name the baby - Carbon Dioxide removal? Greenhouse gas removal? Gas Geoengineering?

[Andrew Lockley]

I am planning to start a new wiki on the various techniques such as
fake plastic trees, biochar etc, designed to remove GHGs from the
atmosphere.

To avoid the naming dramas, I suggest the following, but would invite
new/better suggestions:

Carbon Dioxide removal? (too specific)
Greenhouse gas removal? (too geeky?)
Gas Geoengineering? (will anyone know what it means)

A

[Stuart Strand]

Greenhouse gas remediation.

Remediation of pollutants has a history.


  = Stuart =

Stuart E. Strand
167 Wilcox Hall, Box 352700, Univ. Washington, Seattle, WA 98195
voice 206-543-5350, fax 206-685-3836
skype: stuartestrand
http://faculty.washington.edu/sstrand/

Using only muscle power,  who is the fastest person in the world?
Flying start, 200 m 82.3 mph! http://en.wikipedia.org/wiki/Sam_Whittingham
Hour http://en.wikipedia.org/wiki/Hour_record
55 miles, upside down, backwards, and head first!

[Andrew Lockley]

http://en.wikipedia.org/wiki/Greenhouse_gas_remediation

has now been created. Please keep the main geoengineering page slim
and post more substantial information on the new page.

i hope you like my categorisation, please change it if not.

A

2008/12/31 Stuart Strand <sst...@u.washington.edu>:

[Mike MacCracken]

Dear Andrew--While I have not yet had time to check out your efforts and
offer thoughts on editing, some ideas for the next effort.

So that you are not just covering the removal of CO2, I would think
something like "Atmospheric composition management" of "Active management of
atmospheric composition" would be best--you might even have it be a
subheading for "Atmospheric composition" and then have links from
geoengineering-related entries. In addition to the removal ideas for CO2,
you could cover any that arise for methane, and even go back to the ones
proposed for CFCs that included lasers to decompose them, with the laser
beam bounced back and forth between mirrors on mountaintops to get a
sufficiently long pathlength to give high probability of striking a
molecule.

And, of course, one would want to somehow link this in to mitigation of
GHGs--which would be said to do at the source. And you would need to link to
ideas about reforestation/afforestation.

Mike MacCracken

[Stuart Strand]

Is radiative forcing additive linearly?

  = Stuart =

Stuart E. Strand
167 Wilcox Hall, Box 352700, Univ. Washington, Seattle, WA 98195
voice 206-543-5350, fax 206-685-3836

[Ken Caldeira]

You can of course add radiative forcing "linearly". (What other kind of addition is there?)

An important question is whether climate response to the sum of radiative forcings is the same as the sum of the climate responses to individual radiative forcings.

The answer to this question depends on the size of the perturbation and your tolerance for approximation.

Recall the maxim: "To first order, everything is linear !!"

( More strictly speaking, "To first order, differentiable functions are linear." )

[wig...@ucar.edu]

It is more complicated than this. However, the reason
that we use rad forcing is that we generally assume
that forcings can be added (as does IPCC). I have looked
at this with forcings that are in the 21st century range.
Within the uncertainties in calculating forcings for
individual items, forcings can be added at least for
global forcing. The uncertainties are such that it is
impossible to disprove additivity. I suspect that additivity
works less well regionally -- but the noise is greater so the
task of disproving additivity is even harder here. I do not
know anyone who has looked at this.

A more important issue is whether additivity works for
responses (temp. precip. etc). We have looked at this
extensively with many different forcings and forcing
combinations. For most things, additivity holds (so the
issue of forcing additivity becomes moot). There seem to
be problems when trop. ozone is one of the forcings.

Tom.

++++++++++++++++++++++

> You can of course add radiative forcing "linearly". (What other kind of
> addition is there?)
>
> An important question is whether climate response to the sum of radiative
> forcings is the same as the sum of the climate responses to individual
> radiative forcings.
>
> The answer to this question depends on the size of the perturbation and
> your
> tolerance for approximation.
>

> Recall the maxim: "*To first order, everything is linear !!"*
>
> ( More strictly speaking, "*To first order, differentiable functions are
> linear.*" )

[Mike MacCracken]

Dear Stuart:

The issue is a bit more complicated than Ken indicates:

1. Radiative forcing is measured (well, actually calculated) for the tropopause. It does make a difference in the response the degree to which the resulting forcing results in a change in the surface relative to the tropospheric energy balance, especially for the hydrological cycle influence.
2. The geographic pattern also matters, though perhaps not for the short term. But if one has all the forcing in the Northern Hemisphere versus Southern, one will get a different response due to the land/ocean difference, etc. (this was the case for example during mid-20th century when sulfate forcing in NH led to a slowing of warming or even a cooling, but did not do so in the SH). Also, the orbital changes that drive the ice age cycling actually create (independent of changes at the surface) virtually no annual global forcing—all they do is redistribute energy by season and latitude, so for that case, a zero forcing is causing ice age cycling (through a lot of feedbacks, etc.).
3. There is also the issue of how long the forcing persists—short time ones like volcanic eruptions have a large forcing, but due to short time they are aloft, the response does not reach equilibrium and eventually goes away. A small, persistent change can, however, have a longer term effect as it activates some of the longer term feedback processes.
   

And I am sure there are further nuances.

Mike MacCracken

[Dan Whaley]

I understand the intent to include all greenhouse gases, but the reality is that while there is a history of emissions control for many gases, there is really no established history for the active *removal* of all gases.  The simple fact is that unless I am forgetting something I know of zero proposals to  enable the direct atmospheric removal of anything other than CO2.

Are there biologic processes for instance that demand atmospheric N2O or atmospheric CH4 instead of CO2?  Perhaps, but none that I am aware of proposed by humans for mitigation purposes.

I think Atmospheric Carbon Removal is the closest thing we here have come up with that accurately identifies the category. 

It distinguishes it from CCS (i.e. flue-gas capture and sequestration) at focuses it specifically on OIF, Lackner trees, and some of David's concepts.  Accelerated weathering perhaps.

D

[Andrew Lockley]

There's a proposal on the wiki for CFC destruction using lasers. I
thought it worthy of inclusion. There are probably other techniques
I'm not aware of.

details at http://en.wikipedia.org/wiki/Greenhouse_gas_remediation#CFC_Photochemistry

A

2008/12/31 Dan Whaley <dan.w...@gmail.com>:

[Dan Whaley]

I suppose, although the abstract mentions that a 10 to 20 fold  theoretical improvement in efficiency would be needed to even get the proposal within rational reach of consideration. 

There should probably be a grouping in these wikis between the ideas which have received some serious consideration over time versus the offhand proposals which even the propsers see as farfetched.  To the uninitiated, it appears that all these concepts are approximately equivalent.

Also-- "blowback" effects from N2O?  Strange use of language.  Any rational methodology simply deducts the radiative forcing of N2O produced from the CO2 sequestered and only claims the conservatively calculated net benefit.  Most models in the southern ocean put that at considerably less than 10%.  I wouldn't say that's one of the things that makes OIF 'controversial'...  it's a factor for sure-- but so is accounting for all CO2 produced by the consumption of fossil fuels involved in carrying out the experiment itself.  The effects on deep ocean oxygen and acidity, or downstream nutrient depletion would probably be better topics of debate.

d

[Ken Caldeira]

I was somewhat flippant, but my comment holds ...

Tom indicates that for the ranges expected this century, climate effects are largely in a linear domain, and this seems reasonable to me.

As Mike points out, we know that the climate responds differently to different patterns and types of radiative forcing even if they have the same global mean radiative forcing. Whether these effects are additive depends mostly on whether you are in a range where linear approximation is "good enough" for some specific purpose.

However, if you think the world is full of "tipping points" (where that is an irreversibility or perhaps a discontinuity) but neither A nor B would be sufficient to push you past the "tipping point" but A + B collectively would be enough, then we would expect the linear approximation to fail.

___________________________________________________
Ken Caldeira

Carnegie Institution Dept of Global Ecology
260 Panama Street, Stanford, CA 94305 USA

kcal...@ciw.edu; kcal...@stanford.edu
http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab
+1 650 704 7212; fax: +1 650 462 5968  

[Mike MacCracken]

Dear Dan and Andrew—It would be interesting to see if an analysis could be done for laser destruction of methane. Its concentration is much higher (thousand times or so) than for CFCs and it must be a good deal less stable, so energy might be lower to break it apart. Then there is the question of the benefits side and doing so for climate change instead of stratospheric ozone depletion. There are already lots of pretty cost effective mitigation measures for methane—so might be worth someone looking at disassociating it in atmosphere (its 20-year Global Warming Potential compared to CO2 is 75, so reducing its concentration would have an early effect—just what we need).

Mike MacCracken

[wig...@ucar.edu]

Ah ha !!!

Let's put a lot more water vapor in the atmosphere, which
will increase OH, and enhance CH4 destruction.

So, what is the GWP for water vapor?

(For those still hovering on the cusp of New Year's
alcoholic celebrations, I should point out that the above
suggestion is just tongue in cheek.)

All the best to all the group for 2009.

Tom.

++++++++++++++++++++++++++++++===

[ALittleSlow]

Does carbon sequestration cover it?

[Sam Carana]

Many of the graphs relating to global warming are exponential, rather
than linear. Additionally, there are several scenarios in which the
combination of several tipping points can lead to a runaway greenhouse
gas effect that feeds on itself through positive feedback mechanisms.
For an example, read the page at:
http://en.wikipedia.org/wiki/Clathrate_gun_hypothesis

For decades, people have warned about this. Back in the early 1990s, a
poll of the world's leading climatologists showed that many feared
that the greenhouse effect could be unstoppable if emissions of
polluting gases were merely frozen and not cut. In December 1991,
Greenpeace asked 400 climate scientists if they thought the greenhouse
effect might reach the point of no return in the near future. Of the
113 scientists who returned their questionnaires, almost half thought
a runaway greenhouse effect is possible, and 13 per cent thought it
probable.

James Hansen, who heads the NASA Goddard Institute for Space Studies,
recently said that human activity is causing greenhouse gas levels to
rise so rapidly that his model suggests there is a risk of a runaway
greenhouse effect, ultimately resulting in the loss of oceans and of
all life on the planet:

"In my opinion, if we burn all the coal, there is a good chance that
we will initiate the runaway greenhouse effect. If we also burn the
tar sands and tar shale (a.k.a. oil shale), I think it is a dead
certainty."
http://www.newscientist.com/blogs/shortsharpscience/2008/12/nasa-scientist-warns-of-runawa.html

I wrote about how Venus became a victim of such planetary warming
resulting in a runaway greenhouse effect, at:
http://geo-engineering.blogspot.com/2007/11/venus-runaway-greenhouse-effect-warning.html

Even if the risk of such scenarios occurring on Earth were small, it
makes sense to do the following:
- describe the risk and estimate the chances of manifestation, timelines, etc;
- identify tipping points, feedback mechanisms and give estimate
ranges of their combined impact;
- investigate ways to avoid it, mitigate it, etc;
- conduct comparative analysis of the various proposals
- make recommendations

I urge everyone who can make contributions to join this group and post
comments, views, proposals and suggestions here.

For evaluation criteria, to be used in above comparative analysis, see
my post here under "ranking the ideas", at:
http://groups.google.com/group/geoengineering/msg/751aa59e3cc5e8ff

Cheers!
Sam Carana

"We all hope that things will turn out right, but we must think about
what to do, in case it doesn't!"

=========== in response to: ==============

[Sam Carana]

How about:
Reducing Greenhouse Gases by Geoengineering, or RG3

Cheers!
Sam Carana

[Stuart Strand]

N2O is reduced to N2 by nitrous oxide reductase, the terminal enzyme in bacterial denitrification.  Methane is biologically oxidized to methanol by methane monooxygenases and subsequently to CO2 by methanotrophic bacteria.  These widespread microbial processes are limited in their environmental activities at trace ambient levels, but they could be enhanced. Other methods of oxidizing and reducing N2O and CH4 may be possible.  CFCs are dechlorinated by anaerobic bacteria, and chemical methods for their removal from the atmosphere have been proposed.  The topic of greenhouse gas removal from the atmosphere should not be restricted to CO2 removal.  “Greenhouse gas remediation” is succinct, refers to remediation of pollutants, and is inclusive.

 

  = Stuart =

 

Stuart E. Strand

167 Wilcox Hall, Box 352700, Univ. Washington, Seattle, WA 98195

voice 206-543-5350, fax 206-685-3836

skype:  stuartestrand

http://faculty.washington.edu/sstrand/

[Andrew Lockley]

I'd love to see ideas given some kind of weighting, so I hope some
brave people can do this.

I think that it's worth leaving the article in question as 'greenhouse
gas remediation' as there may well be other ideas that come forward
for non-CO2 GHGs in due course.

As regards the 'blowback' effects - I was just trying to get across
the risk that OIF experiements could unleash some horrors on the
ocean, and the nutrient effects etc mentioned are the kind of thing I
was trying to highlight. I've made changes, but please check them to
make sure I've understood correctly.