66 Comments

We're in the middle of an ice age - and you want to cool the planet?!? Won't that substantially increase winter deaths?

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artificial volcanoes appears to be the current leading scientific proposal

In what way is scattering precious sunlight into space supposedly "scientific" - when much of the planet is still a sterile, frozen, icy wasteland for 365 days a year?

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Nuclear power.

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The American Geophysical Union yesterday seriously considered artificial volcanoes. The proposal was countered by the idea of robot-driven ghost ships to fire sea salt into the air for a somewhat similar reflective effect.

But artificial volcanoes appears to be the current leading scientific proposal:

"Sulfur injection into the stratosphere is considered to be the leading candidate for geoengineering, since nature has done this many times via volcanic eruptions, and we have some idea of what to expect."

-- Wunder Blog

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Not being an earth scientist and certainly having no detailed knowledge of the causes and effects of induced geological activity I am very wary of such a solution. I think there are several arguments against such an approach:1.It is not permanent. As we geometrically increase our CO2 emissions, we would have to geometrically increase the volume of our induced geologic activity.2.There is not way to know (as far as I know) whether the induced geologic activity will affect any particular part of the earth. It is therefore likely that such activity will adversely affect significant portions of the globe as has happened during major volcanic eruption events such as Krakatoa or Mount Saint Helens. (The only events which I am even passing familiar with).3.The volume of such activity would be enormous, since even Krakatoa does not seem to have had any lasting effect. This in itself would significantly affect some portion of the globe chosen for this activity.4.Other products of geologic activity, such as heavy metals, other particulates and steam would seem to have separate adverse effects that in turn would have to be mitigated.5.As per Number 1 above, even the successful use of such a technology would not obviate the necessity to reduce carbon emissions in the long term. The argument that postponing the reduction of such emissions simply pushes the much larger cost and environmental impact off to the future where it will most likely be too large to handle. (If it is not already).6.Messing with the earth in this way is like handling a ticking time bomb. The results, in terms of environmental and economic disruption, could be catastrophic and I have no confidence that they can be predicted. (This objection could be reduced or removed over time though.)7.The ozone depletion angle is worrying. It may be minor compared to the effects of global warming, but other solutions are or may be available that do not exacerbate this problem. (I am also not sure that this would be minor given Number 1 above.)8.Use of this “solution” would deflect us from the real solution, which is reduction of CO2 emissions.I am sure that others would have better and more informed opinions, but just my two cents.

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Increase in atmospheric carbon dioxide is undoubtedly increasing climate warmth. However I suspect that an even greater affect on warmth is the baring of soil by increase in annual crop acreage, roads, buildings, grazing, and desertification. You may see an article that discusses this in more detail in http://charles_w.tripod.com...

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See my added to the post.

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I think SO2 cannons would be useful because it might give us more time to observe the effect of CO2 on the climate and will let us make a more informed adjustment. If climate sensitivity is high then we will have to fire them quickly and we will be not much worse off than if we hadn't waited and ignored the SO2 option. However, if climate sensitivity is low then we will make a much better adjustment.

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Regarding Tim's and Mitchell's point, this strikes me as no more sane than any other form of superstitious last days romanticism.

There are few if any singularities in nature. It is far more likely that we are reaching the inflection point on a sigmoid.

Regardless of the plausibility of such an outcome, it seems to me very much more responsible to presume the more modest one and risk being happily surprised than the other way around.

I don't actually relish the idea of your Singularity, though. I have no idea why you would want to encourage such a thing.

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Many seem to be saying that disaster seems to follow from continued exponential growth in CO2, so we must stop at some point, so we must stop now. This last step in the argument just doesn't follow.

I agree, and would replace your last step by: "...and almost certainly the sooner we stop, the less disastrous." (Which also doesn't follow from the preceding two steps, but which I think is correct -- hence the "and.")

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@Scott Aaronson: Glad to be of assistance! Now, all we have to do is find some alien race capable of giving us $1 billion worth of precious metals in exchange for using our planet as target practice in 630 years...

Anyway, FWIW, I don't even think humanity needs the gain in real wealth today to be capable of handling a mega-meteor shower in that many years. But it's not like we can test this any time soon.

However, I think now you would have to revise your position. Earlier, you found it flat out incomprehensible to value life in such a way as to make the previously discussed tradeoffs. Now, I think you would agree it reduces to the more comprehensible question of how humanity's ability to handle specific catastrophes will change.

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Tim Tyler: "We'll have AI and nanotechnology within 50 years. That will make climate change into an irrelevant storm in a teacup."

I wrote about this issue recently. It could even be the subject of a post here: what is the rational way to approach problems of unsustainability if you expect a Singularity? The answer I proposed is essentially to compartmentalize: treat sustainability as a matter of mundane quantifiable governance, like macroeconomics, and treat the Singularity as a highly important contingency that can't be timed, like a natural disaster. I would still defend that as a first approximation, but clearly the interaction can be more complex: if you really do think that the Singularity will almost certainly happen within 50 years, then you won't care about environmental changes "thousands of years hence", or even those slated for the second half of this century. In general, expectation of a near-term Singularity should skew preferences towards adaptation rather than mitigation.

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Re: thousands of years hence

We'll have AI and nanotechnology within 50 years. That will make climate change into an irrelevant storm in a teacup.

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Scott, I presume that my exhortation will at best move people's values only a bit, and that my values are not in fact that different from most others' values - if others lie to themselves about what they want I probably do this as well. In general I want to advocate policy that gets people what they want, and in the case I considered in my post, how long to delay pain, I'm comfortable with that. I'm less comfortable with people getting what they want when what they want is existential disaster, but hey I'm just one person and so my wants aren't likely to make that much difference in the final outcome.

Many seem to be saying that disaster seems to follow from continued exponential growth in CO2, so we must stop at some point, so we must stop now. This last step in the argument just doesn't follow.

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The biggest problem I have with ideas that involve blocking out the sun is that sunlight and heat are not exactly interchangeable. For example, the rate at which water evaporates is affected by temperature, but the effect of direct exposure to sunlight is actually greater. Pan evaporation measurements have already shown a decreasing trend in the rate of evaporation, despite global warming, due to global dimming.

Evaporation is no trivial matter. It is, for example, fundamentally necessary to thermohaline circulation. THC is, incidentally, kind of a big deal. Among many other things, it is believed to be important in regulating the amount of carbon dioxide in the atmosphere. So large-scale and intentional global dimming could actually make the problem worse.

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Prof. David Archer of the University of Chicago department of Geosciences is of the opinion that contemporary global warming left unchecked is in fact likely to set of a series of events leading to the relatively sudden release of seabed methane clathrates some thousands of years hence, possibly enough to trigger a much larger global warming event. He does raise the ethical implications of this scenario when he discusses it. So the 630 year question is not entirely a hypothetical.

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