linky to earlier topic/earlier picture seems broken, 'view source' says it should be to http://rabett.blogspot.com/2014/12/what-we-have-here-is-failure-to.html
Not to seem ungrateful, but oceans and wetlands are both large sinks and sources of CH4 and CO2, but the eye in the sky people get more toys than the ocean guys or the rice farm guys.
From the beginning, the IPCC has not fully considered the fate, transport, and equilibriums of such gases between the atmosphere and water. IPCC adopted work done in the context of the atmospheric chemistry of halogenated hydrocarbons. Air guys tend to think in models like https://upload.wikimedia.org/wikipedia/commons/c/c2/CO2_pump_hg.png , which ignores bio-transformation of carbon into CH4, the metabolism of CH4 into CO2, and the equlibrium between dissolved CH4 and clathrates.
They tell us that CH4 has a half-life of a dozen years, and thus its CO2 equivalent is only 24 rather than 86. And, they tell us that CO2 will be in the atmosphere for a long time, but in fact, The IPCC also tells us that CO2 has a half life in the atmosphere on the order of 30 years. (With CO2, they explicitly admit to an incomplete fate and transport model.)
Everybody uses global warming potentials (GWP) without considering that as CH4 is removed from the atmosphere, the reduction in the partial pressure in the atmosphere will allow CH4 to partition from the oceans into the atmosphere, thereby maintaining a relatively stable concentration of CH4 in the atmosphere. As long as there is a source of CH4 in oceans, CH4 concentrations in the atmosphere will remain fairly stable. Note http://www.esrl.noaa.gov/gmd/ccgg/trends_ch4/ goes up, and up. CH4 in the air and water is a function of the total carbon in water. And a reduced partial pressure of CH4 in the water column, will allow clathrates to decay, restoring CH4 to the water column. Ultimately, the atmospheric concentration of CH4 is an equilibrium with clathrates at a given temperature. And, if you get out your slide rule and do the math, you find that the process can act as an isotopic still. I find the isotopic studies less than persuasive.
By focusing on atmospheric chemistry, the IPCC has adopted a deeply flawed fate and transport model for CH4. The IPCC model dramatically misses the point that once the system (including oceans) equilibrates at a given CH4 concentration, that level of CH4 in the atmosphere is as stable as a similarly equilibrated concentration of CO2 in the atmosphere. This is a deep cognitive dissonance within the IPCC "canon".
In pre-industrial times, CH4 was flushed from the atmosphere and water column by cold brines rejected by sea ice formation. At depth (HSZ),the CH4 dissolved in the cold brine was converted to hydrate and thereby sequestered. A GWP of 24 for CH4 is likely valid (only) in time of rapid sea ice expansion (Snowball Earth!).
Hank; I know you like cites, but again this is one of those cases where you will just have to wait for someone to publish a good paper on the global fate and transport of CH4 with a revised GWP. I am retired and have not written an academic paper for 25 years.
> At depth (HSZ),the CH4 dissolved in the cold brine was converted to > hydrate and thereby sequestered. A GWP of 24 for CH4 is likely valid > (only) in time of rapid sea ice expansion (Snowball Earth!).
Hm, so who are the young eager postdocs working on methane transport? Sometimes all it takes is an idea dropped in the right blog to start someone down the track toward looking into an idea. What would you look for? Does this explain why most of the hydrates are buried in sediment?
Unfortunately behind paywall, but there is a new paper with a different POV http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2998.html
Moreover it is pretty clear that various have overstated the clatherate issue, if for no other reason, that arctic sea water below 60 m is undersaturated in methane http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4639778/ (paper gets at some of the issues raised above)
Eli - not sure how undersaturation > 60m would imply anything about methane hydrates? The whole premise of the meta-stable methane hydrates is that they can exist outside the HSZ. The danger would be in shallow shelf areas of the ESS where the water column down to the sea-floor can conceivably be warmed.
Most of this paper's geographical research locations were far from the coastal regions, though when they did get close to the ESS their readings jumped dramatically. If anything, I see the results (particularly Fig. 1) as supporting the meta-stable methane hydrate idea.
Short-Lived Promise? The Science and Policy of Cumulative and Short-Lived Climate Pollutants (MA authored) http://www.oxfordmartin.ox.ac.uk/downloads/briefings/Short_Lived_Promise.pdf
Uhu. It seems the CO2 concentration goes up in winter and falls in the summer. Therefore, those areas which are exposed to more sunlight and have higher temperature are covered by an atmosphere with a lower CO2 concentration. A subtle effect which reduces CO2 forcing a teensy bit.
The methane comments are irrelevant to the subject, which is CO2.
Kevin, undersaturation means that the oceans have a capacity to absorb methane released from dissociation of the methane hydrates. Whether methane from dissolving methane hydrates will reach the atmosphere or not depends on local conditions. One of the things missing from the studies that Eli has seen are vertical profiles. Bubbles at the surface are indicative but not conclusive.
Eli - I meant that > 60m and at locations far away from the ESS really don't apply to the ESS. And that when they *did* get close to the ESS the numbers shot up.
Now, does that *prove* anything? No, but it surely doesn't dampen the enthusiasm :)
UPDATE: The spambots got clever so the verification is back. Apologies
Some of the regulars here are having trouble telling the anonymice apart. Please add some distinguishing name to your comment such as Mickey, Minnie, Mighty, or Fred.
linky to earlier topic/earlier picture seems broken, 'view source' says it should be to
ReplyDeletehttp://rabett.blogspot.com/2014/12/what-we-have-here-is-failure-to.html
Not to seem ungrateful, but oceans and wetlands are both large sinks and sources of CH4 and CO2, but the eye in the sky people get more toys than the ocean guys or the rice farm guys.
ReplyDeleteFrom the beginning, the IPCC has not fully considered the fate, transport, and equilibriums of such gases between the atmosphere and water. IPCC adopted work done in the context of the atmospheric chemistry of halogenated hydrocarbons. Air guys tend to think in models like https://upload.wikimedia.org/wikipedia/commons/c/c2/CO2_pump_hg.png , which ignores bio-transformation of carbon into CH4, the metabolism of CH4 into CO2, and the equlibrium between dissolved CH4 and clathrates.
They tell us that CH4 has a half-life of a dozen years, and thus its CO2 equivalent is only 24 rather than 86. And, they tell us that CO2 will be in the atmosphere for a long time, but in fact, The IPCC also tells us that CO2 has a half life in the atmosphere on the order of 30 years. (With CO2, they explicitly admit to an incomplete fate and transport model.)
Everybody uses global warming potentials (GWP) without considering that as CH4 is removed from the atmosphere, the reduction in the partial pressure in the atmosphere will allow CH4 to partition from the oceans into the atmosphere, thereby maintaining a relatively stable concentration of CH4 in the atmosphere. As long as there is a source of CH4 in oceans, CH4 concentrations in the atmosphere will remain fairly stable. Note http://www.esrl.noaa.gov/gmd/ccgg/trends_ch4/ goes up, and up. CH4 in the air and water is a function of the total carbon in water. And a reduced partial pressure of CH4 in the water column, will allow clathrates to decay, restoring CH4 to the water column. Ultimately, the atmospheric concentration of CH4 is an equilibrium with clathrates at a given temperature. And, if you get out your slide rule and do the math, you find that the process can act as an isotopic still. I find the isotopic studies less than persuasive.
By focusing on atmospheric chemistry, the IPCC has adopted a deeply flawed fate and transport model for CH4. The IPCC model dramatically misses the point that once the system (including oceans) equilibrates at a given CH4 concentration, that level of CH4 in the atmosphere is as stable as a similarly equilibrated concentration of CO2 in the atmosphere. This is a deep cognitive dissonance within the IPCC "canon".
In pre-industrial times, CH4 was flushed from the atmosphere and water column by cold brines rejected by sea ice formation. At depth (HSZ),the CH4 dissolved in the cold brine was converted to hydrate and thereby sequestered. A GWP of 24 for CH4 is likely valid (only) in time of rapid sea ice expansion (Snowball Earth!).
Hank; I know you like cites, but again this is one of those cases where you will just have to wait for someone to publish a good paper on the global fate and transport of CH4 with a revised GWP. I am retired and have not written an academic paper for 25 years.
> At depth (HSZ),the CH4 dissolved in the cold brine was converted to
ReplyDelete> hydrate and thereby sequestered. A GWP of 24 for CH4 is likely valid
> (only) in time of rapid sea ice expansion (Snowball Earth!).
Hm, so who are the young eager postdocs working on methane transport? Sometimes all it takes is an idea dropped in the right blog to start someone down the track toward looking into an idea. What would you look for? Does this explain why most of the hydrates are buried in sediment?
Unfortunately behind paywall, but there is a new paper with a different POV http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2998.html
ReplyDeleteMoreover it is pretty clear that various have overstated the clatherate issue, if for no other reason, that arctic sea water below 60 m is undersaturated in methane http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4639778/ (paper gets at some of the issues raised above)
Eli - not sure how undersaturation > 60m would imply anything about methane hydrates? The whole premise of the meta-stable methane hydrates is that they can exist outside the HSZ. The danger would be in shallow shelf areas of the ESS where the water column down to the sea-floor can conceivably be warmed.
ReplyDeleteMost of this paper's geographical research locations were far from the coastal regions, though when they did get close to the ESS their readings jumped dramatically. If anything, I see the results (particularly Fig. 1) as supporting the meta-stable methane hydrate idea.
This tweet gives me an online (read only) version ...
ReplyDeletehttps://twitter.com/NatureClimate/status/728149014114275330
Short-Lived Promise? The Science and Policy of Cumulative and Short-Lived Climate Pollutants (MA authored)
http://www.oxfordmartin.ox.ac.uk/downloads/briefings/Short_Lived_Promise.pdf
a-r-r-r-r-r-r-r-r-r-s technica ...
http://arstechnica.com/tech-policy/2016/05/piracy-site-for-academic-journals-playing-game-of-domain-name-whac-a-mole/
Uhu. It seems the CO2 concentration goes up in winter and falls in the summer. Therefore, those areas which are exposed to more sunlight and have higher temperature are covered by an atmosphere with a lower CO2 concentration. A subtle effect which reduces CO2 forcing a teensy bit.
ReplyDeleteThe methane comments are irrelevant to the subject, which is CO2.
Kevin, undersaturation means that the oceans have a capacity to absorb methane released from dissociation of the methane hydrates. Whether methane from dissolving methane hydrates will reach the atmosphere or not depends on local conditions. One of the things missing from the studies that Eli has seen are vertical profiles. Bubbles at the surface are indicative but not conclusive.
ReplyDeleteEli - I meant that > 60m and at locations far away from the ESS really don't apply to the ESS. And that when they *did* get close to the ESS the numbers shot up.
ReplyDeleteNow, does that *prove* anything? No, but it surely doesn't dampen the enthusiasm :)