First, man isn't warming the earth. It's the SUN STUPID.
Second, when man tries to outsmart nature he always fails: Cudzu, Gypsy Moths, cloning, meterologists.
God has a plan and is in control. Man cannot change that.
Live life and enjoy the creation. Change it at your own peril.

The ocean is a good absorber of solar energy. It can be shaded by floating reflectors that will reflect the incoming solar energy back to space or to overlying clouds. A large area is required. It can be a flexible mesh of 1-meter square panels that will conform to the wave surface.

Sunshade aerosols are supposed to be injected into the upper stratosphere, but they will eventually come down to the troposphere where they will provide too many cloud condensation nuclei to the air that flows over mountaintops. Moisture that condenses will form water and ice particles too small to coalesce and precipitate. Aerosols are already suspected to be a cause of droughts in western US, Lake Victoria, Himalayas, and elsewhere. Aerosol sunshades might worsen droughts.

First of all, 'Bill' is wrong about the cause of climate change. Climate disruption is very real and the vast vast majority of climate scientists agree that it is caused by burning fossil fuels and that we need to act NOW to reduce emissions and move forward with clean energy. The atmospheric CO2 concentration is heading toward 400ppm, and if we continue on the BAU trajectory, the planet will become uninhabitable.

So, I can see why some scientists are looking at geoengineering such as sunshades. This route must be taken with great caution, since the effects of 'fooling Mother Earth' may prove worse than the effects of runaway climate change.

Why, oh why!, can't we all just pull together and reduce our energy use? Why don't we consider the future of our children and grandchildren first and foremost? Why should they suffer because we're too lazy to act?

Every government on earth should outlaw incandescent lights immediately and insist that every commercial/manufacturing building either paint its roof white or plant a green roof. Why not outlaw personal vehicles that get less than 30MPG? We need these types of actions NOW if we hope to halt catastrophic climate change.

Nancy

This is the most ludicrous thing I've seen in a LONG time.
The earth has gone through numerous warming and cooling phases in its long history. Nothing man can do will affect it.
CO2 is not a pollutant.
Al Gore is not a prophet.
It's too bad that NG has has been swayed by the "Global Warming" hysteria.

This is a terrible idea, as are ALL ideas that propose tinkering with nature, to solve a "problem" that it is not even certain we have. WAY too many unknowns for outcomes.

Er well...I got news for you... in the United States our Air Force has already been doing just that- for almost 10 years. It appears many of our allies have been actively testing as well. What exactly is being sprayed? I'm not quite sure. Two distinct shades of aerosols have been observed in Northern Virginia: a white variety and a darker, almost charcoal colored spray.
They seem to be test spraying prior to a front coming through. If you know the normal air routes over your area and their is an onslaught of persistent contrails off or tangent to the normal corridors, and at a much higher altitude, it might be a spraying operation. Even the weather channel is on board. They changed the background graphics on the 8's a couple of years ago to reflect a hazier and contrail laden sky. Occasionally too, you'll see a ghost radar return on the 8's when there is heavy spraying, but no rain in the area.
Look up at the sky everyday and form your own opinion.

It is ridiculous. This is just an other dead end. Why can't the solve the original problem what is made by the man? It's not the sun's fault...

(who seen tha Matrix movie? they made the same... :)

Such a wonderfully stupid and poorly thought out solution - trillions of reflectors scattered in deep space. Nothing like creating another man made junk yard. And, when the current warming trend changes to a cooling one, who's going to go clean up that mess. This is a solution indicative of our culture - the need for instant gratification and letting someone else worry about the consequences.

This is RIDICULOUS. First of all, 'global warming' is a crock- we're going through a cooling period right now. Aside from that, the earth is ALWAYS going through climate changes, as any scientist worth they're weight in dirt will tell you. To expect the planet to keep a constant temperature is illogical, insane, and just plain out of touch with reality. The Sun doesn't keep a constant temperature, so neither will our planet.
If we try to disrupt the natural order of things, we'll be biting off way more than we can chew. The universe is a complex system, the understanding of which we have a slim and fleeting grasp. Even if you buy into this 'global warming' hype, wouldn't the best thing to do be to lessen our impact on the planet and let it fix it's own problems?
Potentially causing another ICE AGE with toxic ash has got to be the most un-intellegent thing I've ever heard of. This is everyone's planet, and I for one don't want to see it ruined because of a buch of propaganda.

Shutting away the sun and polluting the air can't possibly help anyone.

Watch out Bill, your threatening the Global Warming err... Climate Change crowds religion.

Sometimes it's hard to believe how arrogant some "scientists" can be in thinking they should try to alter the natural cycle because they "understand" what's happening. They then choose to ignore the historical evidence that the Earth goes through warming and cooling cycles. Who are we to say what is the perfect temperature for the Earth?

Man has continuously ruined the balance of nature and has then attempted to fix his mistakes with ideas where the consequences cannot be calculated beforehand. This usually rights one wrong but creates a whole new imbalance. Global warming is a natural trend but humans have definitely altered earth's ecosystems and atmosphere by their lifestyles. We cannot right the wrong of this human impact by unnaturally cooling our planet. We do not and cannot know the effects that such an idea would have, and messing with the atmosphere could have massive negative effects that will be global. We must take responsibility for our actions and those of our ancestors and create more nature-friendly lifestyles and industries. We are not going to stop global warming. It's a natural trend that our planet goes through. But we can stop polluting earth to the harmful extent that we do now and have done for years.

This cooling theory does not seem right. It needs to be fully researched before any nation even thinks about utilizing it. The possible consequences of this action must be known before it becomes a serious consideration. There must also be a global consensus to use this method. No one nation has the right to jeopardize the planet with what they believe to be a solution to a global happening.

I will never be asked to vote on this topic by the ones who would put this plan into action. But I would vote NO on its use until science and research could convince me of its safety for man and everything living thing on this planet. We cannot afford to further destroy our earth.

The question I answered started off by saying "as a last resort"..... Well dah!!! Certainly as a last resort I could only answer Yes. My first resort is to get humanity on the same page. We have spent billions of dollars bailing out countless entities and we can't find the money to fix what we know to be wrong? What a civilization of greed and avarice we've got going here. Maybe, just maybe, we are earning what we get!

Probably the worst idea I have ever seen and this "great idea" has been around for some years. I am disappointed in NGM for wasting paper on it.

This idea to "shade the Earth" is illogical and pure nonsense....much like the the argument for man-made global warming, which is a fabrication based on "junk science" and theoretical climate models, rather than cold, hard, scientific facts. The planet has been gradually cooling since 2001 despite atmospheric CO2 levels continuing to rise. Most of the CO2 in the atmosphere comes from the evaporation of seawater (55%), not man's activities (7%), anyway. CO2 only makes up 0.038% of the atmosphere, which makes it a "trace gas", and man's contribution is a "trace of a trace". Face it global warming believers. Our carbon emissions are insignificant compared to natural factors such as the solar cycle and Earths' natural atmospheric processes, none of which are even fully understood. Trying to tinker with something you don't fully understand is foolish and dangerous. We don't need to waste money on solving a problem that doesn't exist. This idea is as foolish as taxing carbon emissions. Sorry Mr. Gore, but your wrong about climate change and there is a mountain of evidence and facts to prove it.

Bingo JB. Makes the possibility of our scientists in the US and our allies tinkering with the weather all the more serious. Incidentially, there was a lovely program about weather manipulation on the History Channel tonight called "That's Impossible" They talk about chemtrails, cloud seeding, and HAARP. The way it was written it could've been called "Highly Probable".
We are perhaps headed for another "Maunder Minimum" type event right now(a sunspot minima). The sun certainly has quieted as of late. If true it could potentially lead to another little ice age that could last from 25-50 years or more. This summer has already been far cooler than normal in the US and parts of Europe. Are they linked...maybe.

It seems to me to be a dangerous and ludicrous idea. What is the plan if it gets out of hand, and the earth cools to the point of another ice age? Would the millions of tons of tiny particles get cleaned up? I doubt it. Though many scientists claim global warming, there are scientists claiming global cooling. One way or another the human race will go extinct sometime in the future.

As a federal government project manager, I have seen a lot of half baked and crackpot ideas proposed for federal funding. It would appear to me that there are a lot of "concerned scientists" out there that are attempting to cash in on the fear mongering of global warming catastrophes.

It seems there are still many people who doubt that man's use of fossil fuels is contributing to global warming. May I suggest that the doubters take the time to read Mark Lynas's excellent book entitled "Six Degrees - Our Future on Hotter Planet". He gathers together the research of hundreds of scientists from different fields and eminent institutions, outlining the effects of global warming up to 6 degrees, a mass extinction scenario that may well be possible over the next century if we do nothing. What I find particularly scary is the positive feedback mechanisms which kick in as the earth heats up, making it ever more difficult to stop global warming once its started. I am very much in favour of finding a well-researched Plan B as I do not believe man has the foresight, collective will or capability to make all the huge changes that will be necessary in the way we use energy in the short time available. There are no doubt a lot of unworkable ideas out there, but they should all be placed on the table and given careful consideration before they are discarded.

I agree with Gergely Nagy. Has anyone seen The Matrix where the exact same scenario plays out...humans block the sun from solar-powered robots and, in turn, force humans to retreat underground due to a poisoned sky and a lack of sunlight so bad that nothing can live on the topsoil of Earth.

Now, I realize this is a movie; however, if sunlight is blocked from Earth, think of everything that is dependent on sunlight to live, operate, etc. This includes all plants using photosynthesis to create food. This includes any solar operation to generate energy (virtually emission free, minus the setup of the operation). Humans (that's us!) require sunlight in order to absorb Vitamin D, which is essential for a number of physiological functions including the uptake of calcium and phosphorus.

I sure hope whoever is thinking of implementing an idea like this has thought of these consequences. I would rather deal with the fluctuations of the Earth's climate than be subject to a mass extinction.

...And one more point, when the sun disappears, there's this thing called nuclear winter...

This has to be the stupidest idea ever. Even to-day they cannot accurately forecast the weather. Why not cut out logging all the forest lands and remove all the high flying jet aircraft burning up tons of fuel on each and every flight. There are many scientists who do not agree with the global warming crowd. The earth throughout it's history has gone through cycles of cold and warming trends. The audacity of even suggesting such a solution is ridiculous and especially where no quick countermeasures could be taken to nullify such a foolish idea if things get out of control. In my close to 90 years I have never heard of such stupidity. No wonder things are going to pot if this is the best they can come up with. The old propaganda machine is working overtime to nullify dissent to global warming.

How stupid can some "scientists" get?
If it didn't work would they go into space with a broom and dust pan and clean up?

If this idea has truely migrated from the fringe to the scientific mainstream, then we're in trouble. This has got to be one of the more silly solutions to the GW religion.
So, what's their plan when this giant sun shade in the sky is put up, possibly works better than predicted and drives our planet toward an ice age... Are we then going to send highway cleaning crews into space to cleanup the space trash?

Both proposals are further bandaids that won't cure or even strongly ameliorate the disease: Overpopulation. Only a reduction of the planet's population to about two billion persons will be a permanent cure. This can be achieved in roughly 100 years if each woman, world wide, will limit herself to no more than one successful pregnancy.

Have anyone thought about what would happen to the rate of global photosynthesis in plants and trees if the space lens reduce the level of light going to earth. Photosynthesis take co2 out of the earth atmosphere which is the main cause of global warming. if you reduce light, would that mean that the rate of photosynthesis would decrease which mean rate of co2 in the atmosphere would go up which would speed up global warming.

Does this mean the space lens just trade light for co2?

Where do "scientists" (?) get this stuff? Can you imagine if we let some idiot do this and we started having "global freezing" instead?
What are they going to say? OOPS!

Some men need to stop thinking that they are like God and know what's good for the rest of us! Enjoy God's creation every day you have it!

Was the guy's first name that came up with this idea named Al?

I think this is evidence that physicists need to get out of their heads a little more often and actually participate in conversations with real humans. What a complete waste of fossil fuel - blowing the 200 plus million year old wad of ancient and condensed sunlight on permanent sun-deflection? Don't people think that maybe, oh THE SUN, is kind of like the live giving space body? Mucking it up for whatever decedents of our paltry race survive is a pretty selfish move to "save" their hides. Perhaps we should just confess we messed up and work to be less materialistic and more simplistic and unified.

First of all mankind is not responsible for changing the temperature of Earth be it global warming or cooling. Climate change can not be controlled my man.

Remember...star gazers need federal grants to support the equipment that they need to look out into space as well as to continue to live a life in their own zone. They, like the other grant addicted "Scientist" are going to say whatever they need to in order to receive their life sustaining grants. The current administration needs more of these talking this kinda stuff up in order to pass Cap & Trade.

Not only a bad idea, a dangerously irresponsible one. Our warming climate may be a little uncomfortable, but throwing earth into another ice age would be catastrophic, and it doesn't take much to do that. Beware of unintended consequences.

EAJ

This is an appalingly flawed and potentially dangerous idea. It typifies the worst aspects of the issue it tries to address - It is wasteful beyond belief; The Earth is certainly experiencing a warming trend and it is arguably due to excessive, non-sustainable energy production and consumer consumption. This idea proposes to obscenely consume even more by constructing some means of actually throwing away the very energy that is sustainable! All this with out any real knowledge of what such a step-change in the available solar energy falling on the our planet might have on our (currently) life-sustaining environment. Absolutely shocking and a potential winner of an 'Ignobel Award'. The cash and intellectual resources required would be far more profitably employed in trying to efficiently harness solar energy and other renewables. As a scientist, I cannot believe that 'Science' would consider such a backward and self-defeating project. I sincerely hope that this idea is consigned to the 'Do not fund' pile.

What an incredibly STUPID idea! It is very arrogant to think that humans can alter the course of nature. Leave it alone Mr. Angel, the earth has taken care of itself for billions of years and will continue to do so in the future.

Nancy makes the same mistake as multiple others...assuming that "Climate disruption is very real and the vast vast majority of climate scientists agree that it is caused by burning fossil fuels and that we need to act NOW to reduce emissions and move forward with clean energy." The reality is very different.

The cause of warming, and cooling, are sun energy cycles. One primary fact concerning and proving this issue is that a neighboring planet (Mars) experienced a similar degree of warming in the same period that the Earth did...and I know of few SUV's and CO2 producing humans on that planet.

Is it smart to reduce pollution...obviously...yet to reduce global temps the way this article discusses without a total understanding of the results is dangerous...and science can never know the totality of these effects as we simply are not that smart.

Any comments/ideas to the contrary are the result of egos trying to maintain their funding.

Just who is going to move this multi-million piece sunshade when the sun by gravity moves the Earth out from under it?
NGM has lost its common sense for printing such a piece of unsupported junk science.

Of course mankind is changing the temperature of earth! that is the whole point of it. Earth requires Co2 to function, it gives the Earth the proper temperature so life can exist, if the Earth had no Co2 then we would have a temperature of minus 19°C. But now, mankind is producing tons of Co2 and that is creating a stronger greenhouse effect wich leads to bigger temperatures. We changed the climate by creating a larger greenhouse effect than the Earth is used to, and that will have its consequences. Our main natural sun reflector is being destroyed by the climate change, the ice poles. I agree with the idea of installing sun reflectors on the ocean.

This is such a stupid Idea.. Flinging mirrors or other chemicals into our outer atmosphere. All in the name of greed. I even heard one that they found a planet that they think might be like earth 20 million light years away.. mmm wouldn't it be a better idea to protect the one we have. If anything send ionized water vapors into our atmosphere let it drop like rain. I am no genious but it seems to me that I read someplace that water collects around minute particles and drops like rain. we have the equipment we know what is required. Even with this with population growing the way it is how will our farming community feed the upcoming boom of people.
I truely beleive in small wind and solar. sure you wouldn't get a huge volumn of energy out of each system but the acumulated energy from all would be a major energy boost reducing the need for more polluting plants. The cost of doing something like that is about the price of one big wind plant to do our whole state. Yet there again it is greed.who is getting the money is who controls our destiny in my opinion. Do what they want our future desendants are the ones that will pay

In your "Vote", you asked whether filling the stratosphere with reflectors is a good idea or bad. You should have asked a multiple choice question, since you presented two ideas. Stratospheric reflectors is a BAD idea, but putting sunshields in space to block 2% of the sunlight hitting Earth is a GOOD idea. Global warming in the geologic past has always happened slowly enough for life to adapt. But the current epoch of global warming is a sudden spike, happening in only a century, and that makes adaptation by most animals and plants virtually impossible. Since we humans have caused this spike, it's our responsibility to do something to prevent the inevitable mass extinction, and since efforts to cut greenhouse gas emissions will take too long to prevent catastrophic warming, emergency measures to reduce solar heating are called for. Space sunshades are environmentally much cleaner than stratospheric dust. By the way, those space sunshades must actively "station-keep" to stay in front of the sun. If station keeping is turned off, they would drift harmlessly off course in a few weeks and disperse to form a ring around the sun. So quit worrying about them triggering a new ice age.

This is a terrible idea considering the fact that we would become too reliant on the sulfate, causing us to not care about our emissions here on earth. The more pollution we pump out, the more vulnerable we become. Then What happens when our supply of sulfate on earth runs out?

I've had this crazy idea for awhile but until I saw this I had not talked of it. There are large areas of plastic floating in our oceans, some the size of Texas. Why not gather them with nets lashed together with other nets, paint them white and use these to replace the melted ice caps thereby reflecting sunlight as does the ice?

Can't believe you printed this. Now I am scared

And so what happens when we eventually smarten up and global warming starts to receed? Do we go into a mega ice age over emphasized by the 'sunshade' and kill off thousands of species in the process? Any way you look at it, this is a bad idea. We are again refusing to take responsability and these 'scientists' are not thinking through the consequenses of their actions. Sad really...

So NG carefully considers if putting a trillion dollar sun shield in space is a good idea, but they never consider if global warming ISN'T happening?

Did you guys get the news that:

1. July was one of the coldest July's on record?
2. That CO2 is only .03% of the atmosphere?
3. That the earth has heated up and cooled off numerous times in the past?

Dr. Who's science was better thought out than this.

We can cool the planet just by catching enough solar radiation hitting the ground in solar panels and thereby making it even useful to us. The greenhouse effect is caused by the sun hitting the ground heating the ground which then emits longwave that canot escape to space through the polluted atmopshere. So if we take out enough incoming solar radiation through solar panels we reduce at the same time the amount of longwave radiation that is created and thus reduce the green house effect. So just get going and put panels on all roofs, over parking areas, over desert expanses, etc., and convert the solar radiation into practical uses, i.e., electricity.

I am an engineer (Chemical) and a 30+ year member of the National Geographic Society. I have loved the NGS nearly my whole life, and have received every issue since 1978 when I became a member courtesy of my grandfather. For years I have enjoyed learning about the earth, the seas, the stars, the people.

But for the last few years, I have increasingly felt that I am a member of some fringe enviro-group bent on persuading me that Science is cut-and-dried concerning one overwhelming topic: CLIMATE CHANGE (formerly known as Global Warming). Shudder. This article has become, sadly, typical of the kind of tripe trotted out by those oh so much smarter people who Know, Without A Doubt, what is going on in the world, and how to fix it.

The only indisputable fact is that data continues to be gathered, and real scientists continue to evolve their theories of planet and solar behavior. Please remember that it was only 1957-8, just twenty years prior to my membership, that the world conducted the IGY, and started in earnest a tabulation of data about the world around us. Look back at past issues of NG to see their take on this.

I won't go into all the reasons why the issue is far some settled, for it has all been laid out, and the Global Warming (or was it Climate Change) believers will rant that I am some lackey for an oil company (I am not). I will say that when I visited a glacier in Alaska in 2002, there were signs posted along a walking path that showed the position of the glacial face through the years. The retreat of that particular glacier started at least in the 1800s when people started tracking, and likely long before that.

The fact is, the earth had been warming for some considerable time, and may continue, or may begin to cool, as though we are not even here.

I am extremely close to terminating my membership in the Society. I know my dues are funding this type of claptrap, and frankly I disagree with the Society's inability to discern from real scientific activity and crackpot charlatanism. Maybe this was bound to happen without a Grosvenor at the helm, but I do long for articles like the current one on Yellowstone. Thank goodness they throw me a bone once in a while.

Oh, to answer the question, I think this idea (the "shading" of the earth) to be a utterly useless and dangerous concept, and completely out of place in a so-called scientific journal.

Bad Idea!
Filling the atmosphere with garbage to stave off a global warming problem that doesn't exist.
When is NG going to recognize that climatology is just a belief system, not a science.

Extreme measures should be taken only in extreme duress, and certainly not when there are so many other options to explore. It should most especially not be attempted when the long-term consequences of the action is unknown.

This is a case of forward-thinking scientists not thinking things through, and not looking at the cause--only the effect. We would be much better served by exploring visionary science that does not potentially kill the patient in order to find a cure.

Basically a BAD idea for either atmospheric tinkering proposition.
The "global warming" mindset (read: politicians) has little reality/understanding in the whole geologic scale of things. If either is installed as a real geoengineered solution, they do not consider the effects of loss of sunlight on the vegetation that is a dominant CO2 user (it that even is the goal).

How about another catastrophic condition that could happen... (see cover of Aug. 09 issue.)
Volcanic eruption compounding the effects... can the geoengineers turn off their sunlight-blocking scheme at the drop of a hat? No?...Oops.

Global warming/cooling is a NATURAL process regardless of what input Man may or may not have, along with flux in atmospheric gasses. Nature always has something up her proverbial sleeve to throw in the mix. Catastrophic events can and do happen, including warming, cooling and species extinctions. The geologic record has many episodes to collaborate this. If this is our time, then it is.

Hmm... maybe Man should have pushed harder to reach for the stars with greater gusto!
40 little man-years since the moon was reached and where are we now?
And where could we have been?

This article is making me consider cancelling my subscription. It's bad enough that NG has fallen into the global warming hype, but I can't believe they would print something so ignorant. Anthropogenic global warming has NOT been proved! Stop treating like it has. Also, I find it interesting that in the magazine, there's this article, and then one about Yellowstone where it explains that when volcanic eruptions cool the Earth suddenly, WHOLE SPECIES are threatened! That's some contradictory information if I've ever seen it... NG, you are losing my respect.

This article comes very close to the deal breaker. I have been a member since 1958 and have been very upset by the current trend in the magazine. You have gone from informative articles to the current presentation of junk science. This one is the dumbest idea I have ever seen. The idea that climate change is caused by anything man does is in the realm of religion. At least Al Gore is in it for the money with his carbon trading scheme.

I have already canceled getting your DVDs because of the blatant propaganda content. I am seriously thinking about canceling my membership all together unless you get out of the junk science market and get back to the real reason for NG.

I find it difficult to believe that we continue to try to find ways to reduce CO2 emissions with bizarre solutions, instead of addressing the root cause. THERE ARE TOO MANY PEOPLE ON THE PLANET! I hardly ever hear this mentioned. If we concentrate on population control, most of the problems we have - excess CO2 emissions, finding enough land to grow food for everyone, water pollution, declining resources - will be solved. It's simple mathematics. Limiting the number of children to zero or one per family, going forward, will produce results rapidly. Laws would need to be written to try to enforce this.

Another point... Have the scientists proposing we use sun block on the planet considered that it would reduce the amount of clean solar energy we can produce?