Geoengineering is increasingly being discussed (not so sotto voce any more) in many forums. The current wave of interest has been piqued by Paul Crutzen’s 2005 editorial and a number of workshops (commentary) and high profile advocacy. But most of the discussion has occurred in almost total ignorance of the consequences of embarking on such a course.
A wider range of people have now started to publish relevant studies – showing clearly the value of continued research on the topic – and a key one came out this week in JGR-Atmospheres. Robock et al used a coupled GCM with interactive aerosols to see what would happen if they injected huge amounts of SO2 (the precursor of sulphate aerosols) into the tropical or Arctic stratosphere. This is the most talked about (and most feasible) geoengineering idea, based on the cooling impacts of large tropical volcanic eruptions (like Mt. Pinatubo in 1991). Bottom line? This is no panacea.
Figure 1: Results from Robock et al showing the imapct on temperature of their scenarios.
So what are the problems? Robock’s study looks at a subset of the potential ones – in particular, the impacts on precipitation. These arise because evaporation is more sensitive to changes in solar radiation than it is to long-wave radiation – so increasing LW and decreasing SW (as you would have in a geo-engineered future) gives a net reduction in evaporation even if the temperatures stay pretty constant. In the experiments they report on, there is a substantial reduction in rainfall in the northern tropics (especially the Sahel and the monsoonal belts). This is actually quite a robust result: reductions in tropical precipitation were reported in simpler tests of this idea in papers by Matthews and Caldiera and Bala et al.
Figure 2: The impact on precipitation in the geoengineered case compared to the control (no GHGs or geoengineering).
Other problems relate to the speed of any recovery if geo-engineering efforts should falter (let’s really talk about rapid climate change!), and impacts on stratospheric ozone, increases in acid rain in polar regions, possible indirect aerosol effects on high cirrus clouds (hopefully other studies in future will better quantify these). But the results so far give a flavour of the kind of issues any geoengineering implementation will involve. Notably, how does anyone balance temperature changes that effect ice sheets versus the failure of the Indian Monsoon? The Amazon drying up versus the North Atlantic overturning circulation? It would make the current international climate negotiators seem rather like medieval theologians.
Recently I heard geo-engineering likened to climate change methadone – an emergency treatment to substitute one addiction (carbon emissions) with another. This seems rather apt, and like the analogous situation with heroin, methadone isn’t going to be a cure.
#88 – David Benson,
Actually my #87 doesn’t imply there are any bad effects from a sunscreen at L1; but an obvious problem is geopolitical: if you can put a sunscreen there, who decides how much light is blocked, and on what schedule? Could it not be adapted for use as a weapon?
#94 – CL,
Actually, the ozone hole – or rather, the reaction to it – provides the best grounds we have for optimism about international agreements to curb AGW: the Montreal Protocol.
> on what schedule? … adapted for use as a weapon?
Nick, read Teller’s piece and look for later work citing it. This is an idea that would produce a slight overall dimming. It’s not a steerable shadow. Remember how big around the Moon’s shadow is during an eclipse? This is nothing at all like that size, no central dark spot at all. There’s no schedule or selectivity possible, from the geometry involved.
A fairly new blog from one of my longtime favorite publishers has attracted seriously interesting posts by a variety of authors.
Relevance here: ‘alternatives to geoengineering’
http://blog.islandpress.org/
Good writing. Recommended reading.
haven’t read through the comments yet, just wanted to quick mention/ask something…
Over geologic time, chemical weathering of silicate rocks that contain Ca,Mg, and other cations, allows for the inorganic portion of that part of the carbon cycle that takes CO2, ultimately from rocks, and puts it back into rocks.
While CaO is generally (as far as I know) produced from CaCO3, releasing CO2 in the process, I wonder if silicate minerals of the CaSiO3 (or more generally, … well, you get the idea) sort might be used to sequester carbon, speeding up the chemical weathering process. How much energy does it take to grind up typical igneous rocks? As long is the rock is ground up in the process, maybe some mining could be done, offsetting the money and energy costs of CO2 sequestration – maybe the Si could be used for solar cells, etc… and glass for mirrors… some of the mineral dust might be released into the air where it may have an aerosol cooling effect – it would buffer rather than add to acid rain, and would mitigate ocean acidification – tropospheric dispersal could allow for strategic release over the ocean without affecting land areas (perhaps too energy intensive given the short tropospheric residence time, but this aerosol cooling is not the sole purpose – it would take CO2 out of the atmosphere and/or reduce ocean acidification – or releasing it directly to the oceans would replenish the ocean’s ability to take up more CO2 ??) … Anyway, I’m not advocating we rely on this (risks and all that) – solar power looks cheap compared to oil right now anyway – but I just wanted to throw the idea out there. Basically I am wondering how energy intensive grinding up rock is. It can’t be too intensive for coal, or else it wouldn’t be useful as an energy source – but I’m guessing coal is a bit softer than granite or basalt (or andesite or syenite or gabbro or diorite…).
— actually, on that aerosol cooling thing – maybe it could just be put on top of the obsolete oil platforms (obsolete except for being retrofitted with wind turbines) and the wind could scatter it.
— Also, nanoparticle-TiO2 coated tarps could raise surface albedo and perhaps catalyse the oxidation of CH4 as the wind blows over it – well, that’s a bit farfetched perhaps.
Of course there’s coal gassification combined with fuel cells to boost efficiency. And using the waste heat. But whatever happennned to MHD? Did it not pan out?
I advocate turning coal strip mines into solar farms (West Virginia could be a solar state? – not that I want more mountains to be flattened). I’d suggest storing solar heat in coal tunnels but maybe that’s too dangerous! Although maybe compressed air…??
Very little has been said about the idea of creating more marine stratocumulus clouds over the ocean, to increase planetary albedo. A temporary temperature not CO2 concentration fix, but it might buy us some time. Seemingly a fine aerosol of seawater droplets would do the trick…not as dangerous or irreversible as shooting millions of tons of SO2 into the stratosphere.
I’ve put some papers up at http://www.4shared.com/dir/5557099/e3c120b3/sharing.html
Colin
(104) Patrick 027 Says:
“Basically I am wondering how energy intensive grinding up rock is. It can’t be too intensive for coal, or else it wouldn’t be useful as an energy source – but I’m guessing coal is a bit softer than granite or basalt.”
Using the Mohs scale of hardness (which is an ordinal scale), coal varies from around 1.0 (lignite) to 3.0 (anthracite) to 5.5 (bituminous).
Igneous rocks tend to be much harder, with basalt ranging from 6.7 to 7, and granite averages 7.0.
On the whole, igneous rocks have about the same hardness as quartz or glass.
{Capcha says “workable mouth.]
See comment 80.
Gross electrical yield, if it were as hard to powder as hard rock, ~2000 kWh/tonne; net of pulverization, 1950-1975 kWh.
Apropos the Arctic soil carbon store:
Re 55 iron fertilization of HNLI open ocean waters – it does cause massive phytoplankton blooms – 100X the biomass, turns the water green enough to see by satellite – but much of the carbon taken out of the atmosphere gets returned by decay/respiration as it moves up the food chain, and much less gets sequestered with the detritus that rains down to the deep ocean, taking the iron with it. It’s not the magic bullet once thought. google “ironex” to find more detail.
On another kind of geoengineering – what would be the effect of placing windmills in the arctic to spray a fine mist of ocean water when the air temperature is low enough during the winter to freeze it out into salty slushy snow? The idea would be to raise the air temperature so it would radiate away the excess heat absorbed by summertime open ocean, and create more wintertime ice/snow to insulate the methane hydrates and permafrost through the summer. Spreading salty snow over the arctic & adjacent land probably isn’t ecologically sound, but it might be better than runaway methane releases. My gut feeling is that by the time we have the sociopolitical wil to do something like this, it will be too expensive & too late.
Re 107,108,80,77
Thanks!
“Some discussion here has referred to the olivine dispersal idea “…
Well, I guess I should go back and read more – that sounds like what I was thinking of…
“The system is our planet’s biosphere, and tweaking it may very well lead, as Deming warned, to sub-optimization, decay, and the eventual destruction of the system. The fact that such ideas as geo-engineering are being given such serious discussion is troubling.”
I agree, Andrew. The thought of it scares the hell out of me, especially the thought of artificially removing CO2 from the atmosphere. The consequences of removing too much would not be fun, since all chlorophyll-based plant life relies on it, and no plants = no life. The cure could be much worse than the disease.
Tracy (112) — It is thought that humans have so far added an excess of 500 GtC to the active carbon cycle. That is a lot to remove so I’m certainly not concerned about removing too much.
Tracy, where do you get the notion it would even be possible to remove “too much” CO2 from the atmosphere?
Is that something you read someone suggests?
Have you had high school chemistry? That would reassure you. You know how gas bubbles out of a carbonated beverage when you open it? That’s because the amount dissolved in the liquid is out of balance with what’s in the air around it.
If somehow we had a huge outbreak of plants and ferns and mosses and lichen taking over the world and sucking up all the CO2 from the atmosphere — well, that would be returned as soon as any of it died naturally, but the oceans would be releasing CO2 even faster.
Seriously, this isn’t something that can happen on the human time scale. Where did you get the idea from?
Gavin,
You concluded:
Shouldn’t you have written “…, geo-engineering isn’t going to be a cure.”?
Heroin addicts only recover when they accept what they are doing to themselves, and even then many continue on to a squalid death.
We, like most heroin addicts, still seem to be in a state of denial. If geo-engineering is not the answer, can you provide any hope?
Cheers, Alastair.
#114 Hank Roberts
“If somehow we had a huge outbreak of plants and ferns and mosses and lichen taking over the world and sucking up all the CO2 from the atmosphere — well, that would be returned as soon as any of it died naturally, but the oceans would be releasing CO2 even faster.
As I said in my brief (experimental, first) post, the key word was artificial. An outbreak of plants and ferns (hell, even triffids, why not :)) is fine by me. I’d rather it was an outbreak of trees since they’d store it for considerably longer. And er, plants respire too and produce CO2, they don’t just release it on decay, but I’m sure you know that!
Seriously, this isn’t something that can happen on the human time scale. Where did you get the idea from?
Where did I get the idea from? It’s that scary word geo-engineering, which after all means a quick technological fix that will achieve results within the human timescale.
What’s the problem? Too much CO2 released into the atmosphere (which isn’t being absorbed, obviously, since CO2 levels have increased to what, approx 380ppm?) – therefore, the ‘simplistic’ technical solution is to remove it from the atmosphere, rather than prevent it from being produced in the first place. But yes, OK, the oceans will counterbalance – forgive me my stupidity – serves me right for posting late at night (and yes, actually, I do have A level chemistry, thank you)
But OK, you’ve reassured this ignoramous that on a human timescale, removing more than 500+ GtC from the atmosphere isn’t feasible.
Hey, I read this site to learn :) I know, you’re all scary climatologists who leap on us lesser mortals if we dare dip a toe in the climate change debate but you really need to do better at interpreting your data for a wider audience (not necessarily here, I know, you have no wish to dumb down, this is supposed to be about science, not politics etc). Because the Skeptics do a bloody good job at interpreting theirs! Unless you don’t want to win the battle for hearts and minds?
Chuckle. The real climatologists are usually identifiable, and the Contributors who make the site happen are listed in the sidebar.
Me, I’m just another reader, and I agree. Try interpreting in simple words as you understand what’s being written by the scientists — they’re good at telling folks like us when we get it right, get it wrong, or ask good questions.
Tracy (116) — Actually, removing the excess 500 GtC from the active carbon cycle can be done in less than a century by sequestering deep underground carbonaceous meterials such as biochar and torrified wood. The cost is about 15 of the world’s gross product during that interval.
It seems to me that the geoengineers are only substituting one kind of pollution for another kind of pollution. So2 for Co2. Much as oil substituted for coal. Or Freeman Dyson’s mutant trees.
The total energy content of the world is constant and the total entropy is continually increasing.
The First and second laws of thermodynamics.
That is true only if you exclude from the geoengineering category methods that directly remove CO2, such as olivine pulverization and dispersal, which can convert atmospheric CO2 to a stable solid mineral that could lie thinly over much of the world’s land surface without harm, or the above-mentioned burial of charcoal.
Another way to look at the fear of overshoot in removing atmospheric CO2: it is possible to remove 500 GtC about as quickly as it has been added, just as it is possible for a porter in an Everest expedition to carry a load halfway up.
Inadvertently removing far too much of it, putting the atmosphere into as unfamiliar a state as now, but on the other side of the preindustrial 280 ppm, would be like that porter’s forgetting to deliver his load at the intended camp, and instead carrying it on up to the summit.
David, does this presume someone will have solved the problem of coal mine fires, since charcoal ‘mines’ would also be at the same risk, maybe more so since more oxygen would be available in such deposits? Or is the source of your numbers presuming these deposits could be kept from catching on fire in some reliable way?
Stopping the current coal mine fires would make quite a difference to the current situation.
Re #118: Oh dear. Not 15, but 1%, one percent.
Hank Roberts (121) — If properly buried, there would be no oxygen present. One could assure this by pumping in CO2, which chemically binds to coal, so I suppose also biochar and torrified wood. The biggest unknown is just how long those buried carbonaceous materials would last before re-entering the active carbon cycle via the actions of micro-organisms.
The best, most recent, estimate I could find, from some Chinese researchers, puts the world’s coal seam fires at about 1/2% of the total excess CO2 added.
Far more important is cement production at about 4–5% (I think) of the total:
http://www.spiegel.de/international/world/0,1518,575023,00.html
To return to 350ppm CO2 or less, effort and expense will be required to remove the CO2 from the atmosphere. I’m a fan of both reforestation and carbon negative power plants that use forest and agricultural residue as feed stock and CCS on the exhaust stack. We must pursue these or similar activities to return to a healthy climate and will dial back our effort and expense as we approach the final CO2 target, with no chance of overshoot.
My fear is that we craft a solution that we cannot control. One speculation is that the desire for a high yielding alga for bio fuel farming will lead to a genetic engineered monster, an alga that will use the C4 pathway for increased photo-efficiency and some type of altered oil content that will resist decay to allow for maximum yields. If a cell that nature has not seen before is developed and introduced on land or sea, under the best of intentions, we may have a green slime that cannot be controlled. We don’t need a synthetic cellular Kudzu.
CO2 to cement:
http://www.spiegel.de/international/world/0,1518,575023,00.html
Thoughts?
> CO2 to cement.
Hopeful; much covered: http://www.google.com/search?q=%22Moss+landing%22+cement+Calera
Tests haven’t been done yet. Time will tell.
I’d think that eliminating all traces of salt from the product is important. I recall Berkeley has lots of old crumbling foundations made with ordinary concrete but using sea water, a century ago.
Nowadays with rebar in concrete, corrosion is also a concern. Moss Landing is using gas as fuel, not coal, so their stack exhaust gas is far cleaner. Getting clean CO2 out of a coal plant is already a challenge (especially since the Clean Air Act is under so much attack and industry doesn’t _want_ clean coal exhaust, see the mercury rulemaking challenges).
>Much covered (elsewhere)
True, but I was curious about what folks here had to say.
As always, thanks for your thoughts Hank.
John, if you’re worried about the uncontrolled propagation of algae, we’re already very deeply into that scenario. Ocean dead zones, driven by nutrient runoff, are expanding globally; it’s sometimes called “the rise of slime” by oceanographers. The metabolic products from these algae are often neurotoxic and threaten coastal wildlife and humans.
Jim thanks for the feedback. The conditions you describe are already underway, but they are reversible. Dead zones can retract if we reduce the nutrient runoff, increasing cost of energy and fertilizer will push us in this direction. Will we have the wisdom to be proactive and do more? Even the deep ocean becoming anaerobic can be reversed with great effort. If we allow our warming climate to go so far that it causes the shutdown of deep ocean currents responsible for maintaining oxygen levels for aerobic life, a MAJOR effort to reduce atmospheric CO2 could lead to the restarting of the deep ocean currents. Future generations may have no choice but to expend that MAJOR effort with the only alternative facing them being extinction. As hard as it may be to develop CCS, it is trivial compared to what the future will face if we do not face this AGW challenge in our own generation.
Jim, my final thought did not get appended to the last post. My concern is that a genetically engineered “solution” may have severe consequences that are not reversible under any circumstances.
This is the sort of surprise we have to expect — a change that slows down as temperature increase:
http://www.physorg.com/news139237236.html
______excerpt follows_______
The paper, published in a special edition of the Proceedings of the National Academy of Science, showed for the first time ….
“The chemical details of how the atmosphere removes nitric acid have not been clear,” Francisco says. “This gives us important insights into this process. Without that knowledge we really can’t understand the conditions under which nitric acid is removed from the atmosphere.”
An unusual aspect of the molecule helped it escape detection by scientists. The reaction involving this molecule proceeds faster as you go to lower temperatures, which is the opposite of most chemical reactions,” said Lester. “The rate of reaction also changes depending on the atmospheric pressure, and most reactions don’t depend on external pressure. The molecule also exhibits unusual quantum properties.”
http://www.mmm.ucar.edu/people/latham/
JF
David B. Benson #122:
Eh, your typo is a classic :-)
Does a low mean temperature help anyone if the poles stay warm and only the equatorial regions cool?
I hope now most reasonable people realize that natural greenhouse gas emissions from melting permafrost will soon overwhelm any cuts we make (i.e. any carbon dieting scheme is unfeasible):
“…Researchers were investigating “alarming” reports in the last few days of the release of methane from long frozen Arctic waters, possibly from the warming of the sea…” –“Arctic sea ice drops to 2nd lowest level on record,” AP, 27 Aug ’08
A frozen peat bog in western Siberia the size of France and Germany put together contains about 500 billion tons of carbon. Western Siberia has warmed faster than almost anywhere else on the Earth, with an increase in average temperature of about 3C in the last 40 years. More than half the land covered by the topmost layer of permafrost will probably thaw by 2050.
There is even more Siberian permafrost is under the ocean, an area six times the size of Germany containing about 540 billion tons of carbon. That submarine permafrost is perilously close to thawing. Three to 12 kilometers from the coast the sea sediment is just below freezing. The permafrost has grown porous, there is a loss of rigor in the frozen sea floor, and the surrounding seawater is highly oversaturated with solute methane.
“If the Siberian (submarine) permafrost-seal thaws completely and all the stored gas escapes, the methane content of the planet’s atmosphere would increase twelve fold. The result would be catastrophic global warming.” –“A Storehouse of Greenhouse Gases Is Opening in Siberia,” Spiegel, 17 April ’08
Please excuse me for repeating myself, but there is a very inexpensive simple way to immediately cool the Earth: just put a small amount of aerosol into the air to dim the sun. We won’t be able to stop rapid ecosystem collapse without geoengineering. Soon melting permafrost will overwhelm any cuts we make to our emissions.
Brad Arnold, While I agree that the potential for outgassing from permafrost and clathrates is a serious concern, let me get this straight: You suggest that we should give up on controlling carbon outputs, despite:
1)outgassing of ghgs will be a gradual process at first
2)aerosols will have an effect lasting at most a few years
3)we don’t understand all the possible side effects
4)CO2’s influence on climate is one of the best understood, while aerosols remain among the least certain.
That about got it? Excuse me, but wouldn’t it make more sense to play around with terraforming other celestial bodies first before mucking around with the only one we know can support life?
I’m surprised that the same governments that blindly speak of carbon taxes and emission targets do not also talk of simple changes to building codes (for example). If every house and building had nice white roofs we would all save on electricity bills in summer and also greatly reduce the amount of IR conversion. OK it would would look funny to see every house with a white tiled roof, walls and patio etc but if we all knew it was saving us money as well as helping to save our climate we would gladly embrace it. On the other hand a new big tax…Collectively we need to start thinking of using a myriad of simple solutions and right away because it doesn’t appear that a new climate zero energy source capable of replacing fossil fuels is coming any time soon.
I believe that increasing the albedo of low lying clouds has been seriously suggetsed and a solution proposed. In essense unmanned ships would use wind power to seed clouds by pouring water vapour into the air. Apparently it has the backing of two climate modelling teams and could keep the climate stable for decades.
http://physicsworld.com/cws/article/news/35693
There is little probability that governments and industry will ever agree to serious carbon emission reduction plans. No one will seriously do anything until its almost to late.
And then you are only left with geoengineering on funding scale that makes WWII look like a school lunch money. It would be far better for serious climate scientists and those environmentalists who dont subscribe to , 500 milion people in pre industrial society ideal, to seriously consider geoengineering options and study them in time to be able to give serious proposals to governments and industry 20-30 years from now when it finally becomes impossibly to ignore AGW and climate change.
“No one will seriously do anything until its almost to late.”
IMHO, that is where we are now. 2008. Almost too late.
I agree, at some point, there will be an obvious upheaval of some kind, a trigger that panics the masses, and the shockwave to the politicians and CEOs and public will cause such alarm, that there will be a huge flurry of action, and it will be ill-considered, and counter-productive, and make matters even worse.
http://www.youtube.com/view_play_list?p=143E59F5A37A9C84
‘wanted territory’
I am interested if there was rapid brief SO2 increase in March-April and July-August 2008 that might have caused the slumps in the global temperature possitive anomaly compared to the previous months,which can be seen from here by clicking on the wanted month. http://www.ncdc.noaa.gov/oa/climate/research/2008/perspectives.html The drop in the temperatures is mostly due to cooler lands and it is clear because of the property that it warms and cools easier and faster than the water.I know that in March there was volcano eruption in Kamchatka,Russia region and in July in Alaska .It is clear that equatorial volcano event is more influential to the global climate than polar but the first case is followed by significant cooling of the Siberia after the warmest March there and this SO2 might have resided westwards due to typical East winds in this region In addition it is strange that in both cases SST in Nino region,which is belived to be the main reason for the short time fluctuations of the global temperatures, were slightly increasing and no other shear reason for these slumps can be found .
In spite of searching the google neither I can find paper containing statistics for every recent volcanic activity and the quantity of SO2 ,nor any statistical graphics for the mean global SO2 consentration in ppm simular to those which are available fot the CO2.I would like to answer if someone knows a link for such data
If somehow we had a huge outbreak of plants and ferns and mosses and lichen taking over the world and sucking up all the CO2 from the atmosphere — well, that would be returned as soon as any of it died naturally, but the oceans would be releasing CO2 even faster.
It all comes down to economics and politics. The graphs persons in special interest funded research is somehow far more linear, less complex and leads to a conclusion that geoengineering would solve most of not all of our problems. For one it is difficult to predict long term trends and SO2 is not a good replacement either. The intermediates could pose problems, and the threats to human health, lung disease, COPD and asthma are of concern. Currently only small fighter jets can get to the stratosphere and they cannot get enough S02 there to make a difference. Funding into this type of project could prove still quite expensive.
Geoengineering with plants, bacteria and some plankton could provide more realistic and safe alternatives. Think about it, it is just basic chemistry, we could harnass carbon dioxide and capture carbon and increase plant biomass as well.
A little known option for removing carbon from the atmosphere is to collect, ship and dump agricultural (and commercial forestry) residues to the deep sea for long term burial.
A recent publication on this claims high efficiency and immediate availability, based on existing technology. Admitedly some further research would be needed.
Basically, this just might close the anthropogenic carbon cycle causing our problem.
http://www.sciencedaily.com/releases/2009/01/090128212809.htm
Hat tip to: http://www.climateshifts.org/?p=1293
“… After a series of moderate succeses over the past decade, it seems that the idea of sequestering CO2 in the oceans might truely be dead and buried. Project LOHAFEX, a joint Indo-German group, succeeded in seeding an area of 300km2 with over 6 tonnes of iron, resulting in a doubling of plankton biomass in just two weeks. What the team didn’t factor was the power of the ocean’s food web. Instead of the plankton bloom undergoing a natural death and sinking to the ocean floor (along with the sequestered CO2), the phytoplankton became an instant food source for hungry copepods, who in turn were consumed by a swarm of larger crustaceans (amphipods – see inset picture).
This ‘grazing effect’ was apparently absent from previous experiments, which instead stimulated the growth of diatoms. Diatoms differ from most phytoplankton in that they are protected from being eaten by protective shells made of silica. Whilst the experiment did succeed in providing new insights into the dynamics and ecology of plankton, to quote Ken Caldiera ‘I think we are seeing the last gasps of ocean iron fertilisation as a carbon storage strategy’.”