Estimated CO2 Warming Cut By 65%

Any competent researcher involved with the science behind climate change will admit that CO2 is far from the only influence on global climate. It has long been known that short-lived greenhouse gases and black-carbon aerosols have contributed to past climate warming. Though the IPCC and their fellow travelers have tried to place the blame for global warming on human CO2 emissions, decades of lies and erroneous predictions have discredited that notion. For anyone still clinging to the CO2 hypothesis, a short perspective article on the uncertainty surrounding climate change in Nature Geoscience has put paid to that notion. It states that not only did other factors account for 65% of the radiative forcing usually attributed to carbon dioxide, but that it is impossible to accurately determine climate sensitivity given the state of climate science.

In “Short-lived uncertainty?” Joyce E. Penner et al. note that several short-lived atmospheric pollutants—such as methane, tropospheric ozone precursors and black-carbon aerosols—contribute to atmospheric warming while others, particularly scattering aerosols, cool the climate. Figuring out exactly how great the impacts of these other forcings are can radically change the way historical climate change is interpreted. So great is the uncertainty that the IPCC's future climate predictions, which are all based on biased assumptions about climate sensitivity, are most certainly untrustworthy. As stated in the article:

It is at present impossible to accurately determine climate sensitivity (defined as the equilibrium warming in response to a doubling of atmospheric carbon dioxide concentrations) from past records, partly because carbon dioxide and short-lived species have increased together over the industrial era. Warming over the past 100 years is consistent with high climate sensitivity to atmospheric carbon dioxide combined with a large cooling effect from short-lived aerosol pollutants, but it could equally be attributed to a low climate sensitivity coupled with a small effect from aerosols. These two possibilities lead to very different projections for future climate change.

All truthful climate researchers know these facts, yet publicly the party line is that catastrophic changes are in the offing and CO2 emissions are to blame. The perspective authors argue that only by significantly changing the amounts of these other pollutants and carefully measuring the impact on global climate over a period of several decades will science be able to figure out what is going on. “Following this strategy, we will then be able to disentangle the warming and cooling contributions from carbon dioxide and short-lived pollutants, hence placing much tighter constraints on climate sensitivity, and therefore on future climate projections,” they state.

And they said it was all carbon dioxide's fault.

Most of the factors under discussion have relatively short lifetimes in the atmosphere, several less than two months. We do not know how the relative influences of these various substances (referred to by climate scientists as “species”) may change in a warming climate. It is also not clear how to reduce short-lived species under present conditions but the uncertainties in atmospheric chemistry and physics must be resolved if Earth's environmental system is to be understood. Again quoting from the paper:

Of the short-lived species, methane, tropospheric ozone and black carbon are key contributors to global warming, augmenting the radiative forcing of carbon dioxide by 65%. Others—such as sulphate, nitrate and organic aerosols—cause a negative radiative forcing, offsetting a fraction of the warming owing to carbon dioxide. Yet other short-lived species, such as nitrogen oxides, carbon monoxide and volatile organic compounds, can modify the abundance of both the climate-warming and climate-cooling compounds, and thereby affect climate change.

Quantifying the combined impact of short-lived species on Earth's radiative forcing is complex. Short-lived pollutants—particularly those with an atmospheric lifetime of less than two months—tend to be poorly mixed, and concentrate close to their sources. This uneven distribution, combined with physical and chemical heterogeneities in the atmosphere, means that the impact of short-lived species on radiative forcing can vary by more than a factor of ten with location or time of emission. The situation is further complicated by nonlinear chemical reactions between short-lived species in polluted areas, as well as by the interactions of clouds with aerosols and ozone. These processes add further uncertainty to the estimates of radiative forcing.

Unfortunately, climate models neither accurately deal with local effects of these pollutants nor are the complex interactions among these substances understood. That not withstanding, the report is clear—CO2 does not account for even a majority of the warming seen over the past century. If other species accounted for 65% of historical warming that leaves only 35% for carbon dioxide. This, strangely enough, is in line with calculations based strictly on known atmospheric physics, calculations not biased by the IPCC's hypothetical and bastardized “feedbacks.”

Of course, the real reason for the feedbacks was to allow almost all global warming to be attributed to CO2. This, in turn, would open the door for radical social and economic policies, allowing them to be enacted in the name of saving the world from global warming. The plain truth is that even climate scientists know that the IPCC case was a political witch's brew concocted by UN bureaucrats, NGOs, grant money hungry scientists and fringe activists.

Now, after three decades of sturm und drang over climate policy, the truth has emerged—scientists have no idea of how Earth's climate will change in the future because they don't know why it changed in the past. Furthermore, it will take decades of additional study to gain a useful understand climate change. To do this, climate scientists will need further funding. Too bad the climate science community squandered any public trust it may have had by trying to frighten people with a lie.

Be safe, enjoy the interglacial and stay skeptical.

It has been brought to my attention that a more correct interpretation of the statement “augmented by 65%” is that the short-lived species provided a forcing equivalent to 65% of the CO2 value. This would mean that CO2 contributed 61% of last century's warming (0.484°C), not the 35% stated in the article above. In other words, a reduction of 39%. I apologize for the misinterpretation and any confusion it may have caused. Note that this change does not change the conclusions by the perspective authors that “it is at present impossible to accurately determine climate sensitivity,” or that decades of further study will be required to gain a usable understanding of Earth's climate system.

The FUTILITY of Man-made Climate Control by limiting CO2

For me this is the killer argument and the numbers are backed up by acceptance from a renowned UK government advisor.

The FUTILITY of Man-made Climate Control by limiting CO2 emissions, watch:

On average world temperature is ~+15 deg C. This is sustained by the atmospheric Greenhouse Effect ~33 deg C. Without the Greenhouse Effect the planet would be un-inhabitable at ~-18 deg C.

Running the numbers by translating the agents causing the Greenhouse Effect into degrees centigrade:
• Water Vapour and Clouds account for about 95% of the Greenhouse Effect = ~ 31.35 deg C
• Other Greenhouse Gases GHGs account for ~5% = ~1.65 deg C
• CO2 is 75% of that remaining effect accounting for the enhanced effects of Methane, Nitrous Oxide and other GHGs = ~1.24 deg C
• Most CO2 in the atmosphere is natural, more than ~93%
• Man-made CO2 is less than 7% of total atmospheric CO2 = ~0.087 deg C
• the USA contribution to CO2 is ~20% equals = 17.6 thousandths deg C
• UK’s contribution to World CO2 emissions is ~1.8% = 1.6 thousandths deg C.
So closing the whole UK Carbon economy could only affect world temperature by a minuscule and immeasurable amount

Thus closing the carbon economies of the Whole World could only ever achieve a virtually undetectable less than -0.09 deg C. How can the Green movement and their supporting politicians think that their remedial actions and draconian taxes are able to limit warming to only + 2.00 deg C?

So the probability is that any current global warming is not man-made and in any case such warming could be not be influenced by any remedial action taken by mankind however drastic. If the numbers above are even close to the right ballpark, the prospect should be greeted with Unmitigated Joy:
• concern over CO2 as a man-made pollutant can be discounted.
• it is not necessary to damage the world’s economy to no purpose.
• if warming were happening, it would lead to a more benign and healthy climate for all mankind.
• any extra CO2 is already increasing the fertility and reducing water needs of all plant life and thus enhancing world food production.
• a warmer climate, within natural variation, would provide a future of greater prosperity for human development and much more food for the growing world population. This has been well proven in the past and would now especially benefit the third world.

Nonetheless, this is not to say that the world should not be seeking more efficient ways of generating its energy, conserving its energy use and stopping damaging its environments. It remains absolutely clear that our planet is vastly damaged by many human activities such as:
• environmental pollution.
• over fishing.
• forest clearance.
• industrial farming.
• farming for bio-fuels .
• and other habitat destruction.
And there is a real need to wean the world off the continued use of fossil fuels simply on the grounds of:
• security of supply
• increasing scarcity
• rising costs
• their use as the feedstock for industry rather than simply burning them.

The French long-term energy strategy with its massive commitment to nuclear power is impressive, (85% of electricity generation). Even if one is concerned about CO2, Nuclear Energy pays off, French electricity prices and CO2 emissions / head are the lowest in the developed world.
However in the light of the state of the current solar cycle, it seems that there is a real prospect of damaging cooling occurring in the near future for several decades. And as power stations face closure the lights may well go out in the winter 2015 if not before.

All because CO2 based Catastrophic Man-made Global Warming has become a state sponsored religion.

And now after “Splattergate” thanks to the 10:10 organisation the world now knows exactly how they think.

Splattergate is classic NOBLE CAUSE CORRUPTION. It is probably the most egregious piece of publicity ever produced in the Man-made Global Warming cause. This short film shows doubting schoolchildren being blown up and having their entrails spread over their classmates because they may have been less than enthusiastic about the CAUSE. So any misrepresentation is valid in the Cause and any opposition however cogent or well qualified is routinely denigrated, publically ridiculed and as we now see literally terminated.

Doesn't mean what you think it does

  1. The actual letter (available in full at for those who want read it) doesn't mean what you think it does. Just look at figure 1 to see what I mean. Even assuming a low climate sensitivity we are looking at nearly 2C of warming by 2100 assuming we address the short term forcings of methane, tropospheric ozone and black carbon. Assume a higher sensitivity and things get really ugly.
  2. The first sentence from it sums up the reality: Earth’s climate can only be stabilized by bring carbon dioxide emissions under control in the twenty-first century

It still means what I think it means

  1. This does not change their statement “it is at present impossible to accurately determine climate sensitivity,” or that decades of further study will be required to gain a usable understanding of Earth's climate system. The predictions you cite as evidence are made by models and the models are bogus.
  2. They offer no evidence that this is actually the case, it is simply toeing the party line. The reality is that the results from the models are unreliable because a) they are based on wrong assumptions about sensitivity and b) they do not properly capture the chemistry and physics of the non-carbon dioxide pollutants in the atmosphere.

What's the origin of the "CO2 is a strong greenhouse gas" idea?


While viewing a presentation delivered at the American Geophysics Union last year, it seemed to me that the idea of Earth's surface temperature being highly sensitive to CO2 is an idea that has been around for a long time in geophysics.

No doubt you are familiar with the Faint Young Sun Paradox. The solution proposed (I think in the 1960s, and by Sagan amongst others) to this paradox was that the Earth had a slightly higher load of CO2 at the time of the faint sun, and by assuming CO2 had a very strong greenhouse warming effect, the paradox was solved.

I found this to be an argument from ignorance. Just because geophysicists couldn't imagine any other mechanism for ancient warming does not mean their assumption is the real answer.

Would you agree that this "working assumption" has continued in climate research up until the present day?

Would you agree The Faint Young Sun Paradox cannot be solved by invoking strong CO2 warming?

Do you know of any other solutions to the FYSP?

Sorry, I'm mainly an AGW skeptic, but I don't like leaving these little loose ends unaddressed.

-Andrew M.

CO2 wasn't the answer for ancient Earth either

Contraversy over the faint young Sun paradox continues to rage in scientific circles. The late Carl Sagan and cosmochemist Christopher Chyba suggested that high levels of atmospheric ammonia could have shored up the early greenhouse (see "The Early Faint Sun Paradox: Organic Shielding of Ultraviolet-Labile Greenhouse Gases," Science, 23 May 1997). But that idea has problems too, because the ammonia would have required protection from solar radiation, which would have rapidly broken it down. Recently, an interesting article entitled “Fractal Organic Hazes Provided an Ultraviolet Shield for Early Earth” appeared in Science. While primarily concerned with UV radiation levels they also talk about the paradox in general:

The atmosphere of the Archean Earth (3.8 to 2.5 billion years ago) was much different from the present one. The prevailing view of the Archean atmosphere is that it consisted primarily of N2 with lesser amounts of CO2, CH4, H2, and H2O. Solar evolutionary models predict that the young Sun was up to ~30% less luminous than now, but the lack of evidence of glaciation combined with positive evidence of primitive life indicates that Archean surface temperatures were generally as warm or warmer than today. Resolving this paradox is important for understanding the environment of Earth at the time of the origin of life. Although a dense CO2 atmosphere could theoretically have warmed the early Earth, the absence of siderite in fossil weathering profiles constrains the amount of CO2 present in the young atmosphere. Combined greenhouse warming from CO2, CH4, NH3, and other less abundant gases is typically invoked to resolve this apparent paradox. Past studies indicate that N2-CH4 photochemistry produces an organic haze at high altitudes that could cool the planet, offsetting any greenhouse warming. In contrast, we show here that the haze would be optically thin at visible wavelengths and therefore have little cooling effect on climate, but would be optically thick at ultraviolet (UV) wavelengths and thus could shield reduced gases from photolysis. The key is to consider the fractal nature of the haze particles.

It looks like the evidence for CO2 driving things is scant, even 3 billion years ago. And just as carbon dioxide was not the main driver of climate then, it is not the main driver of climate today. Authors E. T. Wolf and O. B. Toon, both from the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder, have their own explanation for why Earth was so warm so long ago:

This work revitalizes the Miller-Urey hypothesis that the early Earth was home to a strongly reducing atmosphere. In particular, the presence of NH3 is of dual importance. As previously mentioned, NH3 mixing ratios of 10–5 or more added to the Archean atmosphere could alone resolve the faint young Sun paradox. However, without UV shielding, an ammonia mixing ratio of 10–5 would be irreversibly converted into N2 in less than 10 years. Ammonia resupply rates during the Archean could not have supported an ammonia mixing ratio above 10–8 without a strong UV shield.

As I said, the controversy rages on. For a decent introduction to happenings on ancient Earth see “Early Life Thrived Despite Earthly Travails,” by Richard Kerr or read our book, The Resilient Earth. Personally, I think science has a long way to go in explaining climate past, present and future. Thanks for the great question.

Is your math correct?

"Of the short-lived species, methane, tropospheric ozone and black carbon are key contributors to global warming, augmenting the radiative forcing of carbon dioxide by 65%."

That quote says that methane, ozone, and black carbon increased the effect of CO2 by 65%. I interpret that to mean that if you double CO2, then you get about 1 degree C due to direct effect of doubling CO2 and then another .65 degree C (from the effect of methane, ozone, and black carbon) added onto that for a resulting total increase of 1.65 degree C. This analysis does not include the effect of increased humidity supported by higher temps, clouds, etc.

Anyway, I agree with the big picture that nobody understands how to accurately model the world's climate.

The Math is SOoo Wrong

Since all global warming and CO2 discussions pointedly ignore water vapor which is responsible for 95% or more of the heat-trapping gases in the atmosphere, the math that CO2 MIGHT be responsible for 35% is totally bogus. The IPCC used a thermodynamic constant for CO2 which they multiplied 12-fold to augment its effect and then ignore the elephant in the room.

Miskolczi and Zagoni have shown quite elegantly that water vapor and CO2 interact such that water vapor, the superior gas here, decreases as CO2 increases, such that the two have a relatively constant effect. This may actually be a slight cooling effect as this would mean less of the superior gas.

Yep, the math here bites as long as you ignore the overwhelming majority of the relevant gases.

The math also has to be wrong as the reputed warming does not exist. The warming only shows up when you leave certain people in the presence of the data and let them add the needed heat through "adjustments." Thus, we are talking about fantasies based on totally, fatally flawed computer models and poorly applied physical principles.

The new HUGE factor not included in the models is the heat flux from the inner planet which may equal 75-100% of the solar input. THAT, for sure, is not in the models and as it is not, they have to fail.

We know so little about the total picture that it is a crime that we have let these computer clowns waste such an obscene amount of money that could have been spent on much more important issues that could really help people.

But we do have the raw data and around the world we find nothing out of the ordinary happening and we are now in a very predictable cooling phase which might be stronger than normal as the Sun is going into a very quiet phase.

CO2 is pant food and is greening the planet. With the coming cold we need all of the food growth advantages that we can get.


The other "species" contributed 65% to the historic warming over the past century that is normally attributed to the influence of anthropogenic carbon dioxide. The other factors "augmented," in other words added to, the influence of CO2 but that does not change the amount of temperature rise that took place. Since the overall global temperature rose by 0.8°C, CO2 itself accounted for only 0.28°C. The math is correct, your interpretation is in error.


Doug: Your quote the article as stating: "Of the short-lived species, methane, tropospheric ozone and black carbon are key contributors to global warming, augmenting the radiative forcing of carbon dioxide by 65%." It does not say anything—at least in the sections you pulled from—about these species "contribut[ing] 65% to the historic warming over the past century."

As you say, the word "augment" means to add to. So if these short-lived species "augmented" the effects of carbon dioxide by 65%, then carbon dioxide accounted for 61%, or 0.48 degrees C, of the observed 0.8 degree C increase in global temperature.

There are a lot of interesting things to take away from this research article, but the idea that it argues that carbon dioxide accounts for only 35% of the increase in global temperatures isn't one of them.

That interpretation may be correct.

Your interpretation may indeed be correct, that CO2 + Short-lived Species = 1.65 * CO2 warming. This would mean that CO2 would have accounted for 0.48°C or 61% of total warming last century, as you state. I read the statement as "having augmented CO2 by supplying 65% of the radiative forcing." This may be incorrect and I have asked Dr. Penner for clarification. I will report here when I receive a reply.

Even if my initial interpretation of the paper's result is incorrect, the result is still that CO2 is much less influential than previously and widely assumed. This does not change the implications for climate model sensitivity, which would still be greatly overstated.

Mea culpa

I may well have misinterpreted the authors' meaning and overestimated the reduction of CO2 driven forcing. Please note that I post two or three columns a week, reviewing data from dozens of papers—I'm bound to make an ocasional error in interpritation. Not that this error was a gross one, I had the impact correct and was within an order of magnitude :-)

My misinterpretation does not change the fact that CO2 can only be held accountable for 60% or less of the past century's warming. Ramanathan et al., reported “Regionally, particularly in the tropics and subtropics with highly absorbing particles during the dry season, anthropogenic aerosols can decrease the average solar radiation absorbed by the surface by as much as 15 to 35W m2 and can increase the atmospheric heating, within the lowest 3 kilometers of the atmosphere, by as much as 60 to 100% (see “Aerosols, Climate, and the Hydrological Cycle,” in Science).

Even NASA has admitted that aerosols are more potent than previously suspected. A study led by Drew Shindell of NASA's Goddard Institute for Space Studies says that, in the high latitudes the impact of aerosols (sulfates and black carbon) may account for 45% or more of the observed warming which has occurred in at the poles over the past three decades.

Also note that these changes are not accounted for by the IPCC findings. The IPCC rated the confidence in aerosol forcing very low, with very wide error bars, so they didn't get included in the models. That is why these papers are noteworthy—they provide new numbers that were suspected by some, but not confirmed.

Of aerosols and models

Stu, when it comes to aerosols and climate models things are not as clear cut as many believe. These pollutants, some natural and some man made, are very short lived and can be affected by other climatic events such as wind and precipitation. Most sources are regional (the UN estimated that half of the climate warming over India and china was due to the "brown clouds" of Asia). The unpredictable lifetime of aerosols plays havoc with computer model time steps.

On top of the human contributions, a major impact comes from volcanoes. They inject ash, water vapor and sulfur compounds into the atmosphere. Unfortunately, how often they occur, where they occur and how big they are is unpredictable. This led modelers to estimate the impact of aerosols with simple average values.

These estimates are basically always wrong. They over estimate when there is no eruption and under estimate when an eruption is taking place. Plus, the characteristics vary from one eruption to another and location is extremely important in calculating global impact. In short, models do such a bad job with aerosols they would probably be better off without them (not more accurate, just better off because eruptions cannot be accurately be predicted).

I am currently (very carefully) reading another paper on historical impact of volcanoes on global climate that is very interesting. I will be reporting on this soon.

RE: Wrong

'Still ignoring the water vapor = the math HAS to be wrong. Water vapor is responsible for >95% of the heat-trapping quality of the atmmosphere.

The other heat-trapping gases cannot and do not augment anything. Methane may be a stronger heat-trapping gas than CO2, but it is in the ppb, not ppm as is CO2. Methane is also slowly decreasing, which would counter the effects of CO2 rising. There is no reputed positive forcing factor. Other gases do not function to "serve" CO2.

In fact, water vapor, considered wrongly as a big positive forcing factor by the IPCC (true only in a real greenhouse where convection is prevented), is part of a huge, global heat engine which, as the water cycle, carries heat to altitude where it is lost to space. There is clear evidence that this cycle has ramped up as it should during the recent warming and is in part responsible for keeping the warm peak as low as it was, being less warm at the peak than in the 1930s.

35%, 65% - all meaningless when you honestly include water vapor and the water cycle. CO2 is harmless and in fact beneficial as plant food; plants utilize water and nutrients more efficiently and are more temperature tolerant with higher CO2.

As a trace gas, CO2 cannot, does not, and will not drive the climate. It's effect, if any, is marginal and probably undetectable, despite the claims of dishonest temperature keepers who systematically adulterate the data to create warming. Using rural, raw data, it is clear that we have nothing unusual happening in our climate and we are having no effect.

Even if CO2 was contributing 0.28oC, our contribution is <5%, or <0.014oC. So, if we stopped producing ALL CO2 today we would lose 1.4 100ths of a degC, which would b undetectable. If we decreased CO2 production by 40% (very unrealistic, but hey!) we are talking about 5 or 6 1000ths of a degC. This is totally meaningless and would have no effect on anybody. Such efforts would be truly damaging for no gain of any kind.

The sun was supposedly only

The sun was supposedly only 70% as bright 4.5 billion years ago as it is now. Given that clouds reflect about
30% of incoming radiation from the sun, I immediately thought of this reference:

No clouds, no continents, only oceans, and the earth would
have been about as warm as it is now.

Another take on FYSP

Good article reference. As I said, the controversy continues in scientific circles. Anyone dare to utter the words “scientific consensus” or “settled science?” And yet AGW was supposed to be the consensus opinion—in a pigs eye.

I agree about H2O

I totally agree that the single most important greenhouse gas is water vapor. Unfortunately for the global warming booster club, H2O is highly variable and hard to characterize. This, along with the fact that there is no way to regulate the ¾ of Earth's surface that is covered with water, makes it unsuited to play the role of villain in the anthropogenic global warming passion play.

For all those jumping in to defend H2O's honor, I presented the article above not to belittle water vapor's contribution by omitting it, but rather to show that even without other major factors—insolation changes, variability in cloud cover and a basic understanding of atmospheric chemistry and physic to name a few—the case for CO2 is very weak. Consider this yet another nail in the AGW theory's coffin.