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.
The primary issue is not warming per se, but distribution of heat. Increased CO2 causes the arctic to warm, which melts ice, which floods coasts. Add sulphur and the entire planet can cool, but the arctic will still warm (and oceans acidify) as mankind keeps adding CO2. I noticed the graph shows arctic injection as a possibility. Is that an attempt to address this issue? How well can the cooling effect be localized to the poles?
RE: 29 I don’t think there would be any spikes in surface ocean pH or longer term impacts either. The quantities are just too small. Most of the aerosol would descend at high latitudes, but a significant fraction would also fall out globally, including over land. However, no studies have been carried out on the potential acidification impacts and would need to be before any large scale projects.
RE: 43 The idea of designing engineered particles instead of using those formed by chemical reactions is just that. An idea. It isn’t clear if it could be done either to reduce potential ozone depletion or extend the lifetime and increase the backscattering of the particles. My prediction is that by the time such materials could be produced in the quantities required, we will no longer need them.
RE: 51 Because of the way in which both upper tropospheric and lower Overworld stratospheric air moves, aerosol precursor added to either one at high latitudes is expected to drift south to around 30 degrees N within a few months. This is based on observations of volcanic eruptions at high latitudes. In addition to possible distal effects on monsoons, the aerosol formed cannot be contained to say within a few degrees of its formation and may require much more than if the area of interest to have the sunlight reduced is for example, 80 degrees N to the pole. There is still debate as to whether some kind of short term solar radiation reduction can be obtained by upper tropospheric releases that would have lifetimes of less than one season and that would not have spillover impacts like the ones mentioned here.
Edward Greisch wrote: “We all know that we have to convert all coal
fired power plants to nuclear worldwide by 2015, but it won’t happen because the
average American has an irrational fear of all things nuclear.”
We most certainly don’t “have to” build any new
nuclear power plants, let alone “convert” all coal-fired plants to nuclear,
in order to eliminate all GHG emissions from electricity generation.
The USA has vast commercially-exploitable solar and wind energy resources, that
are more than sufficient to produce several times as much electricity as the entire
country currently uses, and to electrify our transportation systems as well. This
can be done using existing technology, and it can be done far more quickly and at
much lower cost than building new nuclear power plants, with none of the toxic pollution
and grave dangers of nuclear power. And the technology is rapidly improving and
dropping in cost as it achieves economies of scale. Moreover, once the infrastructure
for harvesting wind and solar energy is built, the “fuel” is ubiquitous,
limitless, and free and there are zero GHG emissions — which is not true of the
nuclear fuel cycle.
By 2015 many, many gigawatts of new wind, solar photovoltaic and concentrating solar
thermal electric generation will be online in the USA and other developed countries
— long before even a single new nuclear power plant is operational. And in the
developing world, where rural electrification is vital for human well-being and
social and economic development, and where it is economically impossible to build
or operate large centralized nuclear power plants and the grids to distribute their
electricity, there is an revolution is small-scale distributed wind and solar electricity
generation. China in particular is rapidly becoming a world leader in both the
production and deployment of wind and solar technology.
There is simply no need for nuclear power, so there is no need to deal with its
toxic pollution and the grave dangers of catastrophic accidents or attacks on nuclear
facilities or fuel transports, or the risks of nuclear weapons proliferation associated
with the proliferation of nuclear power technology and nuclear fuels.
See: Changes in Earth’s Albedo Measured by Satellite
Bruce A. Wielicki, Takmeng Wong, Norman Loeb,Patrick Minnis, Kory Priestley, Robert Kandel,
Science 6 May 2005:
Vol. 308. no. 5723, p. 825
DOI: 10.1126/science.1106484
They say:
“Measurements from space since the 1970s give a global annual Earth albedo of ~0.29. The average incident solar radiative flux is 341 W m-2, so that a change in albedo of 0.01 represents a global energy balance change of 3.4 W m-2, similar in magnitude to the impact of doubling carbon dioxide in the atmosphere. Global albedo can change with changes in Earth’s cloud fractional coverage, cloud thickness, aerosol amount, forest cover, or snow and ice cover. For example, a 2-year change in albedo was caused by the large Mount Pinatubo volcanic eruption in June 1991. Stratospheric aerosols from the eruption increased global albedo by up to 0.007 because of the reflection of an additional 2.5 W m-2 of solar radiation over the following 2 years”
People have pointed out many reasons to *not* want to do geoengineering via sulfate aerosols. Let me point out some more, akin to the decreasing relative usefulness of:
– avoiding generating CO2 via efficiency
– capturing CO2 at a power plant
– capturing CO2 from the air later on
Sunlight is useful:
a) It’s necessary for plants, and slowing their growth worldwide is not a plus, and Liebig’s Law of the Minimum is relevant.
b) Solar PV and CSP need it to convert to electricity, and reducing their efficiency is not a plus.
c) Solar thermal systems on rooftops need it to heat water for household use or swimming pools.
d) It can lessen use of electricity for lighting.
SO, why on earth would we spend a lot of energy to *lessen* the useful energy we get from the Sun? I.e., raise the albedo high in the atmosphere?
We have:
Visible light ->
surface ->
useful energy + visible reflected + heat emitted
and the real goal is reducing the emitted heat, either by increasing the fraction of captured useful energy, or increasing the surface albedo to reflect more of the energy in visible wavelengths.
Why would we not want to:
e) Convert more sunlight into electricity and useful heat at ground level, especially if the sun-capturing elements generate less waste heat than {surfaces they cover, powerplants displace}. People have proposed floating PV farms to cover lakes, for example [which might also reduce evaporation a little]. PV panels definitely improve dark roofs. Higher-efficiency PV generates less direct waste heat.
f) Work hard to increase the albedo of built-environment surfaces, especially in sunny areas. For example, see p21-36Part 2 Cool Urban Surfaces and Global Warming, in a talk of Art Rosenfeld, CA’s famous efficiency pioneer.
This doesn’t remove CO2 from the air, and it’s nowhere near as important as efficinecy & cutting back on GHGs, but it can certainly help with local UHI effects, and reduce power for air conditioning.
I think e) and f) are likely to be negative-cost actions.
g) Finally, if one can’t use some acreage for power, useful heat, or growing something useful, maybe one can find ways to raise its albedo terrestrially, which surely seems cheaper and safer than using energy to keep more sulfates in the atmosphere.
I once did a humorous back-of-the-envelope calculation that 3 year’s world production of aluminum would suffice to cover Greenland with aluminum foil, which is probably not a Good Idea (covering ice is especially silly).
Less crazy, might be to cover hyper-arid lands with mirrors on wooden frames (thus sequestering some carbon). Deserts at least already have lots of sand, although course, using them for solar power is preferable. If there are areas of tundra whose soils won’t let trees grow, that might work as well.
More seriously:
Some Albedos:
.02-.35 water (depending on angle)
.05-.20 asphalt
.10-.27 urban areas
.15-.20 tundra
.25-.30 desert
.75-.95 new snow
It’s not obvious how one would practically do much to raise the albedo of oceans, but lakes might be plausible, and urban/asphalt can certainly be improved.
Sulfates might try to raise the average albedo from .29 to .30 fairly uniformly. On the other hand, if one can raise about 2% of the globe by about .5, that gets the same .01 effect to offset the temperature effects of CO2 doubling. Land is 29% of the surface, so we’d need to raise albedo by .5 on 6.9% of the land.
According to Rosenfeld’s pitch, dense urban areas are about 1% of *land*, and less-dense urban areas are another 1%, so that’s 2% of the 6.9%, leaving 4.9% of the land. Hyper-arid lands are supposed to be about 4% of land, but there’s plenty more arid land, and of course mirrors would raise albedo from .30 to .95 (at least), so it’s better than .5.
====
This is *not* a proposal to start doing this, and obviously, I haven’t done any serious studies, just really rough numbers. It’s just an observation that:
a) We should do all the obvious things (emission reduction, efficiency, albedo increase in normal built environment, solar power).
b) BUT IF we feel the need to increase albedo for a while, global aerosol production seems dominated by local terrestrial changes.
I would like to hear some discussion of the proposed geo-engineering solution of fertilising the oceans with iron or other minerals so as to sequester the CO2 through plankton. My gut response is that this would cause massive algal blooms, but maybe I’ve misunderstood. What are the costs/benefits of this approach?
Can aerosols in high latitude winter atmospheres cause warming by trapping more radiation than they reflect?
[Response: Very good question. Answer yes… but it’s a complicated story (aerosol type etc.) – we have a paper upcoming on just such impacts. – gavin]
I’m once again disappointed by RC’s dismissive attitude toward even stop gap proposals to blunt the worst effects of AGW via geoengineering.
Methadone maintenance is one analogy, here’s another:
The house (read planet) is burning down. The editors at RC would have us watch it burn down while saying we didn’t build it right in the first place, so we’ll just let it burn and build it again. I (and others) would say let’s throw some water on it (read geoengineering) and if we have to deal with some water damage, so be it.
I’m not advocating that we shouldn’t address the root cause, fossil fuels. On the contrary, but looking at current climate trends scares the crap out of me and we may have to do something more drastic in the short term to prevent disastrous consequences.
Question for RC editors and readers:
If you were a subsistence farmer in the river deltas of Bangladesh and were given the choice of uncertain weather or the certainty of being flooded out of your home by sea level rise, which would you choose?
Edward Greisch writes (predictably):
What you know and what we all know exhibit some divergence.
Peter Backes, 57
I don’t think your analogies are very illuminating. The unfortunate Bangladesh farmer (and billions of others) is likely to get uncertain weather *and* sea level rise, and all the geo-engineering suggestions I have seen so far look to me as if they will guarantee additional woes without fixing the problem.
It’s like the words of the doctor, ” The surgery was successful, but, er, the patient died..”
All the info that is coming in concerning global prospects alarms me greatly, so I share your distress. Just that I think it would be wiser to cease the activities that we *know* already are making things
worse. Well-meaning suggestions are fine, but mostly they appear to me to be ill-considered and just digging ourselves into a deeper hole. If we cannot protect the forests we already have, what’s the point in suggesting planting new ones in deserts, and so forth ? What’s the point in adding iron to the oceans and messing them up even more with algal blooms, etc ?
I think everyone should watch the presentation that Jim Galasyn (thanks) posted. If that doesn’t wake people up to our dire situation, I doubt anything will. Here it is again
http://progressive.atl.playstream.com/nakfi/progressive/Sackler/sackler_12_07_07/jeremy_jackson/jeremy_jackson.html
Peter Backes #57: I think you completely missed what the RC post is trying to argue. It is not dismissive of geo-engineering as such. It is pre-emptive of naive technology faith, already being used today by the inactivists to justify not doing anything.
A more proper metaphor would be: stocking up gasoline in your cellar, well knowing that the fire station is right across the street :-)
I’m curious what all the geo-engineering naysayers would say _if_ we had a somewhat different situation:
Due to a natural reduction in solar output (that has recently been understood to be long term), a new and apparently very severe ice age is starting. Should we be exploring geo-engineering solutions to mitigate this new natural global cooling?
[Response: None of those statements are true. But just for fun, let’s assume they were – what is the easiest way to raise temperatures? Deliberate manufacture and release of HFC’s. Dirt cheap, no stratospheric injection required due to stability, GW potentials in the 10’s of thousands, little or no effect stratospheric ozone. What’s not to love? In other words, new ice ages are the very least of our problems. – gavin]
Hank says, “it’s not the whole biosphere at risk here, except for very human-centric definitions of biosphere. It’s mostly the charismatic megafauna that are in trouble (if you include people as charismatic; debatable, yes).”
LOL! I don’t disagree with taking the long view, but I do suggest that it’s more than just the charismatic megafauna at risk — it’s whole ecosystems in which those species are embedded. For example, remove the apex predators, like great sharks (which are already functionally extinct) and their entire ecosystem unravels in a trophic cascade, typically leaving a desert populated with a few opportunistic species. This has been observed off the N. Carolina coast.
Personally, I’m horrified at the idea of witnessing the last dolphins and whales washing up dead, killed by starvation and neurotoxins from Karenia brevis algae blooms. Maybe that’s human-centric of me; I prefer to think of it as empathic.
As Prof. Jackson says, “The future is bright for dinoflagellates.”
Jim, 62, I was quite shaken by Jeremy Jackson’s lecture. The rise of slime.
There are streams, ditches, ponds, locally here, amidst agricultural land. They appear devoid of life, just black slime. I think that this is because of run-off from the surrounding fields which are regularly blasted with chemicals to speed up the growth of monoculture of grass, which is converted into silage and fed to cows, (which are also forced in a similar way to maximize milk yield, and have very short and un-natural lives). Eutrophication.
Compare those watercourses to the few relatively pristine and unpolluted streams left, which are actually still quite interesting to look into because of the varied species they contain.
Seems we are doing a similar thing, writ large, for Earth. We end up with a few scavenging bands of humans, a bit like the Inuit, eating rats and cockroaches, wandering along the shores of septic, stinking seas, and looking for useful bits of metal amongst the detritus of the dead civilization that turned the forests into deserts.
Does anybody think this is a good idea ? Does anybody think we will do anything effective to avoid that result, in the time we have available ?
The way I see it, I cannot think of any greater crime that people have committed, or could commit. This awesomely beautiful fabulous planet produced us, and, instead of honour and respect, we turn it into a poisonous junkyard. We don’t deserve to survive.
Whose to blame ?
reCaptcha ‘next tyranny’
Hey CL, have you seen Wall*E? I think you’d like it. The whole first act is a meditation on the scenario you describe, almost completely without dialog.
Thanks for the tip, Jim. I just watched the quicktime trailers. Maybe I’ll see it complete someday.
Do you ever walk the sea shore ? the quantities of manmade rubbish, mostly plastic, is astounding. It wasn’t like that, even thirty years ago. I guess the holocene-anthropocene era will be marked in the geological record by a layer of plastic fragments, fossilized dolls heads, compressed milk bottles, fishing net, and the like.
Some people think that the human population will crash, back down to palaeolithic levels, and then start all over again, but maybe wiser. But the easily found ores and oil won’t be available, so I doubt that the sequence of events could follow the same course to rebuild civilization the way it has developed. And I doubt there’ll be much around to hunt and gather.
Some people have faith in technological innovations to save us. Perhaps there’ll be some surprises, but seems very ‘iffy’ to me.
But I don’t rule it out completely. I have some documents that record patented ideas to make horse-drawn vehicles more comfortable. Investors were very excited at the time and seem to have had no awareness or foresight that in a couple of years the early motor cars would make their transport obsolete.
I came across a striking photograph, which kinda sums up the whole of human prehistory and history, complete with depleted, ravaged landscape, and our love of weapons and gadgets, and, judging by the guy’s eyes, mood altering chemicals.
http://whatsinmyipod.blogspot.com/
“All we have to do to destroy the planet’s climate and its biota and leave a ruined world to our children and grandchildren is to just keep on where we’re going today, just keep releasing greenhouse gases at current rates, just keep degrading and homogenizing and destroying our biological resources, just continue releasing toxic chemicals at current rates, and by the latter part of this century, the world won’t be fit to live in.” – April 2008, James Speth, Professor of Environmental Policy at Yale University
reCaptcha, ‘urgently war’
RE: 60
I’ve been following RC for years and I don’t think I’ve missed the point of this post or of previous posts on this subject. RC does not like the idea of geoengineering, period.
I don’t like the idea either. After all, we are already unintentionally geoengineering the planet with carbon emissions that desperately need to be brought under control.
The question RC has not, in my opinion, addressed honestly is this: What if we find ourselves, despite all of our best efforts to rapidly control greenhouse gasses, past Dr. Hansen’s famous ‘tipping point’ in a few years? What if the forecasts say we are going to have a sea level rise of a meter or more before the end of the century? Do we do nothing?
The subject of geoengineering is not going to go away because smart people hide away in their academic ivory towers. My hope would be that the folks at RC would take on this question in a serious manner and vet the short term solutions that would do the least harm and be the most predictable in result. If the climate starts to run away, you can bet someone’s going to do it whether RC participates or not.
I’d like to suggest a subject line for a future RC post: “In Case of Emergency”
I’m not opposed to geoengineering in principle, but we should be very sure that it will have the desired effects before we implement.
There’s a semi-serious post at Cquestrate:
Terrifying, but seductive.
> huge, clean, nuclear
Two out of three ain’t good enough.
I like my idea better — carve big limestone or dolomite or chalk boats, float-tow them out above the handiest undersea volcano, equip them with ‘smart bomb’ heat seeking steering, and scuttle them so they dive right into the magma.
More jobs, less fallout, comparable effect.
Peter Backes, nobody likes the idea of geo-engineering. And still we may end up having to resort to it.
As for preparation, none is needed. There are two bottlenecks, a small one and a big one: (1) logistics, and (2) knowing what the heck you are doing, and how the system will respond.
As to (1), less than even a small war, of which the US alone has a couple going as we speak.
As to (2), it’s called climatology. We need urgently to get much, much better at it anyway, precisely because of the ongoing unintentional geoengineering. Intentional geoengineering is just one narrow application. Everything RC, and the scientists behind RC, are doing will benefit it if it comes to pass. Playing Dr Strangelove now is just sicko.
Peter, #66. Well what we can do NOW is reduce our carbon output, extending the time over which we can ascertain what will work.
Hank, #68, I think that idea is a bit silly. For any sufficiently large boat, neither stone has the required tensile strength. So you’d have to make large flotillas out of many smaller boats. And how will we get them? Convicts carving them and manhandling to the sea?
You’d be far better off making something that will use seawater and carbon to create sequestered carbon in situ and dump it there. At least that way the mountain is freely coming to mohammed.
RE: 69
Martin – Thank you for agreeing that geoengineering might become necessary! (and I have not been advocating that a geoengineering solution is necessary at this time)
Of course the scientists at RC are a valuable resource on this subject – that’s why I’ve been chiding them to take it more seriously.
With respect to the Dr. Strangelove analogy, I don’t agree. Better to have a plan to fight a fire before one starts. There’s nothing Dr. Strangelove about being prepared (and we’re not talking about a mine shaft gap).
Assuming the methadone analogy is reasonable, does that mean that injecting aerosols as a “temporary fix” is so wrong? The point is that sometimes you need to buy time, and it seems to me there is a reasonable argument that in this case that is true. I’m not a climate scientist (I’m a mathematician), but from what I can gather things are pretty bad, and even if you make the Pollyanna assumption that global carbon usage could decrease significantly and quickly (say 2% a year for the next 40 years, hah hah) we’re still in deep doodoo. I mean is it better to let an addict die, or put them on methadone and give them a chance? They might die anyway, but is it worse? Other bad things might happen, but is it worse than being dead right away?
Peace…
Btw Hank, I posted your idea over at Cquestrate, with attribution. Fun discussion over there.
As Hank notes, we are always free to do nothing and let Earth shed itself of most of us.
As an alternative, I believe a climate “emergency” will happen fairly soon, such as an ice free Arctic Ocean, a resulting spike in Arctic temperatures, and a frightening acceleration of the melt of Greenland.
Since such a scenario could quickly spin out of control and lead to the shedding of most people from Earth anyhow, I don’t see how we won’t try geoengineering…unless of course wars, cascading financial failures and resource shortages make such plans impossible to organize…back to paragraph 1.
I’d rather RC take a more neutral tone on the subject of geoengineering and compare the various options dispassionately.
Jason, there’s no geoengineering proposed so far that’s credibly going to stop increasing the amount of CO2 in the atmosphere and the ocean, and anything else is missing the point given the rate of change in the oceans. You’re _seeing_ dispassionate assessments. Come up with a proposal that will keep the ocean pH constant and you’ll see passion.
___________
“strain receives”
Hank,
How about this (however unlikely it is) as a scenario where geoengineering would be justified:
Even with just above today’s CO2 levels, massive amounts of methane start to be released as the Artic warms in a large positive feedback effect. CO2 emissions are dramatically reduced in response, but geoengineering is needed to stop the methane emissions.
In comment 27 gavin said,
When I brought it up, I did so because it differs in kind from the sulphate aerosol thing. It is an exact remedy rather than an inexact one. Otherwise said, rather than being a SACTCAR measure, it is a BTRO one. So even if it did cost more, this would not suffice to dismiss it from consideration.
In that previous discussion, Dr. R.D.Schuiling asserted the cost per tonne CO2 would be US$10-15. (Some discussion here has referred to the olivine dispersal idea as mine; it is not.)
Captcha “into Puritani”
Steve, your scenario is not unlikely at all; if fact, these new methane emissions may have been detected already. Large quantities of CO2 may also be released, on the order of 100s of gigatons.
This positive feedback is very worrying, and it’s hard to imagine any geoengineering scenario that can mitigate it.
Steve, once you assign any significant risk to the scenario of clathrates boiling out of the ocean sometime in the next half millenium or so, you’ll be arguing very hard for reducing the total CO2 in the atmosphere, along with Hansen — not continuing burning fossil carbon and adding other stresses like a sulfate cloud.
Apropos setting off a nuclear bomb in a limestone, someone should look into the nuclear bomb tests done on Pacific coral atolls for any evidence it makes sense.
“The bomb Bravo vaporized two complete islands of Bikini Atoll and part of Nam, the island at which it was detonated.”
http://www.bikiniatoll.com/guyer.html American Journal of Public Health.2001; 91: 1371-1376
Too much water in any limestone material means way, way too much radioactive fallout downwind.
The idea fails sanity check.
What immediately occurs to me is two things. One, the originator of the idea can’t be serious and should therefore refrain from commenting, and two, the comminution efficiency of a nuclear explosion would be several orders of magnitude lower than that of proper rock pulverizers. For hard rock they typically take 25 kWh(e) per tonne if 80 percent of the mass is to be in sub-100-micron particles, 50 kWh(e) per tonne for 80 percent below 25 microns.
Steve Reynolds, 76,
“…but geoengineering is needed to stop the methane emissions.”
What geoengineering do you think would be effective re methane emissions ?
Someone thinks that “4.5 billion people could die from Global Warming related causes by 2012”
http://www.agoracosmopolitan.com/home/Frontpage/2007/01/08/01291.html
I fail to understand why sequestering massive amounts of carbon fails to be ‘geo-engineering’.
[Cpathcha cryptically remarks “partition both”.]
Er, yeah.
For those who like selling newspapers, this is the kind of article they like.
A “weeks old” theory.
Baloney
“Bibliographic reference courtesy of Brad Arnold who has an extensive resrarch background on Global Warming.”
He should have done more resrach.
Hank: “…you’ll be arguing very hard for reducing the total CO2 in the atmosphere, along with Hansen…”
My scenario already assumed that. My point is whether it is prudent to have a well considered, researched, and maybe pilot tested plan in case that is not enough.
Jim and CL,
Stratospheric aerosols appear to be able to cause global cooling, but of course unwanted side effects could be a problem (unlikely to be worse than CL’s link though).
Finding the best method and understanding its limitations seems to me to be worthy of considerable research effort.
CL wrote in 81:
Where the heck is he pulling the figure 2012 from? Why should I give his opinion any weight? I know of some people out in the UK that still think the sun revolves around the earth. Doesn’t mean that I am going to regard the view any more credible.
Don’t get me wrong: I believe that methane hydrates are a real threat. But the author you cite clearly isn’t an expert — the hydrate hypothesis (“clathrate gun”) goes back not weeks, but about eight years.
Please see:
Profile of James P. Kennett
Tinsley H. Davis, Freelance Science Writer
Proc Natl Acad Sci U S A. 2007 February 6; 104(6): 1751–1753.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1794309
> worthy of considerable research
What direction for research does anyone see suggested after reading
Robock et al ?
[Response: Link updated – possibly Rutgers’ was having bandwidth issues (?) – gavin]
#82 David R. Benson “I fail to understand why sequestering massive amounts of carbon fails to be ‘geo-engineering’.”
It doesn’t matter in the least whether you call it that or not. The point is that it would slow the increase in GHG concentrations in the atmosphere, without inevitable serious side-effects, which none of the other forms of geo-engineering proposed, so far as I recall, would do.
Hank Roberts (86) — Your link comes up 404 Not Found.
Nick Gotts (87) — What are the bad effects of a sun screen at L1? Other than cost and that it does nothing for ocean acidification?
We could use like 100 nuclear weapons in a massive ‘controlled demolition’ to set off the Toba supervolcano again!
Or, you know, maybe that’s a bad idea…
David, Gavin’s updated the link for Robock (thank you Gavin).
> Sunscreen at L1
1) building it locally
2) getting it there (or some other appropriate location)
3) keeping it there (it’s metastable, requires fiddling)
4) getting back (see 2)
There’s a preprint draft of Teller et al. (1997) here that elaborates:
http://www.osti.gov/accomplishments/documents/fullText/ACC0229.pdf
Attaining the ability to build a space elevator or three would seem to me more likely an accomplishment.
Then we could try dumping material into the upper atmosphere or very near Earth orbit f in an energetically feasible way, and rely on its re-entering the atmosphere to remove it (and it might in the meantime bring down some
If (heh) having a conductive element extending out that distance didn’t bring down the wrath of the ionosphere in a planet-sized lightning bolt, or something else we haven’t imagined. Remember those tether experiments.
Basically I think it’s clear no one managed to successfully imagine the results of even the very simplest geoengineering humanity could accomplish — changing the level of CO2 by a few hundred parts per million.
Nor the second simplest — inventing chlorofluorocarbons.
Nor the interaction of the two.
And people imagine we could rush into a far more complicated intentional change, without mucking up?
Remember the Fermi Paradox. The odds are that we are right on track as a species to do what all the others ahead of us have done with their own planets. And it’s awfully quiet in the universe.
Andrew (a different Andrew than me) wrote: “W. Edwards Deming, the great statistician and management theorist, showed that a lack of understanding of a system led invariably to its tweaking.”
Could you for example explain how our lack of understanding of a unified theory of gravity and quantum mechanics has led to tweaking of the universe?
Deming is the guy who was credited for remaking the Japanese economy, figuring prominently in books celebrating the success of that economy. On the other hand, the issue of the 1990 “Kingdom of Denmark Nikkei Put Warrants” (which will Google easily enough if you are not familiar with those), pretty much sums up the “value” of all that management science the Japanese avidly sponged up at Deming’s knee. The Nikkei 225 closed 1990 at 38,916, and hasn’t been above 30,000 since July of 1990, and hasn’t been above 20,000 since March of 2000.
Just put me down as a management theory skeptic, if not outright management theory denialist.
Hank, the most credible way I see to reduce emissions is to wait for peak oil, natural gas and coal to kick in. As far as I am aware, only Dave Rutledge of Cal Tech has looked at the implications of fossil fuel limits on atmospheric GHGs.
But alas, this even with a peak of 440 ppm co2, we are already overheated and I seriously doubt geoengineering would do what is required fast enough–get the atmosphere back to ca. 290 ppm co2.
Even so, I would like to know how a combination of methods (no silver bullet) might add up. I haven’t read the paper you mention but am curious if they modeled a future with peak oil, etc. included or do they use the SRES scenarios?
See #54.
Geo-engineering via:
a) Continual atmospheric aerosol injection
and/or
b) Putting mirrors in orbit
lessen the amount of sunlight reaching the Earth, and do nothing to reduce CO2 issues.
Can someone who is keen for either of give me some pointers to explain why the costs (in $ and energy) for those are *less* than the sorts of things that one of the world’s top energy-efficiency experts says we can do on Earth? You have to count the losses from having less sun for solar power and less sun for crops, and (maybe) for acid rain damage. I’d much rather:
– absorb sunlight usefully where possible
– reflect it where not, and thus raise the albedo of Earth at selected places
*Please* look at that Art Rosenfeld piece. Is there some reason we must chase energy-expensive schemes with negative side-effects when there is a lot of low-hanging fruit that actually *saves* energy?
Timothy Chase, 85, I didn’t mean to suggest that article was in any way authoritative, just interesting to see how some folks think, and how the science gets muddled as it gets into the public arena. I guess the 2012 date is possibly intended to alarm and catch the eye to get readers. It worked on me that way :-)
Thanks for posting the Robock link, Hank. If there’s a possibility of messing up the Asian and Indian monsoons, that rules it out, IMO.
However, having been fervently anti-nuclear, I’d be willing to reconsider in the light of Blees and Hansen’s suggestions, if, IF, the waste problem and uranium mining problems were solved.
But what if we end up with nuclear and coal and oil and renewables, wind, solar, geothermal, etc ? I remember people saying tv would kill the book, then cassettes and CDs, would replace the book, then computers…we seem to end up using all of them…the demand for lavish use of energy seems insatiable.
In principle, we could have international treaties to ban the use of dirty fuels, but in practice, e.g. limiting nuclear weapons, protecting forests, oceans, rivers, CITES, etc, have rather limited record of success.
We don’t seem to have a choice between good and bad, just bad or even worse.
What if China, or USA, or Russia decide unilaterally to place some substance into the stratosphere or whatever ? I guess the rest of us will just have to accept the results, however awful and misconceived, just as we have to accept the results of ozone hole, rising sea level, and vapour trails from aircraft overhead.
CL, you might want to reread Gavin’s opening post for this thread where he brought up Robock.
People are throwing out a lot of advanced concepts here without a lot of thought about feasibility.
Sulfate injection–at best, this is a temporary solution. Aerosols decay on a timescale of months to years. CO2 keeps on giving. Aerosols decrease incident visible light and do nothing about IR–visible light’s a pretty useful commodity.
Sun shield at L1–This is not a trivial proposition. First, it would have to orbit L1-so it’s not 100% stationary. Second, it would have to have sufficient propellant and guidance to maintain position and attitude even as it intercepted a significant amount of solar wind, light, etc. Third, the closest to this we have in current proposal is the sunshield for the James Webb Space Telescope. This is bleeding edge technology, and the scale of the L1 sun screen would be much larger. Fourth, radiation could be a siginificant life-limiting issue. Finally, again, we’re making the trade–visible light for IR. Not a good trade.
Space Elevator–ain’t gonna happen. First, the center of mass of the elevator has to be at geostationary orbit. Not only does this require exceptionally strong fibers, the whole thing has to pass right through the radiation belts–again likely limiting lifetime and safety of the concept. I’ve never seen a satisfactory treatment of these issues–especially radiation. As far as I can tell, this is a pipedream.
Climate change may demand that we embrace less than stellar strategies to buy time, and the longer we delay, the poorer our options become. Still, the best options we have at present remain conservation, increased use of renewables and low-tech ideas like biochar.
Yes, Hank, you’re right. Silly of me. I’m actually trying to read everything on this site, to catch up on what’s been said since the beginning. It’s quite a lot ! Main question in my mind at this instant, why some think Lovelock’s Gaia is teleological ? Seems to me, Daisyworld is no more teleological than Darwin. The division between biology and geology, (life and non-life) is in our heads, an intellectual convenience we overlay upon reality. The way all the systems inter-relate, e.g. Great ocean conveyor, sequestration, etc,- looks very much like physiology to me, just that we don’t yet have any conceptual frame (e.g. other similar planets to compare) that permit deeper understanding of what Earth actually is…I’m rambling :-)
reCaptcha, ‘success shivering’
My engineering project only requires us to change the way people behave — special interests acknowledge our common bonds, ordinary folk willingly perform long-term sacrifices to mitigate incompletely understood consequences, etc.
In short, I think we’re going to get the full measure of whatever it is that AGW has in store.
captcha: Croker Emporium
(I didn’t know captcha was a Michael Caine fan.)
Should we be more worried about earlier melting of methane hydrates in the shallow parts of the Arctic Ocean ?
Ok, sun screen at L1 is out. (Good!)
Now lets get moving on useful ideas, such as biochar, producing lots of top soil, sequestering carbanacous materials deep underground, burning torrified wood instead of coal.
{Capcha says “Mount leveled”. Must have recently visited Appliachia.]