
Re-Engineering the Earth - robg
http://www.theatlantic.com/doc/200907/climate-engineering
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CWuestefeld
The amount of global warming we're experiencing is still a matter of debate,
and certainly the specific climatic responses are mostly unknown. One day it's
"we'll see increased hurricane activity due to global warming", and then it's
180 degrees around to saying that hurricane activity will decrease.

My point isn't to deny global warming, but to show that we don't really
understand very well how climate works. We may be on a deadend path right now.
But people who want a radical change -- whether it's one of the suggestions in
this article, or simply an enormous decline in CO2 emissions -- may turn us
off that dead end, but they do so by closing their eyes and hitting the gas
pedal simultaneously. Nobody _really_ knows where we'd wind up.

The article points out that the effects may be uneven. But I think it's worse
than that.

Returning CO2 levels to historic lows, or blocking solar radiation, might not
be able to return the system to its original state: these reactions may not be
reversible. Our environment has many factors that keep us at equilibrium, and
many of these things have been working diligently to take up slack. Why should
we think that these things will simply unwind back to their original state?

~~~
anamax
> Returning CO2 levels to historic lows, or blocking solar radiation, might
> not be able to return the system to its original state: these reactions may
> not be reversible.

I thought that it was generally agreed that CO2 levels had been much higher in
prehistoric times. If so, it's unclear why recovering from lower levels in the
future would be irreversible when we got here from there before.

~~~
CWuestefeld
Well, surely the CO2 level itself could be reversed. But what other elements
of the system's equilibrium will be changed in the meantime.

For example, the actual amount of temperature increase observed is less than
the CO2 level increase would suggest. Suppose that whatever agency has
tempered the temperature increase has "woken up", and continues to do so as
CO2 decreases. Then a return to "proper" CO2 levels (if you can call any level
proper) would mean serious global _cooling_. And this might not be evident
until it's too late.

Of course, I'm making that up, but there's no reason to think that it's
implausible.

~~~
anamax
> Suppose that whatever agency has tempered the temperature increase has
> "woken up", and continues to do so as CO2 decreases.

Why is that a reasonable thing to suppose?

We're assuming that we got to here from there before. Why is it reasonable to
assume that we can't do so again?

Yes, maybe something else has changed, but shouldn't you at least go to the
trouble of identifying actual possibilities instead of just assuming that they
exist?

~~~
CWuestefeld
There are any number of processes that will occur easily in one direction, but
can have... dramatic... results in the other direction. Consider, by analogy,
breaking H2O into hydrogen and oxygen, vs. recombining them. Or, for more fun,
consider a girl wearing a skirt, jumping on a trampoline. The process of going
up is ordinary, but what happens on the way down is quite a bit different.

It's easy to dream up scenarios in the environment that might work this way.
Algal blooms that have been pushed along by increased CO2 will affect the
equilibrium between other types of sea life -- plankton up the line through
large predatory fish. Moving up the food chain, creatures use input food less
efficiently (carnivores need to kill much more food by mass than bunnies). So
the algae enables plankton, which in turn feeds mackerel which in turn enable
more sharks, but turning it around, as the algae recedes, the mackerel are
pressured by the already-larger shark population, so they may well be
decimated by the CO2 decrease. (I don't know if this specific example is
correct -- it’s certainly oversimplified -- but the concept is certainly
conceivable).

Reiterating: it’s very complex, we don’t really know.

~~~
anamax
> There are any number of processes that will occur easily in one direction,
> but can have... dramatic... results in the other direction. Consider, by
> analogy, breaking H2O into hydrogen and oxygen, vs. recombining them.

Ooh, dramatic. Except that the issue is irreversible.

You can split and combine hydrogen and oxygen repeatedly and the same thing
happens every time.

We don't see evidence of dramatic effects from the last time CO2 levels were
high and went down. (We also don't see evidence of the predicte runaway
temperatures either, but I digress.)

If you're going to argue that this time will be different, shouldn't you have
something better than "we don't know"?

Yes, we might see species changes. However, niches don't stay empty. And, the
claim was "irreversible temperature changes".

~~~
CWuestefeld
> Yes, we might see species changes. And, the claim was "irreversible
> temperature changes".

Ahh, I think I expressed myself badly. I didn't mean that temperatures could
return, _period_ (although on second reading, my text does convey that). I
meant that things couldn't be reversed as in a movie being played backwards,
returning things to their original state.

I think we're actually in agreement, but talking past each other due to my
poor initial phrasing.

~~~
anamax
> I meant that things couldn't be reversed as in a movie being played
> backwards, returning things to their original state.

Even if aliens took all of the "excess" CO2 out of the atmosphere tomorrow,
manipulated the climate so it was always 1969 weather-wise (because that's the
definition of perfection), and gave us an endless supply of dilithium
crystals, things 10 years from now would be different than they are today.

Change always happens. The relevant question is good vs bad. (I don't see how
one can assume that new species will necessarily be bad.)

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dylanz
We could turn the major deserts into forests if we wanted to. Geoff Lawton did
this in the lowest, saltiest place in the Dead Sea, on 10 acres, with nothing
but passive water harvesting earthworks, and selective planting. Now, that 10
acres is completely green, and produces enough food for quite a few families,
and neighbors.

Imagine the rainforest, and 90% of it being edible. Seasonal and successional
plantings, so when you walk through it, you can't help but stepping on food.
Cassava, Potato, etc, all underneath the ground where you can't see as well.

~~~
GavinB
Thanks for the tip, Dylan. Google reveals this excellent video:
<http://www.blog.thesietch.org/wp-content/permaculture.swf>

Very cool stuff, worth checking out. And much better than pumping sulfur into
the atmosphere . . .

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greengirl512
Umm...sulfur dioxide causes acid rain. Why would anyone seriously think that
pumping it into the atmosphere in mass amounts could even be an option?
Seriously..is there something I'm missing here?

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ph0rque
The article fails to mention one low-risk, high side-benefit idea: plant more
trees.

~~~
amalcon
The article did mention this. The problem is that, while trees absorb a lot of
CO2 in the spring, they emit most of it in the fall. Freeman Dyson had
proposed a solution whereby we breed a special kind of tree that stores most
of the CO2 in its roots, rather than emitting it in the fall.

For what it's worth, that is the most pleasant method the article mentioned.

~~~
rsheridan6
That might turn out to be a feature - more carbon in the winter and less in
the summer could = smoothing out seasonal variation, if my wild speculation is
correct.

At any rate, I don't see how you could turn a desert or a field into a high
biomass forest without sucking up lots of CO2. Of course, once it's full-grown
it will be in equilibrium, losing carbon as fast as it gains it.

