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How do human CO2 emissions compare to natural CO2 emissions?

What the science says...

Select a level... Basic Intermediate

The natural cycle adds and removes CO2 to keep a balance; humans add extra CO2 without removing any.

Climate Myth...

Human CO2 is a tiny % of CO2 emissions

“The oceans contain 37,400 billion tons (GT) of suspended carbon, land biomass has 2000-3000 GT. The atpmosphere contains 720 billion tons of CO2 and humans contribute only 6 GT additional load on this balance. The oceans, land and atpmosphere exchange CO2 continuously so the additional load by humans is incredibly small. A small shift in the balance between oceans and air would cause a CO2 much more severe rise than anything we could produce.” (Jeff Id)

At a glance

Have you heard of Earth's carbon cycle? Not everyone has, but it's one of the most important features of our planet. It involves the movement of carbon through life, the air, the oceans, soils and rocks. The carbon cycle is constant, eternal and everywhere. It's also a vital temperature control-mechanism.

There are two key components to the carbon cycle, a fast part and a slow part. The fast carbon cycle involves the seasonal movement of carbon through the air, life and shallow waters. A significant amount of carbon dioxide is exchanged between the atmosphere and oceans every year, but the fast carbon cycle's most important participants are plants. Many plants take in carbon dioxide for photosynthesis in the growing season then return the CO2 back to the atmosphere during the winter, when foliage dies and decays.

As a consequence of the role of plants, a very noticeable feature of the fast carbon cycle is that it causes carbon dioxide levels to fluctuate in a regular, seasonal pattern. It's like a heartbeat, the pulse of the Northern Hemisphere's growing season. That's where more of Earth's land surface is situated. In the Northern Hemisphere winter, many plants are either dead or dormant and carbon dioxide levels rise. The reverse happens in the spring and early summer when the growing season is at its height.

In this way, despite the vast amounts of carbon involved, a kind of seasonal balance is preserved. Those seasonal plant-based peaks and troughs and air-water exchanges cancel each other out. Well, that used to be the case. Due to that seasonal balance, annual changes in carbon dioxide levels form regular, symmetric wobbles on an upward slope. The upward slope represents our addition of carbon dioxide to the atmosphere through fossil fuel burning.

Fossil fuels are geological carbon reservoirs. As such, they are part of the slow carbon cycle. The slow carbon cycle takes place over geological time-scales so normally it's not noticeable on a day to day basis. In the slow carbon cycle, carbon is released by geological processes such as volcanism. It is also locked up long-term in reservoirs like the oceans, limestone, coal, oil or gas. For example, the "37,400 billion tons of 'suspended' carbon" referred to in the myth at the top of this page is in fact dissolved inorganic carbon in the deep oceans.

Globally, the mixing of the deep ocean waters and those nearer the surface is a slow business. It takes place over many thousands of years. As a consequence, 75% of all carbon attributable to the emissions of the industrial age remains in the upper 1,000 m of the oceans. It has not had time to mix yet.

Fluctuations in Earth's slow carbon cycle are the regulating mechanism of the greenhouse effect. The slow carbon cycle therefore acts as a planetary thermostat, a control-knob that regulates global temperatures over millions of years.

Now, imagine the following scenario. You come across an unfamiliar item of machinery that performs a vital role, for example life support in a hospital. It has a complicated control panel of knobs and dials. Do you think it is a good idea to start randomly turning the knobs this way and that, to see what happens? No. Yet that is precisely what we are doing by burning Earth's fossil fuel reserves. We are tinkering with the controls of Earth's slow carbon cycle, mostly without knowing what the knobs do - and that is despite over a century of science informing us precisely what will happen.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!

Further details

Before the industrial revolution, the CO2 content in the air remained quite steady for thousands of years. Natural CO2 is not static, however. It is generated by a range of natural processes, and absorbed by others. The carbon cycle is the cover-all term for these processes. It has both fast and slow components.

In the fast carbon cycle, natural land and ocean carbon remains roughly in balance and has done so for a long time. We know this because we can measure historic levels of CO2 in the atmosphere both directly, in ice cores and indirectly, through proxies. It's a seasonal response to things like plant growth and decay.

In stark contrast to the fast carbon cycle, the slow version operates over geological time-scales. It has affected carbon dioxide levels and therefore temperatures throughout Earth's history. The reason why the slow carbon cycle is so important is because many of the processes that lead to long-term changes in carbon dioxide levels are geological in nature. They take place over very long periods and do so on an erratic basis. The evolution of a species that has deliberately disturbed the slow carbon cycle is another such erratic event.

Annually, up to a few hundred million tonnes of carbon pass through the slow carbon cycle, due to natural processes such as volcanicity. That's small compared to the fast carbon cycle, through which some 600 billion tonnes of CO2 pass to-and-fro annually (fig. 1). However, remember that the fast carbon cycle is a give-and-take seasonal process. The slow carbon cycle instead runs in one direction or another over periods typically measured in millions of years.

Global carbon budget

Fig. 1: Schematic representation of the overall perturbation of the global carbon cycle caused by anthropogenic activities averaged globally for the decade 2012–2021. See legends for the corresponding arrows and units. The uncertainty in the atmospheric CO2 growth rate is very small (±0.02 GtC yr−1) and is neglected for the figure. The anthropogenic perturbation occurs on top of an active carbon cycle, with fluxes and stocks represented in the background. Adapted from Friedlingstein et al. 2022.

Through a series of chemical and geological processes, carbon typically takes millions of years to move between rocks, soil, ocean, and atmosphere in the slow carbon cycle. Because of these geological time-scales, however, the overall amount of carbon involved is colossal. Now consider what happens when more CO2 is released from the slow carbon cycle – by digging up, extracting and burning carbon from one of its long-term reservoirs, the fossil fuels. Although our emissions of 44.25 billion tons of CO2 (in 2019 - source: IPCC AR6 Working Group 3 Technical Summary 2022) is less than the 600 billion tons moving through the fast carbon cycle each year, it adds up because the land and ocean cannot absorb all of the extra emitted CO2: about 40% of it remains free.

Human CO2 emissions therefore upset the natural balance of the carbon cycle. Man-made CO2 in the atmosphere has increased by 50% since the pre-industrial era, creating an artificial forcing of global temperatures which is warming the planet. While fossil-fuel derived CO2 is a small component of the global carbon cycle, the extra CO2 is cumulative because natural carbon exchange cannot absorb all the additional CO2. As a consequence of those emissions, atmospheric CO2 has accumulated to its highest level in as much as 15 to 20 million years (Tripati et al. 2009). This is what happens when the slow carbon cycle gets disturbed.

This look at the slow carbon cycle is by necessity brief, but the key take-home is that we have deeply disturbed it through breaking into one of its important carbon reservoirs. We've additionally clobbered limestones for cement production, too. In doing these things, we have awoken a sleeping giant. What must be done to persuade us that it needs to be put back to sleep? 

Cartoon summary to counter the myth

Cherry picking

This Cranky Uncle cartoon depicts the "Cherry picking” fallacy for which the climate myth "Human CO2 emissions are small" is a prime example. It involves carefully selecting data that appear to confirm one position while ignoring other data that contradicts that position. Source: Cranky Uncle vs. Climate Change by John Cook. Please note that this cartoon is illustrative in nature and that the numbers shown are a few years old.

Last updated on 17 September 2023 by John Mason. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Argument Feedback

Please use this form to let us know about suggested updates to this rebuttal.

Further reading

Real Climate goes in-depth into the science and history of C13/C12 measurements.

The World Resources Institute have posted a useful resource: the World GHG Emissions Flow Chart, a visual summary of what's contributing to manmade CO2 (eg - electricity, cars, planes, deforestation, etc).

UPDATE: Human CO2 emissions in 2008, from fossil fuel burning and cement production, was around 32 gigatoones of CO2 (UEA).

Denial101x video

Here is the relevant lecture-video from Denial101x - Making Sense of Climate Science Denial


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Comments 351 to 375 out of 380:

  1. MA Rodger @350 :

    Quite so.   There is also kind of disjointedness to the "laundry list".   Almost as if someone were using a program to generate random denialist phrasings.

    Or pehaps the list is a sort of Poe.   Une blague.

  2. 1. More testing for temp & c02 happens in or close to rural areas. Common sense logic. I need no link to prove. Why would you?

    2. Saying the ocean increase of 8 inches since 1800's? When was the last time you saw vast amounts of brilliant scientists up & down the coastlines with yardsticks or God help me dipsticks measuring the lines as the ocean ebbs and wanes a great amount of times more than eight inches many times within decades yrs mnths wks days hrs mins? Maybe the guys back in the 1800's were comparing satellite images to determine the beginning rises? I do not need a link to prove this is b.s. Nor should you.

    3. C02 gauges determining 400 parts out of 1,000,000 are c02? Fancy thermometer you have there & that is all it is. Electrochemical sensors? Did they count the atoms? Did they feel them? Smell them? Sorry el ch sensors only are in c0 detectors. C0 is even lower ppm than c02. C02 detects by measurements of laser intensity. Fancy thermometer. & Considering C02 can only possibly take up .05 to 5% of a given area that would mean variant temp detect would need be within those ranges as well. & Typal it would take the area of 3 average adults to have required amount of oxygen atoms needed to bond with carbon for such a reading of 400 ppm? Fancy thermometer. And this junk measures the laser intensity (pressure on the silicone chip... yes that's all.) in order to assume raises in c02 due temp rises? Fancy. Like if you had a concealed area void of all carbon oxygen etc and you lit a match to it the inner temp would not raise because only c02 can raise a temp! I do not need a link to prove this as quakery nor should you.

    4. Global warming causes tsunamis? Do they mean the consistent average of 2 a yr which has never shown an increase as far as I know to 3 is & has been caused by humans? I do not need a link. Suddenly I am hungry for sausage though. How about you?

    5. If .04 % of atmosphere is c02 & of that .04 we contribute .0016 of it that means we are changing approximate .00005 of atmo. An alien bug shifted a cosmic wind storm with a furt... seriously it did! But .00005% of your outhouse wallscovered in pink panther fiberglass... your still gonna shiver during snowy winter outdoor poo runs. Suddenly I no longer feel like sausage. Do you?

    6. 2 degrees!!!! Omgomgomg! Over 200 yrs! Imagine if that happened in a minute? It does. & Within an hour day week month season decade century Millennium four score seven years etc. I even heard it goes up & down by higher than 2° in those time increments! Could you imagine waking up one morning and it was like 10°!!! This is why Eskimos don't visit Africa... they would melt. Animals, especially humans cannot adapt to extreme 2°+ changes... impossible... especially if they happen over decades... trust me that's what common sense scientists say. I'm trying to make a segue with Abe right now but politics are not allowed here. Shoulda txt 5 score & 8 yrs. Nor should you... sorry just trying to stick to a format here.

    7. It's been millions of yrs since the earth has been this hot or had this much c02 & man was not even in existence back then which proves man did it! So who did it? Wooly mammoths? Hairy hippos? It's like saying your great grandmother to the ten millionth power got pregnant which prove the guy dating your daughter will not where a condom. Yeah I know... poor link. Norse soot dew. 

    8. 8% of our c02 production is what we breathe out. Gw alarmists should put a bag over there heads to help us get to the 0% c02 in the air which is what they want so that all plant life can die followed by all other life but at least surfers will not wipe out when a hundred ft high wave crashes upon them. Annette Fettuccine. Ignore her doo.

    9. Animals breathe too... little effers. Get over here fido. It's time I introduced you to Mr. Gallon size ziplock. I'll leave the pasta in there so you can have a last meal. Dogs don't know it's not seven degrees hotter for Kevin bacon... nor does he.

    10. You would think that after all this blaming mankind for every catastrophic thing that happens in nature from the monsoons to the tidal waves to rats overrunning Portugal the one's hitting the near end panic buttons with all their summits & committees & conferences & picnic BBQs & gov funding & YouTube funny cat video empirical research would come up with a way to significantly bring the average gt down by at least half a degree of our controllable portion so we could have only one & one half the amount of disasters. Like one and one half of a Suzuki. 

    The moral of the story.

    Spending time preparing for the unavoidable will save more lives than attempting to eliminate mankind's effects toward the consequences of a chaotic nature. Therefore gw are murderers by way of their ignorance. It is like they are watching a man beat child while attempting to prove a too many carbohydrates will make man beat child... now if we can just keep Frankie Avalon from the spaghetti we might save a child from abuse!


    [BL] Long, mostly off-topic Gish Gallop snipped.

    To our usual commenters: please refrain from responding to this until we have had the time to check if this particular user is another sock puppet of a previously-banned user.

    [BL] July 20 moderation update. Although this user does not appear to be a previously-banned user, the behavior so far violates several aspects of the comments policy - especially with respect to staying on topic.

    All comments must be on topic. Comments are on topic if they draw attention to possible errors of fact or interpretation in the main article, or if they discuss the immediate implications of the facts discussed in the main article. However, general discussions of Global Warming not explicitly related to the details of the main article are always off topic.


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  3. A note on the Basic tab of this rebuttal. An astute reader noticed that the paragraph under Figure 1 stated that 40% of the additional carbon is absorbed, but this disagreed with the values in the figure. A check of the original source confirmed the reader's observation. It appears that in the original writing, the 60/40 split was reversed.

    The rebuttal has been corrected to use the 60% value.

  4. As this is your first post, Skeptical Science respectfully reminds you to please follow our comments policy. Thank You!

  5. Responding to ecgberht

    I believe the MIT referred to is this one.

    "Greater than 90 per cent of the carbon dioxide input to the atmosphere–ocean system each year derives from the natural decay of organic carbon"

    However, they contribute zero % to the increase in CO2 in the atmosphere as this article explains. ecgberht is falling foul  of misinformation.

    The IPCC reports cover ongoing research into the natural CO2 fluxes in great detail. ecgberht would do well to read the relevant chapter in the report. 

  6. I realize the article is out of date but I believe my logic would hold for 2022 as well as 2007.

    The increase in ppm CO2 in the atmosphere by 2 ppm each year is pretty constant. That amounts to an additional 15.64 Gigatons per year. That's in the ballpark of the 60/40 split for absorption.

    Ignoring the ocean absorption, that 15.64 Gigatons is 3.5% of the absorption over land. I'm wondering whether increasing vegetation/forest/etc. by 3.5% would hold atmospheric CO2 ppm constant. Then stretch that to 10% and we can forget about CO2 absorption plants. It seems more elegant than diverting trillions of dollars to renewables and batteries.

  7. Doug Cannon @356 ,

    Before pursuing that idea of CO2 control by increasing mass of vegetation, it would be worth doing some back-of-envelope estimations.  Potential increased tonnage of woody plants (and carbon content) per square km, as well as carbon in soil microbes/fungi . . . and where these requisite vast areas would go.  And the ongoing supply of phosphates & other nutrients.  And the continued increase needed.   And the cycle of rotting.  You might be unpleasantly surprised at the impracticalities involved.

    Seaweed/algal stimulation by distributing iron salts over the pelagic ocean has been suggested . . . but failed to show practicality.

    Simpler quicker & cheaper to use wind /solar /nuclear solutions  ~ which we will have to do anyway, as fossil fuels run out.

  8. Eclectic @357

    I find it hard to believe that the earth is at its maximum capability of supporting vegetation and couldn't increase it by 3.5%. Since 1960 we've improved land use to a level equivalent of over 3 Gigatons of CO2 annually.

    I had done some estimates. Based on an average absorption of 77.5Tons per acre we would need an additional 200 million more acres. That's a little over .5% of total land mass. Not an easy task but certainly a reasonable target.

    Even if we couldn't totally balance existing fossil fuel emissions we could make a pretty good dent. Maybe even enough to forego the need for battery back-up on a scale necessary for electric power generation. Hopefully we could get a capacity factor of close to 60% with a combination of wind and solar and only need 40% of existing fossil for electricity. (Then incentives for non plug-in hybrids could delay the downside of all-electric vehicles, which would otherwise delay the decommissioning of coal fired electricity.....but that's an issue for another day.)

    I realize there's lot of money dependent on renewables and EVs which would make any such strategy unpopular with much of the investment and media community. But we're not getting far with the current approach of big meetings every few years to lie about goals with no plans.

    Not to worry about running out of fossil fuels. We have over 240 years of known reserves at current useage (coal-139, oil-54, natural gas-49). We'll run out of lithium before fossil fuels.

  9. Doug @358, 356...

    It's my understanding that vegetation is both an absorber and emitter of CO2. So, just increasing vegetation by a small fraction isn't going to do much to change the overall balance. There certain is some sequestation, so it's a good thing to do, but it would take far more than a 0.5% change to offset all human emissions. And, in fact, we are currently operating in the opposite direction with deforestation in important places like the Amazon. So, we'd need to first reverse that, and then reforest from there.

    Regarding, "[a] lot of money dependent on renewables and EV's," it's not exactly clear what you mean by this. Wind and solar are now cheaper than all fossil fuel sources, so it's actually cheaper to replace retiring FF energy with clean energy free of carbon emissions. Ostensibly, these means it will cost less to transition to renewables than it would be to continue using FF's.

  10. In addition, you state, "We'll run out of lithium before fossil fuels." I question that assertion.

  11. Doug Cannon @ 358:

    Where do you get your 77 tons per acre number from? Is that tons of carbon, or tons of CO2 equivalent? And since you are using acres, is that an imperial ton, rather than metric?

    I am fairly familiar with forest carbon cycles in the boreal forest, and 77 tons per acres is close to 200 metric tonnes per hectare, which is a reasonable number for entire ecosystem carbon in the boreal forest. But this includes tree biomass, root biomass, leaf litter, dead branches, and soil carbon. And soil carbon (in the boreal forest) is often as much or more than the tree biomass. And this ecosystem carbon does not accumulate in a day, or a year, or even a decade - we're talking centuries-old ecosystems.

    Please explain your calculations, and give us a rate of carbon uptake per year. Then you can compare it to annual fossil fuel emission rates. Then you can calculate how much area is needed to offset current emissions - and then how much area (and time) is needed to suck out the CO2 we've already added over the past century..

  12. Doug @358 , please show the general outline of your back-of-envelope calculations.  There are numerous important factors applicable to your scheme.

    For instance ~ and I know you did not mean it that way ~ your 240 years of coal/oil , multiplied by your 0.5% of total land mass . . . comes to 120% of total land area.   Interesting !

    But seriously, Doug, when you look at Canadian/Siberian tundra, and at semi-deserts (etc) . . . there is almost zero scope for major forest development (being land which is incompatible with high-carbon plants i.e. trees).   And afforestation elsewhere, would mean replacement of crops which do ultimately produce human food.   Not to mention 8 billion citizens revolting in the streets as you attempt to enforce a vegetarian lifestyle.

    Yes, you should buy lithium-mining company shares at present.  But battery technology is advancing very rapidly ~ and there is no shortage of sodium, aluminum, etcetera.

    ## Please show your workings, Doug.  Including the effective average number of years for a forest to reach maturation/stasis (regarding carbon uptake).

    Doug, your heart is in the right place.  But there is an H.L. Mencken quote to the effect of:  For every complex problem, there's a solution that is simple, neat, and wrong.

  13. RE: Rob Honeycutt 360

    Here's my reference for known fossil fuel reserves

    Estimates on lithium range from 20 years to 200 years. Would be interestedto know if you have some more definitive information.

    Re: Rob Honeycutt 359

    If we accept the original premise above, the earth is a net absorber of 17 Gigatons annually. The land having 11 Gigatons of net absorption. So more land vegetation should provide more net absorption. The .5% is the proportion (200 million acres) of total land required to absorb the CO2 emitted by fossil fuels. I would be interested in a better analysis of this if you have one. That was the original question I presented.

    Regarding your staement "it will cost less to transition to renewables than it would be to continue using FF's." That may be true for developing countries who have growing needs for power and no access to natural gas. But you shouldn't misunderstand staements that say renewables are cheaper than FF.

    In the U.S. for example there is little need for added electrical power.

     It would take little or no up front capital investment to continue with FF. Theoretically to totally replace The terrawatts of U.S. energy with solar and battery backup would require a $1.7trillion investment. That is no doubt not the way to proceed, but it's the cheapest renewable route.

    Here's a link to eia 2020 cost of electric utilities.

    For large wind turbines: base cost $1265/kw plus 35.14/kw each year

    For solar PV : base cost $1313/kw plus $15.25/kw each year

    For combined cycle gas: base cost $958 plus $12.20/kw each year Plus $1700/Mwhr (my estimate).

    It gets complicated when you have to take into account if solar and wind have a capcity factor of 25% and 35%. So as long as we continue to use renewables with fossil backup you can just amortize the cost of renewables over 30 years and compare to FF it replaces when they're operating. If you want to completely eliminate the FF backup you have to multiply the costs of renewables by 3 or 4 and add cost of battery backup.

    I don't think we should argue the economics to  justify renewables. We need to argue for the benefits.



  14. refer my 362.

    $17/Mwhr, not $1700. 

  15. Doug @ 363:

    If we accept the original premise above,

    It's not a premise. It's based on measurements.

    the earth is a net absorber of 17 Gigatons annually. The land having 11 Gigatons of net absorption.

    So far, so good.

    So more land vegetation should provide more net absorption.

    In a very general sense, yes, but it depends entirely on what this "new vegetation" is replacing. Are you thinking of planting something on land that has no current vegetation, and no current soil carbon? Exactly where is this "new vegetation" supposed to appear?

    The .5% is the proportion (200 million acres) of total land required to absorb the CO2 emitted by fossil fuels.

    This is where you lose me. As you stated in comment 356, you determine that 15.64Gt is 3.5% of the total land uptake (450 Gt/yr in figure 1 of the OP). Your total land required still appears to be based on your 77.5 tons/acres value you provided in comment 358.

    The entire land ecosystem as it stands is only capable of an additional 11 Gt/yr uptake (over and above the 439 Gt/yr it is releasing). If we created a duplicate land system covering the same area that all our current vegetation covers, it will both absorb and release CO2 just like the existing one. What is it about this new land cover that you are proposing that is different from the current one, that makes you think that we only need a much smaller area than the current vegetation covers?

    New vegetation on bare soil does not have carbon uptake rates anywhere near the numbers you seem to think it does. (You have not yet provided the source of your 77.5 tons/acre number in comment 358.)



    [RH] Note there's a policy against link only posts.

  17. Doug, your numbers on renewables are incorrect, I think because you're only looking at installation costs rather than levelized costs.

    You can read the 2022 EIA LCOE Report here.

  18. Doug @363... "It would take little or no up front capital investment to continue with FF."

    This is also incorrect. All forms of generation have a useful lifetime and eventually need to be decommissioned and replaced. What is happening is much of the new added generation as well as replacement generation is being filled with some form of renewables. Renewables are currently scaling exponentially

    Moreover, the cost of FF sources is rising as renewables continue to fall in cost. The previous link to the EIA LCOE report this year includes the cost of grid level storage since those cost are now starting to fall below the levelized cost of peaker plants.

  19. The source of the 77.5 t(CO2)/acre quoted @258 is shown in the link @366. It is not a figure for annual sequestration (which is evidently being expected @358 and which would be a few percentage points of this 77.5t figure) but total sequestration. And I think it is too low. It is derived from cocoa plantations so a figure which may not be representative of replanted global woodlands.

    In numbers I am more familiar with, 77.5t(CO2)/acre is (as the link says) 191.6t(CO2)/ha or [x100/3.664=] 5,200t(C)/sq km. 

    Over the period 2010-19, there has been 53M ha of lost tropical forest (according to OurWorldInData). And since AD1850, the figure given is 1,400M ha. The Global Carbon Project give budgets showing estimated emissions from land-use-change (this mainly due to deforestation) as 13Gt(C) for 2010-19 and 203Gt(C) since AD1850. These numbers suggest a carbon sequestration intensity for natural woodland of 24,500t(C)/sq km or 14,500t(C)/sq km, the former figure tropical, the latter perhaps global. These numbers are far greater than that given in the #366 link.

    We can dodge calculating the annual uptake by considering how many sq km of forest would need to be planted to draw down today's annual CO2 emissions (which would be necessary to stabalise GHG forcing). That would be roughly 500,000 sq km or 0.3% of global land, or 0.5% of the 100M sq km global productive land, annually. Note that globally 38M sq km is currently forested, and a similar amount would be naturally scrub or grassland so also not very useful for sequestering our CO2. Thus the potential for land available to sequester our FF CO2 emissions would be somewhere near 25M sq km and such a level of replanting would provide sequestration for perhaps 50 years of our FF emissions at present levels of FF-use.

  20. To see the annual uptake in the link in comment 366, you have to read past the first page/Introduction. Further down, they have a section titled "Annual Carbon Accumulation Rates". There, they give a figure of 2.0 tCha/yr.

    They also refer to it as "the rate of carbon accumulation in aboveground biomass" [emphasis added]. As I noted above, soil carbon, leaf litter, and dead branches. etc. (usually called "detritus") can be important carbon storage reservoirs in many forests.

    Forestry practices can have major consequences on soil carbon and detritus. For example, after clearing a section of boreal forest to harvest timber, the land becomes a strong carbon source as the soil carbon decomposes due to increases sunlight and warmer soil temperatures. This is a much larger loss of carbon than any  gains from rapid young tree growth.

    So Doug Cannon's "solution" is not the panacea he thinks it is.

  21. To MA Rodger, re #369

    Thanks for your input. That's about 40% less than my rough estimate of 200 million acres.

    I think I can summarize the various replies to my query:

    Yes, but it would be extremely difficult and we're too committed to renewables to focus elsewhere.

    Signing off. Thanks to all.

  22. Rob Honeycutt #367

    My numbers include all cost, not just installation. I didn't assume any MW/yr, or discount rate from which you could compute LCOE. With the same assumptions My numbers would agree with eia except they may be 2 years out of date.

    You have to compare the total solar cost/ MWhr excluding taxpayer payments ($36.10/Mwhr) to just the variable cost avoided by not operating the combined cycle unit when solar is available: $37.05-8.56 =$28.49/Mwhr. That's basically what we're doing today.


    What I was addressing was the the up front capital cost and the lower capacity factor show a major investment. Actually the 2022 eia report show this even more clearly

  23. Doug... Yes, what you're comparing is the "up front capital costs" which all new facilities incur. The up front capital costs for FF is lower, but then you're burdened with supplying that facility with fuel for the lifetime of its existence. Whereas, the up front cost of renewables are higher but they require no fuel for their lifetime. This is exactly what LCOE is. 

    Investors do not base their decisions only on up front capital costs but rather on the ROI they will see over the lifetime of the project. Renewables also generally have a shorter lifespan for any given installation, but in that span of time the investor reaps the entire return faster and moves on to a new project well before they can see their full return on a dollar-for-dollar investment for a FF based facility.

    This is why renewables are now scaling exponentially.

  24. In addition, capacity factor is irrelevant for LCOE and investment decisions since the grid buys power based on the lowest available price, not on when the power is available.

  25. Not sure how it would enter the overall dollar calculation, but there may well be circumstances where there is value in a generation system that can give close-to-zero marginal cost (short or longer term).  That would apply especially to solar installations, but slightly less so for wind.

    There is that ~ and the difficulty of long-term LCOE estimations of "renewables" which are rapidly changing in technology & build costs.

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