<p>Your comparison to water vapor is a bad one.  </p>

<p>The amount of water vapor in the atmosphere does increase with atmospheric temperature.  This is because more evaporation occurs and can be held as vapor longer, thus offsetting the equilibrium of water vapor.  Cold air will cause more water vapor to condense back to liquid.  This process of water cycling occurs on the order of hours/days.  </p>

<p>This is in stark contrast to carbon dioxide, which does not condense out of the atmosphere when it cools.  Nor does carbon dioxide evaporate from the surface of the earth.  Instead, it is a byproduct of respiration and combustion.  Carbon dioxide stays in the atmosphere for 100s of years before it gets deposited or chemically converted.  Furthermore, carbon dioxide becomes part of geological processes in the carbon cycle that takes 1000s of years, not days.</p>

<p>So, to summarize, carbon dioxide does not directly increase in the atmosphere due to temperature rise, because it is not constantly evaporating from the Earth's surface and condensing in the atmosphere.  Carbon dioxide does not condense at normal atmospheric temperature... it won't condense until it gets as cold as -78.5 degrees C, which does not occur on the surface of the Earth [in this climate regime].</p>

<p>It should be noted that carbon dioxide will indirectly increase in the atmosphere with temperature rise.  This is because of feedback mechanisms.  For instance, with increasing temperature, trees will be more dry on average and will thus combust more easily.  More wildfires are expected as temperatures rise, and with them come more carbon dioxide emitted during the fire.  There is also the possibility that increases in global temperature will cause feedbacks in the geologic cycle that lead to more volcanic activity, which is another source of carbon dioxide emissions. And, as Michael points out, the methane released when permafrost melts will eventually oxidize with the hydroxyl radical into carbon dioxide and water vapor. </p>

CC BY-SA 3.0
2017-02-04T04:16:28.787Z
I'd like to add that increasing temperatures cause melting of permafrost, which allows release of trapped methane. This methane then oxidises to carbon dioxide in the atmosphere.
Gimelist
CC BY-SA 3.0
2017-02-04T04:26:23.550Z
Yes Good Point!
f.thorpe
CC BY-SA 3.0
2017-02-04T04:28:34.383Z
I never believed co2 behaved as h2o, that's just where the idea of the confusion of inverse came from.  Good information on it not directly being caused by temperature rise.
Acumen Simulator
CC BY-SA 3.0
2017-02-04T04:36:59.503Z
You used water as your comparison point, which is why I discussed it.
f.thorpe
CC BY-SA 3.0
2017-02-04T06:22:11.977Z
Actually CO2 would increase further (as a feedback mechanism) with temperature rise, as the solubility of CO2 in the oceans decreases with increasing temperature.
jamesqf
CC BY-SA 3.0
2017-02-04T15:07:39.337Z
@jamesqf yes, especially as the amount of CO2 in the oceans increases.  But nothing like the evaporation of water from the oceans.
f.thorpe
CC BY-SA 3.0
2017-02-04T03:42:06.827Z
2017-02-08T03:21:08.500Z
2017-02-08T03:21:08.500Z
f.thorpe
<p>There are processes operating on geological timescales that link CO<sub>2</sub> (specifically CO<sub>2</sub>, not GHGs) to changing temperature, namely chemical weathering (the chemical breakdown of in situ rock at/near the Earth surface). When aluminosilicate minerals react with carbonic acid (rainwater+CO<sub>2</sub> formed in the atmosphere), minerals dissolve, releasing their cations (e.g. Si<sub>2</sub><sup>+</sup>, Al<sub>2</sub><sup>+</sup>, Ca<sub>2</sub><sup>+</sup> etc) and soluble anions (e.g. bicarbonate 2CO<sub>3</sub><sup>-</sup>). These get washed to the ocean where calcium carbonate shelly organisms incorporate them into their shells, eventually die, and fall to the sea floor. This is a principle geological mechanism for removing CO<sub>2</sub> from the atmosphere and an important part of the carbon cycle.</p>

<p>The link to climate comes from its control on weathering processes. Generally, chemical weathering processes are more efficient when it is wetter and warmer. So at planetary scale, over long time periods, if it gets warmer, the amount of CO<sub>2</sub> in the atmosphere should decrease, which in turn reduces the greenhouse effect. </p>

<p>So from this basic physical understanding, your premise that increasing temperature can CAUSE increased CO<sub>2</sub> concentrations has little to no basis in relation to our understanding of the climate and carbon systems, quite the opposite in fact (temperature increases cause draw down of CO<sub>2</sub> due to chemical weathering). Alternatively, we have a known mechanism (the greenhouse effect) supported by empirical observations that CO<sub>2</sub> influences global temperature.</p>

CC BY-SA 3.0
2017-02-07T20:34:47.653Z
So increased temperature actually decreases co2 concentration?  If you exclude human interaction...
Acumen Simulator
CC BY-SA 3.0
2017-02-07T21:36:07.033Z
@user38826 on time scales on hundreds and thousands of years, increased temperature will cause this reaction to go faster. This is only one factor out of many controlling carbon dioxide, and it will not decrease concentration. Only slow it down a bit. Just like jumping from a 200 metre bridge instead of 220 metre bridge. You're going to die anyway.
Gimelist
CC BY-SA 3.0
2017-02-09T10:36:06.977Z
This is one of the principle mechanisms by which the Earth natural regulates CO2 in the atmosphere, but it is slow, changing over long timescales (millennia to millions of years). As Michael suggests, the recent increase from 280ppm to 400+ppm is an unprecedented change in natural history and it is highly unlikely that such natural processes will  adjust to keep pace.
mdh488
CC BY-SA 4.0
2017-02-07T19:56:34.977Z
2020-04-12T05:47:05.853Z
2020-04-12T05:47:05.853Z
mdh488
<blockquote>
  <p>The general consensus is that co2 increase causes temperature increase, why is the reverse situation not studied (if it is I could not find any studies).</p>
</blockquote>

<p>To be brutally honest, it's not studied because what you have posited is nonsense.</p>

<p>That said, the reverse situation has been studied in a broader context. $\mathrm{CO}_2$ is soluble in water, with the solubility decreasing with increasing temperature. This is one of the key reasons the exit from a glaciation is much more rapid than is the onset of a glaciation. Atmospheric $\mathrm{CO}_2$ levels plunge during a glaciation due to absorption by the oceans. Once conditions are right for a glaciation to end, the warming makes that dissolved $\mathrm{CO}_2$ come out of solution, which causes more warming, which causes even more dissolved $\mathrm{CO}_2$ come out of solution, ... This positive feedback loop makes the exit from a glaciation quite rapid.</p>

<p>The last time this happened was about 12000 years ago. It is not happening now. The oceans are currently absorbing most of the excess $\mathrm{CO}_2$ we humans are pumping into the atmosphere. </p>

CC BY-SA 3.0
2017-02-03T17:29:19.117Z
Thank you for your on topic answer.  Not grateful for the hostility, but good answer.
Acumen Simulator
CC BY-SA 3.0
2017-02-03T18:56:02.203Z
So does the ocean continue to absorb co2 because we are so far from the temperature equilibrium? or is the concentration difference in air and ocean driving this?
Acumen Simulator
CC BY-SA 3.0
2017-02-04T08:29:23.937Z
Oceans absorb about 25% of all the emissions, not "most of the excess CO2". Another quarter is absorbed by plants, and the rest remains in the atmosphere
fede_luppi
CC BY-SA 3.0
2017-02-04T08:41:28.340Z
Check out the Global Carbon Project http://www.globalcarbonproject.org/carbonbudget/16/highlights.htm
fede_luppi
CC BY-SA 3.0
2017-02-04T08:46:02.917Z
The amount absorbed by oceans is fairly constant year to year, whereas the proportion absorbed by land varies every year from 20-30%, because for example, years with strong droughts (El Niño) plants struggle and can grow too much, hence absorbing less CO2 from the atmosphere
fede_luppi
CC BY-SA 3.0
2017-02-06T17:05:34.943Z
@fede_luppi So we've got plants and the ocean logarithmically slowing down the rate of co2 accumulation, while co2 emissions exponentially increase.  Am I putting this together correctly?
Acumen Simulator
CC BY-SA 3.0
2017-02-03T16:50:57.620Z
2017-02-04T00:47:54.743Z
2017-02-04T00:47:54.743Z
David Hammen
<p>Warming climate conditions can cause carbon sinks, notably permafrost, to release carbon dioxide and that is in addition to the CO<sub>2</sub> from fossil burning that induced the warming and causes additional warming as well, <em>so yes, climate change causes CO<sub>2</sub> in the atmosphere to increase</em>. This is an example of a carbon feedback or <em><a href="https://royalsocietypublishing.org/doi/10.1098/rsta.2017.0263" rel="nofollow noreferrer">Earth system feedback</a>.</em> Others include methane emissions from wetlands, where warming causes release of a greenhouse gas that makes warming stronger. There is also feed back that offsets warming, such as warming shortening the time for methane to break down.</p>

<p>What we do not have is any evidence of naturally occurring global warming sufficient to cause all or even most of the raised CO<sub>2</sub> levels we are currently experiencing. Most of the CO<sub>2</sub> rise is attributable to fossil fuel burning and land use changes, with an additional component from all forms of carbon feedback.</p>

CC BY-SA 4.0
2020-04-11T22:35:05.573Z
2020-04-12T05:53:21.323Z
2020-04-12T05:53:21.323Z
Ken Fabian
<p>A rather late answer on this question, but here goes: The idea that &quot;global temperatures cause the increase of CO2.&quot; is fairly easily refuted.  The usual line of reasoning is that the solubility of CO2 in water decreases as temperature increases, so the rise in global temperature implies that the oceans will have released some of the dissolved CO2 that it contains.  The premise is correct, but the conclusion is a non sequitur as it ignores the fact that the solubility of CO2 in water also depends on the difference in the concentrations of CO2 between the surface ocean and the atmosphere.  As we have released CO2 from fossil fuels into the atmosphere, the partial pressure of CO2 in the atmosphere has risen, and so the oceans have been taking up more CO2, not less.</p>
<blockquote>
<p>How do we know this is true? .  The argument is easily refuted by the
observation that the rate at which atmospheric CO2 levels are rising
is less than the rate at which we are releasing CO2 into the
atmosphere from fossil fuel use, which implies that the natural
environment must be a net carbon sink, taking in more carbon each year
than it emits.</p>
<p>More formally, let Ea represent annual carbon emissions from
anthropogenic sources (fossil fuel use and land use change), En
represent the carbon emissions from all natural sources (the oceans,
soil respiration, volcanos etc.) and Un represent the uptake of carbon
by all natural carbon sinks (oceans, photosynthesis, etc.), Ua would
be the uptake of carbon due to anthropogenic activities, but this is
essentially zero, so we can safely exclude it from the analysis.  Then
assuming that the carbon cycle obeys the principle of conservation of
mass (any carbon emitted into the atmosphere that is not taken up by
natural sinks remains in the atmosphere), the annual change in
atmospheric CO2 is given by:</p>
<p>C' = Ea + En - Un</p>
<p>This can be rearranged to give an estimate of the difference between
annual emissions from all natural sources and annual natural uptake by
all natural sinks.</p>
<p>En - Un = C' - Ea</p>
<p>We have accurate, reliable data for the growth of atmospheric CO2 and
for anthropogenic emissions (for details, see Cawley, 2011). Both of
these are displayed below, along with an estimate of the net natural
carbon flux En - Un.  The fact that the net natural flux is negative
clearly shows that natural uptake has exceeded natural emissions every
year for the last fifty years at least, and hence has been opposing,
rather than causing the observed rise in atmospheric CO2.</p>
<p><img src="https://i.sstatic.net/fZfsT.png" alt="enter image description here" /></p>
</blockquote>
<p><a href="http://www.skepticalscience.com/print.php?n=1259" rel="nofollow noreferrer">source</a></p>
<p>Some time back, I wrote a journal paper refuting a related climate myth, which outlines some of the evidence that the rise in atmospheric CO2 is anthropogenic, and is not a natural phenomenon.</p>
<p><a href="http://pubs.acs.org/doi/abs/10.1021/ef200914u" rel="nofollow noreferrer">Gavin C. Cawley, &quot;On the Atmospheric Residence Time of Anthropogenically Sourced Carbon Dioxide&quot;, Energy &amp; Fuels, volume 25, issue 11, pages 5503–5513, 2011.</a></p>
<p>This answer is adapted from my <a href="https://skeptics.stackexchange.com/questions/3435/does-co%E2%82%82-cause-global-warming/17707#17707">answer</a> to a similar question on the Skeptics SE.</p>
<p>&quot;The general consensus is that CO2 increase causes temperature increase, why is the reverse situation not studied (if it is I could not find any studies).&quot;</p>
<p>There are actually plenty of studies of this, it is just that the issues were largely resolved over fifty years ago.  The main mechanism is the temperature dependent solubility of CO2 in the oceans, there is an excellent textbook on this by <a href="https://www.elsevier.com/books/co2-in-seawater-equilibrium-kinetics-isotopes/zeebe/978-0-444-50946-8?countrycode=GB&amp;format=print" rel="nofollow noreferrer">Zeebe and Wolf-Gladrow</a>.  There is also an effect of temperature on the biosphere, which is a bit more difficult to pin down, but see the references in the relevant section of the IPCC report.  The research is there, but we have known for a <em><strong>long</strong></em> time that the rise in CO2 is not the result of natural processes, so there will be no papers explicitly making this claim (at least from people who understand the basics) because there has been no new evidence to support it.</p>

CC BY-SA 4.0
2021-07-28T09:27:22.407Z
2021-07-28T09:27:22.407Z
Dikran Marsupial
<p>One reason is that we know exactly where the current increased CO<sub>2</sub> comes from.  That is, we know from economic data how much petroleum, natural gas, &amp; coal is extracted and burned.  From that simple chemistry lets us compute the amount of CO<sub>2</sub> produced, and we find that (after allowing for factors such as e.g. some being absorbed by the oceans) that the amount created by burning fossil fuels matches the observed increase.</p>

<p>(There are also more subtle measurements, such as isotope ratios, which I'm not qualified to expound in any detail...)</p>

<p>Another reason is that for warming to have caused the observed increase in CO<sub>2</sub>, there'd have to be some other cause for the warming.  No such cause has been found.  Suggested causes such as variation in solar output have been ruled out by measurements.</p>

CC BY-SA 3.0
2017-02-03T19:14:52.637Z
So you're saying since we know what is causing the co2 increase, we can rule out other causes?
Acumen Simulator
CC BY-SA 3.0
2017-02-03T21:46:49.330Z
CO2 has an isotopic signature: "...fossil fuels do not contain 14C. By studying how the concentration of 14C has changed in the atmosphere, scientists have determined that the atmospheric increase in carbon dioxide is dominated by fossil fuel emissions." https://www.esrl.noaa.gov/gmd/outreach/isotopes/
jeffronicus
CC BY-SA 3.0
2017-02-03T23:05:12.377Z
@user38826: Simplistically, yes.  We know where the CO2 comes from, we know from theoretical calculations about how much warming it should cause, and we find that that's just about how much warming is actually happening.  That does seem to rule out other causes as major factors, doesn't it?  Then add the fact that all the other possible causes we can think of are not actually happening...
jamesqf
CC BY-SA 3.0
2017-02-03T23:13:22.203Z
It doesnt rule out other factors as the dominant cause of global warming.... so many factors are interdependent.  It DOES answer my question though, and makes perfect sense.
Acumen Simulator
CC BY-SA 3.0
2017-02-04T06:18:01.860Z
@user38826: How can "other factors" possibly be the dominant cause, if those other factors aren't present?  Also, we'd need two mysterious "other factors": one to produce the observed warming, another to remove the warming that the increased CO2 should have produced - and maybe a third to explain why the observed warming produced by the mysterious "other factor" is exactly what should be produced by CO2 from fossil fuels.  You might read up on Occam's Razor.
jamesqf
CC BY-SA 3.0
2017-02-04T08:29:36.647Z
@jamesqf There are several factors that can cause climate change... since climate has changed repeatedly before human intervention.  Maybe co2 is dominant, maybe not... that is out of the scope on this question though.  Nothing against the validity of your remarks... I'm just trying to understand all the relationships.  Great info btw.
Acumen Simulator
CC BY-SA 3.0
2017-02-04T19:14:38.040Z
@user38826: Yes, and we know what those factors are.  For instance, the Ice Ages are driven by orbital variations - https://en.wikipedia.org/wiki/Milankovitch_cycles - but those aren't in a warming phase now.  Increased solar output could cause warming, but the sun hasn't increased its output.  Massive volcanic eruptions could emit lots of CO2 and cause warming (if SO2-driven cooling didn't dominate), but I think we'd have noticed those :-)  But we DO know CO2 has increased due to fossil fuel burning.
jamesqf
CC BY-SA 4.0
2020-04-11T03:40:14.247Z
@a_donda: Sure.  Ever bother to look at the time scale of plate tectonics (millions of years) vs that of the ice ages (tens of thousands of years)?  Plate tectonics & continental arrangement might well determine whether ice age cycles can exist, but when they do, they are driven by the Milankovitch cycles.  FWIW, we are not in an ice age at the moment: the last one ended about 10-12 thousand years ago.
jamesqf
CC BY-SA 4.0
2020-04-12T05:09:13.103Z
@a_donda: You know perfectly well what I meant. You are just playing games with words, doing a bit of Humpty-Dumpty “When I use a word it means just what I choose it to mean — neither more nor less”.  Which is fine if you're off on a visit to Wonderland, not so good if you intend to communicate with other people.
jamesqf
CC BY-SA 4.0
2020-04-12T13:19:55.727Z
@jamesqf I would have commented on ice ages as well, we are currently in an ice age, ice age has a defined scientific meaning. It is when a significant portion of continental crust is covered in ice sheets, thanks to Greenland and Antarctica the current earth qualifies. glacial periods are effected by M. cycles ice ages are not.
John
CC BY-SA 4.0
2020-04-13T16:53:49.683Z
@John: Again, you are just playing games with words, choosing to use the term "ice age" in a way that is different from its generally accepted meaning.
jamesqf
CC BY-SA 4.0
2020-04-13T17:36:24.740Z
@jamesqf That depends on what you mean by "generally accepted".  In the scientific context, it is "generally accepted" that we are in an ice age. Given that this is an earth sciences site, I think it makes perfect sense that people are correcting you.
JMac
CC BY-SA 4.0
2024-10-26T02:24:36.397Z
@jamesqf Occam's razor is just a tongue in cheek, or, at worst, a fatal fallacy. Using the same argument physicists are out of their minds to suggest dark matters when the gravity doesn't add up; I'll say it's a bit of both.
Simon Eatwell
CC BY-SA 4.0
2017-02-03T18:58:03.550Z
2020-04-12T05:43:24.303Z
2020-04-12T05:43:24.303Z
jamesqf
<p>My main question is how do we know that increase in global temperature does not CAUSE an increase in CO<sub>2</sub> concentration?</p>

<p>I am trying to develop my mental model of what's going on for the climate change issue.  There is definitely a correlation between global temperature and CO<sub>2</sub> concentration, this is not disputed.  The general consensus is that CO<sub>2</sub> increase causes temperature increase, why is the reverse situation not studied (if it is I could not find any studies).</p>

<p>This thought comes from the statement I've seen that water vapor concentration is more correlated to global temperature  than CO<sub>2</sub>, but this is intuitive since warmer air holds more water vapor than colder air.  Does the same intuition hold for CO<sub>2</sub>?</p>

<p>I am not an expert on the subject; so I understand that I may be way off base with my reasoning.  I also openly accept  edits to my question if it is not structured or presented properly.</p>

CC BY-SA 3.0
2017-11-15T15:36:16.110Z
To be fair: Climate change *does* cause changes in greenhouse gas concentration. Think methane being freed from the thawing arctic tundra, or decreasing CO2-solubility in warmer ocean water. Unfortunately, that doesn't stop that gas from contributing even more to climate change ...
Hagen von Eitzen
CC BY-SA 4.0
2019-05-08T23:17:50.637Z
"There have been predictions, and some evidence, that global warming might cause loss of carbon from terrestrial ecosystems, leading to an increase of atmospheric CO2 levels." https://en.wikipedia.org/wiki/Climate_change_feedback#Positive
Lehs
<climate-change><temperature><co2>
Does climate change cause increase in CO2?
Acumen Simulator
# Does climate change cause increase in CO2?

(Asked by: username_0 on 2017-02-03)

My main question is how do we know that increase in global temperature does not CAUSE an increase in CO2 concentration?

I am trying to develop my mental model of what's going on for the climate change issue. There is definitely a correlation between global temperature and CO2 concentration, this is not disputed. The general consensus is that CO2 increase causes temperature increase, why is the reverse situation not studied (if it is I could not find any studies).

This thought comes from the statement I've seen that water vapor concentration is more correlated to global temperature than CO2, but this is intuitive since warmer air holds more water vapor than colder air. Does the same intuition hold for CO2?

I am not an expert on the subject; so I understand that I may be way off base with my reasoning. I also openly accept edits to my question if it is not structured or presented properly.

**Tags:** climate-change, temperature, co2

> **Comments:**
> **username_1**: To be fair: Climate change *does* cause changes in greenhouse gas concentration. Think methane being freed from the thawing arctic tundra, or decreasing CO2-solubility in warmer ocean water. Unfortunately, that doesn't stop that gas from contributing even more to climate change ...  
> **username_2**: "There have been predictions, and some evidence, that global warming might cause loss of carbon from terrestrial ecosystems, leading to an increase of atmospheric CO2 levels." https://en.wikipedia.org/wiki/Climate_change_feedback#Positive  

---

## 6 answers

### Answer by username_5 on 2017-02-03. Score: 12 | Accepted answer

One reason is that we know exactly where the current increased CO2 comes from. That is, we know from economic data how much petroleum, natural gas, & coal is extracted and burned. From that simple chemistry lets us compute the amount of CO2 produced, and we find that (after allowing for factors such as e.g. some being absorbed by the oceans) that the amount created by burning fossil fuels matches the observed increase.

(There are also more subtle measurements, such as isotope ratios, which I'm not qualified to expound in any detail...)

Another reason is that for warming to have caused the observed increase in CO2, there'd have to be some other cause for the warming. No such cause has been found. Suggested causes such as variation in solar output have been ruled out by measurements.

> **Comments:**
> **username_0**: So you're saying since we know what is causing the co2 increase, we can rule out other causes?  
> **username_11**: CO2 has an isotopic signature: "...fossil fuels do not contain 14C. By studying how the concentration of 14C has changed in the atmosphere, scientists have determined that the atmospheric increase in carbon dioxide is dominated by fossil fuel emissions." https://www.esrl.noaa.gov/gmd/outreach/isotopes/  
> **username_5**: @user38826: Simplistically, yes.  We know where the CO2 comes from, we know from theoretical calculations about how much warming it should cause, and we find that that's just about how much warming is actually happening.  That does seem to rule out other causes as major factors, doesn't it?  Then add the fact that all the other possible causes we can think of are not actually happening...  
> **username_0**: It doesnt rule out other factors as the dominant cause of global warming.... so many factors are interdependent.  It DOES answer my question though, and makes perfect sense.  
> **username_5**: @user38826: How can "other factors" possibly be the dominant cause, if those other factors aren't present?  Also, we'd need two mysterious "other factors": one to produce the observed warming, another to remove the warming that the increased CO2 should have produced - and maybe a third to explain why the observed warming produced by the mysterious "other factor" is exactly what should be produced by CO2 from fossil fuels.  You might read up on Occam's Razor.  
> **username_0**: @username_5 There are several factors that can cause climate change... since climate has changed repeatedly before human intervention.  Maybe co2 is dominant, maybe not... that is out of the scope on this question though.  Nothing against the validity of your remarks... I'm just trying to understand all the relationships.  Great info btw.  
> **username_5**: @user38826: Yes, and we know what those factors are.  For instance, the Ice Ages are driven by orbital variations - https://en.wikipedia.org/wiki/Milankovitch_cycles - but those aren't in a warming phase now.  Increased solar output could cause warming, but the sun hasn't increased its output.  Massive volcanic eruptions could emit lots of CO2 and cause warming (if SO2-driven cooling didn't dominate), but I think we'd have noticed those :-)  But we DO know CO2 has increased due to fossil fuel burning.  
> **username_5**: @a_donda: Sure.  Ever bother to look at the time scale of plate tectonics (millions of years) vs that of the ice ages (tens of thousands of years)?  Plate tectonics & continental arrangement might well determine whether ice age cycles can exist, but when they do, they are driven by the Milankovitch cycles.  FWIW, we are not in an ice age at the moment: the last one ended about 10-12 thousand years ago.  
> **username_5**: @a_donda: You know perfectly well what I meant. You are just playing games with words, doing a bit of Humpty-Dumpty “When I use a word it means just what I choose it to mean — neither more nor less”.  Which is fine if you're off on a visit to Wonderland, not so good if you intend to communicate with other people.  
> **username_12**: @username_5 I would have commented on ice ages as well, we are currently in an ice age, ice age has a defined scientific meaning. It is when a significant portion of continental crust is covered in ice sheets, thanks to Greenland and Antarctica the current earth qualifies. glacial periods are effected by M. cycles ice ages are not.  
> **username_5**: @username_12: Again, you are just playing games with words, choosing to use the term "ice age" in a way that is different from its generally accepted meaning.  
> **username_13**: @username_5 That depends on what you mean by "generally accepted".  In the scientific context, it is "generally accepted" that we are in an ice age. Given that this is an earth sciences site, I think it makes perfect sense that people are correcting you.  
> **username_14**: @username_5 Occam's razor is just a tongue in cheek, or, at worst, a fatal fallacy. Using the same argument physicists are out of their minds to suggest dark matters when the gravity doesn't add up; I'll say it's a bit of both.  

---

### Answer by username_3 on 2017-02-04. Score: 6

Your comparison to water vapor is a bad one.

The amount of water vapor in the atmosphere does increase with atmospheric temperature. This is because more evaporation occurs and can be held as vapor longer, thus offsetting the equilibrium of water vapor. Cold air will cause more water vapor to condense back to liquid. This process of water cycling occurs on the order of hours/days.

This is in stark contrast to carbon dioxide, which does not condense out of the atmosphere when it cools. Nor does carbon dioxide evaporate from the surface of the earth. Instead, it is a byproduct of respiration and combustion. Carbon dioxide stays in the atmosphere for 100s of years before it gets deposited or chemically converted. Furthermore, carbon dioxide becomes part of geological processes in the carbon cycle that takes 1000s of years, not days.

So, to summarize, carbon dioxide does not directly increase in the atmosphere due to temperature rise, because it is not constantly evaporating from the Earth's surface and condensing in the atmosphere. Carbon dioxide does not condense at normal atmospheric temperature... it won't condense until it gets as cold as -78.5 degrees C, which does not occur on the surface of the Earth [in this climate regime].

It should be noted that carbon dioxide will indirectly increase in the atmosphere with temperature rise. This is because of feedback mechanisms. For instance, with increasing temperature, trees will be more dry on average and will thus combust more easily. More wildfires are expected as temperatures rise, and with them come more carbon dioxide emitted during the fire. There is also the possibility that increases in global temperature will cause feedbacks in the geologic cycle that lead to more volcanic activity, which is another source of carbon dioxide emissions. And, as Michael points out, the methane released when permafrost melts will eventually oxidize with the hydroxyl radical into carbon dioxide and water vapor.

> **Comments:**
> **username_4**: I'd like to add that increasing temperatures cause melting of permafrost, which allows release of trapped methane. This methane then oxidises to carbon dioxide in the atmosphere.  
> **username_3**: Yes Good Point!  
> **username_0**: I never believed co2 behaved as h2o, that's just where the idea of the confusion of inverse came from.  Good information on it not directly being caused by temperature rise.  
> **username_3**: You used water as your comparison point, which is why I discussed it.  
> **username_5**: Actually CO2 would increase further (as a feedback mechanism) with temperature rise, as the solubility of CO2 in the oceans decreases with increasing temperature.  
> **username_3**: @username_5 yes, especially as the amount of CO2 in the oceans increases.  But nothing like the evaporation of water from the oceans.  

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### Answer by username_6 on 2017-02-07. Score: 3

There are processes operating on geological timescales that link CO2 (specifically CO2, not GHGs) to changing temperature, namely chemical weathering (the chemical breakdown of in situ rock at/near the Earth surface). When aluminosilicate minerals react with carbonic acid (rainwater+CO2 formed in the atmosphere), minerals dissolve, releasing their cations (e.g. Si2+, Al2+, Ca2+ etc) and soluble anions (e.g. bicarbonate 2CO3-). These get washed to the ocean where calcium carbonate shelly organisms incorporate them into their shells, eventually die, and fall to the sea floor. This is a principle geological mechanism for removing CO2 from the atmosphere and an important part of the carbon cycle.

The link to climate comes from its control on weathering processes. Generally, chemical weathering processes are more efficient when it is wetter and warmer. So at planetary scale, over long time periods, if it gets warmer, the amount of CO2 in the atmosphere should decrease, which in turn reduces the greenhouse effect.

So from this basic physical understanding, your premise that increasing temperature can CAUSE increased CO2 concentrations has little to no basis in relation to our understanding of the climate and carbon systems, quite the opposite in fact (temperature increases cause draw down of CO2 due to chemical weathering). Alternatively, we have a known mechanism (the greenhouse effect) supported by empirical observations that CO2 influences global temperature.

> **Comments:**
> **username_0**: So increased temperature actually decreases co2 concentration?  If you exclude human interaction...  
> **username_4**: @user38826 on time scales on hundreds and thousands of years, increased temperature will cause this reaction to go faster. This is only one factor out of many controlling carbon dioxide, and it will not decrease concentration. Only slow it down a bit. Just like jumping from a 200 metre bridge instead of 220 metre bridge. You're going to die anyway.  
> **username_6**: This is one of the principle mechanisms by which the Earth natural regulates CO2 in the atmosphere, but it is slow, changing over long timescales (millennia to millions of years). As Michael suggests, the recent increase from 280ppm to 400+ppm is an unprecedented change in natural history and it is highly unlikely that such natural processes will  adjust to keep pace.  

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### Answer by username_7 on 2017-02-03. Score: 3

> The general consensus is that co2 increase causes temperature increase, why is the reverse situation not studied (if it is I could not find any studies).

To be brutally honest, it's not studied because what you have posited is nonsense.

That said, the reverse situation has been studied in a broader context. $\mathrm{CO}\_2$ is soluble in water, with the solubility decreasing with increasing temperature. This is one of the key reasons the exit from a glaciation is much more rapid than is the onset of a glaciation. Atmospheric $\mathrm{CO}\_2$ levels plunge during a glaciation due to absorption by the oceans. Once conditions are right for a glaciation to end, the warming makes that dissolved $\mathrm{CO}\_2$ come out of solution, which causes more warming, which causes even more dissolved $\mathrm{CO}\_2$ come out of solution, ... This positive feedback loop makes the exit from a glaciation quite rapid.

The last time this happened was about 12000 years ago. It is not happening now. The oceans are currently absorbing most of the excess $\mathrm{CO}\_2$ we humans are pumping into the atmosphere.

> **Comments:**
> **username_0**: Thank you for your on topic answer.  Not grateful for the hostility, but good answer.  
> **username_0**: So does the ocean continue to absorb co2 because we are so far from the temperature equilibrium? or is the concentration difference in air and ocean driving this?  
> **username_8**: Oceans absorb about 25% of all the emissions, not "most of the excess CO2". Another quarter is absorbed by plants, and the rest remains in the atmosphere  
> **username_8**: Check out the Global Carbon Project http://www.globalcarbonproject.org/carbonbudget/16/highlights.htm  
> **username_8**: The amount absorbed by oceans is fairly constant year to year, whereas the proportion absorbed by land varies every year from 20-30%, because for example, years with strong droughts (El Niño) plants struggle and can grow too much, hence absorbing less CO2 from the atmosphere  
> **username_0**: @username_8 So we've got plants and the ocean logarithmically slowing down the rate of co2 accumulation, while co2 emissions exponentially increase.  Am I putting this together correctly?  

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### Answer by username_9 on 2020-04-11. Score: 1

Warming climate conditions can cause carbon sinks, notably permafrost, to release carbon dioxide and that is in addition to the CO2 from fossil burning that induced the warming and causes additional warming as well, *so yes, climate change causes CO2 in the atmosphere to increase*. This is an example of a carbon feedback or *[Earth system feedback](https://royalsocietypublishing.org/doi/10.1098/rsta.2017.0263).* Others include methane emissions from wetlands, where warming causes release of a greenhouse gas that makes warming stronger. There is also feed back that offsets warming, such as warming shortening the time for methane to break down.

What we do not have is any evidence of naturally occurring global warming sufficient to cause all or even most of the raised CO2 levels we are currently experiencing. Most of the CO2 rise is attributable to fossil fuel burning and land use changes, with an additional component from all forms of carbon feedback.


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### Answer by username_10 on 2021-07-28. Score: 1

A rather late answer on this question, but here goes: The idea that "global temperatures cause the increase of CO2." is fairly easily refuted. The usual line of reasoning is that the solubility of CO2 in water decreases as temperature increases, so the rise in global temperature implies that the oceans will have released some of the dissolved CO2 that it contains. The premise is correct, but the conclusion is a non sequitur as it ignores the fact that the solubility of CO2 in water also depends on the difference in the concentrations of CO2 between the surface ocean and the atmosphere. As we have released CO2 from fossil fuels into the atmosphere, the partial pressure of CO2 in the atmosphere has risen, and so the oceans have been taking up more CO2, not less.

> How do we know this is true? . The argument is easily refuted by the
> observation that the rate at which atmospheric CO2 levels are rising
> is less than the rate at which we are releasing CO2 into the
> atmosphere from fossil fuel use, which implies that the natural
> environment must be a net carbon sink, taking in more carbon each year
> than it emits.
>
> More formally, let Ea represent annual carbon emissions from
> anthropogenic sources (fossil fuel use and land use change), En
> represent the carbon emissions from all natural sources (the oceans,
> soil respiration, volcanos etc.) and Un represent the uptake of carbon
> by all natural carbon sinks (oceans, photosynthesis, etc.), Ua would
> be the uptake of carbon due to anthropogenic activities, but this is
> essentially zero, so we can safely exclude it from the analysis. Then
> assuming that the carbon cycle obeys the principle of conservation of
> mass (any carbon emitted into the atmosphere that is not taken up by
> natural sinks remains in the atmosphere), the annual change in
> atmospheric CO2 is given by:
>
> C' = Ea + En - Un
>
> This can be rearranged to give an estimate of the difference between
> annual emissions from all natural sources and annual natural uptake by
> all natural sinks.
>
> En - Un = C' - Ea
>
> We have accurate, reliable data for the growth of atmospheric CO2 and
> for anthropogenic emissions (for details, see Cawley, 2011). Both of
> these are displayed below, along with an estimate of the net natural
> carbon flux En - Un. The fact that the net natural flux is negative
> clearly shows that natural uptake has exceeded natural emissions every
> year for the last fifty years at least, and hence has been opposing,
> rather than causing the observed rise in atmospheric CO2.
>
> ![enter image description here](https://i.sstatic.net/fZfsT.png)

[source](http://www.skepticalscience.com/print.php?n=1259)

Some time back, I wrote a journal paper refuting a related climate myth, which outlines some of the evidence that the rise in atmospheric CO2 is anthropogenic, and is not a natural phenomenon.

[Gavin C. Cawley, "On the Atmospheric Residence Time of Anthropogenically Sourced Carbon Dioxide", Energy & Fuels, volume 25, issue 11, pages 5503–5513, 2011.](http://pubs.acs.org/doi/abs/10.1021/ef200914u)

This answer is adapted from my [answer](https://skeptics.stackexchange.com/questions/3435/does-co%E2%82%82-cause-global-warming/17707#17707) to a similar question on the Skeptics SE.

"The general consensus is that CO2 increase causes temperature increase, why is the reverse situation not studied (if it is I could not find any studies)."

There are actually plenty of studies of this, it is just that the issues were largely resolved over fifty years ago. The main mechanism is the temperature dependent solubility of CO2 in the oceans, there is an excellent textbook on this by [Zeebe and Wolf-Gladrow](https://www.elsevier.com/books/co2-in-seawater-equilibrium-kinetics-isotopes/zeebe/978-0-444-50946-8?countrycode=GB&format=print). There is also an effect of temperature on the biosphere, which is a bit more difficult to pin down, but see the references in the relevant section of the IPCC report. The research is there, but we have known for a ***long*** time that the rise in CO2 is not the result of natural processes, so there will be no papers explicitly making this claim (at least from people who understand the basics) because there has been no new evidence to support it.


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