Solar Shade to Reverse Global Warming

[Fraser]

The overwhelming scientific consensus predicts that human emissions of carbon dioxide will warm the planet over the coming decades and centuries. By how much and how quickly is still up for dispute, but most agree it's time to take action. Reducing carbon dioxide emissions is the key, but what if it's already too late, and the temperature tipping point has already been reached? Dr. Roger Angel from the University of Arizona takes a page from the book of C. Mongomery Burns and suggests a gigantic sunshade placed in space above the Earth might help keep us cool.

Read the full blog entry

[Hadron]

Cute feel-good idea, except that GlobalWarming has not been proven to be anything more than normal climatic cycles. Orbital precession is more likely the cause, IMHO. The Greens are always fretting about something...

[hansb]

The overwhelming scientific consensus predicts that human emissions of carbon dioxide will warm the planet over the coming decades and centuries. By how much and how quickly is still up for dispute, but most agree it's time to take action. Reducing carbon dioxide emissions is the key, but what if it's already too late, and the temperature tipping point has already been reached? Dr. Roger Angel from the University of Arizona takes a page from the book of C. Mongomery Burns and suggests a gigantic sunshade placed in space above the Earth might help keep us cool.

Read the full blog entry

Interesting idea. But less sunshine on earth could also mean that even less carbon dioxide will be fixed by photosynthesis.

Next job: create a good filter. Kind of sunglasses

[tony873004]

A collection of 200 meter wide shades to block the same amount of sunlight as a 2000 km wide shade? It would take 100 million of them.

Instead of placing that at L1, why not just place them in medium-Earth orbit at 15000 km. This is too high for drag to ever bring them down. You'd never need to adjust their orbits because unlike L1, this is stable. Being 100 times closer to Earth, they'd each block ten thousand times as much sunlight as their counterpart at L1. Unlike their L1 counterparts which will block sunlight 100% of the time, they would only block sunlight 13% of the time. But instead of requiring 100 million of them, we'd only need 70,000 of them.

Still sounds like a bad idea to me. If you're going to go through this trouble, just develop technology to place giant solar cells in orbit and microwave the energy back to Earth. Then we wouldn't need to burn fossil fuels anymore.

[wizard888]

All in all, it would be a mind-bogglingly large undertaking, requiring launch technology and space-based manufacturing light-years beyond anything we’ve done to date.

I gues here we have a classical "light-years" bad astronomy.
Or may be I am mistaken?

[Ronald Brak]

Silly, silly, silly. If they were one micron thick with a density two and a half times that of water it would cost the entire GDP of the United States just to get them into low earth orbit. That is over 11 trillion dollars. And that's using cheap Russian launchers not expensive stuff like the space shuttle. It would be far cheaper to gradually shut down fossil fuel power plants and relace them with wind, solar and nuclear power and to relpace gasoline guzzelers with fuel efficent hybrids and electric cars. This might cost less than 5% as much as solar shields.

And even if you did build solar shields, it might be better to put them into a low polar orbit rather than L1. Although they will only shade the earth half the time they can be a simpler design, will be cheaper to launch and will have most of their effect at the poles where the icecaps we don't want to melt are.

[Nachor]

Wouldn't it be easier to capture an asteroid, move it to L1 and use that as a base, mine and building place at the same time?

IIRC that was how K. S. Robinson had them build the "Soletta" in the Mars Trilogy, a construction to actually warm Mars, but could be used as a sunshade too. Was basically constructed like venetian blinds, just really big.


But the easiest way getting away with global fever would be getting more efficient, like Ronald mentioned. Plus, we wouldn't run out of oil in a few decades.

[moshulu]

Shading the planet would not prevent increasing ocean acidity, which is emerging as the other serious downside of rising CO2 levels.

[Bynaus]

Such a sunshade would better be placed in the vicinity of Venus... so our descendants (in a few 1000 years) could discuss about how to further terraform the planet, now that its atmosphere and surface have cooled down...

[moofhead]

I'll leave the implementation details to the engineers, but anything that blocks sunlight from the Earth gets my vote. I hate sunshine and it's too darn hot outside, not to mention all the other negative effects of global warming.

[Roanoke]

OK, let's assume we can launch a zillion solar shades. That will happen right after the federal debt is paid off. Fine. They will help block the sun's light during the day...and they will also block the stars for all Earth-based and Hubble-orbit astronomers. It takes a genius to come up with an idea this stupid!

[eburacum45]

Gregory Benford suggested this a while ago; I have seen it proposed several times.
Angel suggests that the shades could be manufactured on, and launched from, the Moon, another idea I have seen before. If we ever get a manufacturing capacity on the Moon this would be well down the list of priorities; but if global warming ever becomes disastrous then such a solution might be necessary.

It may be possible to incorporate photovoltaic solar power collectors on these sunshades at the L1 point, and the set up might end up paying for itself by producing power for space based industries.

In some ways it would be easier to locate the sunshades in near-Earth orbit; they would not shade the Earth much more efficiently, as the Sun's rays are more or less parallel at the Earth's orbital distance. Another problem in the medium term is that such a swarm of sunshades might be a navigation hazard near the Earth, especially if we ever get round to building space elevators.

A problem with locating a large flat object at the L1 point is that solar wind and light pressure independently try to push it toward the planet; you need a space anchor, a weight which passes beyond the L1 point toward the Sun and drags the shade back.
Unfortunately this anchor then tries to go into a faster orbit round the Sun, so you need to angle the sunshade to compensate for this drag and to keep station.

In short, the solar shade concept is quite complex, and needs a lot of active maintenance- not something you can just park and forget.

[lpretorius]

This proposal is beyond belief. Let us for a change think differently about solving global problems with new space technology and at great cost. Use existing technologies with innovative ideas and projects that solves many issues at the same time. As I see it ~
1. The problem is Greenhouse Gases (GHG) pollution = essentially CO2 + Methane
2. The solution is Sun + Photosynthesis + CO2 = Carbon fixed + O2 if I remember Biology 1 correctly. This is what Trees Do for free.
Thus, on a Global Scale:
a. Make it an offence to cut down a tree unless it is an invader species
b. Make slash and burn in the rainforests a crime against humanity, but create sustainable projects (or pay a stipend until the projects are viable) for the poor that does this in order to survive. It must STOP immediately!
c. Create a Global Warming Fund to receive fines imposed on every GHG polluter at a rate/ton released. This will ensure that they then make it an imperative to reduce/stop pollution. This fund can then be used for anti Global Warming Projects.
d. Create enormous desalination plants on the coasts of the deserts in the world and pipe clean water into the hinterland.
e. Establish Israeli style Communes/Kibbutz farms where the poor can relocate to and live a quality aggrigarian community style life.
f. Use the proven Israeli irrigation technology to produce food for the poor and plant millions of fruit bearing trees on these farms.
g. Get the World Food Aid Organizations (funded by Governments) to start moving Aid Funds to these projects to allow the poor to learn to "fish for themselves".

Get the Polluters to earn GHG Credits by contributing to and establishing projects in the poor zones of the world – these always seem to be found near water scarce areas. These must:
g. Fix Carbon by creating a carbon based material (can be used for house building material) from a CO2/Methane processing plant that allows them to sell the oxygen gas and/or the carbon products which then produces an income. Solar power must be used as Energy.
h. Create huge PV or Solar Furnace power generating Farms in the deserts and feed this Energy into the power grid to reduce the energy demand from coal fired power stations.

In my humble opinion, much better for the world and its scarce resources and social ills, than “cool shades in space”, that will only enrich the aerospace industries.

[eburacum45]

I agree with you entirely. All those things are worth encouraging. However it may the the case that we need to regulate the Earth's temperature at some point in the future; sunshades would be one way of doing that. The Sun is gradually getting brighter over time; in 500 million years or less (some say much less) the Earth will need such temperature regulation or it will be uninhabitable.

Here is an image I have made of a sunshade in the L1 position shading the planet Venus, allowing that world to be terraformed; there are a series of mirrors positioned behind the planet to give some illumination during the planet's 120 day-long night.
http://www.orionsarm.com/worlds/statites.jpg

[Cylinder]

I gues here we have a classical "light-years" bad astronomy.
Or may be I am mistaken?

Mistaken. It's the same as saying "miles beyond" - a reference to a distance measure instead of a temporal one.

[samsara15]

Seems to me global warming is a proven case. However...

Someone on another thread suggesting dumping a reasonable amount of iron filings into the oceans would absorb all the excess carbon dioxide. Others commented that doing so might produce unpredictable and maybe even undesirable cooling. Anyone have any measureable comments on that idea? I think any human actions must be undoable by other human actions, hopefully not costing an infinite amount of money.

[Ray Bingham]

What a ridiculous idea. About as ridiculous as asking the oil companies to develope an alternate energy source.

The article mentions that the shade he proposes will absorb a certain percentage of the suns energy. If it absorbs that energy will it not then have to radiate it away again. Or just melt and vaporize away. How much energy can a shade placed in total unprotected sunlight absorb before it just starts radiating it on through to us.

[Ronald Brak]

Seems to me global warming is a proven case. However...

Someone on another thread suggesting dumping a reasonable amount of iron filings into the oceans would absorb all the excess carbon dioxide. Others commented that doing so might produce unpredictable and maybe even undesirable cooling. Anyone have any measureable comments on that idea? I think any human actions must be undoable by other human actions, hopefully not costing an infinite amount of money.

It has been estimated that it would cost $50 per ton of carbon absorbed to seed the Southern ocean with iron. This is quite expensive so it should be cheaper to replace burning fossil fuels with low emission alternatives such as wind solar and nuclear. So if coal was taxed at a high enough rate to pay for seeding the ocean, the price would be so high that soon no one would buy coal.

Now if after you had stopped using fossil fuels for energy and you still wanted to remove CO2 and you didn't mind the expense, then seeding the Southern Ocean with iron might be a good way to do it.

[Ronald Brak]

The article mentions that the shade he proposes will absorb a certain percentage of the suns energy. If it absorbs that energy will it not then have to radiate it away again. Or just melt and vaporize away. How much energy can a shade placed in total unprotected sunlight absorb before it just starts radiating it on through to us.

Something shiny should be able to reflect most of the heat away. In fact, being shiny is the only way a micron thick shield is likely to survive. (But yeah, it is a silly idea for our current problem.)

[tony873004]

...In some ways it would be easier to locate the sunshades in near-Earth orbit; they would not shade the Earth much more efficiently, as the Sun's rays are more or less parallel at the Earth's orbital distance...

They'd be a lot more efficient. It would be an inverse square relationship. A shade 15,000 km from Earth is 100x closer than a shade at L1, which is 1,500,000 km. It would shade 100² or 10,000 times as much sunlight as its L1 counterpart.

[Ronald Brak]

They'd be a lot more efficient. It would be an inverse square relationship. A shade 15,000 km from Earth is 100x closer than a shade at L1, which is 1,500,000 km. It would shade 1002 or 10,000 times as much sunlight as its L1 counterpart.

This doesn't sound right. Consider what happens during a solar eclipse. My guess is that provided a solar shield is less than a thousand kilometers in diameter and is somehow kept in the right position, then at L1 little or none of its shading effect should be wasted.

[tony873004]

Thinking about it, you guys are right. The inverse square would affect only a specific region on Earth. For example, a 200 meter shade sitting only inches off the ground would completely shade 200 meters of Earth, and provide no shade to the rest of Earth. At 1,500,000 km from Earth, it would provide an extremely small amount of shading for any one specific point, but every point on the sun-facing side of Earth would be minutely shaded. But in either case the same amount of solar radiation is deflected.

Thanks for making me think about that.

[Ronald Brak]

Thanks for making me think about that.

My pleasure. Please point out when I make errors as I tend to from time to time.

[Jerry]

I don't see how this could be a feasible solution to global warming. It MIGHT just barely, be a technology that could be used to diffuse or re-route a hurricane. This would almost certainly call for an reflecting, near earth orbiting array that disrupts air flow into a storm center - extremely expensive, but so are hurricanes.

There is nothing wrong with these pie-in-the-sky solutions...Except that they give the general public an undeserved warm fuzzy that our technology will overcome the threat of global warming without reducing hydrocarbon burning.

Wrong!

[Burt]

In the original article: "The best place to build this structure would be at the Earth-Sun L1 Lagrange point - a stable spot in space where the gravity from the Earth and the Sun cancel each other out." This is very common error made in many articles.

L1 is not where the gravity from the Sun and Earth cancels. At such a point, an object will tend to follow a straight line instead of an orbit around the Sun and rather quickly move away from the point.

At L1, Earth's opposite pull decreases (but not cancels) the net gravity working on the object to the precise value needed for the object to have the same orbital period around the Sun than Earth has. So it stays directly between Sun and Earth with minimal corrective energy.

[studabakahawk]

hi let me just say that the theory postulated by the esteemed Mr.Burns, is of course stolen ,like the pennies from a dead mans eyes. as are all things in Mr. Burns great vault.
if you look up Larry Niven,Sci Fi writer and read 'RING WORLD', or any of the offshoot stories that he came up with,in his Ring series of short stories, youll see that this is more or less where this idea should be developed from.
he freely credits this concept to a Professor Dyson, who suggested chopping up the other planets in the solar system to encapsulate the sun!
this would harness all the suns power, for our use. based on the idea that as one dot in space we recieve enough energy from the sun to heat and nourish all of the earth for millenia,so putting the sun in a box would give us oddles of energy to really cause some havoc.
but Dyson likened doing this with todays technology as to building a golden gate bridge that floats in the air unsupported.
so niven wrote a series of stories about large screens creating a ring around the earth set far enough apart to give darkness to large parts of the earth and to let it rotate and travel to give day & night effects.
the sun side would absorbe solar power, and send that back to earth.
using this concept to cool the earth would do just as well, simply dont have any breaks in the screen.
this would be right on with his Ringworld story, he postulated hi walls on either side of the outer base which is where we would live( down in between those walls) and the walls would hold in the atmosphere and it would revolve giving gravity and keep every thin from bouncing around or floating away.
i like the concept and the idea sounds just barely possible, barly...

[jlhredshift]

And the pollution from the rocket launches would......

[GBendt]

Hi,

If you put something at a Lagrange spot, it will only stay there if the thing being put is something SMALL. The Lagrange spot is a SPOT in a mathematical sense, it is nothing to house something of a size of thousands of miles.

Further, the means to build the shade and bring it to the Lagrange spot simply do not exist, and it will be a lot more expensive to develop and build it than is the reducing of greenhouse gases. There is a tendency to propose solutions which cost money, instead of proposing solutions that tackle the cause of the problem.
There are people who may make a fortune from the development, construction, transport and maintenance of the shade. It might cost thousand times the money for the ISS. Who is to pay that bill?
Currently, NASA hasn´t even the money available to build a lifeboat for a the ISS.

Regards,

Günther

[gazelle1978]

I was just thinking from a geological point of view the earth is pretty cool at the moment being in an interglacial period and there being ice at the poles which for most of the earths history has not been the case. Also the carbon dioxide levels are extremely low from a geological point of view, carbon dioxide levels have been 20 times present day levels.
If you seriously wanted to cool the earth you could throw dust into the atmosphere by detonating a few nuclear warheads, not sure if this would work on venus though.
Also eburacum45 mentioned that solar radiation is increasing as the sun's hydrogen is used up. You could fix this by placing a large object in orbit round earth and jupiter this would raise the earths orbit over the eons

[studabakahawk]

what rocket launches???? by then i would think we would have realised that a maglev propulsion system would hurl space craft out of the atmosphere,and construction would take place on and around the moon, where else could you create things large enough to do any good but in a zero gravity enviornment.
science fiction is fantasy, of course, but its mother is science and the facts that are postulated are ment to stimulate the mind of her children( scientists)
sci fi writing thrived in the 50-70's and the meger start we have in space is due to its impossible yarns, but i think the early space pioneers had Asimov,and Clark whispering in their ears, and i wonder where are our Great story tellers to spark our imagination now that were on the door step of the Dream?
yes mathamatics is the language, no doubht, but we need the spark of imagination to give that language the urge to create . and you gotta believe