Using a nuclear warhead to expose large amount of limestone

[arusse02]

I saw this national geographical documentary at some point, and it said that when India collided with Asia hundreds of millions of years ago, it formed the Himalayas which ended up uncovering huge amounts of limestone. That limestone in turn reacted with CO2 in the atmosphere and caused an ice age.

Could you similarly use a nuclear weapon under a large limestone deposit to cause that limestone to be exposed to the air in significant quantities? Would that put a dent in global warming or is this just a ridiculous idea from a chemistry/physics perspective? thanks.

 

[Comeback City]

I've never heard that about limestone reacting and causing an ice age, but under the assumption that theory is true, a nuclear warhead would likely have some fundamental chemical effect on the limestone that may hinder its ability to even react with the atmosphere.

a ridiculous idea from a chemistry/physics perspective

Also a ridiculous idea from a legal perspective... imagine trying to get that passed by the UN

 

[Borek]

Exploding enough nukes will effect in a nuclear winter, no need for the limestone.

 

[DrStupid]

Could you similarly use a nuclear weapon under a large limestone deposit to cause that limestone to be exposed to the air in significant quantities?

Carbonation of limestone (according to CaCO₃ + CO₂ + H₂O → Ca(HCO₃)₂) is indeed a known factor for ice ages and in the long term it will counter the current global warming because huge amounts of rock will be exposed to the air (e.g. by melting glaciers). However,

1. this process is way to slow to be relevant for mankind and
2. you would need a rediculous number of nuclear warheads for a significant effect and that's where Borek's reply comes into play.

 

[Gigaz]

Even if a nuclear bomb would expose a few fresh km² of limestone and there's no nuclear winter because we'd only be nuking a few mountains - I think the radionucleides that are created in the process would become a problem long before a significant amount of CO2 is removed from the atmosphere.

 

[DrDu]

Just wanted to mention that there are indeed experiments to remove CO2 using tanks of finely dispersed CaCO3.

 

[trurle]

I saw this national geographical documentary at some point, and it said that when India collided with Asia hundreds of millions of years ago, it formed the Himalayas which ended up uncovering huge amounts of limestone. That limestone in turn reacted with CO2 in the atmosphere and caused an ice age.

Could you similarly use a nuclear weapon under a large limestone deposit to cause that limestone to be exposed to the air in significant quantities? Would that put a dent in global warming or is this just a ridiculous idea from a chemistry/physics perspective? thanks.

The "documentary" you seen is likely very unreliable. Several facts are messed up.
1) Limestone (calcium carbonate) mineral do not have capacity to absorb carbon dioxide. Other minerals contained in limestone rock can absorb (react with) carbon dioxide
2) "Exposed" does mean "exposed to freshwater" rather than "exposed to air". When limestone dissolve in freshwater leaving karsts, it indeed allows air and water access to the silicate minerals (feldspar at most) which ultimately break down to quartz, clay and carbonates, consuming carbon dioxide in the process.

Back to original question, nuclear bombs would be very weak tool to absorb carbon dioxide. Simply pouring water on ground is much more productive.

 

[DrDu]

Thats not quite true. Limestone can absorb carbon dioxide by the reaction
$\mathrm{ CaCO_3 + H_2O + CO_2 \rightleftharpoons Ca (HCO_3)_2}$.
Calcium hydrogen carbonate is soluble and will finally end up in sea water.

 

[trurle]

Thats not quite true. Limestone can absorb carbon dioxide by the reaction
$\mathrm{ CaCO_3 + H_2O + CO_2 \rightleftharpoons Ca (HCO_3)_2}$.
Calcium hydrogen carbonate is soluble and will finally end up in sea water.

Where marine life quickly (on timescale of years) convert it (Ca (HCO3)2) back to limestone.

 

[DrDu]

That's an interesting point. But as far as I understand it,
the autotrophic organisms involved convert bicarbonate into limestone and organic material, not carbon dioxide, which makes a difference.
Furthermore, this process is limited not by the offer of hydrogencarbonate but by trace elements like iron in sea water.

 

[trurle]

That's an interesting point. But as far as I understand it,
the autotrophic organisms involved convert bicarbonate into limestone and organic material, not carbon dioxide, which makes a difference.
Furthermore, this process is limited not by the offer of hydrogencarbonate but by trace elements like iron in sea water.

For autotrophic fixation, true although to very small degree. Most of carbon fixed by diatoms and such in photic zone is soon released - predation chains are effective for planctonic life.
Also, would marine (shell) life be really limited by microelements in shell-building, we would have inorganic calcite crusts common on seabed, which is not true for modern seas.

 

[DrDu]

Interesting in this context:
https://en.wikipedia.org/wiki/Oceanic_carbon_cycle