<blockquote>
  <p>The freezing point of carbon dioxide is -78.5C.</p>
</blockquote>

<p>The temperature at which carbon dioxide sublimates is not a fixed value. It instead is a function of the partial pressure of carbon dioxide. That value of -78.5° C is the temperature at which CO<sub>2</sub> sublimates given a partial CO<sub>2</sub> pressure of one atmosphere. The temperature needed to have CO<sub>2</sub> sublimate given a partial pressure of 40 pascals is much lower than that.</p>

<p>The <a href="https://en.wikipedia.org/wiki/Clausius%E2%80%93Clapeyron_relation" rel="noreferrer">Clausius-Clayperon relation</a> can be used to estimate the temperature at which a substance will sublimate for a given partial pressure. Using the parameter values for CO<sub>2</sub> from James et al., I get a temperature of <a href="https://www.wolframalpha.com/input/?i=3182.48%2F%2823.3494+-+ln%280.4%29%29" rel="noreferrer">131 kelvins</a> (-142° C) for the sublimation point of CO<sub>2</sub> at a partial pressure of 40 pascals or 0.4 millibar. Using a slightly different parameterization, Agee et al. calculate that a temperature of 133 kelvins (-140° C) is needed to make CO<sub>2</sub> sublimate from our atmosphere.</p>

<blockquote>
  <p>Are Ice Ages Affected by the Freezing Out of CO2 in Antarctica?</p>
</blockquote>

<p>Carbon dioxide levels are very low during glaciations (colloquially, ice ages, but we're in an ice age right now). Using the parameterization from James et al. yields a temperature of 127 K (-146° C) as the sublimation temperature for a partial pressure of 18 Pa (0.18 millibar), or 180 ppm CO<sub>2</sub>. The Earth cannot get that cold, so no, ice ages are not affected by the freezing out of CO<sub>2</sub> in Antarctica.</p>

<p><br></p>

<p>References:</p>

<p>Agee, Ernest, Andrea Orton, and John Rogers. "CO2 snow deposition in Antarctica to curtail anthropogenic global warming." Journal of Applied Meteorology and Climatology 52.2 (2013): 281-288.</p>

<p>James, Philip B., Hugh H. Kieffer, and David A. Paige. "The seasonal cycle of carbon dioxide on Mars." Mars (1992): 934-968.</p>

CC BY-SA 4.0
2020-01-07T15:43:14.097Z
How can we be in an ice age right now when people are always complaining about the heat?
Michael Walsby
CC BY-SA 4.0
2020-01-07T16:09:08.887Z
@MichaelWalsby - A pair of massive ice sheets currently cover almost all of Antarctica. Another ice sheet currently covers almost all of Greenland. That pretty much covers the technical definition of what qualifies as an "ice age". The presence of large ice sheets distinguishes the last ~34 million years, plus two other time periods (the late Cenozoic and the late Orderovician), from the majority of the time since the start of the Cambrian where there were **no** ice sheets, period.
David Hammen
CC BY-SA 4.0
2020-01-07T17:52:50.827Z
@ebv - The "Ordervician" was a DYAC. It should have been Ordovician, as you noted. My use of "late Cenozoic" when I should have written "late Paleozoic" -- that's something I can't blame on autocorrect.
David Hammen
CC BY-SA 4.0
2020-01-07T20:32:10.720Z
A number of articles on the internet say that CO2 does freeze in Antarctica at temperatures below -78.5C, but as it sublimates at about the same temperature there is no net build-up. Things may have been different in much colder times.. Buried under water ice in a snowball Earth, when the ice reached a temperature  higher than the freezing point of CO2, it would become a gas under pressure and probably find a way out, depending on the thickness of the water ice above.
Michael Walsby
CC BY-SA 4.0
2020-01-07T23:49:18.120Z
@MichaelWalsby - A number of articles on the internet say the Earth is flat.
David Hammen
CC BY-SA 4.0
2020-01-07T13:46:00.120Z
2020-01-07T14:11:16.117Z
2020-01-07T14:11:16.117Z
David Hammen
<p>During an ice age little CO2 will reach the arctic,it will be absorbed by sea water in all the oceans,This will create a positive feedback,lower CO2 level in the atmosphere will make it even colder so the liquid water will absorb even more CO2.</p>

<p>Cold water can hold large amounts of dissolved gasses,When the ice age ends large amounts of CO2 will be released creating a positive feedback loop further increasing the heating.</p>

<p>One of the problems with the climate change we see now is that the oceans are getting hotter,This will lower the waters capacity to absorb CO2 from the atmosphere.</p>

<p>At some point if the heating goes on the ocean water might start releasing more CO2 than it absorbs.</p>

CC BY-SA 4.0
2020-01-07T07:37:31.930Z
It would be interesting to know how cold the polar regions can get in a very hard ice age. It must be a lot colder than they are now.
Michael Walsby
CC BY-SA 4.0
2020-01-07T07:41:23.313Z
@MichaelWalsby this i do not know:) maybe somebody else know this.
trond hansen
CC BY-SA 4.0
2020-01-07T07:29:24.410Z
2020-01-08T13:07:23.510Z
2020-01-08T13:07:23.510Z
trond hansen
<p>The freezing point of carbon dioxide is -78.5 <span class="math-container">$\small\mathsf{^o}$</span>C. Occasionally this low is exceeded in Antarctica, and small quantities of CO<sub>2</sub> are frozen out, but are returned soon after to the atmosphere. Is it possible that during an ice age more substantial quantities of CO<sub>2</sub> are frozen out, and could it be enough to affect the climate and worsen the ice age? Could this phenomenon also occur in Siberia?</p>

CC BY-SA 4.0
2020-01-07T13:56:41.990Z
Re *Occasionally this low is exceeded in Antarctica, and small quantities of CO2 are frozen out, but are returned soon after to the atmosphere.* That is incorrect, and it is based on the value of -78.5° C. The correct value is about -140° C, and that's for current amount of carbon dioxide in the atmosphere. Carbon dioxide levels are considerably less than current during glaciations ("ice ages"), which reduces the temperature even further.
David Hammen
CC BY-SA 4.0
2020-01-07T14:37:25.857Z
As a point of reference, people have been continuously occupying both the South Pole and the Vostok Station for decades, and both sites have regularly seen the temperature drop below -78.5° C for extended periods of time. Yet neither site has reported any carbon dioxide frost. That temperature (-78.5° C) is not nearly cold enough to create carbon dioxide frost given earthly concentrations of carbon dioxide in the atmosphere.
David Hammen
CC BY-SA 4.0
2020-01-07T15:38:59.233Z
At present time, not enough CO2 is precipitated to produce a visible frost. But I was enquiring about what might have happened when conditions were much colder.
Michael Walsby
CC BY-SA 4.0
2020-01-07T16:19:20.383Z
@MichaelWalsby - At present, zero $\text{CO}_2$ precipitates to form frost. A temperature of -100° C (the current theoretical minimum) is not nearly cold enough. Even a temperature of -120° C (a very generous estimate of the coldest temperatures during the last glacial maximum) is not nearly cold enough.
David Hammen
CC BY-SA 4.0
2020-01-07T16:24:25.720Z
You are far from the only one to have wondered whether carbon dioxide naturally precipitates during the very long and very cold Antarctic winter based on the widely reported value of -78.5° C. The conditions under which that widely reported value are technically correct (the conditions under which dry ice is created) are irrelevant with regard to the Earth's climate for the last 500+ million years.
David Hammen
CC BY-SA 4.0
2020-01-07T18:00:29.887Z
@ebv - I'm not sure about the Cryogenian, and times before that. CO2 levels were far higher than they were in the last 500+ million years. Those high CO2 levels coupled with reduced solar output might well have resulted in CO2 ice sheets on early Earth. I **know** that I've seen at least one article in a journal paper that made that hypothesis, but I can't find it.
David Hammen
<co2><climatology><ice-age><antarctica>
Are Ice Ages Affected by the Freezing Out of CO2 in Antarctica?
Michael Walsby
# Are Ice Ages Affected by the Freezing Out of CO2 in Antarctica?

(Asked by: username_0 on 2020-01-06)

The freezing point of carbon dioxide is -78.5 $\small\mathsf{^o}$C. Occasionally this low is exceeded in Antarctica, and small quantities of CO2 are frozen out, but are returned soon after to the atmosphere. Is it possible that during an ice age more substantial quantities of CO2 are frozen out, and could it be enough to affect the climate and worsen the ice age? Could this phenomenon also occur in Siberia?

**Tags:** co2, climatology, ice-age, antarctica

> **Comments:**
> **username_1**: Re *Occasionally this low is exceeded in Antarctica, and small quantities of CO2 are frozen out, but are returned soon after to the atmosphere.* That is incorrect, and it is based on the value of -78.5° C. The correct value is about -140° C, and that's for current amount of carbon dioxide in the atmosphere. Carbon dioxide levels are considerably less than current during glaciations ("ice ages"), which reduces the temperature even further.  
> **username_1**: As a point of reference, people have been continuously occupying both the South Pole and the Vostok Station for decades, and both sites have regularly seen the temperature drop below -78.5° C for extended periods of time. Yet neither site has reported any carbon dioxide frost. That temperature (-78.5° C) is not nearly cold enough to create carbon dioxide frost given earthly concentrations of carbon dioxide in the atmosphere.  
> **username_0**: At present time, not enough CO2 is precipitated to produce a visible frost. But I was enquiring about what might have happened when conditions were much colder.  
> **username_1**: @username_0 - At present, zero $\text{CO}_2$ precipitates to form frost. A temperature of -100° C (the current theoretical minimum) is not nearly cold enough. Even a temperature of -120° C (a very generous estimate of the coldest temperatures during the last glacial maximum) is not nearly cold enough.  
> **username_1**: You are far from the only one to have wondered whether carbon dioxide naturally precipitates during the very long and very cold Antarctic winter based on the widely reported value of -78.5° C. The conditions under which that widely reported value are technically correct (the conditions under which dry ice is created) are irrelevant with regard to the Earth's climate for the last 500+ million years.  
> **username_1**: @ebv - I'm not sure about the Cryogenian, and times before that. CO2 levels were far higher than they were in the last 500+ million years. Those high CO2 levels coupled with reduced solar output might well have resulted in CO2 ice sheets on early Earth. I **know** that I've seen at least one article in a journal paper that made that hypothesis, but I can't find it.  

---

## 2 answers

### Answer by username_1 on 2020-01-07. Score: 9

> The freezing point of carbon dioxide is -78.5C.

The temperature at which carbon dioxide sublimates is not a fixed value. It instead is a function of the partial pressure of carbon dioxide. That value of -78.5° C is the temperature at which CO2 sublimates given a partial CO2 pressure of one atmosphere. The temperature needed to have CO2 sublimate given a partial pressure of 40 pascals is much lower than that.

The [Clausius-Clayperon relation](https://en.wikipedia.org/wiki/Clausius%E2%80%93Clapeyron_relation) can be used to estimate the temperature at which a substance will sublimate for a given partial pressure. Using the parameter values for CO2 from James et al., I get a temperature of [131 kelvins](https://www.wolframalpha.com/input/?i=3182.48%2F%2823.3494+-+ln%280.4%29%29) (-142° C) for the sublimation point of CO2 at a partial pressure of 40 pascals or 0.4 millibar. Using a slightly different parameterization, Agee et al. calculate that a temperature of 133 kelvins (-140° C) is needed to make CO2 sublimate from our atmosphere.

> Are Ice Ages Affected by the Freezing Out of CO2 in Antarctica?

Carbon dioxide levels are very low during glaciations (colloquially, ice ages, but we're in an ice age right now). Using the parameterization from James et al. yields a temperature of 127 K (-146° C) as the sublimation temperature for a partial pressure of 18 Pa (0.18 millibar), or 180 ppm CO2. The Earth cannot get that cold, so no, ice ages are not affected by the freezing out of CO2 in Antarctica.

References:

Agee, Ernest, Andrea Orton, and John Rogers. "CO2 snow deposition in Antarctica to curtail anthropogenic global warming." Journal of Applied Meteorology and Climatology 52.2 (2013): 281-288.

James, Philip B., Hugh H. Kieffer, and username_1 A. Paige. "The seasonal cycle of carbon dioxide on Mars." Mars (1992): 934-968.

> **Comments:**
> **username_0**: How can we be in an ice age right now when people are always complaining about the heat?  
> **username_1**: @username_0 - A pair of massive ice sheets currently cover almost all of Antarctica. Another ice sheet currently covers almost all of Greenland. That pretty much covers the technical definition of what qualifies as an "ice age". The presence of large ice sheets distinguishes the last ~34 million years, plus two other time periods (the late Cenozoic and the late Orderovician), from the majority of the time since the start of the Cambrian where there were **no** ice sheets, period.  
> **username_1**: @ebv - The "Ordervician" was a DYAC. It should have been Ordovician, as you noted. My use of "late Cenozoic" when I should have written "late Paleozoic" -- that's something I can't blame on autocorrect.  
> **username_0**: A number of articles on the internet say that CO2 does freeze in Antarctica at temperatures below -78.5C, but as it sublimates at about the same temperature there is no net build-up. Things may have been different in much colder times.. Buried under water ice in a snowball Earth, when the ice reached a temperature  higher than the freezing point of CO2, it would become a gas under pressure and probably find a way out, depending on the thickness of the water ice above.  
> **username_1**: @username_0 - A number of articles on the internet say the Earth is flat.  

---

### Answer by username_2 on 2020-01-07. Score: 3

During an ice age little CO2 will reach the arctic,it will be absorbed by sea water in all the oceans,This will create a positive feedback,lower CO2 level in the atmosphere will make it even colder so the liquid water will absorb even more CO2.

Cold water can hold large amounts of dissolved gasses,When the ice age ends large amounts of CO2 will be released creating a positive feedback loop further increasing the heating.

One of the problems with the climate change we see now is that the oceans are getting hotter,This will lower the waters capacity to absorb CO2 from the atmosphere.

At some point if the heating goes on the ocean water might start releasing more CO2 than it absorbs.

> **Comments:**
> **username_0**: It would be interesting to know how cold the polar regions can get in a very hard ice age. It must be a lot colder than they are now.  
> **username_2**: @username_0 this i do not know:) maybe somebody else know this.  

---

