137 replies to this topic

[dickbill]

I was listening to public radio about global warming effects and they were mentioning again the possibility of throwing volcanic ashes into the stratosphere. This dust would reflect sunlight a bit, but i find the idea extremely dirty, with lots of unknown possible side effects, like this dust could be a major disease vector in addition to allergenic effects on our health.

The nearest best thing would be to send into orbit very light reflective material like MYLAR that could cover hundred of square kilometers and that would let pass photosynthetic wavelenght. On an equatorial very low earth orbit, the cloud would pass in a couple of minutes, looking like a slight darkening of the sky in the equatorial regions. The low orbit would guaranty the cloud would clear after several years, to stop any possible harmfull long term effects.
At 1g/square meter material, a mid-size launcher like Ariane, that is able to send in a single launch ~30 tons in LEO, could cover a surface of 30 millions square meters or 30 square km. So an orbiting 'sunlight filter' of ~ hundred square kilometers, very well delimited in a dedicated and reserved spatial area, is in today's capabilities. Each nation would pay for one launch and that'd be a good step against a global warming disaster.
It has been more than a 100degres nonstop here in Texas for the last month and I am not a big fan of further global warming.

[Jarad]

Yeah, I have thought about this same idea. A series of say 1-mile diameter mylar sheets in orbit, like the shadow squares in the Ringworld series. You could fine tune the amount of light blocked by tilting them relative to earth, or better yet, make them slightly parabolic and attach a solar panel at the prime focus, and beam solar power back to earth (that way you both block sunlight, and reduce the need for burning fossil fuel).

Jarad

[Shadowalker]

Well, 30 sq kilometers is insignificant in terms of area, considering my county in Mississippi alone is something more than 2000 sq kilometers. It would take more than 60 such launches just to cover my county.

It's hard to see how a feasible number of launches could make much of a difference anywhere.

[dickbill]

Maybe the thing is too good at adressing the nefarious effects, but you don't want to advertise it too much because it would be an incentive for not fighting the causes: the excessive fossil fuel consumption.
I wouldn't use miles wide sheets though, because the smaller, the simpler, the better, and the cheapest.

The guy at the radio (I couldn't pick up the name, but he just wrote a book about GW) said the difference between the last Ice-Age and today is 8 degre centigrade, world average, and this is at least what we should also expect by 2100. No more ice cap, raised water level and no drinkable water. That's scarry. Of course, decreasing CO2 emissions today won't change anything. It's too late, the CO2 has accumulated and now the effects are irreversible.
I am also afraid of Murphy's law, it will be bad, but if it can be worse, it will be worse. I am talking about the Sun. We could get lucky with a slight decrease in solar output, or very unlucky with an unpredictible solar increase, sort of little ice-age of the Middle Age, but inverted, and there is nothing we could do about that. I am not sure the climate models for GW take that sort of bad luck into account. If we are unprepared and that happens, we're done. So we absolutely need an active shield now.

[dickbill]

Well, 30 sq kilometers is insignificant in terms of area, considering my county in Mississippi alone is something more than 2000 sq kilometers. It would take more than 60 such launches just to cover my county.

It's hard to see how a feasible number of launches could make much of a difference anywhere.

Yes it's small. So the decrease in insolation would be equally small. But add that to the development of renewable ressources (wind, solar), decrease in CO2 emissions and green house gazes and we might have the beginning of the end of GW in sight, to quote Winston Churchill.

About that, I have a good self sarcastic joke. During WWII, it was obvious on the paper, that the german had military superiority in technology and number, so the french recognized that and surrender accordingly, but the english, being not as smart as the french, didn't see that and they continued the fight stupidly...
So sometimes you must do the dumb thing to keep hope.

[deSitter]

I think aggressive tree and corn planting might work out better. We need Johnny Appleseed, not Cosmo Narcissus.

-drl

[dickbill]

I try to make my lawn survive, and it doesn't, my tomatoes died, so a tree...a cactus maybe. The 'de-greening' of Texas is a serious possibility.
Poor Johnny No-Shoes should better find a pair of boots because today, he would die of Nile Virus-infected mosquito bites on his feet. The world has changed too much, what has worked in the past will not work anymore.

[Jarad]

Well, 30 sq kilometers is insignificant in terms of area, considering my county in Mississippi alone is something more than 2000 sq kilometers. It would take more than 60 such launches just to cover my county.

The earth receives about 50,000,000 square miles of sunlight (that's the area of the circle we subtend perpendicular to the sun). One circle of mylar just a bit more than 1.1 miles in diameter would block 1 square mile of sunlight. So to reduce the total radiation hitting the earth by 0.1%, we would need 50,000 such sunshades, or a proportionately smaller number of larger shades (for example, roughly 2500 ones that are 5 miles in diameter).

In order to make it a global effect, you would want a fairly large number of shades so that you could make it a relatively even 0.1% loss everywhere rather than a large loss in a small area.

So it's a fairly major project. But still interesting to think about, and at least feasible with current technology. The mylar is fairly low weight, although each one would need some amount of guidance and control as well.

I think aggressive tree and corn planting might work out better.

Long term, that will help. But it may not occur fast enough.

Jarad

[dickbill]

So, what about if the satellite sprays a liquid/droplets at the same time that the droplets are coated with a reflective layer, or maybe the reflective layer is polarized and will naturally diffuse to the outside of these particles. Let's assume the solution can polymerise in space during the spraying process and forms a reflective film of almost unimolecular thickness, now floating in LEO.
This time the weight per surface area would be much less than a gram per square meter. Let's assume 1 milligram per square meter, and the 30 metric tons of payload can be sprayed over 30 000 square kilometers...

[deSitter]

It's too easy to lose track of numbers here. Go to the top of the tallest building in your city. Even if it's New York, the horizon is barely 30 miles away. I dare you to make a mylar sheet that covers metro New York.

There is only one way to deal with excessive CO2 in the atmosphere, and that's to use it up and store it in the ground. That's what plants do. Fortunately plants can be found that grow like - well weeds. It's sure to at least mitigate things. But I think the permafrost is going to melt, and that will reduce any human action to a sort of pitiful puppet show anyway. It's time to get used to a population reduction of up to 90 percent, and hope the remaining 10 can last. There just isn't going to be any food soon.

-drl

[Joel F.]

Danny,

No ragweed!!

Thank you!!

[simpleisbetter]

I think aggressive tree and corn planting might work out better. We need Johnny Appleseed, not Cosmo Narcissus.

-drl

Yep. For those who worry about or believe in the nonsense of GW, or that we can control it.

[dickbill]

Plants will grow OK, but you want to burry them before they had time to release their carbon either by direct fire burning or by fermentation. But a 10 foot deep hole won't do, we'll have to dig deeper holes with some impermeable layers to stop the reemission.
So It might take longer than you think. The excess carbon is from the oil and coil reserves that were buried this way and now that this carbon is released, it won't go back 10 miles underground for free.
Removing the carbon alone, even if we started now, won't stop the momentum of GW. It's way way too late for that. You're right with the mylar DeSitter, but that's a technical problem that can be worked out. It doesn't have to be a sheet or a film, it could be anything with some reflective properties that could cover a large area in space. Somewhere around the world, there are some chemists that have some ideas how to do that. That's just one thing, but we'll need a full arsenal of measures. Increasing the albedo at the poles, I don't know how, but somebody knows, might be another thing.

[deSitter]

Well as a large scale project, what about radical cloud seeding, e.g. injection of sea water mist into the lower atmosphere? The salt would act as nucleation centers leading to cloud formation. This could be sustained indefinitely and targeted to the arctic climate. The key problems to attack are the melting of the permafrost and collapse of the ocean current conveyer.

http://physicsworld....-climate-change

Apparently a fleet of seeding ships using Flettner rotors capable of significant mitigation could be constructed for around $5 billion. That's within the range of Mark Zuckerberg and Bill Gates personally. Such a massive geo-engineering project would be the moral and technical equivalent of a home-bound space exploration program and would not only provide thousands of jobs, it would provide a much needed boost of confidence and hope for the future.

-drl

[deSitter]

Here's something "ex ore equitum" - John Latham's home page at NCAR:

http://www.mmm.ucar.edu/people/latham/

This really sounds like something that can be done immediately. It's not even that expensive. One of these rotor ships would certainly be less complicated than a deep water oil rig.

-drl

[dickbill]

INcreasing cloud cover and reflectivity is very interesting. That would be the first active global measure taken against GW. Avoiding the complete disapearance of the north polar cap and the melting of the permafrost is one of the last battle we cannot afford to loose, at all cost.
That's the equivalent of the Battle of Britain for GW.
Because after that comes the south cap and the continuous acidification of the oceans that ends to hypoxia, but here we are talking extinction event.

So Latham's idea should be attempted. It's not as clean as a space shader, but not too dirty either. It's just sea water, with some microorganisms and halogen salts spreading, not perfect, but way better than throwing ashes in the stratosphere, IMO. In the first link in physicworld, there are some comments that mention the unexpected side effects, such as the negative effects of the halogens to the ozone layer, but at some point we'll have to choose the 'less worse'.

Quote from Latham's web site:
"Conclusions from our Work to Date
...Although design work on the major technological aspects of our work has progressed well despite the absence of funding..."
Allright, so the US is going to a major drought this year, with alternance of excess water through flooding and long dry periods, the corn production has been cut 70%. The cost I don't know, but probably in the billions of dollars, and the guy can't find funding for his project?

I am going again to sarcastically propose to use the high frequency trading machines AND, for a measure of equilibrium, to use the Vatican bank accounts.

[dickbill]

In the worse case we risk that:
A global oceanic anoxic event. Good article on Wiki:
http://en.wikipedia....ki/Anoxic_event

Edit, I have to quote this:
"...Ironically these deposits of sedimentary organic materials may have accumulated into lipid rich deposits. It is now widely believed that most of today's fossil oil reserves were formed in several distinct anoxic events in earth's geologic history..."
What goes around comes around.

[deSitter]

That is a crazy fact. And man, I really didn't need something else to worry about But thanks. I'll add that to the "Venus tipping point" scenario.

I just hope people come around.

-drl

[Mister T]

:foreheadslap:You guys are over looking the obvious.

the moon nearly perfectly blocks the sun during an eclipse.

we just park the moon in the right spot and enjoy the shade!

[deSitter]

Or we could just shorten the day!

-drl

[ColoHank]

Perhaps we should demand that our leaders view global warming as an environmental issue rather than as a political one, and that they start planning for the long term instead of for the next election. Fat chance of that, but a guy can dream, can't he?

[dickbill]

The extremely popular and mediatized Cdt Cousteau was somehow an opponent of the Global Warming alarmists. I've heard him say, probably also in the 80's, that the doomsday scenario was not founded, because the buffering capabilities of the ocean will always be able to absorb any extra amount of CO2 we might produce. Beside that, he was a fierce opponent of polluting the oceans, but he didn't consider CO2 acidification an imminent threat. At the time I kind of believed him, especially because corals were supposed to remove the CO2 as carbonates and the oceans seem too vast to be saturated by CO2 anyways. But here we are, wiki reports a global decrease from pH 8.25 to 8.14. and corals seem yo have a harder time to remove CO2 as carbonate of calcium...
http://en.wikipedia....n_acidification
Quote:"About a quarter of the carbon dioxide in the atmosphere goes into the oceans, where it forms carbonic acid. Ocean acidification, which like global climate change is driven by excessive levels of carbon dioxide, has been regarded by climate scientists as the "equally evil twin" of global climate change"

That's another battle we shouldn't loose: loose 'our' corals. Hopefully they will adapt to a small change in pH to be able to calcify even in more acidic conditions, IF, big IF, they have the time to adapt.
It shows the importance for us of fighting by any means, to at least slow down global warming. It might give Earth ecosystems some precious extra time to adapt to the new conditions, rather than just crash.

[Jarad]

Guys, I would like to see this conversation continue, but let's stick to the scientific aspects and avoid the political/personal.

Thanks,

Jarad

[deSitter]

Here's Rasch, Latham, and Chen's latest paper;

http://www.mmm.ucar....m Chen 2009.pdf

Note that this program makes no overarching assumption about the origin of deleterious climate change, just that it's very bad if the polar ice caps and permafrost melt and that it's likely that at least some of the warming is anthropogenic. Therefore no partisan argument can apply. It's simply a matter of proactive intervention vs. waiting and hoping.

The possibility of such a massive program undertaken by all the world's countries who share this globe, is very exciting. But how to get this in front of the people who can act?

-drl

[llanitedave]

Hey, folks, let's stick to the "sunscreen" aspect of this. Trying to broaden the discussion into general GW issues will doom this thread.