Control of methane, soot, and other short-lived climate-forcing agents has often been described as a cheap way to "buy time" to get carbon dioxide emissions under control. But is it really?
Expectations for the outcome of the Cancun climate talks seem to be running low, and the suggestion has emerged that maybe we should forget about controlling CO2 emissions for now, and instead do something with short lived climate forcing agents like methane or soot. This is often described as "buying time" to put CO2 emissions controls into place. For example, in a recent New York Times Op-Ed, Ramanathan and Victor write:
"Reducing soot and the other short-lived pollutants would not stop global warming, but it would buy time, perhaps a few decades, for the world to put in place more costly efforts to regulate carbon dioxide." — Ramanathan and Victor
The idea that aggressive early action to control short-lived climate forcing "buys time" to do something about CO2 has often been pushed in the past, e.g. in various newsletters and press releases associated with the UNEP Atmospheric Brown Cloud program, for example
"The BC reduction proposal is not proposed as an alternative to CO2 reduction. At best, it is a short term measure to buy a decade or two of time for implementing CO2 emission reduction strategies." — Ramanathan, writing in the UNEP Black Carbon Newsletter.
To be fair, it should be acknowledged that such pleas for more attention to short-lived climate forcing are almost invariably accompanied by a salutary reminder that it is really CO2 that needs to be gotten under control, as in the quote above. Achim Steiner, writing in the same issue of the Black Carbon Newsletter writes "Paying attention to black carbon should not distract people from the real issue at hand, carbon dioxide." A similar sentiment is expressed in the Ramanathan and Victor op-ed. While emphasizing the central importance of CO2, Penner et al. argue that "…to provide short-term relief from climate warming, the short-lived compounds that induce warming need to be brought under control within a timescale of a few decades." (They also make the intriguing suggestion that doing so might provide a global experiment that could help constrain climate sensitivity.) Writing in Science, Stacy Jackson concludes that "… a focus on CO2 may prove ineffective in the near term without comparable attention to pollutants with shorter lifetimes"
All of this is well-intentioned stuff, none of it denies the central importance of CO2, and I’m sure there are many benefits to be had from reducing soot emissions sooner rather than later. Given the large agricultural component of methane emissions, keeping these emissions from growing in the face of a the need to feed a growing number of people is a serious challenge that must ultimately be met. But still, these proposals tend to convey the impression that dealing with the short-lived forcings now will in some way make it easier to deal with CO2 later, and that’s wrong. In this post, I will explain why.
To get a feel for the issues in play, we’ll first take a look at methane vs CO2. This provides a clean example, because methane has a straightforward, well-characterized warming effect which is easy to compare with that of CO2. If you’re just looking at the concentration of methane and CO2 at a given time, the methane/ CO2 equivalence is pretty easy to figure, since you can turn them both into the common currency of top-of-atmosphere radiative forcing. For example, doubling CO2 from 300 ppm to 600 ppm yields a clear-sky radiative forcing of 4.5 W/m2. Doubling methane from 1ppm to 2 ppm yields a radiative forcing of 0.8 W/m2, but since we started from such a low concentration of methane, it takes many fewer molecules of methane to double methane than to double CO2. Per molecule added, methane yields about 54 times as much radiative forcing as CO2. Note that most of this effect has nothing much to do with any special property of methane, but arises simply because the radiative forcing for most greenhouse gases is logarithmic in concentration, so you sort of get the same radiative forcing for everybody upon doubling their concentration — but if you start with somebody whose concentration is low, it takes many fewer molecules to double. That means that the CO2 equivalent of methane depends on what concentration you are starting with. If you started from a concentration of 10ppm, then the equivalence factor drops to 10. If you start out with equal amounts of methane and CO2 (300 ppm), then the equivalence factor drops further to 0.5. In that sense, methane is, intrinsically speaking, a worse greenhouse gas than CO2, though the crossover is at values that are so high they are only relevant (at most) to the Early Earth. ( I ran these calculations with the Python interface to the NCAR radiation model, provided in the Chapter 4 scripts of my book, Principles of Planetary Climate. They are done using an idealized clear-sky atmospheric profile, so the numbers are a bit different from what you’ll find in the IPCC reports, but it’s nice to have a calculation simple enough you can re-do it yourself.)
Things get a lot trickier when you try to bring time into the problem, because methane and CO2 have vastly different atmospheric lifetimes. Methane oxidizes to CO2 in about 10 years, and since we are dealing with so little methane, that extra ppm of CO2 you get after it oxidizes adds little ongoing warming. That means that the methane concentration in the atmosphere is determined by the methane emission rate averaged over the previous ten years, and the methane component of warming disappears quickly after emissions cease. In contrast, about half of CO2 emitted disappears into the ocean fairly quickly, while the other half stays in the atmosphere for thousands of years. Therefore, the atmospheric burden of CO2 in any given year is determined by the cumulative emissions going back to the beginning of the Industrial Revolution, and the warming persists for thousands of years after emissions cease. Over the long term, CO2 accumulates in the atmosphere, like mercury in the body of a fish, whereas methane does not. For this reason, it is the CO2 emissions, and the CO2 emissions alone, that determine the climate that humanity will need to live with for a time that stretches into the future at least as long as the time since the founding of the first Sumerian cities stretches into the past. The usual wimpy statement that CO2 stays in the air for "centuries" doesn’t begin to convey the far-reaching consequences of the amount of CO2 we decide to pump out in the coming several decades.
As a reminder of that, here’s a graph from the NRC Climate Stabilization Targets report (of which I was an author) summarizing how cumulative carbon emissions set the climate thermostat for the next 8000 years and more.
The numbers on each curve gives the total cumulative carbon emissions (in gigatonnes) during the time when human activities continue to emit carbon. These results are based on calculations by Eby et al using the UVIC coupled carbon/climate model, and they are really just a reprise of what Dave Archer has been telling all of us for years (e.g here, here and here). It turns out that it matters little to temperature whether all the CO2 is emitted in a carbon orgy near the beginning of the fossil fuel era, or spread out over a few hundred years. It’s cumulative carbon that counts, and pretty much it is the only thing that counts. A cumulative emission of a trillion tonnes of carbon just might keep the Earth below a warming of 2ºC, in line with earlier estimates equating the European Union target warming threshold with cumulative carbon (see our Trillion Tonne post). The peak warming scales approximately linearly with cumulative emissions, and the warming you get at the peak is pretty nearly the warming you are stuck with for the next millennium, with only slight declines beyond that. We are currently about halfway to our first trillion tonnes, but given the miracles of exponential growth, we are going to get there pretty quickly if nothing changes. If you go beyond, and dump 2355 gigatonnes into the atmosphere before kicking the fossil fuel habit, then the global mean temperature will still be 3ºC warmer than pre-industrial in the year 8000. That gives plenty of time for bad stuff to happen, including deglaciation of Greenland, loss of the West Antarctic Ice Sheet, or a destabilizing PETM-type soil carbon release. Note further that these calculations were done with a model designed to have a climate sensitivity similar to the IPCC median. Therefore, even if you hold the line at a trillion tonnes, there is still about a 50% chance that warming will exceed 2ºC.
Let’s suppose, however, that we decide to go all-out on methane, and not do anything serious about CO2 for another 30 years. To keep the example simple, we’ll think of a world in which methane and CO2 are the only anthropogenic climate forcing agents. Suppose we are outrageously successful, and knock down anthropogenic methane emissions to zero, which would knock back atmospheric methane to a pre-industrial concentration of around 0.8 ppm. This yields a one-time reduction of radiative forcing of about 0.9W/m2. Because we’re dealing with fairly short-term influences which haven’t had time to involve the deep ocean, we translate this into a cooling using the median transient climate sensitivity from Table 3.1 in the NRC Climate Stabilization Targets report, rather than the higher equilibrium sensitivity. This gives us a one-time cooling of 0.4ºC. The notion of "buying time" comes from the idea that by taking out this increment of warming, you can go on emitting CO2 for longer before hitting a 2 degree danger threshold. The problem is that, once you hit that threshold with CO2, you are stuck there essentially forever, since you can’t "unemit" the CO2 with any known scalable economically feasible technology.
While we are "buying" (or frittering away) time dealing with methane, fossil-fuel CO2 emission rate, and hence cumulative emissions, continue rising at the rate of 3% per year, as they have done since 1900. By 2040, we have put another 573 gigatonnes of carbon into the atmosphere, bringing the cumulative fossil fuel total up to 965 gigatonnes. By controlling methane you have indeed kept the warming in 2040 from broaching the 2C limit, but what happens then? In order to keep the cumulative emissions below the 1 trillion tonne limit, you are faced with the daunting task of bringing the emissions rate (which by 2040 has grown to 22 gigatonnes per year) all the way to zero almost immediately. That wasn’t very helpful, was it? At that point, you’d probably like to return the time you bought and get a refund (but sorry, no refunds on sale items). More realistically, by the time you managed to halt emissions growth and bring it down to nearly zero, another half trillion tonnes or so would have accumulated in the atmosphere, committing the Earth to a yet higher level of long-term warming.
Suppose instead that you had focused all efforts on reducing the growth rate of CO2 emissions from 3% to 2%, averaged over 2010-2040, forgetting about methane until the end of that period. In this scenario, the cumulative carbon emitted up to 2040 is only 713 gigatonnes, giving more time to avoid hitting the trillion-tonne threshold. The warming from CO2 in 2040 is about 1.2C, but we have to add in another 0.4ºC because we haven’t done anything to bring down methane emissions. That brings the warming to 1.6C, which will increase further beyond 2040 as the cumulative carbon emissions approach a trillion tonnes. However, since methane responds within a decade to emissions reductions, we still get the full climate benefit of reducing methane even if the actions are deferred to 2040. The same cannot be said for deferral of action on CO2 emissions.
The following cartoon, loosely based on Eby’s calculations shows two illustrative scenarios: one in which early action is taken on methane, at the expense of allowing cumulative CO2-carbon emissions to rise to around 1.7 trillion tonnes, and another in which action on methane is delayed until 2040, allowing cumulative emissions to be held to a trillion tonnes. The curves can be diddled a bit depending on how much short term warming you get from controlling additional short-lived gases, and how much extra cumulative carbon emissions you assume goes along, but it is really hard to come up with any scenario where you come out ahead from acting early on the short-lived forcings instead of going all-out to reduce the rate of CO2 emissions.
There are a few greenhouse gases other than CO2 that have lifetimes sufficiently long to lend some urgency to their control. That would include HFC23 with a lifetime of 260 years, CFC13 with a lifetime of 640 years and SF6 with a practically unlimited lifetime. Most of the rest are more like methane than they are like CO2 (e.g HFC31 at 5 years)
Absorbing aerosols — soot, loosely speaking — have a number of complex regional effects that make it difficult to treat their climate impact on an equal footing with that of well-mixed greenhouse gases. Soot falling on snow or ice has an unambiguous warming effect, manifest particularly strongly at high latitudes and high altitudes. For airborne absorbing aerosols, though, it is hard to even know whether they have a warming or cooling effect on surface temperature, or leave it more or less unchanged. Except over high albedo surfaces, airborne aerosols mainly heat the atmosphere by direct solar absorption, at the expense of reduced solar absorption at the surface. When the shading is not too strong, the main consequence is a reduction of the convection that would ordinarily carry solar energy from the ground to the atmosphere. This profoundly influences precipitation, and the atmospheric circulation, especially in the tropics. In extreme cases, the atmospheric absorption can even shut down convection completely, leading to stabilization of the tropospheric lapse rate and a severe surface cooling, as in the Nuclear Winter limit (see also the more elementary discussion of this limit in Chapter 4 of Principles of Planetary Climate).
A further consideration is that most activities that emit soot also emit precursors to reflecting aerosols which cool the planet. It is unlikely (and probably undesirable) that one would be able to limit one without also limiting the other. Hence, the net implication of the black carbon component is probably that it will help offset some of the warming caused by eliminating sulfate aerosols. That’s good, but it’s not what you bargained for if you were expecting a cooling for your money. The main thing about soot and the stew of toxic emissions going into the Atmospheric Brown Cloud , though, is that there are compelling human health, agricultural, and regional climate reasons to eliminate them, regardless of the side effect on global temperature. These are things that need to be done regardless of the climate implications (positive or negative), just as there is a need to supply the developing world with reliable clean water. It is pointless to make an already complicated climate negotiation yet more complicated by wrapping such things into the mix. It is nonetheless worth noting that many of the things one would do to reduce soot emissions, such as substituting natural gas for coal, or burning coal in cleaner, more efficient power plants, also would tend to reduce CO2 emissions, and such double-wins are of course to be sought and pursued ardently (note Gavin’s op-ed on co-benefits of CO2 reduction).
IPCC-style Global Warming Potentials attempt to trade off radiative forcing against lifetime in a Procrustean attempt to boil all climate forcings down to a single handy-dandy number that can be used in climate treaties and national legislation. In reality, aerosol-forming emissions, short-lived greenhouse gas emissions, and CO2 emissions are separate dials, controlling very different aspects of the Earth’s climate future. CO2 emissions play a distinguished role, because they ratchet up the Earth’s thermostat. It’s a dial you can turn up, but you can’t turn it back down. CO2 is a genie you can’t put back in the bottle. Climate forcings should not be aggregated. Each category should be treated in its own right. Otherwise, there are perverse incentives to do too much too soon on short-lived forcings and too little too late on CO2.
Timothy Chase,
The problem on the Canadian Shield isn’t the rocks–rather the lack of soil. It was stripped away by the glaciers and deposited as a bounty for the Great Plains…’til we pissed that away in the dustbowl. So unless you can figure out how to grow wheat on granite…maybe some sort of wheat-lichen hybrid?
And the Python award for dry humor goes to. . . Dappledwater!!
“Being dead is an impediment to adaptation. . .”
I’m almost certain I could find it in my heart to believe that.
Ray Ladbury wrote in 301:
I did say that the soil over the Canadian Shield was thin — although I didn’t quite realize that over so much of the Shield the soil is nonexistent. At the same time much of Western Canada isn’t over the Canadian Shield. But even there you are going to be dealing with subsidence as permafrost melts, clearing of rock, the high acidity of tundra and the acidity of brown forest soil as it becomes moist, the lack of infrastructure and climate zones that continue to move northward — rendering so much long-term investment mute.
Ray Ladbury wrote in 301:
Well, just so long as it is a wheat-lichen *hybrid*. We wouldn’t want any corporation making money off this situation with genetically modified crops. People may go hungry — or starve, I suppose — but I have my principles to consider!
Ah, more humor, this time from Timothy Chase! Well, the news is pretty horrible on balance, so we might as well laugh.
Speaking of news, a couple of years back we had a bit of a brouhaha here about drought in the Southeast; at that time the consensus was that you couldn’t attribute drought in the Southeast to AGW. (Or ACC; whichever.) I missed it till now, but ClimateProgress reported in October on a study that came to a different conclusion:
http://climateprogress.org/2010/10/28/global-warming-extreme-wet-dry-summer-weather-in-southeast-droughts-and-deluges/
I’d wave my hands about this a bit, but that’s not worth much even when stuck on the roadside, I find.
By the way, don’t get all happy and excited upon reading that “the rest of the microbial community should not be assumed to get at risk.”
That’s
— absence of evidence, not evidence of absence, and
— slime. http://www.google.com/search?q=jeremy+jackson+rise+slime
typo: above should read “the rest of the microbial community should not be assumed to be at risk ….”
Dappledwater raises a good point. Humans adapt. Most other organisms can’t deal at all with such fast change.
(It’s still adaptation, even if millions die.)
Not that this has anything to do with my original point.
As to those discussing Canada – I should point out that Canada is already an exporter of grain. The Canadian shield only covers half of Canada – I find it hard to believe that Canada is anywhere close to a theoretical maximum harvest.
The Canadian shield is host to diverse ecosystems. Bogs and marshes, permafrost, bare rock and vast boreal forests. Saying there is “no soil” is a) wrong, and b) a gross oversimplification.
Even if we could, chopping down the forests would probably be a really bad idea.
I’m growing tired of having discussions about such complicated subjects in black and white terms. I need a break. Have a great Christmas, everyone.
re 299,246 Dapple
Said link provides an excellent example of gibberish from the peerage, though it might have some meaningful content.
It has by no means been completely sorted out by me, as of yet, but a few points are interesting indications of how confusion arises, even among the peers that write the paper.
First observation is that we have in the abstract of the paper the use of the term 300% saturated, which is, on the face of it, nonsense, since one can not dissolve more than the maximum that can be dissolved. Looking to simply sort out how this could be, Table 1 demonstrates no such 300%, and equation (2) agrees, though the flip from percentage of saturation to percentage of undersaturation is silly. And then I discover that the Table 1 numbers, labeled as level of saturation, but in fact are area fractions instead. And then, why are they only talking about aragonite when calcite is more dominant, and why do we care since we are only concerned with dissolved CaCO3? Along the way, we note that the peers miss-spelled ‘stoichiometry’, which is of course a pardonable offense.
There are many fields where various ‘super’ prefixes are added to indicate more than normal conditions, which might be what they mean by the 300% but so far, they don’t say that.
Said link was useful in clarifying that the shorthand ‘carbonate’ actually refers to calcium carbonate, and not just any carbonate compound.
I have scurried to my chemistry book, and have made it through Table 1 and equation (2), but am wondering if the operationally important answers will be there, since the discussion now seems to descend into computer model stuff.
Update!!
There is one paragraph on page 516 that basically says there is great variation in the effects of ‘acidification’, and then descends to the meaningless statement:
“Scleractinian corals were found to survive and recover
after experiencing decalcification in acidic water (Fine
and Tchernov, 2007)”.
Again, this is meaningless since there is no prospect of ‘acidic’ water, though nobody seems to have told Tchernov that acidification does not mean actually becoming acidic.
Prepared with my open chemistry book, a question for the chemistry folks is: What is the stoichiometric (that just means weight) concentration of CO2 in water, and associated pH, that removes CaCO3 that is dissolved in seawater from that seawater at a significant rate. If there are other — carbonates around, does this affect the process? Then, what is the concentration of CO2 needed to actually dissolve solid CaCO3, that being calcite/aragonite shells already formed? Would not the originally dissolved CO2 be replaced one for one with the CO2 released in the reaction? Then, what is the degree of concentration of dissolved CaCO3 needed for growth of the various calcite/aragonite shelled creatures – – though Table 1 infers we don’t care since anything less than saturation of aragonite is ruination?
Clearly, what I do not understand is much. I wonder how well this subject in understood. The Steinacher paper does not speak well for the community.
301 303 Ray Ladbury, Timothy Chase
Notice, that we got the dirt and Canada got the water.
Maybe we should make a deal.
302 Kevin McKinney
Being blockheaded is also an impediment to adaptation.
Sharing water could prevent both the next dustbowl and enable standing forests to take up CO2. But horrors, this might disturb the ecosystem; though of course, being dead might also disturb something or other.
re “oil seepage from the ocean floor” – most of the seafloor is underlain by Mid Ocean Ridge Basalt, which has accumulated a thin crust of sediment over the hundreds of millions of years that the basement rock has been moving away from the ridges.The basalt is not a source rock for oil, and the sediment that has accumulated isn’t thick enough, warm enough, or high enough biogenic content to produce oil. The only place oil seeps from the ocean floor is at continental margins where high rate burial of biogenic sediments creates pressure/temperature profiles that create oil – like in the Gulf of Mexico from the Missippi River.
Forgot the link for my previous post – http://www.ngdc.noaa.gov/mgg/ocean_age/data/2008/ngdc-generated_images/whole_world/2008_age_of_oceans_p1024.jpg any ocean floor thats color shaded is not seeping oil
Jim Bullis, we no longer have the dirt. It blew away and is now mostly in the Gulf of Mexico–one of many elements in our patrimony we have pissed away.
Fine: Scleractinian coral species survive and recover from decalcification
http://www.sciencemag.org/content/315/5820/1811.full
cited by:
http://scholar.google.com/scholar?hl=en&lr=&cites=6332364602742886392&um=1&ie=UTF-8&ei=4pASTfi_N4e4sAOshOmDDw&sa=X&oi=science_links&ct=sl-citedby&resnum=1&ved=0CBsQzgIwAA
https://darchive.mblwhoilibrary.org/bitstream/handle/1912/2834/bg-6-515-2009.pdf?sequence=1
Biogeosciences, 6, 515–533, 2009
http://www.biogeosciences.net/6/515/2009/
Imminent ocean acidification in the Arctic projected with the NCAR
global coupled carbon cycle-climate model
311 Brian Dodge
It sounds like you believe the line that deep ocean water sits still. It does not.
I provided Pochapsky references earlier.
This afternoon I dug up a my old copy of: John G. Bruce, Current Studies South of Bermuda, Woods Hole Oceanographic Institution, Artemis Report Number 37, Feb. 1964. It is DTIC AD0602475 which is a Defense Dept. unclassified report that is said to be available to anyone with a grant. The Abstract says: – – the mean velocity being 10 – 12 cm/sec between 600 fathoms and the bottom. (at around 2000 fathoms here) (A packrat huh, keeping this 45 years.)
312 Brian Dodge
That is a great illustration, but your conclusion about oil seepage seems overstated. It looks like all the ocean areas are colored. If you are right we should tell the offshore deep ocean oil drillers to pack up and go home.
But we watched oil seep in widely varied locations during the BP video show. Huh?
Re Jim Bullis – First observation is that we have in the abstract of the paper the use of the term 300% saturated, which is, on the face of it, nonsense, since one can not dissolve more than the maximum that can be dissolved.
I haven’t looked at that paper, but generally speaking, you can have supersaturation, and it occurs because reactions don’t always reach thermodynamic equilibrium rapidly, or instantaneously for that matter. Kinetic barriers to nucleation and growth of new phases can allow supersaturation to occur. Growth of a new phase can/will require diffusion of heat and matter, thus requiring a gradient, so the concentrations of heat and matter will vary, so even if something is only saturated at the phase boundary, it may be supersaturated at some distance. And saturation can be affected by the surface characteristics. For example, because of the surface tension of water, small droplets have some internal pressure, which increases the saturation vapor pressure at the droplet surface – hence they will be at equilibrium at RH above 100 %, where RH is defined for a flat surface of pure water – of course, droplets forming on soluble aerosols will have reduced equilibrium vapor pressures and may exist at smaller RH’s for that reason, even RH less than 100 % – as solute concentration decreases, larger RH is needed to keep the droplet in equilibrium – this is the condition a haze particle faces; as the droplet grows the concentration of solute decreases with increasing volume while the effect of surface tension decreases with increasing radius, so the curvature effect eventually dominates; when the equilibrium RH decreases with increasing droplet size, the droplet is now a cloud droplet. See ‘Kohler curve’.
>> … any ocean floor thats color shaded is not seeping oil
> It looks like all the ocean areas are colored…. Huh?
Jim, you’re counting gray as a color. Brian isn’t. Look at the picture.
Note “Florida” and “Texas” and “Mexico” — the offshore area is shown in the same gray color as the area above sea level.
I’m commenting for later readers and any kids looking for homework help who wonder about the illustration described.
And with that, to all, I wish a happy and peaceful stretch of winter holidays, and will switch most of my attention to family and neighbors.
311, 312 Brian Dodge
Other links are to Swallow with this as an example: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B757G-48BCXVH-15&_user=10&_coverDate=12%2F31%2F1958&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1587174511&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=fd6b4ff56b2382ad14c37936a8a5171b&searchtype=a
This is just the abstract and offer to sell the report.
Here the report is 20 to .8 cm/sec at different depths.
Swallow makes it into the Weart chronicle, but Pochapsky and Bruce do not. At one later point Pochapsky worked in the Lamont org headed by Ewing. I wonder if they saw things the same way.
Correction to my last:
Weart did put in a few footnotes on Pochapsky papers, but did not seem to have read them. Otherwise the Ewing position on really old deep oceans would have been difficult to defend.
http://www.sciencemag.org/content/329/5989/319.abstract
Modeling:
Prev | Table of Contents | Next
Published Online 24 June 2010
Science 16 July 2010:
Vol. 329 no. 5989 pp. 319-322
DOI: 10.1126/science.1188703
Simulated Rapid Warming of Abyssal North Pacific Waters
*To whom correspondence should be addressed. E-mail: smasuda@jamstec.go.jp
(If James Annan is watching this, perhaps he will comment; can’t tell much about the simulation with only the abstract)
Abstract
Recent observational surveys have shown significant oceanic bottom-water warming. However, the mechanisms causing such warming remain poorly understood, and their time scales are uncertain. Here, we report computer simulations that reveal a fast teleconnection between changes in the surface air-sea heat flux off the Adélie Coast of Antarctica and the bottom-water warming in the North Pacific. In contrast to conventional estimates of a multicentennial time scale, this link is established over only four decades through the action of internal waves. Changes in the heat content of the deep ocean are thus far more sensitive to the air-sea thermal interchanges than previously considered. Our findings require a reassessment of the role of the Southern Ocean in determining the impact of atmospheric warming on deep oceanic waters.
J. Bullis – Said link provides an excellent example of gibberish from the peerage
Which is you roundabout way of stating you don’t understand it.
First observation is that we have in the abstract of the paper the use of the term 300% saturated, which is, on the face of it, nonsense
How about you locate and read the full paper, which is freely available. Further discussion is fruitless unless you make the effort to learn. I don’t have the time to correct all your woolly-headed ideas.
Again, this is meaningless since there is no prospect of ‘acidic’ water, though nobody seems to have told Tchernov that acidification does not mean actually becoming acidic
Trotting out tired old denier memes is rather boring Jim. Are you sure you are not here simply to troll?.
Hank Roberts @ 300 – There are some rather odd comments in that paper. I’m sure the rest of the oceanographic community is aware that pH is not a homogeneous fixed value for the global ocean. I don’t know why the authors thought it so important to point that out. pH and temperature can fluctuate markedly in some locales, and yet some organisms adapt to those conditions given sufficient time.
The real issue is that ocean acidification, stratification, reduced upwelling, eutrophication, hypoxia etc all represent a rapidly moving target for marine life to adapt to. Even those species which have adapted to conditions of large fluctuations may soon find themselves outside of thresholds which they are able to tolerate.
Hank Roberts @ 314 – try googling ” Galapagos+coral+1982-1983 El Nino”.
321 Hank Roberts
Thanks for that abstract and reference that seem to be along the same line I have been taking, most recently in noting that effect in the Labrador sea data shown in:
http://www.argo.ucsd.edu/Research_use.html#atlantic
The authors here seem not so interested in the fact that at depths from 600 to 1400 meters, the temperature goes from around 3.0 to aroung 3.5 degrees C. They pointed more at the ‘deep convection event’ which seems somewhat likely to be part of the process leading to what I point out.
318 Hank Roberts,
I see your point, though the ‘gray areas’ do not seem to enclose oil development areas very well. But no matter, there seems to be sufficient deep water motion to mix whatever seepage there is, from wherever, across the extent of the deep ocean.
317 Patrick 027
Quite right on various occurences of supersaturation, but it does not look like this is what is going on. Maybe I will find out otherwise as I hope to plow a bit further into this paper.
322 Dapple and 321 Hank,
Maybe it seems I am beating this carbonate stuff to death for no reason. Somewhere between a hunch and an intuition, I see an interesting possibility in the overturning current in combination with plankton capturing CO2, yes, indirectly, as CaCO3.
Previously I had argued that heat would be transported in meaningful quantities to the deep ocean, thus reducing atmospheric temperature increases somewhat, but certainly causing sea level increase.
If there is a possibility of capturing CO2 in surface waters by whatever mechanism, and transporting these to the far more voluminous deep ocean regions, this could be a CO2 capture system.
My long ago awareness of sluggish but still significant deep ocean currents has always been troubling in the face of the almost fixed deep ocean hypothesis. But awareness of these currents is not the same as really understanding them. However, it seems that deep ocean currents have to relate to some extent to vertical water motions, and this would seem to be a means of heat being carried downward. Seeing the possibility of CO2 also being carried downward gives this issue a lot more importance.
Didactylos wrote in 210:
Not something to be lost in the shuffle. And it is open access.
Please see:
I do wish people would give a proper reference when they give a reference, though. The last name, et al. year makes things a bit more difficult to dig up.
Timothy Chase and Didactylos,
The problem I see is that we are maintaining agricultural production at such high levels only by depleting finite resources–e.g. petroleum-based fertilizers and pesticides, deep aquifers, etc. Moreover, in so doing, we are damaging other resources–look at the effect of agricultural runoff on the Chesapeake, for instance. If we manage by some miracle to increase production to even higher levels, we will merely deplete these resources more quickly and further decrease the long-term carrying capacity of the planet. I am afraid I draw little comfort from the possibility that we may purchase a little time by consuming our seed corn.
Ray Ladbury wrote in 330:
I don’t disagree. And if you look back you will see that Didactylos didn’t either. He was speaking mid-century, and he was arguing that the case for the global collapse of modern civilization mid-century hadn’t been made by Barton Paul Levenson. He was arguing for water management. See 210 and 232. And for water management he cites the same source Barton Paul Levenson. See above. I don’t think you would disagree with either of these positions taken by Didactylos. As far as I know the position he takes with respect to agriculture is mainstream — or at least was. At least from what I have seen mid-century projections for agriculture in the United States don’t look that dire — yet. He wasn’t insisting that such projections were right, either. But he wanted to discuss the literature rather than have his position misrepresented — as it was being misrepresented at one point. See Didactylos 210 and 220 and Barton Paul Levenson 215.
And long-term? Didactylos wouldn’t argue that climate change won’t eventually cause the the collapse of civilization. See 232. Then people seemed to lose sight of the time frames. I was thinking end of century. He may still have been thinking mid-century, and everyone was leaving the time frame they were assuming unstated. And I was “disagreeing” with Didactylos but directing my discussion towards you by essentially underscoring what you had said and elaborating upon it — in part because I felt enough people were arguing with Didactylos already. People tend to become unreasonable when they feel attacked and put on the defensive — and several people simultaneously arguing with you will oftentimes result in your feeling attacked.
Timothy, While I agree that Barton has some homework to do before he’s made his case, I would also contend that his is not an implausible scenario. Midcentury will indeed be a period of extreme stress on the biosphere and on our ability to feed what (I hope) will be the crest of human population. In looking to bound potential impact of climate change, it is not a scenario that we can dismiss lightly by mumbling incantations like “water management” and “alarmist”. For one thing, the scale of water management that would be required means we’d have to get started right about…10 years ago. Given our track record on energy–where again, we are about 40 years behind where we should be–this doesn’t exactly fill me with hope.
I would say that in general, we are about 40-50 years behind where we should be in all aspects of developing a sustainable economy…and even if we manage to negotiate food insecurity, environmental degradation, climate change and resource depletion, we’ll still have to confront something that isn’t even on the radar screen yet. How do we have a stable economy when population is actually decreasing and aging? If people think the sovereign debt crisis is a bear, wait ’til they confront that one.
331 Timothy Chase, Ray Ladbury, Didactylos et al.
Now that we have much common basis for discussion, consider the resources that are hugely abundant. These are coal and water. I realize that there are those who would not put water on the list, but in the context of climate crisis, perhaps it is time to rethink our boundaries on this point.
I maintain that the question is whether we can use these resources wisely. If there was a policy of limiting increases in use of coal such that CO2 from that increased use was no more than the amount of CO2 that could be taken up by new systems, an example of such being forest agriculture, then there might be a balanced policy here that would hold for a long time.
We might discuss whether it would be necessary to balance current rate of coal caused CO2 as well. But if the scope of the forest project were limited to just balancing the increase in coal from this day forward, then the cost might not seem as daunting as Didactylos sees it.
I was concerned when I saw the Craig Ventner activities related to production of genetically modified algae, where that seems potentially hard to control. On the other hand, genetically modified trees seem like a reasonable thing to consider in order to get the growth and climate suitability of a very large new forest in areas not presently heavily forested.
But a larger form of agrarian solution could involve nothing more than stimulating growth of plankton in the ocean. According to elementary information, plankton presently grows in bands are adjacent to land masses, due to the need for nutrients from land which are airborne over the bands. The goal would be to stimulate plankton growth so that it grows more rapidly on the edges of the present bands, and the bands would also be enlarged by a modest amount. The action needed would be some system of enhancing distribution of nutrients that are currently limited to what winds can carry from land.
Happy holidays.
Jim Bullis,
Water is in fact one of the limiting factors in most calculations regarding our prospects for the simple reason that everything we do requires it.
Similarly, coal, even if there were a feasible carbon capture scheme, is finite. I would much rather see it held in reserve for a feedstock to chem labs than burned.
And of course the biggest problem: our leaders aren’t leading. They are allowing the people to bask in their ignorance. Human stupidity and ignorance seem to be the only two inexhaustible resources we have to work with.
Tim Chase 331,
Which part of “70% of Earth’s land surface will be in severe drought by 2050-2055” did you not understand?
Ray 334,
Cf Albert Einstein’s comment…
Jim Bullis, what I get from all of your comments is this: you are willing to move heaven and earth (literally) to perpetuate the use of coal for generating electricity.
That makes no sense. There really is nothing else to say about it.
RayLadbury:
That one is currently being “confronted”, by the white American Christian right, search a bit on “Demographic Winter” – climate change is meaningless to folks concerned with insuring their own genes and culture predominate.
flxible@338,
Yes, knowing that the problem is being contemplated by imbeciles will, I’m sure, be a great comfort to me.
Ray Ladbury @ 313:
Sigh.
We still have plenty of dirt. “Dirt” gets made all the time, and proper soil management, along with proper crop management, insures that there will be more “dirt” tomorrow than today, if only they do the needful.
The problem is that intensive farming no longer includes “do the needful” as a step. It doesn’t pay to engage in soil conservation or management, so farmers don’t do it as much as they used to.
And that’s where the dirt went — down the toilet along with the rest of sound business practices.
Another good idea, Jim. Whales used to take care of that:
http://rspb.royalsocietypublishing.org/content/early/2010/06/14/rspb.2010.0863.full
Found among these: http://scholar.google.com/scholar?q=stimulating+growth+of+plankton+in+the+ocean
Barton Paul Levenson wrote in 335:
For starters, the bit where it says “peer reviewed.”
Well, I’ve sat this discussion out, pretty much–probably a good thing. Food for thought, though, all of you–so thanks.
And Merry Christmas!
(ReCaptcha gnomically opines, “slightly perbrial.”)
ReCaptcha, perhaps in a holiday religio/political spirit–is showing me:
Ephesian Rentist
And to all a good night.
BPL: Which part of “70% of Earth’s land surface will be in severe drought by 2050-2055″ did you not understand?
Tim: For starters, the bit where it says “peer reviewed.”
BPL: I’ll let you know when I hear back from J. Climate.
Barton Paul Levenson wrote 346:
Sounds good — and I wish you luck.
http://maps.thefullwiki.org/Cold_seep
“Cold seeps were discovered in 1984 by Dr. Charles Paull in the Gulf of Mexico at a depth of . Since then, seeps have been discovered in other parts of the world’s oceans, including the Monterey Canyon just off Monterey Bay, California, the Sea of Japan, off the Pacific coast of Costa Rica, in the Atlantic off of Africa, in waters off the coast of Alaska, and under an ice shelf in Antarctica. The deepest seep community known is found in the Japan trench at a depth of 6400m ”
http://www.mbari.org/benthic/coldseeploc.htm
http://www.gulfbase.org/facts.php
“The Gulf of Mexico basin is a relatively simple, roughly circular structural basin approximately 1,500 km in diameter, filled in its deeper part with 10 to 15 km of sedimentary rocks that range in age from Late Triassic to Holocene (approximately 230 m.y. to present). ”
“Since Late Jurassic time, the basin has been a stable geologic province characterized by the persistent subsidence of its central part, probably due at first to thermal cooling and later to sediment loading as the basin filled with thick prograding clastic wedges[1] along its northwestern and northern margins, particularly during the Cenozoic.”
[1] “prograding clastic wedges” is geology speak for a large pile of sediment eroded from mountains or continents that’s grown thick enough to begin cementing into sedimentary rock, and gets thicker/older further away from the source.
http://www.halliburton.com/public/solutions/contents/Deep_Water/related_docs/GOM_DWMap.pdf
http://emvc.geol.ucsb.edu/downloads.php#SBoil
http://people.whitman.edu/~yancey/califseeps.html.
“2. DEEP SEEPS
Oregon–1800-2000m; Alaska–4400m; JAPAN–1100m, and Trench 6400m
These are methane and sulfide seeps at various locations in the Pacific. The Oregon ones are on the continental shelf. The Alaska ones are in the Aleutian Trench. The Japan ones are in Sagami Bay and Okinawa Trough (about 1100m) and the Japan Trench.”
http://www.tdi-bi.com/our_publications/ogj-hf-july02/figures/fig5.gif Oil formation requires >100 deg C, which occurs below ~3km sediment thickness. Because the old deep seafloor starts at about 2-3 degrees centigrade, has had millions of years to lose the heat it originally had near the mid ocean ridge, and has moved away from the hotter mantle underlying the ridge, the geothermal gradient is lower and would require even deeper burial to achieve oil maturation temperatures.
http://www.geology.yale.edu/~ajs/1999/07-09.1999.02Hedges.pdf discusses the decrease in rate of burial as the distance offshore increases, and the concurrent increase in the amount of oxidation and removal of the organic fraction of sediments, because they are exposed for longer periods to diffusing oxygen and microbial degradation the slower they are buried.
www-odp.tamu.edu/publications/110_SR/VOLUME/…/sr110_02.pdf shows the stratigraphy of a core from the abyssal plain northeast of S. America, which collected turbidites from the Amazon and Orinoco basins. the core is ~500 meters long, and represents 50 million years of seafloor history. The slow 1 cm per thousand year accumulation of sediment exposed the organic contents to oxygen diffusing in from the seawater, and allowed microbial metabolism to “burn” the carbon therein to CO2, which was carried away by bottom currents.
http://science.jrank.org/pages/47908/ocean-basins.htm
http://www.enotes.com/earth-science/abyssal-plains
ecco.jpl.nasa.gov/~jwillis/willis_grl_10.pdf – Argo floats and satellite altimetry used to better measure and constrain MOC; he finds that the flow of surface water north (and necessarily bottom water South) to be ~18 Sv, the number I used for a crude estimate for overturning time.
http://www.sciencemag.org/content/286/5442/1132.abstract
“Chlorofluorocarbon-11 inventories for the deep Southern Ocean appear to confirm physical oceanographic and geochemical studies in the Southern Ocean, which suggest that no more than 5 × 106 cubic meters per second of ventilated deep water is currently being produced. ” (=5Sv, less than 1/3 the Atlantic thermohaline circulation)
Keep in mind that the coastal upwellings (Benguela, East Africa,) that short circuit the AMOC, and reduce the flow available to ventilate Pacific deepwater, make its residence time longer. There are areas of deep ocean where the currents are sufficient to scour the sediments off the bottom, but the existence of the abyssal plains with their smooth coat of ancient sediments argues for large areas of ocean bottom with slow currents.
I am sceptical of assumptions in this post.
Assumption 1. We can trust the trillion tonne argument. This seems to argue that another half trillion tonnes of CO2 can be added to the atmosphere and we can still keep in the comfort zone of an average temperature rise across the earth of 2°C.
Firstly 2°C may not be much of a comfort zone – even a one degree temperature rise may be worse than expected. In “Intensification of hot extremes in the United States”, Diffenbaugh and Ashfaq report that substantial intensification of hot extremes could occur within the next 3 decades, below the 2 degrees Celsius global warming target currently being considered by policy makers. Elsewhere Diffenbaugh says
“Frankly, I was expecting that we’d see large temperature increases later this century with higher greenhouse gas levels and global warming, I did not expect to see anything this large within the next three decades. This was definitely a surprise.” and
“It’s up to the policy makers to decide the most appropriate action but our results suggest that limiting global warming to 2 degrees C does not guarantee that there won’t be damaging impacts from climate change.”
Secondly the climate models should not be wholly trusted because they may underestimate both “known unknowns” and “unknown unknowns”. One of the proponents of the “trillion tonne theory” said of the low point in Arctic Ice in 2007
“Some claims that were made about the ice anomaly were misleading. A lot of people said this is the beginning of the end of Arctic ice, and of course it recovered the following year and everybody looked a bit silly.”
It seems clear now that Arctic sea ice is disappearing faster than the quote from Prof Allen implies and the albedo effect is serious and Arctic sea ice is some sort of tipping point. I doubt that this was fully represented in the computer models used in the calibration of the trillion tonne theory. I also understand that most climate models do not fully incorporate other potentially important feedbacks, such as temperature dependant greenhouse gas emissions from the Siberian tundra.
Assumption 2. We cannot (“economically” or “practically”) extract CO2 from the atmosphere. Yes we can. Biochar is one way. The most internationally recognised expert on biochar is Johannes Lehman who has said.
“To fully understand the potential of biochar, we have to realise that there’s a large amount of carbon dioxide cycling annually from the atmosphere into the biomass by photosynthesis, being recycled by micro organisms, back to the atmosphere. This is a huge amount of carbon that is cycling annually between the atmosphere, the plants and back to the atmosphere. So much that every few years (actually about fourteen years), the entire atmosphere has gone once through the biomass, (the plant biomass) and back out again. So if we capture only a small proportion of that carbon annually fixed by photosynthesis and are able to divert it from this fast biological carbon cycle into a much slower cycling, biochar cycle, we have a technology that then delivers net reductions of Co2 in the atmosphere. If you compare this annual cycle, that’s about sixty or eighty megatonnes of carbon through the plant biomass, with the annual anthropogenic emissions that are anywhere in the neighbourhood of seven or nine megatons annually then you realise that we only need a small fraction of this annually cycling carbon to be captured into a biochar cycle to put a significant dent into the emissions.”
There are, of course, other ways of extracting carbon from the atmosphere, even without fancy technology: chop a tree sink it in the sea.
Assumption 3: The long term is much more important than the near term. The near term is full of dangers and unexpected consequences. The current cold spell in Europe may be one minor example. If damage is too great in the near term, there will not be enough resources to cope with the long term.
Concentration on the long term may downplay the importance of the rate of climate change. Given time, we may be able to reorganise food production to cope with new climates, rebuild the infrastructure disrupted by changing climate and, just possibly, invent new technologies.
348 Brian Dodge
You put a lot into this comment, of which I particularly notice the information on deep oil discoveries that contradict your earlier assertion in 311 that the colored ocean areas would not seep oil. You add methane seepage information which would also be potentially corrupting of carbon dating results.
You conclude noting that there are large areas of deep ocean with slow currents. Here I point out that I am noticing measurements of deep ocean currents in the 2 cm/sec up to 30 cm/sec and these speeds would qualify as ‘slow’. My point is that the MOC should include these deep regions since the opportunity for seawater transport is huge, even though the rate is so slow. For explanatory purposes only, consider Northerly flowing surface current down to 50 meters and Sourtherly flowing deep currents down to 5000 meters. The relative cross section of the deep flow would be 100 times larger, whereby a continuous cycle with 2 cm/sec at the deep part would require 2 meters/sec at the surface.