
Mitigating the risk of geoengineering - julianpye
http://news.harvard.edu/gazette/story/2016/12/mitigating-the-risk-of-geoengineering/
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philipkglass
Since we're past the point where emissions cuts alone can keep long term
warming below 2 C, I do expect active geoengineering efforts later this
century. Solar radiation management with aerosols is not a long term fix but
could keep positive feedback effects damped while slower long term fixes (like
emissions reduction plus accelerated silicate weathering) roll out.

The attractive thing about sulfate aerosols is that they could be formed from
sulfur dioxide, which is cheap to form via sulfur combustion and disperses
excellently because it's a gas. Delayed oxidation reactions cause SO2 to form
nuclei for aerosols. Even though calcium carbonate is also inexpensive, I
don't think there is a comparably cheap/easy way to deliver a fluid precursor
for it to the upper atmosphere. The closest I can think of is aerosolizing a
calcium hydroxide solution that would carbonate _in situ_ via reaction with
atmospheric CO2... but calcium hydroxide is only slightly soluble in water.
You'd need to lift a lot of extra water mass.

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tbrownaw
_past the point where emissions cuts alone can keep long term warming below 2
C_

Isn't that 2C supposed to have come from "just give me a damn number" rather
than any analysis of likely impacts?

I'm going to be very amused if we somehow stop any _warming_ without reducing
co2, and die off when all the shellfish keep dissolving.

~~~
philipkglass
Yes, it's a pretty arbitrary number: [https://www.carbonbrief.org/two-degrees-
the-history-of-clima...](https://www.carbonbrief.org/two-degrees-the-history-
of-climate-changes-speed-limit)

I don't think that "amused" would exactly be my reaction if we kill off all
the wild shellfish :-/

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neon_electro
What do potential geoengineering efforts mean for homeowners and businesses
with installed solar power generation?

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wlesieutre
Relatively minor, nobody's talking about blocking 50% of the sunlight, more
like 1-2%.

Pretty straightforward for direct photovoltaic generation, but the wider
consequences on the (very complicated) Earth system are hard to say. Would it
affect wind patterns (and wind power generation as a result)? What about
plants/animals/agriculture?

~~~
diggernet
And how do we undo it when we discover we don't like the side effects?

~~~
aetherson
I mean, you have to ask yourself what you actually believe about the climate.

Do you think that climate change is somewhere between "unbounded costs ranging
in the hundreds of trillions of dollars over the course of 2050-2150," and
"the death of humanity and/or all multicellular life on Earth"?

Because if so, the side effects of geoengineering probably aren't _that_ bad,
and even if they are, they're apparently only as bad as what you think the
costs of doing nothing are.

On the other hand, do you think that climate change is either non-existent or
some kind of relatively mild thing that will cause $100 Trillion dollars or
less over the course of a century? Then probably geoengineering is not for you
-- but that also means that you're somewhere outside the orthodoxy on climate
change.

If you believe that climate change is a real big problem (ie, hundreds of
trillions of dollars or much more in damages over a century timeline) AND that
it is stoppable by being _really_ persistent in asking people to use solar and
wind power, then I don't think that you're being very realistic.

~~~
diggernet
So the alternatives you propose are (in reverse order):

> I don't think that you're being very realistic.

> you're somewhere outside the orthodoxy on climate change.

> the side effects of geoengineering probably aren't that bad

Hubris.

~~~
aetherson
I don't think that you understood my comment very well.

So, look, if you don't believe that climate change will be disastrous, then
you're perfectly within reason to say that geoengineering is a really bad
idea. The beef that people have with you will not be that you're wrong to be
opposed to geoengineering, their beef will be that you're wrong to think that
climate change is no big deal. I'm not here to fight that fight. If that's
your position, fine.

If you DO think that climate change is a big deal (and by big deal, I mean you
think it's somewhere between "likely to stall all economic growth worldwide
for centuries" and "likely to kill all of humanity"), then it's kind of hard
to imagine what _worse_ consequences geoengineering could possibly have.

And particularly, if you do think that climate change is a big deal (as
described above), there aren't a lot of very realistic options besides
geoengineering. It may be that even if we stopped ALL carbon emissions RIGHT
NOW, we'd _still_ have really bad climate change. And obviously,
realistically, we just won't stop all carbon emissions now. We won't stop all
carbon emissions in a decade, or two decades, or three. I _am_ prepared to
argue with you if you imagine that we can stop all carbon emissions now.

The only fourth way I can imagine is that someone might somewhat reasonably
believe that in the near future, technological advance will get us out of
this. That we'll discover some way to do massive carbon-less power generation
at very low cost and/or that we'll discover an obviously unproblematic way to
do carbon sequestration on enormous scale. I will say that if you assign a
high probability of disastrous climate change, I don't see how you'd assign a
similarly high probability of those exact technological advances. In fact, I
might call such precise foresight... hubris.

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diggernet
I'll give you this... your ending was well played.

And I'll grant that if you truly believe that climate change is "likely to
kill all of humanity", that easily leads to a "damn the consequences" attitude
toward fighting it.

However, your expression of the alternatives eliminates a lot of nuance. For
example, suppose that climate change is "likely to stall all economic growth
worldwide for centuries", meeting your definition of "a big deal". Is it
really hard to imagine what worse consequences geoengineering could possibly
have? What if geoengineering is "likely to kill all of humanity"?

So, yes, I'll remain at least as concerned about geoengineering (and "damn the
consequences" thinking) as I am about climate change.

~~~
aetherson
Okay, that's not crazy. I have a few responses:

1\. I think that you're probably underselling "stall all economic growth for
centuries." It's not that different from "kill all humans" (for example: it
would be hugely globally destabilizing. The odds of nuclear war would go way,
way, way up. For another example: it might well either restart exponential
population growth like we had in the late 19th/early 20th centuries, or else
cause a demographic death spiral).

2\. It's pretty hard to believe that climate change is very likely to go right
up to the edge of "stall economic growth" and not have a very significant
chance of tipping over to worse scenarios. You already implicitly believe in
some positive feedback cycles here.

3\. It is actually pretty hard to imagine that specifically aerosolizing
sulfur dioxide is going to cause really catastrophic consequences that global
warming won't already. As other commenters have pointed out, volcanic
eruptions cause massive sulfur releases already. If you believe that the
environment is so, so, so sensitive to any changes that any change you might
make is likely to cause spiraling destruction of the ecosystem, well, then
doesn't it seem likely that our many existing changes have already sent us
past the point of no return? Like, if we're making 100 changes on the scale of
sulfur release (which we are), and one change much, much, much larger than
sulfur release (carbon release), it seems a little unlikely that sulfur
release is the straw that breaks the camel's back.

There are some possibilities for nuance here! You can reasonably believe that,
for example, ocean acidification is the bigger problem than temperature change
per se, and sulfur release doesn't solve ocean acidification, and indeed may
slightly (very, very, very slightly) contribute to it and more importantly may
encourage people to regard carbon release as unproblematic and thus encourage
more carbon use and thus more ocean acidification.

But I don't usually see people making targeted critiques like the one above,
the kind of critique that only applies to one specific proposal. It's usually
just sort of a general reaction to anything other than reduction targets. And,
honestly, reduction targets aren't going to work, guys. Not alone.

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codecamper
another naive article, this time from Harvard, that fails to mention the term
"ocean acidification". At some point krill cannot form their exoskeletons,
bringing an abrupt end to whales and other sea creatures.

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curtis
I don't think it's reasonable to expect _every_ article about global warming
to mention "ocean acidification". Displacing fossil fuel power generation with
nuclear power plants would certainly reduce ocean acidification, but
nevertheless most of the nuclear power articles I've read neglect to mention
this fact.

There are other forms of climate engineering that would address C02 directly.
One that's received a fair amount of press is "iron fertilization"[1]. I don't
know, but my guess is that most people who talk about "solar geoengineering"
(of any sort) probably think we're going to be doing solar geoengineering,
iron fertilization, and probably multiple other forms of climate engineering
at the same time. But not every article that discusses iron fertilization
mentions sulfur dioxide, and not every article that talks about stratospheric
sulfur dioxide mentions iron fertilization.

[1]
[https://en.wikipedia.org/wiki/Iron_fertilization](https://en.wikipedia.org/wiki/Iron_fertilization)

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cnp
And people laugh at the chemtrail folks... All of this research is taking
place right in the open.

