Jamais Cascio-- on the problematic idea of 350

[Dan Whaley]

You will appreciate this one Greg...

http://www.fastcompany.com/blog/jamais-cascio/open-future/350

350
BY Jamais CascioTue Oct 27, 2009 at 2:55 PM
350 parts-per-million is the carbon limit. How will we get back there?

350.org

It may be odd to focus a political movement on a relatively obscure
bit of science, but a world-wide push to limit concentration of
atmospheric carbon dioxide to 350 parts-per-million made a big splash
last week, with rallies and gatherings all over the planet focusing on
drilling this number into the public consciousness. The number comes
from work done by (among others) NASA's James Hansen, looking for
potential climate "tipping points." 350ppm for CO2 is a safe limit--
get too much beyond it, and the dangers multiply.

It's an audacious goal, for reasons of both communication and science.

In terms of communication, while a simple meme like "350" or "350ppm"
fits nicely on protest signs and bumper stickers, it's a term without
much context for the vast majority of the populace. In and of itself,
that's not a problem; however, it can make a visceral connection to
the concept more difficult. Activists adopting the 350 meme will need
to match rhetoric with education, to make the number meaningful.
Again, not impossible, but likely an ongoing challenge.

The scientific audacity with the 350 meme comes from a single, simple
fact: current concentration of atmospheric CO2 is roughly 385ppm. That
is, we already exceed the 350 limit, and most climate scientists say
we'll be hard-pressed to keep from going over 450ppm by the middle of
the century. And carbon dioxide takes centuries to cycle out of the
atmosphere--even if we stopped all anthropogenic sources of CO2 right
this minute, we'd still see too-high concentrations for years to come.

(Even more troubling: even if we stopped all anthropogenic carbon
sources immediately, we'd still see continued warming for at least
decades, possibly longer, simply from the thermal inertia of the
oceans. Absent a radical step, we're guaranteed to see at least
another degree or two of warming, no matter what we do.)

If this sounds like I think the 350 movement is a bad idea... I don't.
I rather like the simplicity of the meme, and the target is--if
difficult--smart. It's not saying "let's keep things from getting too
much worse," it's saying "let's make things better." That's the kind
of goal I like.

But getting back to 350ppm requires more than a rapid cessation of
anthropogenic sources of atmospheric carbon. It requires an
acceleration of the processes that cycle atmospheric CO2. Planting
trees is an obvious step, but it's slow and actually doesn't do enough
alone. We'll also need to bring in more advanced carbon sequestration
techniques, such as bio-char. The combination of the two would likely
bring down atmospheric carbon levels, given enough time.

Unfortunately, we may not have enough time.

If efforts to eliminate carbon emissions continue to happen at a pace
most generously described as "leisurely," we will almost certainly
face a situation where we approach and even pass critical tipping
point concentrations. Ocean thermal inertia means that climate
benefits from emission cessation won't be seen for decades. There's a
very real scenario where finally get it right, both cutting out
anthropogenic emissions and sequestering megatons of carbon via plants
and bio-char ... and still face terrible environmental consequences,
simply because we didn't act fast enough.

That's where we start to talk about much more radical, and potentially
dangerous, steps. Geoengineering to hold temperatures down is one; to
meet the 350ppm goal, we will likely also start looking at large-scale
methods to sequester carbon, such as with triggered algae blooms.

350ppm is an audacious goal, but one worth striving for. But its
challenge comes not just in the effort to eliminate anthropogenic
carbon emissions around the world--a massive endeavor alone--but also
in figuring out how to remove the extra carbon already there. I hope
that the 350 leaders have thought through the implications of what
that means.

[Images: "Organized Spelling B" by Wade in Da Water on Flickr,
Creative Commons Licensed; "Summer Bloom in the Baltic Sea" by NASA
Visible Earth]

[John Nissen]

Hi all,

Jamais Cascio is described as an "environmental futurist" and has
written a book with the title "Hacking the Earth" [1]. It's great that
somebody is pointing out the implication of the 350 ppm target!

But he shares a very common scientific belief which I do not understand:

"(Even more troubling: even if we stopped all anthropogenic carbon
sources immediately, we'd still see continued warming for at least
decades, possibly longer, simply from the thermal inertia of the
oceans. Absent a radical step, we're guaranteed to see at least
another degree or two of warming, no matter what we do.)"

With global warming, the land and atmosphere warm faster than the
oceans. If emissions stopped overnight, the oceans would still be
warming up, thus cooling the atmosphere, rather than warming it. Thus
the thermal inertia of the oceans would drag down the global temperature
(mean of surface temperatures over the globe). Am I right?

Cheers,

John

[1] http://www.lulu.com/content/6048806

--

[John Gorman]

I think the point is as follows:

If we fix the CO2 at say 2 times preindustrial then the net forcing will not
instantly get the global temperatures up to their long term steady state.
The oceans will lag.

It sounds as if you are thinking of the net forcing which has resulted in
the temperature rise for the land has gone away-but it hasn't in the case
you have quoted. The CO2 level will stay constant for centuries even if all
emissions stop today.

There was a very recent post or link on this recently which quoted 3deg for
doubling of CO2 in the short term but 6deg long term. This link, which I
cant find just now, used data from some much earlier time when the doubling
had already resulted in almost completely ice free poles. This is presumably
what will happen now if we get to doubling and don't do something about it.
The Arctic is melting now. It isn't going to stop melting just because we
stop increasing the temperature. So there is a temperature inertia or lag
due to ocean heat capacity but an even bigger one due to ice cap latent heat
of melting.

john gorman

[Peter Read]

The 3 degrees long term equilibrium temperature rise was in Hansen's Dec 17
2008 Bjerknes Lecture to the AGU. Sorry, don't have the URL.

To avoid it then the need is to return to (or near to) preindustrial LEVELS,
as I maintain is both feasible and socio-economically desirable through
carbon stock manmagement that gets C out of the atmosphere and puts it
somewhere safer [NOT deep ocean I would argue, but into biochar soil
improvement of poor tropical soils]

To simply reduce emissions to zero results in continued warming towards 3
degrees, while waiting a millennium or so for the existing CO2 level to
disperse

Peter

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[Eugene I. Gordon]

I bring to your attention the following:

the latest Lindzen paper
http://www.drroyspencer.com/Lindzen-and-Choi-GRL-2009.pdf Be warned this is
tough.

A simple to understand over review is:
Climate Sensitivity Estimates: Heading Down, Way Down? (Richard Lindzen's
New Paper) by Chip Knappenberger

Using the same climate science; (I am ultra kind to call it science, it is
not yet mature enough) Lindzen concludes that Hansen et al estimate a
sensitivity that is almost 10X too large; Lindzen claims a delta of +0.5 C
for CO2 concentration doubling.

You are all intelligent fair human beings, but you carry your biases on your
sleeves. Would you bet your reputation or your retirement funds on either of
these gentlemen being right. I doubt it. I suggest you all might temper the
discussion here with a grain of uncertainty. However, I also understand that
if Lindzen is right, geoengineering becomes of virtually no importance.

-----Original Message-----
From: geoengi...@googlegroups.com
[mailto:geoengi...@googlegroups.com] On Behalf Of John Gorman
Sent: Sunday, November 01, 2009 12:34 PM
To: j...@cloudworld.co.uk; dan.w...@gmail.com
Cc: geoengineering

[Dan Whaley]

John Nissen,

I might recommend Susan Solomon's recent paper.
http://www.pnas.org/content/early/2009/01/28/0812721106.full.pdf

A key paragraph:

Global average temperatures increase while CO2 is increasing and then
remain
approximately constant (within +/-0.5 °C) until the end of the
millennium despite zero further emissions in all of the test cases
shown in Fig. 1. This important result is due to a near balance
between the long-term decrease of radiative forcing due to CO2
concentration decay and reduced cooling through heat loss to
the oceans. It arises because long-term carbon dioxide removal
and ocean heat uptake are both dependent on the same physics of
deep-ocean mixing. Sea level rise due to thermal expansion accompanies
mixing of heat into the ocean long after carbon dioxide
emissions have stopped. For larger carbon dioxide concentrations,
warming and thermal sea level rise show greater increases and
display transient changes that can be very rapid (i.e., the rapid
changes in Fig. 1 Middle), mainly because of changes in ocean
circulation (18). Paleoclimatic evidence suggests that additional
contributions from melting of glaciers and ice sheets may be
comparable to or greater than thermal expansion (discussed further
below), but these are not included in Fig. 1.

Dan

[David Schnare]

Ken has made it clear on multiple occasions that this is not the forum to argue about whether CO2 is causing a warming effect.  Our discussion is based on a premise (and that's all it is) that the globe is getting warming, a lot warmer, because of CO2.  Based on that premise, we discuss what we could do about that.

 

If you insist on bringing up the underlying premise, you have to accept that Solomon's paper begins with the same premises (CO2 is causing significant warming now), while Lindzen is explaining observations. 

 

As a scientist, I tend to like to begin with actual observations, not model-based speculation.  As an attorney, I accept that, often, someone else has established the starting line, and my job is to win the race from that point, even if it is wildly unrealistic and indeed even if it is simply wrong. 

 

You do what you gotta do, but I'd like to see this group return to the days when we discussed the technology and science of GEOENGINEERING.

 

David Schnare

--
David W. Schnare
Center for Environmental Stewardship

[Mike MacCracken]

If we stopped all emissions, of all GHGs and aerosols, what would be removed
first are the aerosols. The sulfate cooling offset is estimated at 1.1 W/m2
so their loss would lead to a strong warming influence. The black carbon is
estimated by IPCC at about 0.4-0.5 and by Ramanathan and others to be twice
that. Their loss would lead to a less positive forcing, so, if all these
emissions stopped, the net would be a small warming influence. Stopping all
emissions, of course, tropospheric ozone warming influence would also end
over months. And then methane influence would go down over decades. So, one
would tend toward a lessened warming influence. And some, but not a lot of
the CO2 would be taken up. So, stopping all forcing does reduce the warming
influence.

If you want to see a graph of the effects of ending all GHG emissions (the
tables have information on aerosols), go to a recent proceedings paper I
have posted at http://www.climate.org/PDF/MacCracken_Erice.pdf, where you
will also see my views about how to utilize the different time scales to
promote an agreement between developed and developing nations at
http://www.climate.org/topics/climate-change/maccracken-proposal-north-south
-framework.html

These notes are all about forcings, as the forcing will determine the
climate that the world heads toward. The ocean slows the transition to
equilibrium. If you want to see what is, in effect, a geoengineering set of
simulations by the modeling groups of the world, look at the graph of the
IPCC projections of temperature. One sees the results for the various SRES
scenarios, but the yellow/orange line shows the results for holding all
concentrations and aerosol loadings constant. Holding CO2, N2O, and
halocarbon concentrations constant requires some very large percentage
reduction in their emissions; for methane the cutback is much less. But
cutting CO2 emissions by 80-90% to keep its concentration constant will
surely lead to a sharp reduction in SO2 emissions, and so a very sharp
reduction in their cooling influence, and perhaps in black carbon and its
somewhat smaller warming influence, meaning that to hold the aerosol burden
constant, there must be substantial emissions of aerosols/aerosol precursors
(just what is being discussed for geoengineering, except in the
troposphere). You can see that about 0.5 C further warming goes on, and this
is the oceans catching up to the land.

Mike MacCracken

[Eugene I. Gordon]

What if the premise and numerical relationship between CO2 concentration and warming is wrong and Lindzen is much closer to the truth? Is there still a place for geoengineering at all? If CO2 is not causing significant global warming then is there a need for CO2 removal? I am not sure that global warming and geoengineering are orthogonal issues.

 

In any case I agree with david that we should not be discussing global warming but stick to the technology and funding possibilities for research on geoengineering.

 

Gene Gordon

 

From: geoengi...@googlegroups.com [mailto:geoengi...@googlegroups.com] On Behalf Of David Schnare
Sent: Sunday, November 01, 2009 2:04 PM
To: dan.w...@gmail.com
Cc: geoengineering
Subject: [geo] Re: Jamais Cascio-- on the problematic idea of 350

 

Ken has made it clear on multiple occasions that this is not the forum to argue about whether CO2 is causing a warming effect.  Our discussion is based on a premise (and that's all it is) that the globe is getting warming, a lot warmer, because of CO2.  Based on that premise, we discuss what we could do about that.

[John Nissen]

Hi Mike, and others,

What would happen if we could halt all CO2 emissions overnight?

As you say, Mike, we have to add up all the climate forcings.  If CO2 emissions were halted overnight by closing coal-fired power stations, then we'd have:
1) much of the CO2 positive forcing (currently around 1.6 W/m-2) continuing for centuries;
2) the almost immediate removal of sulphate from troposphere and thus loss of its cooling effect (resulting in increased net positive forcing);
3}the removal of black carbon, aka soot, and (a) its slight reflective effect, but also (b) its darkening effect on snow and ice in the Arctic.

As you say in your paper, as emissions continue to increase, both warming and the commitment to future warming are increasing at the a rate of 0.2 degrees per decade.  This equates to 2 degrees this century, from effect (1).   Moreover, it appears, from the Climate Congress in Copenhagen last March and subsequently, that the current trajectory of emissions could lead to at least 4 degrees warming [1].

But I believe, whatever we do about emissions, the so-called "polar amplification" effect will continue.  This is on the assumption that the regional warming in the Arctic is largely driven by warming surface waters of the Gulf Stream entering the Arctic ocean.  As the Atlantic surface waters would continue to warm, the amplification would continue.  Thus the Arctic sea ice would continue its trend towards summer disappearance.  (However Tim Lenton disagrees, saying that the removal of carbon black alone would be enough to halt the retreat, see 3b above.)

Our conclusion must be that emissions reductions, however severe, are (by themselves) extremely unlikely to prevent a temperature increase of at least 2 degrees this century, and certainly cannot prevent the Arctic sea ice summer disappearance (if the current trend for retreat continues).  Removal of carbon black will undoubtedly help to preserve Arctic sea ice, but by itself could not be relied upon.

Thus the science is conclusively pointing to the need to be prepared for SRM geoengineering to cool the Arctic.

It is often said the SRM geoengineering should be used "as a last resort".  But that assumes that we wait until things get much worse, when it could be too late.  So when is the best time for deployment?  Surely it is before the positive feedback effects grow any larger.  Therefore:

        The optimum time for SRM deployment is right now.

And if you consider the risks of geoengineering are enormous, spend your energy on finding a way to reduce them!  We can be researching on this while in parallel gearing up for large scale deployment.

One of the greatest dangers from letting the Arctic sea ice disappear, and Greenland ice sheet disintegrate, is the effect of sea level rise on food supply.  Lester R. Brown, founder and president of the Earth Policy Institute, wrote about the possibility of food shortages bring down civilisation [2].  He is acutely aware of tipping points and danger of sea level rise.  He said about our current predicament:

Time is our scarcest resource...  The world is in a race between political tipping points and natural ones...  Can we prevent the Greenland ice sheet from slipping into the sea and inundating our coastlines? ... It is hard to overstate the urgency of our predicament.  Every day counts.

I recommend reading the whole article.  It helped me to appreciate what we are up against.

Cheers from Chiswick,

John

[1]  Four degrees and beyond: How soon is it coming?
http://blogs.nature.com/climatefeedback/2009/09/4_degrees_and_beyond_how_soon.html

[2] Scientific American, May 2009. "Could food shortages bring down civilization?" by Lester R. Brown:
http://www.scientificamerican.com/article.cfm?id=civilization-food-shortages&page=5

---

[Mike MacCracken]

Hi John—First, I would note that polar amplification is included in the estimates of the rates of warming (whether 0.2 C/decade or higher to get 4 C). Cooling the Arctic would reduce this effect.

Second, on the cause of faster sea ice reduction than models are projecting, I know there are a lot of suggestions this is due to soot emissions. My problem with that explanation is that the observations described in Quinn et al ( Quinn P K, Shaw G, Andrews E, Dutton E G, Ruohoairola T and Gong S L ,2007: Arctic haze: current trends and knowledge gaps, Tellus B 59 99–114) indicates that soot deposition in the Arctic has been declining. It is true that global emissions may be going up (due to China and India, one would presume), so a pure correlation suggests it might well be soot that is correlated with the increased decline of sea ice, but studies of Arctic haze (presented at last December’s AGU meeting in SF) indicate that the air trajectories into the Arctic come mainly from Europe (Atlantic to Urals, so including much of Russia), and black carbon emissions from Europe have come down due to emissions controls and from Russia and eastern Europe due to shutdown of the worst power plants due to economic slowdown. Reduced black carbon into the Arctic would be leading to less uptake of solar, so hard to see how increasing global black carbon emissions are accelerating the sea ice retreat (what matters are trajectories into the Arctic and what is happening in the upwind regions).

The observations also show that sulfate deposition has been going down, for the same reason, and this would likely increase the solar radiation reaching the sea ice (clear skies would be cleaner and clouds less bright), so, as noted in my ERL article, my supposition is that it is reduced sulfate that is leading to the acceleration of sea ice melting. This all needs to get confirmed by checking out the data on light levels reaching the surface through the year, which Dutton and NOAA may well have. If this sulfate hypothesis is correct, then we have thus performed something like a reverse geoengineering experiment. And we can estimate roughly what the flux change was. And so, as the article suggests, we might well be able to reverse the warming by increasing tropospheric sulfate (which I favor instead of stratospheric sulfate—see article for reasoning) during the sunlit season in the Arctic, and so for a lot less SO2 emissions than we have had in the past (so we can see what ecological and other effects were). As I say, a good bit of supposition, but a lot that could quite readily be investigated over several years.

On issue of uncertainties and surprises, I think it is quite possible that trying to push back toward conditions of recent past via tropospheric sulfate might well, after a relatively short and focused research and development effort, be better understood and have less likelihood of surprises than proceeding along with greater and greater GHG concentrations and warming.

Cooling the Arctic would have the advantage of giving back the amplification effect—so help keep midlatitudes from warming so much and might well slow the rate of rise of sea level, even perhaps helping to stabilize the polar ice sheets. There are indeed questions to be looked at (e.g., would SO2 become sulfate in the Arctic, would geoengineering in the Arctic shift the ITCZ and could that be balanced by some sulfate injection over the Southern Ocean, etc.), and these topics seem to me to be well within our research capacity because the sulfate loading likely needed is, at least in the Arctic, within our experience.

I am all for reducing black carbon emissions further to help the sulfate effort along and Tim Lenton may be right that ridding the Arctic of all soot deposition would allow sea ice to return—another question that could readily be looked at. But I think the changing and geoengineering role of sulfate may well be more critical.

I also agree that time is critical. The Arctic is already in what might be called dangerous decline. I don’t think waiting to use geoengineering at some distant future point is the way to go for then any application would have to be very strong to induce the desired result, if it is possible at all. One normally tries to put out fires when they are small or localized than when the whole building is aflame.

Best, Mike MacCracken

On 11/1/09 12:34 PM, "John Gorman" <gor...@waitrose.com> <mailto:gor...@waitrose.com>  wrote:

  
 

[Marty Hoffert]

All:

David Keith & Andy Revkin are right that we should not be over-interpreting every perhaps natural climatic fluctuation as evidence of global warming however much that feeds into the human psychodrama.  That in no way detracts from the robust finding that the secular trend of rising global mean temperature, polar cap melting and sea ice recession from continued CO2 emissions is overwhelmingly supported by data. And given our present fossil fuel based energy system, and independently estimated global climate sensitivity, the prospect of CO2 growing to at least 450 ppm causing future warming at or above 2 degrees Celsius later this century & persisting into the next is likewise a near certainty.  Why on Earth do some argue about this still?

Attached is a paper published  in '92 by yours truly & Curt Covey in Nature showing that for consistency with paleoclimate data from two very different periods, the mid-Cretaceous and the last glacial maximum -- NOT from climate models or the climate-change-irrelevant ERBE data in Lindzen's latest GRL piece  --  Lindzen's weak climate sensitivity estimate of 0.5 degrees Celsius warming for CO2 doubling must be wrong. Past climate changes are major constraints. We find a pale-ocalibrated climate sensitivity of ~ 2.5 degrees Celsius including the usual fast feedbacks -- consistent with the 3 degrees or so cited by Jim Hansen, a value roughly doubled in glacial-interglacial transitions involving "slow" CO2 feedbacks; most likely from ocean carbon pumps [see, e.g., Volk, T., and M.I. Hoffert (1985) "Ocean Carbon Pumps: Analysis of Relative Strengths and Efficiencies in Ocean-Driven  Atmospheric CO2 Changes." In E.T. Sundquist and W.S. Broecker (Eds.) The Carbon Cycle and Atmospheric CO2: Natural Variations Archean to Present, pp. 99-110, Geophysical Monograph 32, American Geophysical Union, Washington, DC.].

Were climate as insensitive as Lindzen claims, it would be virtually impossible to explain the large warming (e.g., the mid- Cretaceous, the Paleocene-Eocene Thermal Maximum, etc.) and cooling (e.g., the quasi-periodic hundred-thousand-or-so year long glaciations of the past few million years) excursions of past climates relative to now.  This should have, on the face of it, resolved the issue for good. Lindzen's unwillingness and inability to deal with this in his response to us in Nature (also attached) has, for most knowledgeable climate researchers, settled the issue.

But for ideologues with minds made up facts too distracting to their conclusions are best ignored. Admittedly, Dick Lindzen is highly intelligent and ingenious in constructing arguments reinforcing his self-delusion. But in the end you can't fool Mother Nature.  That's not even the worst of it. The worst is that in the global warming "debate" still going on, issues resolved decades ago, particularly the physics, logic and data supporting humankind's global warming from the fossil fuel greenhouse, all of which were legitimately & vigorously debated at the time in hundreds of peer-reviewed papers, are, whether from scientific illiteracy or sheer intellectual laziness, totally IGNORED by present-day climate change deniers. You don't believe fossil fuel burning has, is, and will increasingly cause global warming, by an amount which we can estimate pretty well within some uncertainly bounds, which we can also estimate pretty well?  You want to argue that?  Fine. But if you want scientific credibility you should at least engage peer-reviewed climate science that's been out there for decades.

Have fun,

Marty Hoffert

[Andrew Lockley]

It seems eminently sensible that a plan to restore existing levels of 'pollution' over the Arctic would be a good way forward.  The public acceptability, and the scientific understanding, of previous levels of sulfate pollution is likely to facilitate a quicker launch of such a project with none of the usual hurdles.

This could initially be coupled to further reductions in SO2 pollution as Russian/Eastern European industries continue to clean up.  The banner concept would be 'protecting the environment from unexpected consequences of pollution reduction'

Once deployment technologies become developed, and people become accustomed to the practice of 'replacing pollution', then it should be easier to use science to establish the 'best' level of 'pollution'.

I can't see a cleaner and simpler way into SRM, personally.  This looks like an issue we can potentially push towards.  I'd be very interested in being shot down in flames!

A

2009/11/2 Mike MacCracken <mmac...@comcast.net>

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[John Nissen]

Hi Marty,

I was just looking through some bulky emails to delete them, when I noticed this one on climate sensitivity.  You put 2.5 degrees warming for CO2 doubling.  It is interesting that the climate sensitivity has been reappraised, e.g. by Hansen giving 3 degrees [1] and by Wasdell giving a much higher figure of around 7.8 degrees [2].

Wasdell raises a fundamental point about the behaviour of the climate system over recent Ice Ages when temperature has varied by 5 degrees, yet CO2 has only varied between 180 ppm and 280 ppm.

[quote from [2]]

That raises the fundamental “Emperor’s Clothes” question of climate science:

8.5.1 “If the Charney sensitivity, supported by our modern computer models, projects that a doubling of the concentration of atmospheric carbon-dioxide leads to a temperature rise of 3ºC at equilibrium, then why, in the empirically measured behaviour of the planetary system, does an increase of only 56% in CO2 concentration (from 180 ppm to 280 ppm) lead to a 5ºC change in temperature?”

[end quote]

Now that assumes that the CO2 causes the warming (rather than the polar amplification of Milankovitch signals, as I would suggest [4]).  However I think Wasdell is onto something.  There does seem to have to been systemic optimism in the climate science community about the effect of CO2 emissions on global warming, and we are on course to reach 4 degrees or more, even with the most drastic CO2 cuts one could imagine through a UNFCCC path (especially given the political situation in US and China).

Furthermore the potential contribution of Arctic methane to global warming is being ignored.  

Furthermore, 1.5 degrees is now being accepted as a significantly safer target than 2 degrees [3].  And there are calls for the CO2 level to be quickly brought below 350 ppm, amid concerns about ocean acidification as well as global warming.

How much evidence does the scientific community need, before accepting the requirement for geoengineering?  Perhaps those who still say that geoengineering is too risky (in relation to benefits) should answer this question.  There are some on this list!

Cheers,

John

[1] http://www.columbia.edu/~jeh1/mailings/2011/20110118_MilankovicPaper.pdf

[2] http://www.apollo-gaia.org/Climate%20Sensitivity.pdf

[3] http://globalwarmingisreal.com/2011/06/03/unfccc-chief-says-two-degrees-is-not-enough/

[4] Nissen, J "Arctic sea ice thermostatic control of global temperature", EGU 2011 (to be published)

---

On 02/11/2009 17:16, Marty Hoffert wrote:

All:

David Keith & Andy Revkin are right that we should not be over-interpreting every perhaps natural climatic fluctuation as evidence of global warming however much that feeds into the human psychodrama.  That in no way detracts from the robust finding that the secular trend of rising global mean temperature, polar cap melting and sea ice recession from continued CO2 emissions is overwhelmingly supported by data. And given our present fossil fuel based energy system, and independently estimated global climate sensitivity, the prospect of CO2 growing to at least 450 ppm causing future warming at or above 2 degrees Celsius later this century & persisting into the next is likewise a near certainty.  Why on Earth do some argue about this still?

Attached is a paper published  in '92 by yours truly & Curt Covey in Nature showing that for consistency with paleoclimate data from two very different periods, the mid-Cretaceous and the last glacial maximum -- NOT from climate models or the climate-change-irrelevant ERBE data in Lindzen's latest GRL piece  --  Lindzen's weak climate sensitivity estimate of 0.5 degrees Celsius warming for CO2 doubling must be wrong. Past climate changes are major constraints. We find a pale-ocalibrated climate sensitivity of ~ 2.5 degrees Celsius including the usual fast feedbacks -- consistent with the 3 degrees or so cited by Jim Hansen, a value roughly doubled in glacial-interglacial transitions involving "slow" CO2 feedbacks; most likely from ocean carbon pumps [see, e.g., Volk, T., and M.I. Hoffert (1985) "Ocean Carbon Pumps: Analysis of Relative Strengths and Efficiencies in Ocean-Driven  Atmospheric CO2 Changes." In E.T. Sundquist and W.S. Broecker (Eds.) The Carbon Cycle and Atmospheric CO2: Natural Variations Archean to Present, pp. 99-110, Geophysical Monograph 32, American Geophysical Union, Washington, DC.].

Were climate as insensitive as Lindzen claims, it would be virtually impossible to explain the large warming (e.g., the mid- Cretaceous, the Paleocene-Eocene Thermal Maximum, etc.) and cooling (e.g., the quasi-periodic hundred-thousand-or-so year long glaciations of the past few million years) excursions of past climates relative to now.  This should have, on the face of it, resolved the issue for good. Lindzen's unwillingness and inability to deal with this in his response to us in Nature (also attached) has, for most knowledgeable climate researchers, settled the issue.

But for ideologues with minds made up facts too distracting to their conclusions are best ignored. Admittedly, Dick Lindzen is highly intelligent and ingenious in constructing arguments reinforcing his self-delusion. But in the end you can't fool Mother Nature.  That's not even the worst of it. The worst is that in the global warming "debate" still going on, issues resolved decades ago, particularly the physics, logic and data supporting humankind's global warming from the fossil fuel greenhouse, all of which were legitimately & vigorously debated at the time in hundreds of peer-reviewed papers, are, whether from scientific illiteracy or sheer intellectual laziness, totally IGNORED by present-day climate change deniers. You don't believe fossil fuel burning has, is, and will increasingly cause global warming, by an amount which we can estimate pretty well within some uncertainly bounds, which we can also estimate pretty well?  You want to argue that?  Fine. But if you want scientific credibility you should at least engage peer-reviewed climate science that's been out there for decades.

Have fun,

Marty Hoffert

[snip the cartoon]

[Mike MacCracken]

Hi John—It would be good for those trying to understand the causes of ice age cycling and the potential sensitivity to read the papers of Belgian professor Andre Berger and his group, who have been looking at the roles of the various factors in contributing to climate change. Quite clearly, from their work, CO2 does not need to be responsible for the full change in temperature, and indeed, as I recall, they get a CO2 sensitivity of near 3 C.

As one example of a paper of theirs, see:

Berger, A. The Role of CO2, Sea-Level and Vegetation during the
Milankovitch Forced Glacial-Interglacial Cycles. In Geosphere-Biosphere
Interactions and Climate; Bengtsson, L., Hammer, C.U., Eds.;
Cambridge University Press: Cambridge, U.K., 2001; pp 119-146.

I read it in the book and, unfortunately, the cost for access on the Web seems high—indeed, most of his papers seem hard to access (why we need open access journals—there should be a short time limit on tying up such useful information). Maybe someone else can more easily find open access to this group’s results.

Mike

 From: "John Nissen" <j...@cloudworld.co.uk> <mailto:j...@cloudworld.co.uk>
 To: <dan.w...@gmail.com> <mailto:dan.w...@gmail.com>

[rongre...@comcast.net]

John -  Thanks for bringing this dialog back to climate sensitivity - which obviously is a very key parameter for this list.  You seem to have correctly stated the present view of Dr. Hansen as being 3 degrees C per CO2 doubling.  But in your second citation to the work of Dr. Wasdell, Hansen's view is stated as this being better defined as 6.  Dr. Wasdell recommends 7.8 (as you have reported) - and your  citation [2) for his work gives 3 or 4 additional experimental (not model) strong endorsements of this very large sensitivity value.

  Can anyone else support the larger sensitivity values?  Is the difference only in the time domain?  How does such a large fundamental difference get settled?   Will the final authority be the IPCC?

Ron

---

From: "John Nissen" <j...@cloudworld.co.uk>
To: "marty hoffert" <marty....@nyu.edu>
Cc: eugg...@comcast.net, geoengi...@googlegroups.com, kcal...@globalecology.stanford.edu, anr...@nytimes.com, "Tyler Volk" <tyler...@nyu.edu>, "David Wasdell" <was...@meridian.org.uk>, "Alan Robock" <rob...@envsci.rutgers.edu>, "Stefan Rahmstorf" <stefan.r...@pik-potsdam.de>, "John Shepherd" <john_g_...@mac.com>, "Mark Lynas" <mark...@zetnet.co.uk>
Sent: Friday, August 12, 2011 7:53:53 AM
Subject: Re: [geo] Jamais Cascio-- on the problematic idea of 350

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[Ken Caldeira]

Climate sensitivity to a doubling of atmospheric CO2 is only a well defined term (if at all) if you state what time scales or processes you are including and what you mean by "a doubling of atmospheric CO2".

The higher sensitivity values seem relevant to time scales (i.e., > 10 kyr) where ice sheets and possible biogeochemical (e.g., CH4) feedbacks can kick in at full force.

The lower sensitivity values seem relevant to shorter time time scales (i.e., < 100 yr) when ice sheet feedbacks are not relevant and we assume that CH4 feedbacks need not be considered.

Furthermore, if you instantaneously double CO2 and then let some of the CO2 be absorbed by the ocean and biosphere you will get less of a climate response that if you maintain the doubled CO2 concentration.

My take is that the longer-term response seems to be closer to 6 C whereas the shorter-term response (assuming no big methane feedback) seems closer to 3 C. (For my own subjective probability distribution under these assumptions, I would suggest something like an 80% probability of being in the range of 2/3 to 3/2 of these values , i.e., short-term in the absence of strong methane, probably something like 2 to 4.5 C for a CO2 doubling, and for the longer term, something like 4 to 9 C for a sustained CO2 doubling.)

---

I am planning to give a semi-tutorial talk on this at AGU in the same session that Hansen is speaking in:

CONTROL ID: 1209062
TITLE: Radiative Forcing and Climate Response: From Paleoclimate to Future Climate
PRESENTATION TYPE: Assigned by Committee (Oral or Poster) [Invited]
CURRENT SECTION/FOCUS GROUP: Paleoceanography and Paleoclimatology (PP)
CURRENT SESSION: PP10. Earth System Sensitivity To Radiative Forcings: Lessons From Earth History
AUTHORS (FIRST NAME, LAST NAME): Ken  Caldeira1, Long  Cao1
INSTITUTIONS (ALL): 1. Dept. of Global Ecology, Carnegie Institution, Stanford, CA, United States.
Title of Team:
ABSTRACT BODY: The concept of radiative forcing was introduced to allow comparison of climate effects of different greenhouse gases. In the classic view, radiative forcing is applied to the climate system and the climate responds to this forcing, approaching some equilibrium temperature change that is the product of the radiative forcing times the ‘climate sensitivity’ to radiative forcing.

However, this classic view is oversimplified in several respects. Climate forcing and response often cannot be clearly separated. When carbon dioxide is added to the atmosphere, within days, the increased absorption of longwave radiation begins to warm the interior of the troposphere, affecting various tropospheric properties. Especially in the case of aerosols, it has been found that considering rapid tropospheric adjustment gives a better predictor of “equilibrium” climate change than does the classic definition of radiative forcing.

Biogeochemistry also provides additional feedbacks on the climate system. It is generally thought that biogeochemistry helps diminish climate sensitivity to a carbon dioxide emission, since carbon dioxide tends to stimulate carbon dioxide uptake by land plants and the ocean. However, there is potential to destabilize carbon locked up in permafrost and at least some possibility to destabilize methane in continental shelf sediments. Furthermore, wetlands may provide a significant methane feedback. These and other possible biogeochemical feedbacks have the potential to greatly increase the sensitivity of the climate system to carbon dioxide emissions.

As time scales extend out to millennia, the large ice sheets can begin to play an important role. In addition to affecting atmospheric flows by their sheer bulk, ice sheets tend to reflect a lot of energy to space. If carbon dioxide remains in the atmosphere long enough, there is potential to melt back the large ice sheets, which would add additional warming to the climate system. It is likely that these millennial time-scale feedbacks could double climate sensitivity over that estimated by century-scale models. The inclusion of these feedbacks may be one reason why paleoclimate studies seem to indicate a much higher climate sensitivity than do the current generation of climate models that focus on the physics of century-scale climate change.

What is the relevance of “equilibrium” climate change on a dynamic planet?  Each gas or aerosol has a different time evolution in the atmosphere, so the time evolution of the climate response to a methane release, an aerosol release, and a carbon dioxide release would be very different, even if they had the same initial radiative forcing (or radiative forcing integrated to some time horizon, as is done in Global Warming Potential calculations). Furthermore, the climate response to emissions of these radiatively active substances will depend, to some extent, on the state of the climate system into which these substances are introduced. Changes in continental positions and altitudes can affect snow and glacier feedbacks. Changes in ocean heat transport can affect cloud properties and the distribution of sea-ice.

 For many applications, it may be more fruitful to focus on the time-evolution of the climate response to emissions and abandon the concept of climate sensitivity to radiative forcing.

[Prokaryotes]

But this short term figure of 3C sensitivity, is not in cooperating
various of the interconnected sub feedbacks. Also the initiation
timescale is now different of a view order. The Wasdell paper makes a
solid case, and id like to see some more analyzing from other people.
I consider the paper a must read.

I working on a blog post where i summarize the paper
http://climateforce.net/2011/08/13/climate-shift-impact-risk-assessment-revisited/

Best Regards, Chris Machens

On Aug 14, 3:38 am, Ken Caldeira

<kcalde...@globalecology.stanford.edu> wrote:
> Climate sensitivity to a doubling of atmospheric CO2 is only a well defined
> term (if at all) if you state what time scales or processes you are
> including and what you mean by "a doubling of atmospheric CO2".
>
> The higher sensitivity values seem relevant to time scales (i.e., > 10 kyr)
> where ice sheets and possible biogeochemical (e.g., CH4) feedbacks can kick
> in at full force.
>
> The lower sensitivity values seem relevant to shorter time time scales
> (i.e., < 100 yr) when ice sheet feedbacks are not relevant and we assume
> that CH4 feedbacks need not be considered.
>
> Furthermore, if you instantaneously double CO2 and then let some of the CO2
> be absorbed by the ocean and biosphere you will get less of a climate
> response that if you maintain the doubled CO2 concentration.
>
> My take is that the longer-term response seems to be closer to 6 C whereas
> the shorter-term response (assuming no big methane feedback) seems closer to
> 3 C. (For my own subjective probability distribution under these
> assumptions, I would suggest something like an 80% probability of being in
> the range of 2/3 to 3/2 of these values , i.e., short-term in the absence of
> strong methane, probably something like 2 to 4.5 C for a CO2 doubling, and
> for the longer term, something like 4 to 9 C for a sustained CO2 doubling.)
>
> ---
>
> I am planning to give a semi-tutorial talk on this at AGU in the same
> session that Hansen is speaking in:
>

> *CONTROL ID: * 1209062
> *TITLE: * Radiative Forcing and Climate Response: From Paleoclimate to
> Future Climate
> *PRESENTATION TYPE: * Assigned by Committee (Oral or Poster) [Invited]
> *CURRENT SECTION/FOCUS GROUP: * Paleoceanography and Paleoclimatology (PP)
> *CURRENT SESSION: * PP10. Earth System Sensitivity To Radiative Forcings:
> Lessons From Earth History
> *AUTHORS (FIRST NAME, LAST NAME): * Ken  Caldeira1, Long  Cao1
> *INSTITUTIONS (ALL): * 1. Dept. of Global Ecology, Carnegie Institution,
> Stanford, CA, United States.
> *Title of Team:
> ABSTRACT BODY: * The concept of radiative forcing was introduced to allow

> > ------------------------------
> > *From: *"John Nissen" <j...@cloudworld.co.uk>
> > *To: *"marty hoffert" <marty.hoff...@nyu.edu>
> > *Cc: *euggor...@comcast.net, geoengi...@googlegroups.com,
> > kcalde...@globalecology.stanford.edu, anr...@nytimes.com, "Tyler Volk" <
> > tyler.v...@nyu.edu>, "David Wasdell" <wasd...@meridian.org.uk>, "Alan

> > Robock" <rob...@envsci.rutgers.edu>, "Stefan Rahmstorf" <

> > stefan.rahmst...@pik-potsdam.de>, "John Shepherd" <john_g_sheph...@mac.com>,
> > "Mark Lynas" <markly...@zetnet.co.uk>
> > *Sent: *Friday, August 12, 2011 7:53:53 AM
> > *Subject: *Re: [geo] Jamais Cascio-- on the problematic idea of 350

>
> > Hi Marty,
>
> > I was just looking through some bulky emails to delete them, when I noticed
> > this one on climate sensitivity.  You put 2.5 degrees warming for CO2
> > doubling.  It is interesting that the climate sensitivity has been
> > reappraised, e.g. by Hansen giving 3 degrees [1] and by Wasdell giving a
> > much higher figure of around 7.8 degrees [2].
>
> > Wasdell raises a fundamental point about the behaviour of the climate
> > system over recent Ice Ages when temperature has varied by 5 degrees, yet
> > CO2 has only varied between 180 ppm and 280 ppm.
>
> > [quote from [2]]

> > *

> > That raises the fundamental “Emperor’s Clothes” question of climate
> > science:
>
> > 8.5.1 “If the Charney sensitivity, supported by our modern computer models,
> > projects that a doubling of the concentration of atmospheric carbon-dioxide
> > leads to a temperature rise of 3ºC at equilibrium, then why, in the
> > empirically measured behaviour of the planetary system, does an increase of
> > only 56% in CO2 concentration (from 180 ppm to 280 ppm) lead to a 5ºC change
> > in temperature?”

> > *

> > [end quote]
>
> > Now that assumes that the CO2 causes the warming (rather than the polar
> > amplification of Milankovitch signals, as I would suggest [4]).  However I

> > think Wasdell is onto something.  There does seem to have to been *systemic
> > optimism* in the climate science community about the effect of CO2

> > emissions on global warming, and we are on course to reach 4 degrees or
> > more, even with the most drastic CO2 cuts one could imagine through a UNFCCC
> > path (especially given the political situation in US and China).
>
> > Furthermore the potential contribution of Arctic methane to global warming
> > is being ignored.
>
> > Furthermore, 1.5 degrees is now being accepted as a significantly safer
> > target than 2 degrees [3].  And there are calls for the CO2 level to be
> > quickly brought below 350 ppm, amid concerns about ocean acidification as
> > well as global warming.
>
> > How much evidence does the scientific community need, before accepting the
> > requirement for geoengineering?  Perhaps those who still say that
> > geoengineering is too risky (in relation to benefits) should answer this
> > question.  There are some on this list!
>
> > Cheers,
>
> > John
>
> > [1]
> >http://www.columbia.edu/~jeh1/mailings/2011/20110118_MilankovicPaper.pdf
>
> > [2]http://www.apollo-gaia.org/Climate%20Sensitivity.pdf
>
> > [3]

> >http://globalwarmingisreal.com/2011/06/03/unfccc-chief-says-two-degre...

>
> > [4] Nissen, J "Arctic sea ice thermostatic control of global temperature",
> > EGU 2011 (to be published)
>
> > ---
>
> > On 02/11/2009 17:16, Marty Hoffert wrote:
>
> > All:
>
> >  David Keith & Andy Revkin are right that we should not be
> > over-interpreting every perhaps natural climatic fluctuation as evidence of
> > global warming however much that feeds into the human psychodrama.  That in
> > no way detracts from the robust finding that the secular trend of rising
> > global mean temperature, polar cap melting and sea ice recession from
> > continued CO2 emissions is overwhelmingly supported by data. And given our
> > present fossil fuel based energy system, and independently estimated global
> > climate
>

> ...
>
> read more »

[Ken Caldeira]

In the attached paper, we provide evidence for a long-term climate sensitivity of 6.8 to 7.8 C per CO2 doubling, but this probably depends on having strong functioning methane feedbacks in the Eocene.

My point below was that there is not a right and wrong way to define climate sensitivity, radiative forcing, and so on, but there are different ways. Depending on what you count as a feedback and what you count as a forcing, and what timescales and processes you consider, you come up with different numbers.

I haven't gone through the Wasdell writing in great detail but it seems to be a mostly reasonable, if somewhat imprecise, review of the literature.

An important question is how fast and how powerfully will various feedbacks come into play and how fast will anthropogenic forcing on the climate system be removed by natural processes.  If the timescale of concern is short or feedbacks end up being weak, then Charney sensitivity is probably appropriate for current policy. If timescales of concern are longer or feedbacks end up being more rapid or more powerful than generally anticipated or atmospheric CO2 adjustment time ends up longer than anticipated, then the climate sensitivities estimated from paleo climates become more relevant.

In any case, it is important to separate issues that have to do with differences in definitions from issues that have to do with uncertainty about the facts.


________________
Ken Caldeira

Carnegie Institution Dept of Global Ecology
260 Panama Street, Stanford, CA 94305 USA
+1 650 704 7212 kcal...@carnegie.stanford.edu
http://dge.stanford.edu/labs/caldeiralab  @kencaldeira

See our YouTube:
  Carbon dioxide emissions embodied in international trade
  Past land use decisions and the mitigation potential of reforestation

[John Nissen]

Hi Ken,

Carbon Tracker Initiative has taken Potsdam figures for allowed CO2 emissions to achieve 2 degrees with 20% chance of failure [1].  The Potsdam figures are derived from a range of climate models and climate sensitivities [2] - so their budget figure (886 GtCO2 between 2000 and 2050) might need to be revised downward in the light of Hansen and Wasdell.

As you say, the climate sensitivity as an equilibrium far in the future is not as important as the effect of GHG levels on warming over the coming decades, to achieve a plateau of 1.5 or 2 degrees - preferably the former.  But acheiving the former is extremely tough, as we are on 0.75 degrees already, and have 1.6 W/m-2 forcing from CO2, which won't go away quickly due to CO2's long effective lifetime.

How much budget have we already used since 2000?  According to [1]:  "By 2011, the global economy has already used up over a third of that 50 year budget in the first decade alone. Calculations of global emissions published in Nature indicate 282 GtCO2 have already been emitted in the first decade of this century from burning fossil fuels, with land use change contributing a further 39 GtCO2.  This leaves
a budget of around 565 GtCO2 for the remaining 40 years to 2050. This budget could be further contracted if a position is adopted to limit global warming to 1.5°C or even lower."

It looks from this as if geoengineering to remove carbon dioxide will be required.  (I'm copying this to Stefan Rahmstorf at the Potsdam Institute to comment on the figures.)

But worse still, we have to include methane in the equation.  The direct forcing per given weight of methane is over 100 times that of CO2, though the average over time comes down (e.g. to 72 times over 20 years or 25 over 100 years), due to the decay of methane - mainly by reaction with OH ions.  However 1 Gt of methane maintained in the atmosphere gives equivalent forcing to over 100 Gt CO2.  An annual emission of 0.1 Gt of methane would be sufficient to maintain 1 Gt in the atmosphere.  But 100 Gt CO2 would make a big dent in the budget for CO2 emissions.  So on the basis of the Potsdam budget, we need to keep methane emissions from rising more than 0.1 Gt per annum at most.  Current emissions are estimated at 0.6 Gt per annum.  But, according to Shakhova et al, there is 50 Gt of methane that could be released from the East Siberian Arctic Shelf [3]:

[quote]
They conclude that "release of up to 50 Gt of predicted amount of hydrate storage [is] highly possible for abrupt release at any time". That would increase the methane content of the planet's atmosphere by a factor of twelve.

Ken, don't we come to the inescapable conclusion that geoengineering/intervention is required, both (a) to reduce the CO2 level through carbon dioxide removal (CDR); and (b) to prevent a methane excursion through a combination of solar radiation management (SRM) and local management of the methane environment - if that is at all possible?

Cheers,

John

[1] http://www.carbontracker.org/wp-content/uploads/downloads/2011/07/Unburnable-Carbon-Full-rev2.pdf

[2] http://www.nature.com/nature/journal/v458/n7242/full/nature08017.html

[3] http://en.wikipedia.org/wiki/Arctic_methane_release

---