy to look up and verify.
EPICA Dome C – 800KYr CO2 Data (NOAA)
Download one of the datasets and check it out yourself. Go to the Download Data section and NCEI Direct Download any of the date, for example the first one. Check the middle column, gas_ageBP, and the CO2 value next to it. Notice that the first two rows are 2690 years before present and 3897 years before present. Do a little math and discover that 3897 – 2690 = 1207 years. So the CO2 value of 272.1 covers a time span of over 1200 years. There is no finer resolution than that. That’s a time span more than 17 times larger than the 68 years of the Mauna Loa CO2 record. We have no idea if CO2 went up or down and by how much in that 1200 years. And the further you go back, the larger those time spans are.
Check the Wikipedia article about the depth of ice where those air bubbles get trapped. Go read some articles about gases in ice cores.
And if you aren’t feeling too sheepish about your ignorance, report back to us what you found.
Stinkerp,
A small comment: the 1207 years is the distance in average time of the gas age in the samples, not the resolution of the gas bubbles in one sample.
The resolution is caused by the time difference between the closing of the first air bubbles and the last air bubble closing at the same depth of the ice core.
That is much smaller than the sampling age difference and depends of the amount of snow accumulation at a certain depth.
For the Law Dome ice core, that is less than a decade, for Vostok about 600 years and for the 800,000 years Dome C record it is 560 years.
In addition, here the sampling of the Epica Dome C ice core over the last transition between an ice age and the current warm period:
While the sampling was about 40 times in 1,000 years, thus 250 years distance, the resolution of each sample still is only 560 years for that ice core…
Of course with 40 samples in 1,000 years, the distance between the samples is only 25 years (back to school, boy!), but that doesn’t change the resolution at the time of closing the air bubbles: that remains about 560 years.
As Renee further on said: that is not a symmetric average resolution, but heavily weighted to the latest years before closing the bubble with a long tail spanning hundreds of years.
And as one can see: there is no visible or measurable effect of CO2 on temperature, thus anyway its effect on temperature is small, much smaller that implemented in climate models…
But a Guardian writer with a degree in sociology is allowed to publish their crap?
Classic ad hom comment. Ask what could be right about this post.
I think you may have the rugby player and the meteorologist mixed up.
“A common climate myth is that modern CO₂ is rising faster than anything in 800,000 years.”
And it probably is. So…what. I bet that the number of artificial satellites in orbit and golf courses in southern states is higher, too, right? So what. The soda in my refrigerator fizzes more when I take it out and it warms up. Does the CO2 in the soda control the refrigerator temperature?
Even those “sealed” bubbles aren’t really sealed. Gas will diffuse into or out of the ice. Ever taste ice that’s been in a freezer with a fish?
If the ratio between CO2 and T remains the same over some 800,000 years, there is no measurable migration over that period…
One has tried to calculate the theoretical migration of CO2 through the ice crystals by looking at the increased CO2 near melt layers in the relative “warm” (-23°C) Siple Dome ice core, The result: some 10% broadening (20 to 22 years) for the resolution at middle depth, up tot a doubling at near bedrock. That is all.
https://catalogue.nla.gov.au/catalog/3773250
For the -40°C of Vostok and Dome C, there is no measurable migration over 800,000 years…
Metal ions and maybe some flavors, still can migrate through the ice matrix or a few left water veins (where contamination exists), CO2 and other gases can’t.
I think your analogy may be flawed, my reasoning being is how water freezes at standard pressure in a domestic freezer. It doesn’t freeze in a single go, there is plenty of time for extraneous molecules to diffuse into the liquid water before it freezes. It may also depend on the size of the ice cubes being created and how the ice is formed in the mould, bottom up or top down. Once the ice cube has completely frozen then whatever molecules that have made their way into the ice will be apparent. How do glaciers and pack ice freeze? Is it layer by layer? What effect does increased pressure have on the freezing process and post freezing, particularly on the deeper ice? Does pressure alter the molecular structure of the ice?
Gas diffusion in the firn is a big deal. Before bubbles are sealed in ice, air diffuses through the porous firn layer. This process blends atmospheric signals over time. At high snow accumulation sites like Law Dome, smoothing may be limited to a few decades. However, high resolution ice cores only exist over thousands of years.
At low accumulation Antarctic sites, which provide the deepest and longest records, gas age distributions typically smooth atmospheric CO₂ over ~100 to 300+ years (Kohler, 2011; Nehrbass-Ahles, 2020). https://cp.copernicus.org/articles/7/473/2011/cp-7-473-2011.pdf.
This smoothing is not a simple moving average. For firn smoothing, the gas age distributions are modeled with asymmetric filters like log-normal functions. These filters are derived from physical firn models and are backward-oriented, with variable weighting and more emphasis on relatively recent air but with a tail incorporating older mixed air.
Absolutely correct.
And during glacial ages, when snowfall declines because the air is dryer, the closure of firn to ice can take millennia.
This whole business of ignoring resolution to make tendentious comparisons infects the ice core and d18O paleo-temperature record, too.
This is true.
But I still think it overestimates the sensitivity of the ice cores.
One the firn has been transformed into ice, the assumption is that the gases are trapped forever and the ice never, ever melts.
Yet that’s not necessarily true.
Vibrations in the ice could cause internal cracks that would melt and soon refreeze. But whenever that happened, the trapped gas diffuses a little.
Now this effect may be very slow. And it may be very small, each time it happens.
But the wind blows almost every day so the ice vibrates almost every day.
And there are a lot of days in thousands of years.
If that was true, the rather fixed 8 ppmv/°C over the past 800,000 years would fade with time, but that is not the case: it remains about the same for each glacial-interglacial transition back in time.
Some relative “warm” (-23°C) ice cores like Siple Dome show more variability and higher levels near (summer) melt layers and these were used to calculate the -theoretical- local migration in that ice core: maximum 10% at middle depth for the resolution, which broadens from 20 to 22 years and a doubling near rock bottom. No big deal at all…
https://pdfs.semanticscholar.org/2347/aa5c4efa2658f2b289c8e9c2890d8023e3c8.pdf
The average temperature of Vostok and Dome C, both inland ice cores is around -40°C and no melt layers are detected. The possibility of migration at that temperature is virtually absent…