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.
349 Geoff Beacon,
Your assertion that we can (“economically” or “practically”) extract CO2 from the atmosphere biochar is not correct, though the basic biochar idea has some merit. I say it is not correct because I perceive that it would require use of land, water, machinery, and labor in large measures. Taking land that could be productive for establishing a biochar cycle as you describe is an action that would remove land from potential or actual food production.
I say that it would be better to store carbon compounds in standing forests. Biochar would be a useful adjunct to that basic standing forest system as a part of the eventual forest management process, as a way of cleaning up after limited harvesting as well as a part of brush clearing processes along the way.
While the forest project could be part of an overall mitigation plan, I now would look more carefully at possibilities based on ocean based natural processes.
337 Secular Animist
Sorry you think the subject of coal is closed.
Given the realities of energy, both importance and limitations, I work to find ways to make it all work for everybody.
As I see it, the longed for elimination of coal could be achieved by significant changes in life style, but forcing such change on the public amounts to a form of social engineering that I am uncomfortable with; so my general approach is to find ways to make life as we choose to live it work out in the best way we can manage. Getting CO2 under control is part of making things work out. But pre-judging that it has to involve eliminating coal is short sighted.
The generally held view seems to be that the forest and water plan would be hugely expensive is ignoring of the experience with irrigation systems, most notably the California aquaduct, which has returned investment many times over through agricultural productivity increase, and still has handled a big part of the water needs of Los Angeles County.
278 BPL
In response to my challenging the existence of 1000 year old water, you announced that I should, “Crack an oceanography textbook. It’s not controversial.”
Ah, these words are like the clank of steel to an old warhorse. (Please forgive the metaphor.)
Where might I find such an oceanography text?
[Response: Google “Deep Pacific 14C age” – gavin]
Re 353, gavin inline
I will, but in the meantime look at the paper at: https://abstracts.congrex.com/scripts/jmevent/abstracts/FCXNL-09A02a-1801224-1-foam_whitepaper.pdf
Here they say:
Turbulent diapycnal mixing in the ocean controls the transport of heat, freshwater, dissolved gases, nutrients, and pollutants. Though many present generation climate models represent turbulent mixing with a simplistic diffusivity below the surface mixed layer, the last two decades of ocean mixing research have instead revealed dramatic spatial and
temporal heterogeneity in ocean mixing. Climate models that do not appropriately represent the turbulent fluxes of heat, momentum, and CO2 across critical interfaces will not accurately represent the ocean’s role in present or future climate.
Re 353 gavin inline also,
I found this interesting re the effects of hurricanes in vertical ocean mixing which we discussed a couple years ago:
http://tao-tc.ucsd.edu/WEB_DATA/PUBLICATIONS/DAsaro_cold.wake.frances_GRL_2007aug.pdf
Re 353 Gavin inline
Sampling of the many found items seems to yield nothing that would acknowledge the possibility of corruption of samples by deep bacteria digestion of oil, though it is clear that this is not a simple subject.
A representative statement is by Adkins and Boyle 1997:
Accelerator mass spectrometry (AMS)
studies of the radiocarbon content of contemporary benthic and
planktonic foraminifera have provided our only direct
information on these rates [Broecker et al., 1988; Shackleton et
al., 1988; Duplessy et al., 1989; Broecker et al., 1990a, b;
Duplessy et al., 1991; Kennett and Ingram, 1995]. In these
studies, it is assumed that the age difference between benthic
foraminifera and planktonic foraminifera from the same depth in
a sediment core is equal to the radiocarbon age difference
betweent he waters in which they grew. By comparing benthic
and planktonic pairs from different depths in the core, the
radiocarbon age history of deep water at one site is then
reconstructed.
I suggest that the use of benthos as the reference is fundamentally corrupting of the results.
[Response: Sorry, but this is nonsense. Benthic foram isotopes have been measured for 50 years everywhere in the ocean, compared to in situ water properties, cultured in labs, scanned with electron microscopes, have been replicated up the wazoo, form the basis of a whole science (paleoceanography), show the same patterns across all the oceans, etc. etc. Your idea that somehow all of this is just some artifact because you think they are all eating oil (even in areas where there isn’t any?) is completely without foundation. – gavin]
356 Gavin inline
Would it not be nonsense to rely on age data for deep water to prove that deep water was not moving, when the very fact of moving water would enable the distribution of deep oil products that would corrupt the data to make the data look like water was not moving?
And there is substantial oceanographic data that shows that deep water does move substantially, though sluggishly.
[Response: Huh? If there is a finite age, then there must be movement (otherwise the age would be infinite). Who has claimed that the water is not moving? And where did this nonsense about oil contamination come from? Please get back to discussing something real. – gavin]
357 Gavin
The question is whether water is moving slowly or very, very slowly; like will surface water be brought into the deep ocean at a significant rate with respect to heat and CO2.
If it is 1000 years old, you know of course that this indicates very, very slow motion and it would not be necessary to consider it in the modeling. Neither does Rahmstorf consider the deep ocean to be a significant part of the thermohaline circulation.
The active bacteria in the deep ocean is well known, and since this would leave its products in the deep water, the idea that it would corrupt the dating method is self-evident, and need not have come from anywhere in the peerage. I was reminded of it in connection with the BP spill and then further from recent pictures of the Titanic railing, which was said to have been eaten by said bacteria.
[Response: The deep ocean is not significant to the thermohaline circulation? Really? Well, this is clearly an ingrained issue for you and while I can’t see the obviousness of bacteria messing up 14C dating (or even its sense), you obviously can. You would have thought that if it was so obvious that a well used technique was so flawed someone would have mentioned it, but maybe that’s just me. I think there is little more for me to add. – gavin]
Geoff Beacon @349 — The 0.8 K increase so far already is having some severe consequences.
JB 352: pre-judging that it has to involve eliminating coal is short sighted.
BPL: It’s not pre-judging. It’s post-judging after hundreds of years of experience with the damn stuff.
Jim Bullis #355. I don’t claim that biochar is the answer to “life, death and everything” but I believe that Raypierre is being too optimistic in his “Trillion tonne” scenario. As David Benson says @359 the 0.8 K increase so far already is having some severe consequences. If the physical and political realities are worse than Raypierre believes, what would you do?
Do we keep eating methane generating beef and lamb? (These also crowd out much more productive sources of food.)
Do we keep trucking with soot producing diesel engines?
Do we leave CO2 in the atmosphere because we refuse to pay the price?
Let me know.
It would be interesting to know what climate feedbacks were missing from (or underestimated in) the climate models used in the calculations in the Trillion Tonne Scenario. Arctic sea ice and greenhouse gas emissions from the Siberian tundra are probably missing but other possible feed backs may be missing also: under-sea clathrates, Amazon die-back, carbon sinks failing, insect infestations in boreal forests, forest and peat fires.
How many of these feedbacks might be significant?
Are there any missing ones?
Are any of the feedbacks accounted for in the models for the Trillion Tonne Scenario?
http://blogs.ei.columbia.edu/2010/12/14/deep-ocean-heat-is-melting-antarctic-ice/
Zaehle et al. “Terrestrial nitrogen feedbacks may accelerate future climate change” http://www.agu.org/journals/ABS/2010/2009GL041345.shtml
Is this another feedback missing from the Trillion Tonne Scenario?
Is it sigificant?
Geoff, you’re basically asking for results from a comparison of two or more different climate models — part of a large ongoing effort — and you’re asking for comparison of one old and one new model that are very different.
The original post refers to the UIVC climate model (http://climate.uvic.ca/model/ ) — the documentation for UIVC discusses comparing different climate models and how it’s done by their working group.
Zaehle’s papers (several) describe results from the “O-CN land surface model”– a new model.
You ask what difference Zaehle’s numbers would make — the abstract gives their results: “… increase atmospheric [CO2] in the year 2100 with a median value of 48 (41–55) ppmv, corresponding to an additional radiative forcing of 0.29 (0.28–0.34) W m−2.”
You ask if that’s significant. What would the answer mean?
The original post says “It’s cumulative carbon that counts, and pretty much it is the only thing that counts.” — referring to fossil carbon going into the air, that the total amount is what matters, not how fast we do it. So it wouldn’t matter if it’s from clathrates or coal or tundra, what matters is how much carbon.
Zaehle’s papers say more carbon may stay in the atmosphere a bit faster.
Years ago I worked as a cave guide. On every tour, someone would ask “How many miles of unexplored passages are there in this cave?”
Time will tell. If you look at the climate model comparison work, it’s being published slowly. Your particular question will be answered, but probably not immediately.
361 Geoff Beacon
You say, “- – increase so far already is having some severe consequences. If the physical and political realities are worse than Raypierre believes, what would you do?”
I say, “The most immediate physical reality is that industrial production in the developed world is badly sagging. That will drive the political reality; haphazardly of course due to chaos of our government. My perception is that the political reality will stymie attempts to change our energy supply, whereby nothing much will change, though there could be damage to the economy due to the incompetence of attempts to change this energy system.”
Further I say, “Good or bad weather is not compelling evidence of climate change. Measured increase in heat content of the oceans is evidence of CO2 excess, and increased heat content will probably cause a significant sea level rise.” Where heat content causes ocean surface temperature changes, weather patterns would change.
You ask what I would do, rhetorically I think, but I will answer the direct question.
I would continue to try to sort out the ocean effects which seem to be inadequately handled at this time. I rattle between Junior High level stuff and unreadable papers from the peerage, and then get the ‘that is the way we do it’.
It is particularly curious that deep ocean currents of 2 cm/sec are accepted as truth, but deep ocean water is said to be thousands or more years old. I see this as important since it relates to how the ocean will react to the problem.
The ocean is important in storing heat which would otherwise heat the atmosphere. It also has a role in storing CO2 which works against the fundamental CO2 imbalance. I question why this is not a focus of science, in particular, why would we not stimulate growth of the plankton which is a key part of the mechanism of that storage.
I think people should choose what they want to eat. My choice is usually fish, but it is getting harder and harder to find supplies of that. Breakfasts are almonds and home-made V9. (Better than V8.) But please leave me a good hamburger now and then from ‘organic’ beef.
I know how to build fast cars and trucks that would use around 70% less mechanical energy from whatever generating mechanism, and I should be working more on these. The market is discouraging of this activity, partly because of would be ‘green’ interference.
Diesel engines are good things, though they need not be so big. (My trucks would use one-third sized engines, maybe smaller.) The real issue is not so much about soot as it is about NOx compounds due to the high combustion temperatures. Though regulations are causing costly adaptation, these are desirable and necessary. Good news seems likely with the developments of catalytic converters that would eliminate these NOx compounds. These could do a lot to eliminate the last remnants of soot as well.
It appears we could pay a high price to remove CO2 or we might think a little more find low priced answers. Massive forestation is one cost effective answer, where water distribution would enable the forestation while also providing agricultural productivity to pay the way. Maybe providing nutrients that would stimulate plankton would also work cost effectively.
We should think a little about the obvious stratagems that would foist the load onto the industrial world, though this will reflect back on everyone. Another misguided effort is to hype up electric vehicles as CO2 reducing solutions, which they most definitely are not; and government repeal of the Laws of Thermodynamics will not change the facts – – though ignoring thermodynamics and naive expectations about electric power production will confuse and make cynical the public. Continuation of the system of central power plants is continuation of a hundred year long disaster of waste, and smart grids perpetuate this and shifting to natural gas power plants is a halfway measure that will take away from supplies of natural gas that could be more beneficially used in distributed cogeneration systems for electricity production.
Do we keep eating methane generating beef and lamb? (These also crowd out much more productive sources of food.)
Do we keep trucking with soot producing diesel engines?
Do we leave CO2 in the atmosphere because we refuse to pay the price?
I question why this is not a focus of science, in particular, why would we not stimulate growth of the plankton which is a key part of the mechanism of that storage.
But it has been the focus of scientific study. The extent of scientific knowledge is not governed by your inability, or disinclination to use google.
Iron fertilization won’t work. For an explanation see here:
Can ocean iron fertilization mitigate ocean acidification? = Nope!
Hank Roberts #355
Thanks for your reply but it is not relevant to compare climate models. We should worry about the Trillion Tonne Scenario if the models used have missing feedbacks. It’s not relevant that newer models exist.
The original post does say “It’s cumulative carbon that counts, and pretty much it is the only thing that counts.” But:
1. The post assumes that human activity is responsible for cumulative carbon emissions. But temperature driven feedbacks cause emissions which eat into “our” trillion tonnes – the coal in “clathrates or coal or tundra” are our emissions the “clathrates and tundra” are not but they diminish our leeway.
2. It’s not “cumulative emissions” that count but the amount of greenhouse gasses in the atmosphere. We must extract it.
3. The speed of climate change does matter because the world needs the time to come to grips with the enormity of it all. In economics that’s called Real Options Analysis. Plan for the near term so we can still cope when predictions fail.
Nobody here has given any comfort about modelling feedbacks in the Trillion Tonne Scenario. Is the worrying conclusion that it hasn’t been done?
Jim Bullis #366
Thanks Jim. That’s the sort of thinking we need. I don’t agree with all your conclusions but the division of “experts” into their silos makes it difficult to design lifestyles that will enable us to cope. We need a profession that combines climate science, economics, psychology, town planning, agriculture, horticulture, architecture, etc.
Not much on the horizon.
369 Geoff Beacon
Argh! No engineers needed?
Jim
Stupid of me.
Note to my MP:
Note for Hugh Bayley MP
31st December 2010
Dear Hugh,
Thank you for following up my note to Chris Huhne. You may remember that one of my concerns was the climate modelling that formed the basis of the Trillion Tonne Scenario. I referenced the paper:
Allen et al, “Warming caused by cumulative carbon emissions towards the trillionth tonne”. Nature 458, 1163-1166 (30 April 2009).
The worry that I had then and in earlier notes was that current government thinking does not cope with these contingencies:
– A failure to control global greenhouse emissions soon
– Feedbacks reacting more strongly than expected.
An associated worry concerns the Climate Change Committee, who in referring to one possible feedback, have told me
“we do not assign probabilities to methane release because we do not yet know enough about these processes to include them in our models projections.”
Also I have formed the impression that the speed of Arctic sea ice melting has not been fully appreciated. This is considered to be a significant feedback. See “Disappearing Arctic sea ice”, http://www.brusselsblog.co.uk/?p=45
You may also like to look at “Plan A might fail … so we need Plan B”, http://www.ccq.org.uk/wordpress/?p=139
I occasionally post on an excellent website https://www.realclimate.org, a site run by serious climate scientists. The site is a great help in understanding climate change. A few days ago I posted on this site, which ran a piece relevant to the Trillion Tonne scenario, raising similar concerns to the Chris Huhne note. See:
https://www.realclimate.org/index.php/archives/2010/12/losing-time-not-buying-time/comment-page-8/#comments
This is a topic which is of importance: If the climate models used in the Trillion Tonne Scenario are underestimates, Government policy needs to be updated. I have had no reply from the climate scientists as yet. I will keep you informed.
I will post this note on the RealClimate website.
Happy New Year
Geoff
371 Geoff Beacon,
Thanks for acknowledging a simple oversight.
Happy New Year
You can compare Zaehle’s estimated additional radiative forcing to the last IPCC report’s estimaged numbers.
For the latter if you don’t go to the IPCC source, there’s a good summary here: http://atoc.colorado.edu/~seand/headinacloud/?p=204
Looks like about a 20 percent increase. Not trivial, but not unmanageable.
Compare the size of various stabilization wedges: http://www.worldlingo.com/ma/enwiki/en/Stabilization_Wedge_Game
This sort of thing is being looked at all the time; the next IPCC report is explicitly looking more at uncertainties, this would be one such.
Thanks Hank Roberts #374.
Your calculation that Zaehle’s estimates add 20% to radiative forcing is useful and worrying for me. What about the other feedbacks that may have been underestimated?
Don’t we need to know the size of the problem now so policy makers can be influenced to come up with plausible scenarios? My experience is that government departments are reluctant to believe things that are inconvenient. I am suspicious, for example, of the UK Department for Environment, Food and Rural Affairs as seen through their website. For example their website makes it very hard to find work on the carbon footprint of beef and lamb That is despite the fact they commissioned some good work on the subject. Look at Adrian Williams website here:
http://www.cranfield.ac.uk/sas/aboutus/staff/williamsa.html
Then try and find the work on the DEFRA website without the key code “IS0205 “work he did on the carbon footprints. Using the key code you may also find a later publication “The Environmental Impact of Livestock Production”, a review of research and literature. I read this document as greenwash and an attempt to hide the impact of Dr William’s findings. The Executive summary starts
“The main domestic livestock sectors produce a wide range of products (food, leather, wool
etc) and public services, such as employment, landscape and cultural heritage. However
livestock production impacts on the environment in a variety of ways, both positive and
negative, but there are some systems where there is greater potential for the environment to
be compromised in order to achieve efficient production. The key is to minimise negative
impacts in the most cost-effective way.”
I wouldn’t balance “employment, landscape and cultural heritage” against the climate crisis. Landscape and cultural heritage are either NIMBY terms or meaningless. If we really wanted to create jobs there are easier ways – see http://www.morejobs.co.uk.
Geoff, I did no calculation; I eyeballed two numbers. Not even long division.
Look at the sources I linked to, but such a calculation won’t mean much taken in isolation — it’s at most, if it’s real, one additional factor contributing some uncertainty to one side of a broad uncertainty range. The next IPCC will be assessing this stuff from more than just a couple of numbers.
I think the most you can say is that we’re not confident we know the worst.
No news there, really, except perhaps for the politicians who want more certainty than the facts we know allow.
More unfortunate consequences surface:
http://www.thespacereview.com/article/1723/1
“… black carbon soot emitted by rocket engines…. deposited in the stratosphere, could have a significant effect on the atmosphere should space tourism and other applications of commercial suborbital vehicles generate significant demand for flights….”
http://www.agu.org/pubs/crossref/2010/2010GL044548.shtml
Hank
“The next IPCC will be assessing this stuff” … too late.
Look at practical decisions such as the North Yorkshire incinerator plan. The York Press reports “[Harrogate and Knaresborough’s new MP Andrew Jones] said he would argue that the project would mean North Yorkshire County Council committing £90 million, plus £1 billion in operating costs over 25 years. “
This is one example of future options that will be constrained for decades to come, without the help of the IPCC’s wisdom. If we knew now what truths the next IPCC will pronounce, we could argue for more radical options because we can be certain the picture will be more scary than the last one. Even those of us that idly google the current situation know the situation is scary. We also worry about reports of how the IPCC is politically constrained and out-of-date on publication.
P.S. A more radical solution to the incinerator? Smaller incinerators with heat recovery for local housing and with carbon capture. (See “Incineration is best”, http://www.ccq.org.uk/wordpress/?p=79). There are, of course, others.
P.P.S. A more radical solution to the IPCC. Sorely needed.
378 Geoff Beacon
You slipped that bit about ‘carbon capture’ in which goes beyond the descriptions of the small incinerators in your reference.
Even without that, the cost of the various scrubbers for pollutants, including oxides of nitrogen, make the heat recovery systems difficult to implement in competitition with the old options. Throw in a requirement for ‘carbon capture’ and the whole project is sunk.
We in the USA already have a lot of cost in-effective things going on with trash.