One proposal is a massive reforestation campaign used as a possible method of slowing the buildup of carbon dioxide in the atmosphere. So too was fertilizing vast areas of the ocean with iron to stimulate the growth of carbon dioxide-absorbing phytoplankton.
Another option for mitigating global warming would be to try to control our planet’s radiation balance by limiting the amount of incoming radiation from the Sun. This could be done by increasing the reflectivity of the Earth — its albedo. Calculations show that an increase in planetary albedo of just 0.5 percent is adequate to halve the effect of a carbon dioxide doubling.
Several schemes suggested involved tossing additional dust — or possibly soot — into the stratosphere or very low stratosphere to screen out sunlight. Such dust might be delivered to the stratosphere by various means, including being fired with large rifles or rockets.
Another scheme envisioned placing thousands of large mirrors in Earth orbit to reflect incoming sunlight. Alternatively, billions of aluminized, hydrogen-filled balloons would be lofted into the stratosphere to provide a reflective screen.
Also, the NAS study team thought that vast arrays of pulsed lasers at mountain altitudes could be used to focus intense infrared beams into the atmosphere. The laser beams are on a mission to selectively destroy chlorofluorocarbon molecules in the atmosphere through the process of multiphoton dissociation.
None of these schemes apparently seemed practical in 1992; but maybe it’s time to revisit them?
I don’t believe any of those (save one) suggestions would or should ever be attempted. In fact they sound like silly jokes to me. Increasing phytoplankton in the ocean would have (in the long term) disasterous reprecussions for the global food chain. A short term win though would be a rebound in North Atlantic fish stocks (I think). All of the ideas for dimming the earth (albedo increase, shading etc.) would cause a correlated decrease in natural CO2 sinks in forests and oceans … extremely bad idea … to say nothing of animal disease due to vitamin deficiency. I can’t comment on the lasers though, I don’t know if that would have a secondary affect.
But the trees, oh the trees! Bring on the trees! But not too many please.
As Lovelock stresses Earth is flexible, but above all it’s a system. Systems operate well when everything is withen their “normal operating parameters” (thanks Geordi). To artificially and purposefully bring one parameter into an extreme, because another artificially came to an extreme is in my opinion welcoming feedback. It could be very dangerous. And most of all predicting would likely be extremely difficult due to non-linear and possibly (aargh) chaotic systems.
One of my co-workers has a PhD in nuclear physics. He has over the years convinced me that there are no more technical problems with fission. The remaining work to be done is purely social and political. I have long hoped for reasoned and rational debate about designing and implementing modern safer fission reactors. My hopes for fusion are dim. The by-products of the reaction may be quite benign but the spent reactor is most definitely not. It is quite debatable whether a fission plant or a fusion plant is a worse long term polluter.
But this topic is extremely important … to the front page, +1. Thanks Arthur!
All of the ideas for dimming the earth (albedo increase, shading etc.) would cause a correlated decrease in natural CO2 sinks in forests and oceans … extremely bad idea … to say nothing of animal disease due to vitamin deficiency.
You assume that sunlight is the limiting ‘nutrient’. In many cases strong sunlight causes water and carbon dioxide to be the limiting nutrients. Under thermal stress, the plant must close its stomata to avoid extreme water loss, which cuts off the supply of CO2 info. Odd how strong sunlight can reduce CO2 fixation, isn’t it? One might think this would be different in the ocean, but here too an odd thing happens. The higher a liquid’s temperature, the less gases can be dissolved in it. Reduced temperatures caused by sun shading might allow greater transport of CO2 into surface water from the atmosphere, thus enhancing photosynthesis and carbon fixation there.
The vitamin comment is misguided. The article mentions increasing the Earth’s albedo by only 0.5%, which isn’t going to dilute the sunlight enough to cause vitamin deficiencies. Indeed, vitamin D is produced using UV light and CFCs have increased the amount of UV, so shading might reduce UV back to the pre-CFC levels our skin and frog eggs are used to.
The comment about feedback, non-linearity, chaotic systems, etc. is well received. I have a particular problem with the introduction of soot into the stratosphere. These particles would absorb not only incoming solar radiation from above but also reflected sunlight and radiated. The thermal light from below, thus heating up the stratosphere, the first of the two cold traps that prevent our water from escaping into outer space. This could lead to more water getting up into the mesosphere. I’m not certain what such extreme-high-altitude water vapor and clouds would do, but you might have to throw your current meteorology text book out the window. The laser idea is completely new to me. I’ll have to snoop around some….
Can’t argue with trees…
I didn’t mean the albedo thing to be a vitamin deficiency issue. We would/should change the albedo in the arctics (or at least retain current levels). Besides that’s not so much a dimming issue as a heat transfer issue … so I misspoke (wrote). But the shading stuff. Nasty idea.
I am so happy none of these people have any power. I am so happy they have no ability to waste billions of taxpayer dollars by placing thousands of large mirrors in Earth orbit or vast arrays of pulsed lasers at mountain altitudes.
I very much hope not.
Mirrors would change the reflectivity of the planet, hence changing the albedo. Thus shading and albedo change are not nearly so separate as you make them out to be. You also seem to be worried about certain areas of the planet being permanently in shadow (I’m guessing). A balloon at 20 km. would have to be 187 m in diameter before its shadow on the ground would have an umbra, meaning that nowhere on the ground would anyone see a smaller balloon totally blot out the sun. Couple that with daily rotation, which causes the shadow to sweep across the ground, and it becomes obvious that no area of the ground would be in permanent and total shadow. The effect becomes even more dramatic for satellite mirrors that are higher up and moving faster. I can think of many other objections to these schemes, though. Perhaps you could clarify why you think the shading idea is “nasty”.
I originally objected to the idea of injecting soot into the stratosphere, but I’ve thought of one application where it might be useful. Injections of soot into the Antarctic stratospheric vortex during spring might disrupt the clouds whose nitric acid and water ice particles form the reactive sites where ozone-destroying chlorine radicals are regenerated. This is more palatable than the giant lasers.
So far we have more comments than votes!
is worthless. It doesn’t reflect the opinion of the public at large nor even of the average sciscoop reader. It reflects merely the opinions of those sciscoop readers who wish to express their opinions and don’t believe such polls are worthless. Perhaps if i hadn’t taken a statistics class…..
Hey, the polls are supposed to be fun – and get us some insight on the sciscoop readership who cares enough to vote :-) No, they’re not scientific polls in any sense, of course.
I belive that in all cases, wether the problem be global warming, enemy nukes or your never ending quest for world domination, Mountain Top Lasers are the only real option anyone EVER has!
Really!
J-n
Granted, I’m not aware of any studies or implications beyond what was originally in the article. My choice of word, nasty, is purely due to my gut reaction. It seems like a reactionary and extreme thing to do. And that it seems so is just that, not based on any particular knowledge, it just scares me. The idea of introducing a technology like this to mitigate the consequences of another at least in this case seems dangerous. (And completely analogous to introducing foreign competitors in an ecosystem, sometimes it works, sometimes it doesn’t.) If there ever were policy decisions to implement some of these schemes I would fix the problem of my lack of knowledge so that my fears would be put to rest, or factually (to me) justified. I used to have the gut reaction fears to nuclear fission power, but after some education I no longer do. So, I’ll readily admit that these schemes may be completely benign in consequence and that my fears are unjustified irrationalities due to ignorance. But my feelings are mine, for good or bad.
We can deploy fission reactors comparatively easily so the need for knowledge about their consequences is high. The need for knowledge about these orbital schemes to people like me is low. But the dimming of sunlight has been in the news recently and one of the angles present in the stories is the reduction of vitamin D production. If that is a major factor, increasing the blockage of sunlight will have consequences … seems nasty to me.