Polar Ice Melt and Carbon Dioxide
Country: United States
Date: Winter 09-10
When the polar ice sheets melt, do they release the carbon
dioxide that is trapped in them? How is it released? How is the
carbon dioxide that is trapped in water, like the ocean, released?
There is some carbon dioxide trapped in the
polar ice in bubbles of air. It is released
as the ice melts. So as the polar ice melts
in the summer, carbon dioxide is released to
the air and as the polar ice reforms in winter,
carbon dioxide is stored in the ice.
Ocean water contains dissolved carbon dioxide.
It remains at a fairly constant concentration for
a fixed temperature. Colder water can contain
more dissolved carbon dioxide than warm water.
If the temperature of the water increases, as
has happened in some of the Earth's oceans
over the last thirty years, theoretically,
carbon dioxide could have been released.
However, since the oceans are also a large sink
for carbon dioxide, we would have to say that
as ocean water warms, it has less capacity to
store carbon dioxide.
It is not clear how much longer the oceans can
store excess carbon dioxide from the atmosphere,
irrespective of what the ocean temperature is.
David R. Cook
Climate Research Section
Environmental Science Division
You have asked a bevy of questions, that we could never respond to in detail
and do justice to the breadth of the question, but here is a "short" form.
If and when the polar ice sheets melt, a complex equilibrium (let us assume
equilibrium) occurs: CO2 (and other trapped gases) are in the ice phase,
the solubility of CO2 in salt water at low temperature, CO2 entering the
atmosphere directly, before equilibrium with the salt water can take place.
What inputs/outputs influence the solubility of CO2 in cold salt water.
Remember this is a "dynamic" system. For example, the solubility of CO2 in
salt water depends upon the concentration of the salt, which is changing
because of the melting and snowfall. I'm not sure if melting ice caps
contribute a substantial amount of CO2. I do not have that information at
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Update: June 2012