Scott Saleska on Tuning the Climate
December 6th, 2006Posted by: Roger Pielke, Jr.
[Scott Saleska of the University of Arizona has asked an interesting question in the comments of a post from last week. We have elevated it so that it does go unnoticed. Thanks Scott! -Ed.]
Let’s say air capture, or any of the many geoengineering options being widely discussed (e.g. my colleague here at the UofA, Roger Angel’s recent idea* to block 1.8% of the incoming energy with a gadget at the L1 Lagrange orbital point), ends up being feasible in a few decades. And let’s say we actually reach the point where we can, as Roger [Pielke, not Angel] suggested, tune the atmosphere’s CO2.
What level do we tune it to? And who gets to decide that level? The “worst off” individual (to follow Rawls famous “Theory of Justice”)? Then we probably let the Maldivians decide, since under current projections, sea level rise could completely wipe them off the map. Places like Russia, on the other hand, would probably prefer to have some moderate global warming, because that probably would give them better agriculture in Siberia, and ice-free ports on the north Atlantic.
[* Roger Angel, 2006. Feasibility of cooling the Earth with a cloud of small spacecraft near the inner Lagrange point (L1), PNAS: http://www.pnas.org/cgi/reprint/103/46/17184 (subscription require). Or see the free podcast of his recent talk at our Global Climate Change series at University of Arizona, in which he reviewed a whole range of options from solar cells to Paul Crutzen’s aerosols, to his satellites: http://podcasting.arizona.edu/globalclimatechange.html or any of the others who spoke, focusing mostly on science of climate change]
December 6th, 2006 at 5:11 pm
Thanks, Roger, but my comment about this was actually inspired by NYT reporter Andy Revkin in an email discussion with some of the scientist’s on our climate brief on the distinction between values and science. He wrote, in an email he said we could forward, that
“If things get bad enough that the world has to
resort to artificial cooling to counter our
man-made warming, who gets to set the thermostat,
and at what ’safe’ temperature? (This is one
reason, personally, I don’t hold out much hope for
geoengineering options ever getting deployed.)”
I am not sure that the “who gets to decide?” problem would actually stop deployment of a feasible system (e.g., the analogous problem did not stop development and deployment of nuclear weapons), but I think it an interesting moral and political question.
Of course, if we ever got to the point where these schemes became feasible and economical, it might not be a far jump to even more precise control of the climate that would both save the Maldives and give warm-water ports to Russia.
Best,
Scott
December 6th, 2006 at 5:50 pm
Does anyone disagree with a target temperature that is cold enough to stabilize the Greenland and West Antarctic icesheets, but warm enough to prevent glaciation in Northern Canada?
December 6th, 2006 at 6:09 pm
Scott,
You have stated (qualitatively) that afforestation is a perturbation offsetting increasing CO2. As a biogeochemical specialist, do you have an idea of when we will have an idea what the magnitude of that is?
December 6th, 2006 at 6:20 pm
Scott- Thanks. What is the difference (practically, politically) between tuning the atmosphere using geoengineering and tuning it using energy policies?
Seems to me that the moral and political questions are identical in both cases . . .
December 6th, 2006 at 7:38 pm
>What is the difference (practically, politically) between tuning the atmosphere using geoengineering and tuning it using energy policies?
The most important practical consideration may be that geoengineering could be as much as 500 times cheaper than using energy policies.
The Stern report seems to advocate spending over $500 billion per year using energy policies.
Some aerosol techniques are claimed to cost only about $1 billion per year.
December 6th, 2006 at 7:48 pm
Fix Venus first — we should be able to toss comets in for water, after proving a Lagrange Point sunshield, and learn a lot about what works.
“Build one you can throw away” is always good engineering, particularly when debugging planetary engineering.
December 6th, 2006 at 9:57 pm
The notion that we can actual ‘control’ climate by tweaking a few variables at the margins is very dangerous. The results of such ‘tweaks’ are not predictable.
As an example, consider the ‘management’ of Yellowstone National Park over the last 100 years. Well-intentioned tweaks of the ecosystem of the park created unanticipated problems that were more damaging than the ‘problems’ they were trying to fix.
While Yellowstone’s ecosystem is a coupled, complex, chaotic, non-linear system, it is orders of magnitude less complex than global climate! It is not likely that our ‘intentional adjustments’ of the climate would produce the desired results, just as our unintentional adjustments are not likely to produce predictable results, in my opinion.
December 6th, 2006 at 11:06 pm
Roger,
Frankly, I had never before Revkin’s comment today even fully conceptualized what it would be like to really have such a thing as a climate “tuning” capability. It’s like that scene in “Cast Away” where the Tom Hanks character gets back to civilization and starts playing with an automatic lighter (“click”, and the flame appears – such power!) after having nearly lost his life due to the difficulty of restarting his campfire on the island where he was lost.
Seriously, I haven’t thought through the political or practical ramifications of differences between geoengineering and energy policies, but it is not obvious to me that there are no differences.
In any case, I don’t think we should be choosing between them at this stage. My general thought, contrary to the “climate tuning” hypothetical, is that fixing climate change is an extremely hard problem, harder than most people who have not studied the problem realize. We should, therefore, be comprehensively and aggressively pursing a multitude of options for both adaptation and mitigation, and designing market oriented regulatory approaches that allow the most feasible and economic suite of options to come online when they become deployable. I imagine this would mean more serious thinking and implementation about adaptation up front, along with a combination of the cheaper off-the-shelf conservation and alternative energy sources (a la Pacala & Socolow 2004), with more futuristic technologies (a la Hoffert et al., 2002 and air capture) filling in later, with geoengineering (a la Roger Angel’s satellites) as an emergency backstop.
Dealing with the rich-poor world divide is the other hard part of the global climate change problem, and it is not obvious to me that there aren’t socioeconomic implications for this from choosing energy policy vs. geoengineering (indeed, it seems that implications of some kind are inevitable, though I don’t know what they are). We don’t solve this in the long run without the developing world, and they can’t help solve it before they get less poor. A hard problem that we seem to be making painfully slow progress on, and that smart development economists like Jeff Sachs nonetheless think can be solved given enough political will, maybe they are right.
I know some people are concerned by geoengineering because they think the prospect of a geoengineering solution will make people complacent about the need to start changing energy technologies today, and in the end geoengineering won’t work and we’ll be in a real pickle. Maybe their concerns are correct, but on the other hand if we aggressively adopt a comprehensive approach right from the start, we will be working on both geoengineering and high tech energy sources all along.
Why do you think the moral and political questions are identical between geoengineering and energy policy?
Best,
Scott
December 7th, 2006 at 12:02 am
Steve Hemphill,
Temperate forests have about 100 metric tons C/ha. How many hectares do you want to plant forest on, and we could figure out an upper bound of how much we could sequester. It helps a some, but it won’t solve the problem.
We might arguably get better use of the land if we used it to grow biomass for energy rather than used it for carbon sequestration.
For example, consider the U.S. by itself, the numbers for which I happen to have available.
CASE 1: AFFORESTATION (the value of forest wood as a stock)
U.S. has 130 million ha of arable land.
If we used all for afforestation it (neglecting that we need a lot of it for growing food, but forget about that for the moment): we would get 100 tC/ha * 130e6 ha = 130e8 tons C or 13 gigatons carbon (Gt C) sequestered (one time). This is a little over 6 times what the U.S. emits each year (~ 2Gt C). So we could theoretically sequester 6 years of U.S. fossil fuel emissions with all our arable land.
[note: scientific notation example: 3e6 = 3 time 10 to the 6th power]
CASE 2: BIOFUELS (the value of forest wood as a flow)
Dense plantings of eucalyptus trees can yield 25 metric tons of dry biomass per hectare per year:
25 tons/ha * 16 x 106 Joules/kg (energy content of biomass) * 1000kg/ton = 4 x 1011 J/ha
Total possible annual U.S. biomass energy production = 4 x 1011 J/ha * 130e6 ha = 54e18 J
The US consumes about 80 e18 joules of fossil fuel energy per year, so biomass energy could theoretically displace 50/80 or 60% of U.S. fossil fuel every year, about 1.2 Gt C of CO2 emissions. In 10 years, the cumulative flow of carbon would be equal to the stock of carbon sequestered in CASE 1. So if you plan to use biomass over the long run (more than 10 years), and assuming I did this right, you may get more warming abated per area of land if you use it for fuel than for sequestration. (this is true even if you don’t use such extreme assumptions like using all U.S. arable land for energy or carbon sequestration).
I am not sure if that gets at your question or not. Does it?
-scott
December 7th, 2006 at 1:13 am
Fix venus first? A significant proportion of the greenhouse effect on Venus is due to past and present sulphur dioxide, plus past water vapour (now dissociated and partly lost as hydrogen, with the oxygen retained as carbon and sulphur oxides).
December 7th, 2006 at 4:10 am
Scott:
“What level do we tune it to? And who gets to decide that level?”
As a practical matter, the group that controls the thermostat will make the decisions. If the control is exercised via manipulation of GHG emissions, this is a very large group indeed, requiring much coordination before a decision can be reached, with a long time lag before any changes are felt. The size of the group, response time and absolute/relative costs to the decision-makers may change if technology-based approaches become necessary.
December 7th, 2006 at 5:00 am
Jim, your reference to Yellowstone is slightly off; that’s a story about bureaucratic mismanagment of government-owned resources – resources that would likely be better managed privately or as a state park. Similar stories could be told about mismanagement of federal forests, grazing lands, mineral resources etc.
In the case of climate chage there is no global government and no owner; the story is much more one of groups of affected resources users talking with each other about how to manage an open-access commons that is coming under increasing stress from heavier use. The question is whether, like global fisheries, tropical forests and other ineffectively owned resources, people will be able to collectively get their act together in time to head off the negative consequences to which private self-interest leads.
We have already found that a thermostat exists, and have been unintentionally cranking it in one direction. Will we knowlingly allow our unintended acts to keep turning the thermostat up, or come to an agreement that allows us to exercise some deliberate control?
December 7th, 2006 at 6:00 am
Scott- Thanks. On the ethical issues associated with intentionally modifying the climate, I encourage you to have a look at Dale Jamieson’s 1996 paper “Ethics and intentional climate change” in Climatic Change:
http://www.springerlink.com/content/w673766t3316r474/
Dale wrote this when visiting at NCAR, while I was there, and we had numerous discussions about why his critique (generally negative on intentional climate change) applied to geoengineering but not energy policies. I think that if one accepts his criteria for when it is permissible to intentionally modify the climate, it raises some interesting questions about why the choice of means should make a difference.
Maybe this paper is worth a summary on the blog at some point.
December 7th, 2006 at 2:54 pm
Tom,
You start with the assumption that we can “exercise some deliberate control” of climate change. I do not believe that the assumption is correct, based on the science, the math and real world examples. We can certainly have an effect, but the more complex the system; the less we can control or even anticipate the outcome.
Your argument about Yellowstone reminds me that there are still plenty of people in this world who believe communism and socialism are the best ways to run a country and that past failures are the result of less intelligent people ‘not doing it right’.
On another note, I do not accept that private self interest leads to destruction of the commons, for destruction of the commons is against any users self interest, with the possible exception of the insane! I also note that user come together when there is an apparent problem with the commons. So far, the AGW crisis is still very hypothetical with no real manifestation of a problem any different from the ones that have always existed.
December 7th, 2006 at 9:50 pm
Scott -
No, it doesn’t. I’m talking about the proportion of extent limitations of existing flora that will expand due to increased CO2 (and subsequent reduced water demand, and the further ramifications due to less water useage in existing locations), and how much that increased sink will, given the time it takes for flora to spread and cover to new, now acceptable limits. How much and how long will it take, on average. When will we have a good handle on that?
December 7th, 2006 at 9:56 pm
Fix Venus? The surface temperature of Venus is largely due to the fact that although the atmospheric lapse rate is similar, the sheer mass of the atmosphere leads to a much greater surface temperature.
December 8th, 2006 at 7:33 am
“Fix Venus? The surface temperature of Venus is largely due to the fact that although the atmospheric lapse rate is similar, the sheer mass of the atmosphere leads to a much greater surface temperature.”
So let’s build sunshield such that Venus is always completely in the dark. That should drop the outer atmosphere temperature down to close to the temperature of space…and this temperature will gradually propogate down to the surface.
I guess I could run a calculation of how long it would take for Venus to cool down if it was completely in the shade. Hopefully, it would take less than a hundred years…just so it could be thought about.
Once the atmosphere has essentially completely condensed onto the surface, it could be rebuilt to a more pleasant (earthlike) state. Let’s get someone working on that…there ought to be some good use for another habitable planet.
P.S. In case anyone wants to beat me to the question of how long it would take Venus’s atmosphere…here are some relevant data:
http://en.wikipedia.org/wiki/Atmosphere_of_Venus
P.P.S. I was thinking of calculating the radiative heat transfer rate to space and the mass and specific heat of the constituents of atmosphere of Venus…but I guess one could actually do a fairly decent estimate just by figuring out how quickly temperature drops on a still night on earth. For example, let’s say temperature drops 15 C over 0.5 day (from day to night) during a still night on earth. Well, the atmosphere on Venus has about 100 times the mass, so it would drop 0.15 C over 0.5 days. So to drop 550 C (from 462 C down to -90 C, to solidify the carbon dioxide) would take 550 C divided by 0.3 C per day (that’s 0.15 C per 0.5 days).
Wow! Under two years! Now all we need is that humongous umbrella…
December 8th, 2006 at 7:52 am
D-oh! I was doing my calculation on my watch in the dim light, and used a minus sign instead of a division sign.
The time would 1833 days…or about 5 years. Pretty impressive.
P.S. Of course, it would take far, far longer than that, because the temperature would be stuck at the condensation point of carbon dioxide for a long time.
P.P.S. Ah, here are some convenient CO2 properties (the miracle of the Internet…plus Google):
http://www.uigi.com/carbondioxide.html
The specific heat of the gas is 0.85 kJ/kg, but the latent heat of vaporization is 571 kJ/kg…or 670 times as large. Therefore, we’d get stuck at -78 C for 670 times 5 years, or 3350 years. I hope we wouldn’t have to do that…maybe we could work with an atmosphere that is ~100 percent CO2, so we wouldn’t have to condense all that CO2.
P.P.P.S. I hope someone is checking my math…
December 8th, 2006 at 7:07 pm
Steve Hempill –
I now think I understand your question. You are asking: “What will happen to the terrestrial carbon sink under global climate change?” Is that right?
This is a question nobody knows the answer to for certain, but most people actually expect the sink to get proportionally smaller, not larger, with climate change.
But first some background: of CO2 emitted into the atmosphere from anthropogenic activities (mostly fossil fuel burning and tropical deforestation), only somewhat more than half stays there. The rest is removed by either ocean uptake or land uptake. The ocean uptake is mostly due to the ocean’s response to the perturbation of the atmosphere: more atmospheric CO2 puts the land and ocean out of equilibrium, and the ocean tries to restore the equilibrium by taking up CO2. The source of the land uptake is much more complicated, and not fully understood. Some of it is clearly due to re-growing forests (e.g. in the northeastern U.S. and in central Europe, and probably in China too) that used to be used for agriculture but are now economically marginal for that purpose and have been abandoned and are regrowing. This is a sink that has little directly to do with climate or atmospheric CO2.
Most people think that some portion of the sink must be due to direct CO2 fertilization causing a stimulatory increase in net primary production (NPP) by plants, but it has been hard to see this signal in natural ecosystems so far. All vegetation models and lots of experiments (but not all) show that increased CO2 will increase NPP, but there is some rather vigorous debate about how applicable the experiments are is to real-world ecosystem conditions, and in particularly whether increases in NPP will translate into increases in carbon sequestration in ecosystems. (if increased NPP induced carbon uptake is matched by increases in heterotrophic respiration losses of carbon, then there won’t be much of a sequestration effect)
The models in this realm (coupled climate-carbon cycle models) are in their infancy and disagree on a number of things, and so must be taken with a grain of salt, but for what it is worth, there are two things that all the models that can do this show, without exception: (a) increased CO2 by itself stimulates NPP, and (b) the full suite of climate changes (warming, changes in precipitation, etc) dampens (in some cases reverses) the stimulatory effects of CO2 by itself. Many of the models show a net positive carbon cycle feedback to climate – that is, the net effect of global climate change is to stimulate net carbon *losses* from ecosystems, enhancing rather than dampening the climate change. I think your question anticipates the opposite effect (negative feedback). This is still possible, but the balance of evolving scientific opinion is right now trending the other direction.
Real Climate had a nice summary of a couple related papers on the carbon cycle feedback to climate: http://www.realclimate.org/index.php/archives/2006/05/positive-feedbacks-from-the-carbon-cycle/
Hope this helps,
Scott
December 8th, 2006 at 7:16 pm
On the “tragedy of the commons” issue raised by Tokyo Tom. From most economist’s perspective, climate change represents a tragedy of the commons in its purest form. It could be the paradigmatic example of what a tragedy of the commons is. So the suggestions of some that it is not applicable here don’t make much sense to me, unless they are denying that no harms will arise from climate change (which makes the whole thing a different debate).
I am on record arguing that there are, in fact, some divergences from the simplest tragedy of the commons interpretation, and that these divergences may actually explain some of the local actions by states, etc now being taken to slow climate change. (see Engel, K.H. and S.R. Saleska. 2005. Subglobal Regulation of the Global Commons: the case of climate change. Ecology Law Quarterly 32(2): 183-233. http://eebweb.arizona.edu/faculty/saleska/docs/Engel.Saleska05_subglobal_ELQ.pdf)
But the overall framework is still one in which the lack of economic accounting for damages that polluters cause is what causes the problem. I think it is hard to get away from that reality.
Best,
Scott
December 8th, 2006 at 8:20 pm
Jim:
Climate is certainly complex as you say, so “deliberate” tweaks are difficult. But we know that we are in the midst of an uncontrolled experiment – driving rather blind with our foot on the accelerator. Surely you are not suggesting that it would be irresponsible for us to ease up on the gas? And it may also be worthwhile to consider whether we can fashion a brake, even as we put on our seat belts and brace for a possible bumpy ride.
I think we share opinions about the problems inherent in communism and socialist management of resources.
I would recommend you do more reading on the use of common resources and the “tragedy of the commons” phenomenon. Where individual actors cannot secure the benefit of acting in a sustainable way, rational self interest directs individual actors to take what they can as sson as possible. Where exploitation is light, this is not problematic, but as technology advances and populations grow, the race heats up. Look at the history of the exploitation of marine fisheries for classic examples – including the collapse of whaling, the cod fishery and ongoing overfishing of tuna.
December 8th, 2006 at 8:32 pm
Mark>
>P.P.P.S. I hope someone is checking my math…
One major item: The rate energy is radiated is proportional to T^4, where T is in Kelvin. So cooling will much more rapid at first, and very slow down near the CO2 precipitation temperature.
December 8th, 2006 at 10:40 pm
Hi Steve,
You write, “One major item: The rate energy is radiated is proportional to T^4, where T is in Kelvin. So cooling will much more rapid at first, and very slow down near the CO2 precipitation temperature.”
Yes, I realize that. But actually, my crude estimate was based on cooling during the night on earth. Since the surface temperature on earth is ~15 deg C (288 K), and the surface temperature on Venus is currently about 460 deg C (733 K), my calculation is actually a little conservative–i.e., overestimates the time required–at least until we get Venus down to 15 deg C.
It’s really the huge latent heat removal needed to precipitate all that CO2 from the atmosphere that’s the problem. (Note: I ought to get Tim Lambert and Eli Rabett to help me with that, since neither of them believe in/have heard of latent heat. Heh, heh, heh! Inside joke.)
So…all in all, I still think we’d get down to 15 deg C in less than 5 years. Since the precipitation of all the CO2 would take forever anyway, we probably should stop at 15 deg C or above. What we’d really need would be some sort of super plant or super bacterium that could live in ~100% CO2, and spit out oxygen such that all that CO2 could be turned into O2 in a reasonable time.
By the time we get the umbrella-the-size-of-Venus built, Craig Ventner should have come up with the right designer lifeform to do the job.
December 8th, 2006 at 10:54 pm
“Climate is certainly complex as you say, so “deliberate” tweaks are difficult. But we know that we are in the midst of an uncontrolled experiment – driving rather blind with our foot on the accelerator.”
The whole history of homo sapiens is an “uncontrolled experiment.”
December 9th, 2006 at 1:49 pm
Scott said (the stuff in quotes):
“most people actually expect the sink to get proportionally smaller, not larger, with climate change.”
Define “climate change” please. Are you seriously stating that “most people” expect increasing CO2 will decrease the amount of terrestrial sink?
Who is “most people”??
Then,
“Most people think that some portion of the sink must be due to direct CO2 fertilization causing a stimulatory increase in net primary production (NPP) by plants, but it has been hard to see this signal in natural ecosystems so far.”
Is this a different “most people”? Don’t long term images of Earth show a general net greening, except where land is being wasted?
“All vegetation models and lots of experiments (but not all) show that increased CO2 will increase NPP”
Not all, so the alarmists can cherry pick a few studies to continue to argue their case for catastrophism.
The variability you cite amongst models shows how little we actually know. I think the Precautionary Principle actually says to *not* inhibit the growth in the base of the food chain under these circumstances, despite what the carbon traders / climate change feedwagon recipients / less than nominally educated (e.g. what’s a joule?) alarmists say.
December 9th, 2006 at 4:26 pm
Doesn’t snyone else think the obvious starting point to “what should we tune the climate to” is quite simply where it was before GHG forcing really took over? If we are talking CO2 levels I fail to see how pre-industrial levels is not the very clear goal.
If it is a question of expense/difficulty then I would think we should seek the maximum temperature whereby sea level rise will be 0 or just about imperceptible.
December 9th, 2006 at 4:36 pm
“Doesn’t snyone else think the obvious starting point to “what should we tune the climate to” is quite simply where it was before GHG forcing really took over?”
Ghg forcing has been going on for billions of years. If you are referring to the level before the industrial revolution, it would indeed be the appropriate target – for a Luddite.
December 9th, 2006 at 4:45 pm
Steve,
I outlined for you a quick summary of my percepton of where the balance of scientific opinion is right now on carbon cycle – climate interactions. (hence by “people” I meant scientists who study aspects of the carbon cycle; I am not talking about so-called “alarmists”). Apologies for any rough edges or lack of clarity.
By “balance of opinion” I meant something a good deal weaker than a consensus. This area is not particularly well understood, and the wide variety of different model predictions is one indication of that, as I pointed out, a point which you repeated as well. As I like to say in my class on the topic (and in proposals to motivate the need for more measurements in this area), the wide disparity between models in predicting carbon cycle responses quantifies the scale of our ignorance on this topic, which is large.
I should clarify one distinction that perhaps was as not clear as it could have been: between CO2 effects on plant productivity (which are positive, but usually diminishing going into the future because of a saturating response to elevated CO2), and effects of climate changes (temperature, precip) on productivity, and on other aspects of the ecosystem. Hence, all the models show elevated NPP as a result of higher CO2, but they also all show that NPP is elevated to a lesser degree once climate changes are also taken into account. They (and many, not all, empirical studies as well) also tend to show net positive feedbacks arising from other effects of climate change: not from CO2 effects on plant productivity , but from, e.g., higher temperature stimulation of microbial decomposition, leading to a loss of carbon from soils (or thawing of permafrost leading to decomposition of all that boreal peat).
Please note that I don’t cite the models or the empirical studies as definitive, just indicative. The models represent our best comprehensive embodiment of the mechanisms and principles we think could be important for controlling this. Our best could still be wrong (indeed, some of it at least, must be, because different parts of our best disagree).
You are perfectly welcome to have a different view then the “balance of opinion”, and given the range of thought on this, it is quite plausible that you could find scientists whose views are in accord with your own personal opinion about how the system should work.
Best,
Scott
December 9th, 2006 at 4:58 pm
Sorry, Steve, I should have been clearer (and maybe I should use little words?) I am referring to anthropogenic GHG forcing.
(FYI, in case you care whether I engage you or not, the only reason I have bothered to reply to you this time is because I am charitably assuming you just don’t know what luddite means)
December 9th, 2006 at 5:06 pm
Thanks, Coby, for bringing the discussion back to the starting point! None of us has really engaged my paraphrase of Andrew Revkin’s question very much, have we?
From my perspective, the “obvious starting point” is to slow, and eventually halt, the build-up of GHG in the atmosphere. I suspect we agree on that much. If we seriously engage the hypothetical (where we are free to “tune” the climate to whatever people agree on), however, I am not sure what is obvious. If we go even further: assume climate manipulation is free, and we can even fine tune different parts of the earth differently. Wouldn’t some (maybe even many) want to make their part of the world at least “a little bit” better than what nature gave them? Mightn’t Russia want warm water ports and a breadbasket in Siberia? Mightn’t Canada want a real northwest passage? Maybe the Maldives (and perhaps New Orleans and Denmark?) would actually prefer a little sea-level lowering. Climate becomes another nature resource fully or partially co-opted by human technical know-how. Whether that is good or bad, the question is: what do we do with it, how do we manage it?
Granted, we are in the realm of science fiction here, but to paraphrase Isaac Asimov (or was it Robert Heinlein?) for practical purposes, the world 100 years from now is probably indistinguishable, as far as we are concerned, from science fiction anyway.
Best,
Scott
December 9th, 2006 at 5:07 pm
To Steve Hemphill (“GHG forcing has been going on for billions of years”):
Yes, you are absolutely right, but that is largely irrelevant to the human-centric problem that is current-day global climate change. Compared to what humans are doing now, there has been only relatively modest GHG forcing since humans have been on the planet (only enough to cause the last ice-age), and essentially none at all (relative to what is now underway) since the dawn of recorded human history (which only really got underway after the glaciers of that last ice age receded).
Indeed, for our present predicament, most paleoclimatologists seem to view climate changes of times past as more cautionary tale than reassurance. I wouldn’t have wanted to be around for the “snowball earths” of the neoproterozoic (600-800 million years ago), for example.
Best,
Scott
December 9th, 2006 at 9:56 pm
“Doesn’t snyone else think the obvious starting point to “what should we tune the climate to” is quite simply where it was before GHG forcing really took over? If we are talking CO2 levels I fail to see how pre-industrial levels is not the very clear goal.”
I don’t agree. The world was in the middle of the Little Ice Age before the Industrial Revolution. I fail to see how the Little Ice Age is a clear goal.
December 9th, 2006 at 10:04 pm
OK, I’ll bite. I should decide.
There. Feel better now?
And just so you know, I like to cross-country ski in the winter and fish for trout in the summer. Therefore we should set the gobal temperature to something analagous to the depths of the little ice age. This would greatly expand the days available for skiing and streams suitable for trout habitat (in this country). Seems like an ideal solution to me.
What are you waiting for? Get crackin’!
December 9th, 2006 at 10:51 pm
Scott – I disagree.
“Compared to what humans are doing now, there has been only relatively modest GHG forcing since humans have been on the planet” is a wholely incorrect statement. Ghg’s have caused from 10 to 40 deg C of global warming since humans (depending on one’s classification of “Homo sapiens”) arrived, and the ultimate consideration of the role of convection, which is quite unknown at this time.
So, what we are causing now is an increase of less (maybe much less) than a 10% increase.
And Coby – my simple response is LOL. I relented and checked out your blog – it’s easy to see your target audience is not … shall we say … enlightened.
Let me ask you, how much experience have you had with calculations involving one small word -”joules”?????
A picture of alarmists is clearly emerging – Either:
A: Carbon traders
B: Those on the fear of change (in particular here global warming) dole,
C: Those who fall under the spell of A or B above.
Nordic – How’s this: Skiing into the midnight sun off Mt. Michelson? Of course I’d rather downhill…
December 10th, 2006 at 7:08 pm
Steve,
It appears you are seriously misinformed when you say “GHG’s have caused from 10 to 40 deg C of global warming since humans arrived”.
Consider these widely accepted facts:
(1) Homo sapiens sapiens has existed on the planet for less than one million years.
(2) Current levels of GHG have not been exceeded for at least 3 million, and possibly 20 million years.
(3) The antarctic ice core data shows us that the ice ages over the last million years or so experienced minima of about 180 ppm for CO2, and about 8 deg C less than pre-industrial for temperature.
(4) The current global average temperature is about 15 deg C. In the complete absence of GHG, the global average equilibrium temp is about -18C deg C, or 33 deg C less than today.
These facts imply:
(1) That because humans have never lived in a world that had more GHG than today, it is a physical impossibility for GHGs to have caused more than the 33 deg C warming in this time (i.e. the whole warming effect of GHG). This rules out the top third of the 10-40 range you assert.
(2) In fact, the earth would be uninhabitable by humans (and most other forms of life) if GHG ever were completely removed from the atmosphere (the closest we every got is arguable the “snowball earth” events of 600-800 million years ago, and there was considerably more than zero GHG then, even though the global surface temperature was below freezing almost everywhere). Thus, about the middle third of your 10-40 range is also ruled out as a biological impossibility.
(3) In fact, the paleoclimatic evidence tells us the answer is indeed smaller than the physical and biological impossibilities that your range implies: that CO2 was as low as about 180 ppm, and the temperature about 8 deg C less. This is 100 ppm variation in CO2 (other gases varied as well) and an 8 deg C variation in temperature over the course of human presence on the earth (entirely outside of your asserted range, though given uncertainties variations as high as 10 deg cannot entirely be ruled out). This is what I was referring to in my original comment when I said “relatively modest” variations in GHG forcing.
Further, since the rise of large human civilizations (i.e. the invention of writing and agriculture, probably about 10,000 years ago, and in any case since the last deglaciation) there has been very little variation in GHG forcing at all. It is in that context that the large scale GHG changes stretching back over long time periods (hundred of millions to billions of years, including periods when CO2 is believed to have been 10-30 times current levels) are likely irrelevant to the history of specifically human experience with climate.
Hope this helps clarify some of your apparent confusions,
Best,
Scott
December 10th, 2006 at 10:34 pm
Scott -
I accept your facts, but not your implications. There are a couple of problems with your #1. First off, as we all know but the dogma makes us frequently forget, temperature leads CO2 so the statement “it is a physical impossibility for GHGs to have caused more than the 33 deg C warming in this time” is a non sequitur. Further, even if it were true that CO2 actually caused all the warming, the heat sink of the ocean and ensuing time delay of heating makes your statement irrational anyway.
Your #2 is correct, but has absolutely nothing to do with anything I said.
The biggest problem with your logic is that you are attributing the entire 33 deg C to ghg’s. You are neglecting convection – by convection I mean vertical convection. The lapse rate is approximately the wet adiabat, and that is not a coincidence. We would approach 33 deg C colder without any ghg’s, but there would still be some (very minor) convection, therefore some lapse.
If there were no convection the 33 deg C difference would be much greater. Convection moderates the surface temperature toward the wet adiabatic lapse rate. So, the question *really* is, how much lapse is due to the mechanics of convection vs. radiative effects. If one considers (apples and oranges I know, but putting a “number” on it) that convection controls 23 deg C, then there is only 10 deg C left for ir. 10 deg C was a number I pulled out of … thin air. On the other hand, if we remove the feedback of convection, the surface temp under pure forcing could be 40 deg C or greater – another number I pulled out of thin air.
Maybe you can tell me – Since convection would be basically nil with no ghg’s, how much would it increase going from 280 ppm to 380 ppm, or 480 ppm (assuming the locomotive of flora does combine with future inherent efficiences based on the market to prevent us from actually getting there) – let alone to 560 ppm.
Thanks for your comments.
December 11th, 2006 at 12:08 am
Regarding preindustrial (the LIA) as a poor target for CO2 levels, I think the general though cautious consensus is that the LIA was a result of reduced solar activity and volcanism. It ended naturally, the late 19th and early 20th century warming was largely natural, so I don’t think preindustrial GHG levels would mean temperatures too much cooler than now.
Taking up the sci-fi notion of costless global climate control, it would be tempting and probably a temptation humanity would not resist, but I would only advocate extreme caution. Natural systems have a way of surprising us with unforeseen consequences and subtle interconnectivities.
Who could guarantee a little tweak to ease Canadian prairie winters would not alter percipitation patterns over major agricultural regions etc?
As you say, Scott, the first order of business would be to halt the continuing rise of CO2, not as interference with nature but as the cessation of interference, and then I would advocate lowering it til we are sure sea levels won’t rise, there is just too much global infrastructure dependant on the sea’s current level. If that mean temps around what they are now, I think we would be alright though it seems likely Australian droughts and corral reef death could continue…so a little lower might be safer.
Would we really imagine that life could be so much better with a climate tweak (or two, or three) that the risk of experimenting with our only viable home planet is worth it?
Another thought that occurs to me, in anticipation of more accusations of being a luddite, is that such geo-engineering projects would surely require the kind of global organization that seems to so frighten the anti-UN, anti-Kyoto crowd. Would the same people who fight global emissions controls on the grounds that the UN will take over the world advocate some necessarily similar global organization playing with the world’s climate?
December 11th, 2006 at 11:57 am
Coby> Would the same people who fight global emissions controls on the grounds that the UN will take over the world advocate some necessarily similar global organization playing with the world’s climate?
Probably yes, with good reason.
But if we are talking about advanced capabilities, I see considerable popularity for a service (space based mirrors?) that could offer seasonal reduction in mid-day sunlight strength to local areas. Selling that sevice (say to southern US cities) could a profitable business.