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The latter, of course! I'd be interested in your numbers. H2O is 2.5% of the atmosphere, so I can't see our CO2:H2O production having a significant impact in th

by mkempe 8y ago

The latter, of course! I'd be interested in your numbers. H2O is 2.5% of the atmosphere, so I can't see our CO2:H2O production having a significant impact in that respect; but still, an interesting angle since H2O is a major greenhouse gas. Estimates for biogenic sediment accumulation ranges up to 5 cm per thousand years -- two orders of magnitude smaller than current prediction of the rate of global sea-level rise.

southern_cross 8y ago
Unfortunately I did this seat-of-the-pants calculation years ago, so I no longer have the numbers around. I do remember that using the simplistic 1:1 ratio the net result was considerably smaller than I had originally expected, although still measurable. But when I tried to figure out a more realistic ratio to use I kind of ran into a brick wall. See, for example, the typical molecular complexity of coal: https://en.wikipedia.org/wiki/Coal#/media/File:Struktura_chemiczna_węgla_kamiennego.svg https://en.wikipedia.org/wiki/Coal#/media/File:Struktura_che... (It's been a long time now, but if I remember my organic chemistry correctly each of those unmarked corners is a carbon atom, and each of those may have a hydrogen atom attached to it, and possibly more than one.) A transition away from coal and towards natural gas (which consists primarily of fully-combustible methane at a ratio of 1:2) should lead to both an increase in H2O output and a decrease in CO2 output as compared to coal. (A recent local power plant transition from coal to natural gas claims a carbon emissions reduction of 60%.) Using your 2.5% number, water vapor is already about 60x more common in the atmosphere than CO2 is at 0.041%, and I've seen estimates that it is probably about 15% higher now than it was in the past. (Presumably any H2O output above that has ended up in the oceans.) Given that as a greenhouse gas water vapor is at least 2x (IIRC) as powerful as CO2 and apparently also increasing at a steady clip, you'd think that folks would be paying more attention to this, but instead they just tend to ignore it. In fact they just like to ignore water vapor completely, except maybe when it leads to clouds and such.

by mkempe 8y ago

southern_cross 8y ago

Unfortunately I did this seat-of-the-pants calculation years ago, so I no longer have the numbers around. I do remember that using the simplistic 1:1 ratio the net result was considerably smaller than I had originally expected, although still measurable. But when I tried to figure out a more realistic ratio to use I kind of ran into a brick wall. See, for example, the typical molecular complexity of coal: https://en.wikipedia.org/wiki/Coal#/media/File:Struktura_chemiczna_węgla_kamiennego.svg https://en.wikipedia.org/wiki/Coal#/media/File:Struktura_che... (It's been a long time now, but if I remember my organic chemistry correctly each of those unmarked corners is a carbon atom, and each of those may have a hydrogen atom attached to it, and possibly more than one.) A transition away from coal and towards natural gas (which consists primarily of fully-combustible methane at a ratio of 1:2) should lead to both an increase in H2O output and a decrease in CO2 output as compared to coal. (A recent local power plant transition from coal to natural gas claims a carbon emissions reduction of 60%.) Using your 2.5% number, water vapor is already about 60x more common in the atmosphere than CO2 is at 0.041%, and I've seen estimates that it is probably about 15% higher now than it was in the past. (Presumably any H2O output above that has ended up in the oceans.) Given that as a greenhouse gas water vapor is at least 2x (IIRC) as powerful as CO2 and apparently also increasing at a steady clip, you'd think that folks would be paying more attention to this, but instead they just tend to ignore it. In fact they just like to ignore water vapor completely, except maybe when it leads to clouds and such.