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Oct 01 2012

A solar shield; what could possibly go wrong?

So let’s say, thanks to the reality challenged wingnut brigades and associated ingorati, climate change hits a tipping point. And now the whole world is looking down the barrel of a clathrate gun. Well, there might still be solutions. Afterall, this isn’t just a political problem, at its heart it’s a thermodynamics problem. Any second year engineering student can swear on a stack of tables six inches thick that thermodynamic problems often have solutions. In this case, the solution would have to be … err … large:

Slashgear — A group of scientists from Scotland have suggested a unique approach to fighting global warming here on earth. The scientists believe that the answer to global warming on Earth is a giant dust cloud blasted from an asteroid to act as a sunshade for Earth. According to the scientists, a project that reduced the amount of solar radiation the Earth receives by only 1.7% could offset the effects of the global increase in temperature of 3.6°F.

That might work. We’re not talking about diverting the object significantly, only putting some kind of snowblowers or dust agitators all over it. Which is fortunate: the delta V needed to divert a dino-killer asteroid appreciably and quickly is considerably more by orders of magnitude than Bruce Willils of Ben Afleck had at their disposal in one of the worse sci-fi movies ever produced.

But there are certainly concerns with it. It’s not real controllable, blast too much dust and it’s a long wintery wait while it clears out. The dust would have to be super thick by interplanetary standards to knock insolation down by a point or two during part of earth’s orbit. That would probably mean spectacular meteor showers when some of the dust got close and came streaking in. If the dust wasn’t pretty confidently homogenous — no big city-block sized chunks in it — I suppose that would be OK. Meteor showers are cool. It would have to be regularly renewed, basically streaming; the solar wind would push out small particles quickly and they would leave our vicinity. What else, what am I missing? It could be turned into a weapon of sorts maybe? He who controls the dust controls the universe? Or at least the cryosphere …

17 comments

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  1. 1
    nathanlevesque

    Two words: space umbrella.

  2. 2
    The Lorax

    I’d be more concerned with the additional debris in orbit. How are we going to get interplanetary spacecraft past that? And if it’s not in Earth orbit, how in the seven hells are they going to make a dust cloud that massive?

    Although it might be an even more difficult feat of engineering compared to landing vacuum cleaners on an asteroid, I think blocking the sunlight with low earth orbit shades is the best way to go… they’d be controllable, light-weight so they wouldn’t cause much damage if they re-entered, the engineering would be fairly simple, they’d be close to home if they needed to be modified. Plus, they could act as a first step toward a Dyson Ring. Yeah it would be expensive as all hell, but I think those benefits greatly out-weigh the potential (and somewhat horrifying) risks of a massive dust cloud floating about between us and our source of entropy.

  3. 3
    Aliasalpha

    This sounds similar to the Red Dwarf solution, putting a giant toupee in orbit to cover the hole in the ozone layer

  4. 4
    embraceyourinnercrone

    Earth orbit shades seem much safer and more controllable than a dust cloud. But then I am a believer in the Law of Unintended Consequences. From what little I’ve read so far global climate change is going to have (is already having really) so many sometimes interacting consequences, that humans trying out various large scale mechanical and chemical mitigation projects frankly scares the crap out of me. Whats the worst that could happen….

    I would rather see governments try to encourage use if alternative fuels and invest in research on them. Maybe reward people and companies for lowering their carbon footprint and for things like using mass transit or riding your bike to work or school. Of course at least in many parts of the US that would entail actually HAVING any available mass transit.

  5. 5
    jeremycraft

    Monty Burns was shot for much less.

  6. 6
    aziraphale

    I agree with others that low-orbit shades are preferable. Some of them might even double as solar-power satellites. However they must not be used as an excuse to carry on increasing our use of fossil fuels. That will just acidify the oceans and kill off more corals and other species, some of which are in our food chain.

  7. 7
    leftwingfox

    Maybe I’m just stupid… but, if this is going to cause a significant inbound heat reduction, isn’t it also going to cause a significant inbound LIGHT reduction as well? Won’t that also have a major effect on global photosynthesis?

  8. 8
    M can help you with that.

    leftwingfox –

    That was my concern as well. Maybe sunshades which are transparent in the frequencies important for plant photosynthesis? (A biologist, biochemist, etc. may be necessary here to correct me on whether photosynthesis has a particular light frequency range…and someone with a background in climate science on whether there are certain frequencies which contribute more to solar heat gain.)

  9. 9
    bad Jim

    I like the idea of solar-powered robotic fog boats in the Arctic: an easily throttled increase in albedo in an area that isn’t critical to agriculture. It might not be as cheap or effective as other sorts of geoengineering, but it’s pretty much guaranteed to be safe.

  10. 10
    mildlymagnificent

    The only geo-engineering worthy of serious consideration is “reverse geology” or “enhanced geology”.

    We’ve spent 200 years accelerating beyond all reason the geological processes that release stored carbon. I think the current numbers are that annual oil use is the equivalent of 3 million years of oil accumulation. So our job is to look at the natural processes of drawing down carbon – mainly exposure of ‘new’ rock as tectonic forces create higher mountains. We can’t possibly interfere in tectonic movements, but we’ve got lots of experience in identifying ores, rocks and other materials.

    If we’ve been willing to blow up mountains or gigantic holes to release carbon from certain rock structures, we can do the same for olivine and similar rocks that will absorb carbon. In fact, it’s much, much easier, more quarrying than mining. The only issue will be deciding on the biggest bang for our buck in distributing gravels and dusts to maximise the sequestration benefits.

    I have visions of more or less automatic milling processes on top of mountains letting dusts drift on the wind. But it might be worth the cost, at least initially, to deliver some directly to shallow waters near reefs or acidification hotspots to save some important species or habitats.

  11. 11
    StevoR : Free West Papua, free Tibet, let the Chagossians return!

    jeremycraft : “Monty Burns was shot for much less.”

    Actually he was shot attempting to steal a lolly from a baby which proved much more difficult than the saying led him to believe!

  12. 12
    StevoR : Free West Papua, free Tibet, let the Chagossians return!

    @10. mildlymagnificent :

    The only geo-engineering worthy of serious consideration is “reverse geology” or “enhanced geology”.

    Not sure I agree with that.

    A recent issue of New Scientist magazine (22nd Sept. 2012) had a cover article on geoengineering discused arnage of options including mostfavourably thesunshade option but also noting various problems and “side-effects” such as harming one or two countries whilst helping the rest.

    I think the science and industry which got us into this mess may also be our best hope of getting out of it too.

  13. 13
    aziraphale

    Leftwingfox: to lower the global temperature by 1 degree C we need to cut the incident light by about 1.5%. I think most plants will hardly notice that – and it may be compensated, ironically, by the increased CO2.

  14. 14
    birgerjohansson

    To prevent the arctic methane from thawing out, it may be necessary to do “geo-engineering lite”; inject fine dust (like toner) into the stratosphere of the arctic.
    By the time the dust sinks out of the atmosphere the air will have moved it clear of the arctic, so the dust will not contribute to altering the albedo of the snow and ice.

    This may seem desperate, but a multibillion-dollar scheme to block a tiny fraction of the sunlight reaching the arctic may be the only way to prevent a big methane “burp”.
    — — — — — — —
    As for reducing the acidification of ocean water, I do not know enough chemistry to calculate how much raw material would be needed to buffer the acidification.

  15. 15
    leftwingfox

    to lower the global temperature by 1 degree C we need to cut the incident light by about 1.5%. I think most plants will hardly notice that – and it may be compensated, ironically, by the increased CO2.

    I don’t buy that, at least without hard data.

    CO2 in most cases is not a limiting factor to plant growth. That’s been the big problem with denialists claiming “CO2 is Plant Food”; It’s trivially true, but misleading in that most plants already have access to more CO2 than they can use, and other effects of Global Warming can actually limit growth through water availability, disease spread and the effect of heat on stomata.

    That said, I don’t honestly know how many plants are limited by sunlight, but I would assume that most agricultural crops, which are provided with irrigation and fertilizer would be most sensitive to sunlight as a limiting factor. Worst case scenario, it could mean an 1.5% reduction in global food supplies,

    Short of a

  16. 16
    leftwingfox

    Sorry, disregard the last sentence fragment, I was trying to high-light the line for deletion and hit the “Submit Comment” button accidentally.

  17. 17
    comfychair

    Global Dimming? Sounds awesome! I’m sure there will be no unintended consequences.

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