Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.


Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup


All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Home Arguments Software Resources Comments The Consensus Project Translations About Support

Bluesky Facebook LinkedIn Mastodon MeWe

Twitter YouTube RSS Posts RSS Comments Email Subscribe

Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...

New? Register here
Forgot your password?

Latest Posts


No alternative to atmospheric CO2 draw-down

Posted on 14 February 2013 by Andrew Glikson

This article suggests that the current atmospheric CO2 level is already triggering amplifying feedbacks from the Earth system and therefore, in themselves, efforts at reduction in atmospheric CO2-emission are no longer sufficient to prevent further global warming. For this reason, along with sharp reductions in carbon emissions, efforts need to be undertaken in an attempt to reduce atmospheric CO2 levels from their current level of near-400 ppm to well below 350 ppm. NASA-applied outer space-shade technology may buy time for such planetary defense effort.

The scale and rate of modern climate change have been greatly underestimated. The release to date of a total of over 560 billion ton of carbon through emissions from  industrial and transport sources, land clearing and fires, has raised CO2 levels from about 280 parts per million (ppm) in pre-industrial periods to 397-400 ppm and near 470 ppm CO2-equivalent (a value which includes the CO2-equivalent effect of methane), reaching a current CO2 growth rate of about 2 ppm per year

Figure 1: Part A. Mean CO2 level from ice cores, Mouna Loa observatory and marine sites; Part B (inset). Climate forcing 1880 – 2003. Aerosol forcing includes all aerosol effects, including indirect effects on clouds and snow albedo. GHGs include ozone (O3) and stratospheric H2O, in addition to well-mixed greenhouse gases.

Figure 2: Relations between CO2 rise rates and mean global temperature rise rates during warming periods, including the Paleocene-Eocene Thermal Maximum, Oligocene, Miocene, glacial terminations, Dansgaard-Oeschger cycles and the post-1750 period.

These developments are shifting the Earth’s climate toward Pliocene-like (5.2 – 2.6 million years-ago; mean global temperatures of +2-3oC above pre-industrial temperatures) and possibly toward mid-Miocene-like (approximately 16 million years-ago; mean global temperatures +4oC above pre-industrial temperatures) conditions within a few centuries?a geological blink of an eye.

The current CO2 level generates amplifying feedbacks, including the reduced capacity of warming water to absorb CO2 from the atmosphere, CO2 released from fires, droughts, loss of vegetation cover, disintegration of methane released from bogs, permafrost and methane-bearing ice particles and methane-water molecules.

With CO2 atmospheric residence times in the order of thousands to tens of thousands years, protracted reduction in emissions, either flowing from human decision or due to reduced economic activity in an environmentally stressed world, may no longer be sufficient to arrest the feedbacks.

Four of the large mass extinction of species events in the history of Earth (end-Devonian, Permian-Triassic, end-Triassic, K-T boundary) have been associated with rapid perturbations of the carbon, oxygen and sulphur cycles, on which the biosphere depends, at rates to which species could not adapt.

Since the 18th century, and in particular since about 1975, the Earth system has been shifting away from Holocene (approximately 10,000 years to the pre-industrial time) conditions, which allowed agriculture, previously hindered by instabilities in the climate and by extreme weather events. The shift is most clearly manifested by the loss of polar ice. Sea level rises have been accelerating, with a total of more than 20 cm since 1880 and about 6 cm since 1990.

For temperature rise of 2.3oC, to which the climate is committed if sulphur aerosol emission discontinues (see Figure 1), sea levels would reach Pliocene-like levels of 25 meters plus or minus 12 meters, with lag effects due to ice sheet hysteresis (system inertia).

With global atmospheric CO2-equivalent (a value which includes the effect of methane) above 470 ppm, just under the upper stability limit of the Antarctic ice sheet, with current rate of CO2 emissions from fossil fuel combustion, cement production, land clearing and fires of ~9.7 billion ton of carbon in 2010, global civilization faces the following alternatives:

  1. With carbon reserves sufficient to raise atmospheric CO2 levels to above 1000 ppm, continuing business-as-usual emissions can only result in advanced melting of the polar ice sheets, a corresponding rise of sea levels on the scale of meters to tens of meters, on a time scale of decades to centuries, and high to extreme continental temperatures rendering agriculture and human habitat over large regions unlikely.
  2. With atmospheric CO2 at about 400 ppm, abrupt decrease in carbon emissions may no longer be sufficient to prevent current feedbacks (melting of ice, methane release from permafrost, fires). Attempts to stabilize the climate require global efforts at CO2 draw-down, using a range of methods, including global reforestation, extensive biochar application, chemical CO2 sequestration (using sodium hydroxide, serpentine and new innovations) as well as burial of CO2.

As indicated in Table 1, the use of short-term solar radiation shields such as sulphur aerosols cannot be regarded as more than a band aid, with severe deleterious consequences in terms of ocean acidification and retardation of the monsoon and of precipitation over large parts of the Earth.

By contrast, retardation of solar radiation through space sunshade technology may allow time for CO2 draw-down. Unlike sulphur dioxide injections this will not have ocean acidification effects – an effort requiring a planetary defense project by NASA.

Dissemination of ocean iron filings aimed at increasing fertilization by plankton and algal blooms, or temperature exchange through vertical ocean pipe systems, are unlikely to constitute effective means of transporting CO2 to relatively safe water depths.

By contrast to these methods, CO2 sequestration through fast track reforestation, soil carbon, biochar and possible chemical methods such as “sodium trees” and serpentine (combining Ca and Mg with CO2) may be effective, provided these are applied on a global scale

Such efforts will require an effective planetary defense effort on the scale currently expended on military spending (totaling more than $20 trillion since WWII).

It is likely that a species which decoded the basic laws of nature, split the atom, placed a man on the moon and ventured into outer space should also be able to develop the methodology for fast sequestration of atmospheric CO2. The alternative, in terms of global heating, sea level rise, extreme weather events, and the destruction of the world’s food sources is unthinkable.

Good planets are hard to come by.  

0 0

Printable Version  |  Link to this page


1  2  Next

Comments 1 to 50 out of 53:

  1. Is that" ....previously unhindered by climate instabilities...."?


    The log-log plot is telling. Thanks for the article.



    Frank Johnston

    0 0
  2. I certainly agree that there are many good arguments against employing the kind of solar radiation management that involves injecting sulphates into the stratosphere, but I do not think that ocean acidification as a direct result of this intervention is a serious risk. The amounts of sulphur that people are taking about for SRM are about 5-10 million tonnes per year (about one-half to one Pinatubos per year) (Wigley 2006), which is of the order of about 7-14% of current emissions of sulphur resulting from fossil fuel combustion. These sulphur emissions have a well-known and serious acidification effect on freshwater bodies downwind from industrialized areas and may even have a small effect on some marine coastal areas. But Doney et al (2007) calculate that the effect of anthropogenic SO2 and NOx pollution results in an ocean acidification effect that is only a few percent of acidification resulting from anthropogenic CO2 pollution. Deliberate stratospheric sulphate injection would therefore produce less than 7-14% of those few percent.

    I suspect that countries that employ sulphate SRM, might feel that their attempt at mitigating climate change through sulphate SRM entitles them to continue or increase their fossil fuel consumption. Those CO2 emissions would certainly help acidify the oceans, perhaps at a rate faster than that caused by the geoengineering sulphates.

    To be clear, this is not meant as a defence of geoengineering. I think that it's crazy to contemplate it as an option now.


    0 0
  3. "...has raised CO2 levels from about 280 parts per million (ppm) in pre-industrial periods to 397-400 ppm and near 470 ppm CO2-equivalent (a value which includes the CO2-equivalent effect of methane)"

    IMO, it is misleading to talk about "CO2-equivalent effect of methane" in context of this article because CH4 half-life is only 11y, while we are considering long term context of couple centuries. Effectively, that CH4 becomes CO2 and stays for 10-100ky.

    Unless the permafrost/clathrates melt rate increases and can sustain the elevated level of oxydising methane for long period of time, then methane becomes an issue which does not happen yet. But if it starts, I imagine people would have to setup some flares at major methane release sites: it's better to oxidise this methane straight at the source rather than in 11y somewhere in the upper troposphere with stratospheric WV release...

    0 0
  4. There may be some sequestration hope on the horizon:

    0 0
  5. Thank you for this article.  Has your article "The geological dimension of climate change: Current greenhouse rise rates are the fastest in 65 million years" been submitted/accepted for publication so that we can reference it?

    In Figure 2 of this article you show the 1890-2011 data point.  It might be  helpful to show the trend at this time.

    0 0
  6. Quote,

    an effort requiring a planetary defense project by NASA.

    Even without a review of geo-engineering as a viable technology the above quote poses a challenge. Might have been a possibility in the 1960's but not in todays multi-polar globalised world. We can just about sustain an ISS project beyond that we struggle, think G20 and downhill from there.


    0 0
  7. How about sequestration of carbon on land by regenerating forests in the mostly tropical, global South? Global land carbon stock is estimated to be 3X the total carbon in the atmosphere and has the potential for further storage if we stop deforestation and begin active regeneration efforts. Of course, that would require the global North to go vegan in order to free up the land for the regeneration, which is happening anyways from health considerations as chemical pollutants work their way up the food chain.

    0 0
  8. (-snip-)
    0 0
    Moderator Response: [DB] Before being allowed to place further comments on this website, you must first respond fully to the question about your source for your assertions made here. Please include a link to the reputable source used to make that assertion in your reply. Please then put that response on that thread, not here.
  9. Not only will new trees not grow if we continue to spew ozone precursers into the atmosphere, the existing trees are already dying off all over the world and so we will lose that critical carbon sink.  While it seems incontrovertible that the amplifying feedbacks are running amock, geoengineering won't fix the collapsing ecosystem if we continue burning fuel and polluting.

    So, to postulate:  "By contrast, retardation of solar radiation through space sunshade technology may allow time for CO2 draw-down." misleading, in my opinion.  There IS no more time to allow for CO2 draw-down, because ozone precursor emissions are very closely linked to CO2 emissions, and the forests are in rapid decline right now.  

    For links to science supporting the two assertions (1.  the global trend of forests is towards decline and 2.  ozone underlies the increased susceptibility to biotic pathogens that are attacking trees) please go here:

    0 0
  10. There is no doubt at all that we need sequestration as well as emissions reductions.  I think James Hansen correctly suggested 350ppm as an initial goal for atmospheric CO2 concentration, as that reduction (from around 390 to 350) should be enough of a forcing to counteract the current planetary energy imbalance.  However... as a 'final destination' we would probably aim for below 300ppm.  That's around 700 billion tons of CO2, plus whatever comes back out of the oceans and land in subsequent years and decades.  I really hope we're smart enough (and have enough resources) to do this, because the alternative is pretty grim.

    0 0
  11. Dr.Howard Hanson of the Southeast National Marine Renewable Energy Center, recently reponded to my proposal that ocean thermal energy conversion (OTEC) is a geoengineering thechnic that can provide all of the energy we require by drawing down the surface heat of the ocean saying "OTEC, is not generally based on geoengineering as a premise or motivation. For that to come to be widely accepted, it would be important for refereed journal publications to emerge showing quantitatively and credibly that OTEC has the potential that you assert. I would be interested in seeing such analyses."

    As I am an inventor, not an academic and thus am unlikely to be published, I offer for the the reveiw of group a summary of a presentation I recently gave to the University of British Columbia's Fisheries department - and an article on the EnergyCollective -The Existential Imperative: Ocean Thermal Energy Conversion

    0 0
  12. On the subject of biochar, there seems to be a significant problem:  To char organic material you need a lot of fuel - clearly it would be counter-productive to use fossil fuels, and if we started a massive programme of burning organic matter to produce biochar then we would be putting a great deal of CO2 into the atmosphere for a relatively small amount of carbon sequestered.  That would work in the long term as we would be constantly growing new organic matter as the fuel to produce biochar, but how long would it take to make any significant reductions in atmospheric CO2?  Decades?  Centuries? 

    Any biological sequestration method would surely be too slow for our purposes.  The entire terrestrial biosphere is only absorbing about 25% of our annual carbon emissions, and we can't realistically increase that by more than a few percent.  We certainly can't expect to quadruple it and more.

    Whatever method we use, it's going to have to sequester all of our CO2 emissions (currently 30 billion tons per year), plus enough to make a meaningful impact on the existing atmospheric concentration, so perhaps 60 to 100 billion tons of CO2 per year, every year for the next 50 years at least, to get us back down to ~300ppm, depending on how much we manage to reduce emissions and how fast we need to bring it down.

    That's a lot of carbon.  I hope we find a way.

    0 0
  13. No argument with the thesis that we must reduce atmospheric carbon dioxide but any technological system we adopt will likely be too little too late and if deployed at a sufficient level to actually have an effect will trash our economy.  Worse still, we will run into unexpected consequenses such as releasing already sequestered carbon as we try to sequester more carbon.  No one would argue against the fact that our first priority is to stop putting more already sequestered carbon into the atmosphere and this is well within our technological capacity.  Already, wind is competitive with fossil fuels and solar is just about there.  The main barrier in the way of solar is legislative, not technological.  However, has anyone noticed that atmospheric CO2 goes up and down 7ppm each year or more accurately, 8 up and 6 down.  Natural processes are far more powerful than anything we could devise.  We need to, for instance:  1.  Selectively log, sequester the wood in well built houses and furniture, use all the waste wood to produce organic urea, liquid fuel and any other product that will displace fossil fuel 2. completely stop whale harvesting and let the whale pump recover with it's ability to suck carbon out of the atmosphere. 3. stop the use of palm oil and let the jungles re-form.  A mature jungle doesn't absorb any net CO2.  A jungle growing from scratch is a huge carbon sink (dry wood is 50% carbon or put another way, the amount of carbon dioxide sequestered in wood is close to the wet weight of the wood) 4. Completely change our fisheries policy, 5. Adopt Jim Hansen's system of tax and Dividend and so forth.

    0 0
  14. Icarus, I respectfully submit that biological sequestration would be fast enough for our purposes. In fact, Josep Canadell at CSIRO had estimated that if the world stopped deforestation today, let alone regenerate any forests, then forests would be sequestering 50% of the anthropogenic carbon emissions starting today, not just 25%. And all that deforestation is occurring mainly to support the growth in meat and dairy consumption, which is truly a voluntary activity that is entirely unnecessary for human well-being.

    I would urge reputed climate scientists to set examples, by going vegan themselves. At the moment, I don't know of a single climate scientist who's vegan.

    0 0
  15. @ saileshrao:

    "In fact, Josep Canadell at CSIRO had estimated that if the world stopped deforestation today, let alone regenerate any forests, then forests would be sequestering 50% of the anthropogenic carbon emissions starting today, not just 25%."

    Do you have a link for this?

    0 0
  16. Induced volcanism would require the least effort.  But unpredictable and uncontrolable.  

    0 0
  17. rpauli - Induced volcanism? Quick, to The Core!

    0 0
  18. Haha, KR, that trailer was great, thanks!  Now I know where all the HAARP conspiracies originated.

    0 0
  19. Icarus @12: You may be excessively gloomy about the potential for CO2 sequestration via biochar. An Australian company, Pacific Pyrolysis has developed a slow pyrolysis technology which (so they claim) takes an incoming biomass waste stream and converts about half of its carbon content to biochar. The other half is more than enough to drive the process (no need for fossil fuels after startup) and generates enough electricity to export a surplus from the plant. More information is available here.

    It's true that I am not aware of any independent verification of Pacific Pyrolysis's claims, and a full life cycle analysis would have to include fossil fuels burned during the aggregation and transport of the waste to the pyrolysis plant; however, pyrolysing waste which would otherwise be burned or allowed to rot would seem to be positive.

    0 0
  20. @Daniel Bailey (15), please see, e.g., 

    0 0
    Moderator Response: [DB] Thank you.
  21. @#12, Icarus. Charcoal making does produce a lot of excess energy. Most retorts use the excess energy for producing steam. Pelletizing the charcoal dust from biomass residues takes a lot less energy than raw biomass, another energy saver. 

    0 0
  22. for nice overview on the advantages of re-instating a clean charcoal industry based on biomass residues.

    0 0
  23. The issue of geoengineering raises an interesting conundrum. Acceptance that it's required means that advocates must believe that...

    1) Climate change is real and a threat to humanity.

    2) Concerted global action is required by the world's governments.

    3) CO2 emissions incur a cost to society—a cost directly related to the price of countering their effect through geoengineering, as well as costs of dealing with the impacts of climate change (in other words; a huge amount).

    Given these factors it would be illogical to continue with 'business as usual' at the same time as adopting geoengineering measures, unless we can find a method of geoengineering that precisely removes the CO2 that burning fossil fuels dumps in the atmosphere. In fact, given that—by winding up the climate warming 'flywheel'—we've put ourselves already well on course for at least 2o of warming and several metres of sea level rise, we actulally need to remove all the additional carbon we've put into the atmosphere over the last 150 years or so, as well as any we will need to contnue putting in the atmosphere in the future: a big ask.

    So, overall, getting countries to all agree to geoengineering will only happen at the same time as they all wake up to the imperitive of stopping burning fossil fuels. We're still far away from any serious action, but it's clear that the two will both occur at the same moment. It will not be an either/or.       


    0 0
  24. @Ger, #21:  Very good point.  If we generated electricity from biomass, displacing fossil fuel combustion and producing biochar in the same process, that would be a significant contribution to carbon sequestration.

    0 0
  25. Hello all. I am not a research scientist but I have some basic knowledge of physics and chemistry.

    I have a question about th greenhouse affect from a heating and cooling perspective.  I understand the a hot body will give heat off or transfer heat to a cold body if it the hot body is hot enough - entropy?   I think that I also understand the concept of partial pressure and that as a gas heats up it expands. 

    As we add more co2 to the atmosphere are we not increasing the pressure of the lower atmosphere?  If so, I would expect to see extra heat from generated from pressure as well.  In addition, since space is so cold, why does this extra heat escape faster into ooutser space due to the increased temperature gradient?   I've read that our upper atmospher is cooling and constricting.  Does this effect  help to keep the heat at lower altitudes?  Does  gravity play a role on co2 here?

    Thank you in advance.

    0 0
  26. meb58 @25, CO2 concentration has only increased 110 parts per million by volume since the pre industrial era.  Further, that increase has been accompanied by a loss of oxygen.  Not only does each molecule of CO2 formed draw one molecule of O2 from the air, but much of the CO2 comes from hydrocarbons.  That means approximately (for oil and gas) for each molecule of CO2 formed, two molecules of O2 are lost to the atmosphere, to form 1 x CO2 plus 2 x H2O.  The H2O then precipitates out of the atmosphere for a net reduction.  Further, CO2 dissolves in water more easilly than does O2, so while nearly all the O2 consumed in the reactions is lost (a small part is made up by ocean outgassing), around 50% of the CO2 formed is then dissolved in the ocean.

    The net effect, if any, will be a reduction in pressure.  However, as we are talking about changes in atmospheric composition of about 0.01%, the effect is negligible.

    0 0
  27. meb58, a higher temperature gradient is the result of changing the material across which the gradient exists into a new material that allows a higher gradient to exist. In other words, more CO2 makes the old atmosphere into a new one that has higher insulative properties. If we replace a thin coat with a thick one, we can have a higher gradient. A paradox would exist if the material remained the same material, but changing the composition of the atmosphere is de facto creating a new intermediate material between space and the earth's surface.

    0 0
  28. I think CO2 has been used (laboratory level) as a source of fuel along with sunlight in a soup of some semiconductors and various organisms. This isn't sequestration +producing energy needs in a CO2 neutral process. This is 0 sequestration + producing energy by drawing down CO2... which has the same effect.


    0 0
  29. meb58, I should also mention that hot->cold happens "unquestionably" only in the absence of work, but adding work changes the equation. Humans are engineering chemical reactions that, along with gravity, apply work to the atmosphere as we change its composition.

    Sorry, I am not being more mathematically precise, but the point is that we may need to understand these contributions if we wanted to accurately verify/analyze the Second Law of Thermo.

    [Wikipedia: "heat always flows spontaneously from regions of higher temperature to regions of lower temperature, and never the reverse, unless external work is performed on the system."]

    0 0
  30. Tom curtis, Jose_X,

    Thank you very much!  Your explanations are very helpful.

    ...then, the consumption of O2 occures at the point of combustion?  And forgive my own intillectual density,  even though O2 is consumed to form CO2, doesn't the mass  of the atmosphere now stay the same following the law of conservation?  I am aware that my previous question was quite the opposite...your helpful descriptions are clearing up my own mis-conceptions.

    Still, in my conception of the atmosphere, I see an atmosphere that is growing hotter.  What prevents that extra heat from escaping into space faster?  I equate my question to this example.  Let's take a one square foot cube of steel heated to 150 deg F and place it in a room set at 0 deg F.  I suspect the heat loss will follow some particular and repeatable time frame until the two reach the same temperature.  I uderstand, I think, that the heat loss may be rapid in the beginning and slow as the two begin to reach equilibrium.  However, if we now add heat doesn't the steel block lose heat faster?  ...hmmm may have just answered my own question...the source of heat we are providing is increasing over time and over-runs the ability of our atmospher to dissipate the extra heat...?

    Thank you...I would love to go back to school and revisit physics and chemistry.

    0 0
  31. Tom Curtis,

    I missed what I think is an important detail in your #26 reply above.  I had not realized that the H2O was a by product of the combustion process, or perhaps forgot.  If I understand this correctly then would this extra H20 affect latent heat?  I see this extra H2O as water vapor...?  ...add more heat to more water vapor and bang!

    0 0
  32. meb58, the basic reaction is  CH + O2 -> CO2 + H2O

    I doubt that the mass of the atmosphere can vary in any significant way. Water vapor content is a function of atmospheric temperature, any excess will precipitate as liquid or solid water.

    0 0
  33. Meb58@ 30: " What prevents that extra heat from escaping into space faster?"

    In essense, it does escape faster. A hotter atmosphere will lose energy faster, via increased emission of infrared (IR) radiation, but the followup to that is the question "at what point is a new balance reached?" A new balance is nto reached instantaneously - it takes time. If you want to think of it in a stepwise fashion, the steps are:

    a) energy, as sunlight, is absorbed by the earth-atmosphere system, mostly at the surface (but don't worry about that for now).

    b) energy is lost to space, from the earth and atmosphere, by IR radiation.

    c)  the earth-atmosphere system will be at equilibrium (i.e., a stable climate/temperature) when a) and b) balance.

    d) adding CO2 to the atmosphere makes the process in b) less efficient (IR is less easily transfered through the atmopsphere), so b) decreases and a) is now greater than b).

    e) as long as a) is greater than b), the earth-atmosphere system accumulates energy, and will heat up.

    f) as the earth-atmosphere heats up, it will lose more IR to space (step b)), because hotter objects give off more IR.

    g) the system will continue to heat up until a) and b) balance again, which will be at a warmer temperature than it was before the extra CO2 was added.

    An analogy would be a house with a fixed heater inside, and a fixed temperature outside. The heater will warm the house until the rate of heat loss matches the output of the heater. If you add insulation to the house walls (the equivalent of adding CO2 to the atmosphere), the heat loss will initially decrease, and the house will start to warm up. As the house warms, the increased temperature difference between the inside and outside of the house will cause the heat loss from the house to increase, until it again matches the heater output. The hosue will no longer continue to warm, but the new stable temperature inside the house will be warmer than it was before you added the extra insulation.

    0 0
  34. meb58:

    Note that this discussion of how increasing CO2 cause changes in climate is starting to get off-topic for this thread. If you wish to continue some of these discussions, it would be a good idea to look for a more appropriate thread. Look through the View All Arguments link (beside the thermometer bulb at the top left section of page) to find places that discuss many topics. Any comments you place on any topic you find there will show up on the Comments page that everyone can access using the link in the menu bar under the main header, so it will be seen.

    0 0
  35. meb58 @30, mass is converved, but the atmosphere is not a closed system.  To better understand the relationship, consider the following chart of changes in O2 and CO2 concentratration between 1990 and 2000:

    (Source:  IPCC TAR, discussed in greater detail here.)

    The essential points are that after the combustion of fossil fuels, ocean and land uptake of CO2, and outgassing of O2 from the ocean, there is an increase of 15 ppmv of CO2, and a decrease of 33 ppmv of O2.  CO2 is heavier than O2, with a molar mass of 44 g/mole compared to 32 for O2.  The difference, due to the carbon atom, would represent an increase in atmospheric mass if the only change in concentration were due to combustion.  That is because the carbon was not part of the atmosphere before combustion.  Of course, combustion is not the only process, so the net change is proportional to ((15 * 44) - (33 * 32))/44, or a reduction of 9 times the molar mass of CO2 for every mole of CO2 added to the atmosphere.  That represents a reduction in mass of  19.2 Gigatonnes of mass for every 1 ppmv increase in CO2 concentration.  As the mass of the atmosphere is 5.137 Petatonnes (= 10^15), however, that represents less than 4 ten thousandths of one percent of the atmosphere's total mass.

    You will have noticed that there is not a 1/1 ratio between expected decrease in O2 and expected increase in CO2 in the above chart.  That, as previously mentioned is because of the combustion of hydrogen in hydrocarbons.  As previously mentioned (and again by Phillipe), this H2O precipitates out of the atmosphere, and does not add to atmospheric mass.  The total H2O in the atmosphere is increasing, but that is because of increased temperatures and is largely controlled by the temperature.

    The increase in H2O due to increased temperatures probably exceeds the loss due to combustion of fossil fuels, but only be a small margin as H2O is light (molar mass = 18 g/mole).  It does indeed increase the release of latent energy via precipitation which is a factor in changes in extreme weather events.  It also reduces the lapse rate (a negative feedback) and increases the greenhouse effect of water vapour (a stronger positive feecback).  Whether that adds up to "bang" is for you to decide, but overall it certainly makes the prospects for the future less inviting.

    0 0
  36. To all thank you!  Bob Loblaw, thank you for pointing me in the appropriate direction.  I'll continue with a few uestions elsewhere. 

    Great community here!  I appreciate the help.

    0 0
  37. This whole article is an opinion piece.  There is no back up to it.

    The scale and rate of modern climate change have been greatly underestimated

    The leaked AR5 shows that this statement is not true, and no, I don't think it's required to link to that, as it is in many places.  There was even a discussion here on Ridley's predictions being wrong, with the IPCC's being closer - but ALL above the actual temp.  So the author's statement is clearly wrong.  Where is his back up?  (-snip-)?


    This article suggests that the current atmospheric CO2 level is already triggering amplifying feedbacks from the Earth system and therefore, in themselves, efforts at reduction in atmospheric CO2-emission are no longer sufficient to prevent further global warming.

    Again, without any backup, this is just opinion.  The author can (-snip-) anything he wants.  Where is his proof that amplifying feedbacks are already triggerred, and more importantly, where is his proof that a reduction of CO2 is no longer sufficient.

    0 0
    Moderator Response:

    [DB] Please note that posting comments here at SkS is a privilege, not a right. This privilege can and will be rescinded if the posting individual continues to treat adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

    Moderating this site is a tiresome chore, particularly when commentators repeatedly submit comments in violation of this site's Comments Policy. We really appreciate people's cooperation in abiding by the Comments Policy, which is largely responsible for the quality of this site.

    Finally, please understand that moderation policies are not open for discussion. If you find yourself incapable of abiding by these common set of rules that everyone else observes, then a change of venues will be the offing.

    Please take the time to review the policy and ensure future comments are in full compliance with it. Thanks for your understanding and compliance in this matter.

    All-caps usage and moderation complaints snipped.

  38. Kevin, maybe you can enlighten us about what your actual complain is?

    The author says it his first sentence, which you quoted ("This article suggests ..."), what he is going to be writing about, then makes a coherent argument with references to primay literature. You do not do anything of that kind, so why are you here?

    0 0
  39. Kevin wrote "This whole article is an opinion piece.  There is no back up to it.".  Actually, if you follow some of the links embedded in the article, they will take you to the supporting peer reviewed articles.  It is a shame that you seem unable to restrain your hubris, as I have pointed out, you will get a far better reception if you were to make your point in a more civil manner.  We are happy to discuss science here, including scientific views that go against the concensus; however few of us here want SkS to be the sort of rhetoric-laden content free waffle seen at so many climate blogs.

    So state your case, calmly and without rhetoric, and you will fare much better than you are now.


    0 0
  40. All, there is a good review article here:

    Climatic Change, December 2011, Volume 109, Issue 3-4, pp 745-790, A review of geoengineering proposals,by Naomi E. Vaughan, and Timothy M. Lenton

    Yes, this is possible, mostly through biomass (re-)growth, use, conversion (to biochar), and combustion (plus sequestration!);
    yes, this will take time, and
    yes, an international effort is needed.
    An no, no fancy new technology has to be invented, just political will.

    0 0
  41. Actually, if you follow some of the links embedded in the article, they will take you to the supporting peer reviewed articles

    There is no link provided to a peer reviewed paper which states that the rate of temperature increase is underestimated.  This is a claim of this article.

    The first  link goes to the home page of the Global Cabon cyProject, not a reviewed paper.

    While fig 1 does link to a Hansen Paper (reviewed of course), fig 2 links to a paper by Glikson, with no publishing information.

    One of the main parts of the article, the link to Glikson's article on "The Conversation" about "rates to which species could not adapt", is also just a blog, not a peer reviewed paper.



    These are the main problem statement aspects of the paper.  If the temperature rise is not underestimated, and the CO2 rise rate doesn't threaten species, why is removal of CO2 required.


    I did not state that his paper is wrong.  I am just pointing out that his backup is lacking.


    Note ** I did not mean to violate comment policy by using all caps on the use of the quote "suggest", I was just highlighting that that was all the article could do, was suggest.  I will not all cap anything again.


    0 0
  42. Kevin, if that is the problem, then why not simply ask "please can you give a reference to a paper that demonstrates that the rate of temperature increase is underestimated (or provide additional justification)"?  As I said, the unnecessarily abrasive tone that you have chosen to adopt is doing you no favours here.

    In response to my pointing out that many of the links refer to peer-reviewed papers, you counter with "The first  link goes to the home page of the Global Cabon cyProject, not a reviewed paper.".  This is just argumentative for the sake of it.  Firstly I said that some of the links are to peer-reviewed papers, the obvious corrolary being that some of them are not.  Secondly, the Global Carbon Project is a perfectly reasonable resource for verifying the truth or otherwise of what was being claimed, so your assertion that "backup is lacking" is absurd in this case, and you are making it look as if you are merely here for an argument, rather than for a genuine discussion of the science.

    Regarding Fig.2, they give a link to the actual paper, which itself includes references to all the data sources, so again that complaint seems to me to be merely quibbling.

    If you read academic papers, you will find they sometimes include a degree of specilation/discussion that is not directly backed up by references, so expecting chapter and verse at the end of every single sentence is unrealistic.  Do you reuire this standard from the other climate blogs you visit?

    Please, if you have an issue with the science presented here, then ask questions, ask them politely in a moderate scientific manner, and don't assume that something is wrong just because it seems to disagree with what you have read elsewhere.

    0 0
  43. Kevin, whether the author is right or not about

    "The scale and rate of modern climate change have been greatly underestimated"

    (note that this statement is not about temperature only as you seem to think)

    is obviously an ongoing question. There is evidence that the IPCC has been quite conservative in its projections, so aside from the arguments made in the article itself, the claim is supported by ongoing CO2 emissions tracking the business as usual scenario (follow the link to the GCP, where they list several related peer-reviewed publications), and generally conservative scientific assumptions about the developments and changes following that scenario.

    Your question

    "If the temperature rise is not underestimated, and the CO2 rise rate doesn't threaten species, why is removal of CO2 required."

    is puzzling. First, whether the temperature rise is underestimated or not, the rise in itself follows from first principles of planetary energy conservation and is of concernin any case, but especially at the rate it is happening. Second, the literature is full of negative effects of increasing [CO2], including "threatening species" such as those that cannot cope with decreasing ocean pH values.

    Do you advocate for ignoring rising CO2 and T ?

    0 0
  44. Kevin also questions the substantiation of this comment:

    "This article suggests that the current atmospheric CO2 level is already triggering amplifying feedbacks from the Earth system and therefore, in themselves, efforts at reduction in atmospheric CO2-emission are no longer sufficient to prevent further global warming."

    However this would seem to me as to be so basic an issue as not to really need further substantiation (i.e. it should be background knowledge).  That there are positive feedback mechansims ought to be pretty well known:

    • Water vapour feedback - water vapour is a GHG, and a warmer atmosphere supports a higher water vapour concentration.  This is perhaps the main reason why equilibrium climate sensitivity is likely to be arounf 3 degrees per doubling od CO2, rather than the 1 degree per doubling that can be calculated as the direct effect of the CO2 emissions themselves.
    • Albedo feedback - Arctic sea ice reflects much more visible light from the sun back into space than the dark sea water underneath.  So as Arctic sea ice declines, in response to GHG warming, the Arctic is likely to warm faster as a result of the decreased albedo.
    • Methane is a GHG, and there is a fair bit of it currently trapped in Arctic permafrost.  As the permafrost melts, methane is released and we get more GHG and more warming.

    So there are three positive feedback mechansims for which there is already evidence of having been triggered, that anybody interested in climate change ought to know about already.  Do they really need to be pointed out every time positive feedback is mentioned?

    The second part "...efforts at reduction in atmospheric CO2-emission are no longer sufficient to prevent further global warming." also seems fairly uncontraversial to me as well.  The increase in greenhouse gasses has created an imbalance in the planetary energy budget, and warming will continue until the planet warms sufficiently to restore this balance (which is why there is a distinction between transient and equilibrium climate sensitivity), which will take some time due to its thermal inertia (see here for further info).  So we are committed to some additional warming even if all GHG emissions were to stop immediately.  If we want to avoid this warming that is in the pipeline, we need to do something else to restore the energy balance, such as increasing the albedo (space shade) or active carbon sequestration.

    Please take some time to read the list of "most used climate myths"; you may find that your understanding of some of the fundamental issues is not as strong as you may think it is. 

    0 0
  45. I was interested to encounter this article on diatoms, which says in part

    "Because of their abundance in marine plankton, especially in nutrient-rich areas of the world's oceans, diatoms probably account for as much as 20% of global photosynthetic fixation of carbon (~ 20 Pg carbon fixed per year: Mann 1999), which is more than all the world's tropical rainforests."

    Warming and acidifying oceans are probably not going to help these little critters, making the atmospheric CO2 drawdown equation even more difficult to resolve.

    0 0
  46. Ocean acidification aside, does anyone know what amounts of CO2 would be taken up by the ocean of man stopped releasing excess (unnatural) CO2?


    When I see that the oceans take up some 1/4 of CO2 we release, I wonder if this brings the CO2 into near-term equilibrium with the oceans that fast and the oceans would take up very little more if we ceased CO2 releases or if the oceans are always behind and stopping CO2 releases would then lead to significant decreases in the atmosphere as the oceans continue doing their work. I don't know if the current year's 1/4 removal, for example, is a delayed lag off CO2 from long back or if it is closely tracking what we add on a yearly basis.

    0 0
  47. Jose_X @46
    The increased concentration of CO2 in the atmosphere represents about 43% of accumulative human emissions from FF, cement production & land change, the remainder going into the oceans and the biosphere. This rather consistent % is purely a function of mankind's continually increasing emissions.Equilibrium is a long way off.

    A well quoted reference on atmospheric CO2 lifetimes is Archer 2009 who concludes that if we stop emitting CO2, after about 500 years the result of all our emissions would be an increase in CO2 above pre-industrial levels roughly equal to 20% of our emissions. This remaining 20% will then be left in the atmosphere for tens of thoudands of years.

    (That is exepting the cement releases. The chemistry of cement/concrete reabsorbes its CO2 releases over about 1,000 years.)

    0 0
  48. MA Rodger, thanks for the reference and for the summary.

    A related note from page 5:

    > Finally, the 2007 IPCC report removed the table from the “Policymaker Summary,” and added in the “Executive Summary” of Chapter 7 on the carbon cycle, “About half of a CO2 pulse to the atmosphere is removed over a timescale of 30 years; a further 30% is removed within a few centuries; and the remaining 20% will typically stay in the atmosphere for many thousands of
    years” (Denman et al 2007, page 501).

    0 0
  49. Jose_X @48. the one disclaimer regarding the 20% "effectively forever" is that the percentage of emissions retained for thousands of years into the future depends on the total emissions.  The 20% figure is the approximate value for 1000 Petagrams (1 trillion tonnes CO2), the achievable lower limit of CO2 emissions assuming no geoengineering:

    A more realistic figure for total emissions given current rates of mitigation would be 5000 petagrams, when retained CO2 is significantly higher, and perhaps as high as 30%:

    With the "drill baby, drill!" strategy of the Republican party in the US, and the Harper government in Canada (and the Abbot opposition in Australia) upper limits on emissions may be up to three times that, ie, around 15,000 Pg (15 trillion tonnes). 

    Even the best case scenario results in an increase in global temperature relative to the preindustrial of around 2 C (ie, 1.3 C increase relative to current margins) for the next 10 thousand years.  The intermediate case increases that to around 5 degrees above the pre-industrial, while the worst case puts it out to about 16 C increase (all estimates having a error margins of about +/- 50%).

    0 0
  50. Hi Tom Curtiss @49.

    Thanks for turning Archer's figure 1 round the right way up. In the past I have always met it on its side which does make fully appreciating its content a bit stressful.

    The text of Archer 2009 is a different matter, although you did get me checking who was right.

    The pulses of CO2 he models are in Pg carbon (GtC in my-speak) and not in Pg CO2. Archer describes the size of the smaller of these pulses thus "For comparison, humankind has already released 300 Pg C and will surpass 1000 Pg C total release under business-as-usual projections before the end of the century." Archer's 300 GtC for human releases is surely low, even for 2009 (which if you tot them up would have been 350 GtC back then according to CDIAC, and now over 400 GtC). It also ignores land-use emissions which tot up to a further 160 GtC according to CDIAC which makes today's total release probably over 560 GtC.

    Thus under BAU, I would put the 1,000 PgC emissions milestone as arriving, not as Archer says "before the end of the century", but by mid-century.

    The larger 5,000 PgC pulse he equates to burning of all FF reserves including coal (although likely tar sands & fracked gas probably don't feature). Fuel reserves are always a nightmare, with the numbers quoted ranging from 'reserves from current holes in the ground using current extraction methods' all the way to 'estimated potential global reserves extractable using theoretical methods.' I do think Archer is at the high end of these different figures when he says the 'entire reserviour of fossil fuel' equates to his 5,000 GtC. A figure of 760 GtC (2,795 GtCO2) is encountered commonly which I interpret as 'known reserves less tar sands & fracking'. There is as well resulting carbon feedbacks from permafrost so BAU for 60 years would easily see resultant total accumulative carbon emissions up to 1,500 GtC.

    0 0

1  2  Next

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.

The Consensus Project Website


(free to republish)

© Copyright 2024 John Cook
Home | Translations | About Us | Privacy | Contact Us