What to Make of This?
September 14th, 2006Posted by: Roger Pielke, Jr.
I’m not sure how to assess this news report:
The Bush administration plans to announce as early as next week a goal of stabilizing carbon dioxide levels in the global atmosphere at 450 parts per million by the year 2106, congressional and non-government sources told Platts Wednesday.
Such an announcement, if true, might lead to the establishment of new regulatory policies — either voluntary or mandatory — for the power sector and other sources of CO2 emissions.
But a high-ranking source at the White House Council on Environmental Quality rejected the suggestion, saying the administration has no plans to unveil any new climate-change policies.
Rumors that the White House plans to unveil a new global warming policy have been circulating since August 27, when Time magazine reporter Mike Allen, citing unnamed administration sources, wrote that President Bush’s views on the phenomenon “have evolved.”
In the news story there is a telling response from a representative of the Sierra Club who apparently has decided that anything the Bush Administration does necessarily is wrong, but in expressing his opposition fails to grasp the fact that the effects of stabilization at a particular level are time invariant — that is, as far as the effects of carbon dioxide on climate change, the precise path to stabilization is not important, the time-integrated emissions are what matters because of the long atmospheric residence time of carbon dioxide.
Dave Hamilton, director of the Sierra Club’s global warming and energy programs, said that while the 450 ppm number was fine, the timeline is not.
“We’ve got to make 450 [ppm] by mid-century, not next century,” he said, adding that the administration’s plan “would not stave off the worst impacts of global warming.”
I am doubtful that the Bush Administration will suggest dramatic new policies on climate change. But let’s see what happens. Meantime, the strategy of advancing incorrect policy arguments to support apparent predetermined opposition to policies not yet proposed might be rethought.
September 14th, 2006 at 8:15 am
Roger -
Certainly worth talking Hamilton’s bizarre argument, but (with my media critic hat on) not much worth trying to discuss this based on a story this vague and unsourced. One of the big problems with the anonymous source thing is that you don’t know who’s saying it and therefore you have no way of following up and learning enough to get out of the quicksand.
September 14th, 2006 at 8:30 am
John- I agree, but I also am assuming that if there is something more substantive out there our readership will let us know in the comments or otherwise. Thanks!
September 14th, 2006 at 9:33 am
Before assessing such a policy goal, or the criticism of it, someone would have to explain to me just how such a scenario would play out.
Presumably this goal involves surpassing 450 for many decades, so depending on how long and how much levels exceed 450ppm, Dave Hamilton’s concern seems perfectly reasonable to me. Perhaps it is Roger’s conclusion about the Sierra Club’s motives that is telling and he has decided that anything an environmental advocacy group says is necessarily wrong.
I also can not imagine that such a plan, if it exists, is giving due consideration to carbon cycle feedbacks or the possibility of natural sinks ceasing to remove ~1/2 of our current emissions.
September 14th, 2006 at 9:43 am
Coby- Thanks for your comment, but like Hamilton you have confused emissions and concentrations. Absent some form of artificial direct air capture of carbon dioxide, once concentrations exceed 450 they will be there for centuries not decades as you suggest.
See this paper for a discussion of this common confusion,
http://web.mit.edu/jsterman/www/StermanSweeney.pdf
which has nothing to do with one’s politics.
Earlier this week I gave my views on stabilizing carbon dioxide at 550. Safe to say that I don’t see 450 being realistic either.
Thanks.
September 14th, 2006 at 10:52 am
From E&E News:
http://www.eenews.net/
CLIMATE: White House adviser says ’stay tuned’ for new policies
Darren Samuelsohn, E&ENews PM senior reporter
President Bush’s top environmental adviser urged reporters today to “stay tuned” for new U.S. climate change policies and refused to tamp down speculation that major new proposals may be coming before Bush leaves office in January 2009.
Jim Connaughton, chairman of the Council on Environmental Quality, said Bush has added climate-change policies over the last five-and-a-half years that are consistent with the position he spelled out early in his presidency.
Connaughton was responding to questions about a Time article published Aug. 27 that reported a new U.S. energy policy was upcoming for the final quarter of Bush’s presidency.
Quoting unnamed Bush aides, Time wrote, “The administration is formulating a huge energy initiative designed to ‘change the whole nature of the discussion’ and challenge the G.O.P., Democrats, the oil and electricity industries and environmentalists.”
The magazine said Bush’s views on global warming “have evolved.” It quoted a Bush adviser explaining, “Only Nixon could go to China, and only Bush and Cheney, two oilmen, can bring all these parties kicking and screaming to the table.”
Connaughton said he was not in a position to confirm or deny the Time story’s accuracy.
“I can’t imagine what the source was to that,” he said.
The Advanced Energy Initiative rolled out in this year’s State of the Union address and the Asia Pacific Partnership unveiled last summer are both examples of new White House programs for global warming, Connaughton said.
“We continue to look for new opportunities,” Connaughton told reporters after speaking about climate change and energy efficiency during an event at Washington’s Union Station.
The Time article spurred talk among officials following the climate change policy debate, particularly because Bush in 2001 backed away from his presidential campaign pledge to impose mandatory caps on heat-trapping greenhouse gas emissions. U.S. climate policy has come under sharp criticism from outside its borders, and several U.S. states have also gone ahead with their own mandatory programs.
Asked if the Bush administration was planning major new programs for its final two years, Connaughton replied, “I don’t know. Stay tuned.”
September 14th, 2006 at 12:31 pm
Is a comment to the press really a policy argument?
The technical points of climate science are not easily understood. That’s why they are in technical journals and why the researchers have PHDs.
A more accurate statement would have to be more technical. It would go over most people’s heads and would not be effective advocacy.
September 14th, 2006 at 1:00 pm
Hi Roger,
I don’t think it is true that CO2 concentrations would remain at 450ppm for centuries, rather, current thinking says it would take centuries for concentrations to return to initial levels following a sudden jump. They would begin to fall as soon as net sinks exceeded net sources, granted probably quite slowly. I also don’t think that the carbon cycle is well enough understood to be certain about such figures.
Regardless, you are correct about the common confusion about emissions and concentrations, but it is not a confusion I share. It seems to me that this hypothetical policy that may or may not exist could only make sense if it relies on the error you have pointed out. How else does it make any sense to target a CO2 concentration 100 years from now that as you correctly contend we are almost certain to exceed in half that time?
Such a policy (again, if it exists) could only be crafted by people who incorrectly think that reducing emissions is equivalent to reducing concentrations. I have no idea if David Hamilton is confused about this or not, I would need to see something less ambiguous than the quote under discussion.
September 14th, 2006 at 1:54 pm
Joseph- Thanks for your comments. You write:
“A more accurate statement would have to be more technical. It would go over most people’s heads and would not be effective advocacy.”
Parsing this down:
“A more accurate statement … would not be effective advocacy.”
We discussed this at some length in this thread:
http://sciencepolicy.colorado.edu/prometheus/archives/the_honest_broker/index.html#000912
Thanks.
September 14th, 2006 at 1:57 pm
Coby-
You ask:
“How else does it make any sense to target a CO2 concentration 100 years from now that as you correctly contend we are almost certain to exceed in half that time?”
This is a great question to pose to the EU, FCCC, and IPCC!!
Thanks.
September 14th, 2006 at 2:41 pm
Coby-
On my assertion that exceeding 450 ppm will mean that levels will be above that for centuries, see this IPCC figure:
http://www.grida.no/climate/ipcc_tar/vol4/english/fig6-1.htm
Thanks.
September 14th, 2006 at 2:49 pm
Roger – Coby is correct & you are letting your enthusiasms run away with you. The policy as phrased in the news makes no sense. If we were going to limit ourselves to 450 ppm, then that would be a target for the next few decades, or 50 years, not 100. Setting a target that low that far ahead only makes sense if you think you’re going to overshoot and reduce down to it. Which would happen to some extent if emissions were to strongly reduce – the centuries stuff is as Coby says.
September 14th, 2006 at 3:43 pm
Roger,
That is a scenario involving assumed emissions, not a scietific statement about the lifetime of atmospheric CO2, thus it does not support what you said: “once concentrations exceed 450 they will be there for centuries”. That statement as written is incorrect.
I know that technical correctness tends to make weaker arguments, but my understanding of your writings indicates technical correctness may never be sacrificed without committing some kind of moral misdemeanor.
How about a retraction?
Cheers!
September 14th, 2006 at 5:11 pm
Coby-
Thanks. My last comments on this …
The graph from the IPCC clearly shows that once concentrations go above 450 then net emissions necessarily would have to be negative in order to return to 450. No scenario that I am aware of discusses negative emissions though as I’ve discussed, air capture would be the technology to do it, so if this is what you are referring to then I suppose we’d agree.
On residence times also see the IPCC: “emissions of a greenhouse gas that has a long atmospheric residence time is a quasi-irreversible commitment to sustained radiative forcing over decades, centuries, or millennia, before natural processes can remove the quantities emitted.”
http://www.grida.no/climate/ipcc_tar/wg1/016.htm
But surely we have more important items to discuss than negative emissions scearios leading to 450 ppm!! Lets get back to reality
September 14th, 2006 at 5:27 pm
William-
Surely you are kidding around.
Emissions consistent with particular stabilization levels are frequently characterized in terms of a a total amount of emissions integrated over some time period.
For instance, the widely cited Pacala and Scolow paper on “stabilization wedges” discusses stabilization paths for 450, 500, and 550 out to 2104. I would bet that the news article cited is referring to such a “wedge” strategy but to 2106 since we are now in 2006.
September 14th, 2006 at 8:03 pm
Roger, the graph shows no such thing.
http://www.grida.no/climate/ipcc_tar/vol4/english/fig6-1.htm
The yellow line (bottom in all graphs) shows stablization at 450 with sustained positive emissions. 0 emissions would result in falling concentrations. No carbon capture from the air rquired.
Unless natural feedbacks have taken over, the instant emissions cease, concentrations will start to fall.
That is also my last word on that, I can not force you to rethink it, I can only try to set the record straight for your readers. Thanks for your attention.
September 14th, 2006 at 8:41 pm
Roger,
perhaps you should have a look at this:
http://www.realclimate.org/index.php/archives/2006/01/can-2c-warming-be-avoided/
A decrease in actual atmospheric CO2 concentration over this sort of time frame requires a large reduction in emissions – but not negative emissions!
James
September 14th, 2006 at 8:46 pm
Coby-
Thanks.
When I described _negative emissions_ that refers to a level less than the natural sink. I firmly believe that (in the real world of conceivable policy paths) emissions reductions to this level necessarily requires some form of air capture. You are free to hold another view. However, if your discussions of climate policy are grounded in an expectation that such fantastic levels of emissions reductions are feasible or even possible, then yes we do have a large difference of opinion on this subject.
I seriously doubt that the Sierra Club or the Bush Administration are considering any such negative emission fantasies!
September 14th, 2006 at 8:58 pm
James-
Thanks for your comment. However, I find it hard to understand why I am arguing with climate scientists about basic climate science! Either basic chemistry and physics has been overturned in the past 15 years or I really failed to learn anything;-)
The “overshoot” scenario that you are pointing to at Real Climate includes more than just carbon dioxide, but inlcudes gases with much shorter residence times — methane and nitrous oxide. The Real Climate post consequently talks about “CO2 equivalent” concentrations. If one looks at this metric then it is indeed the case that the shorter lifetime greenhouse gases are removed from the atmosphere on a shorter timescale, thus reducing the CO2 equivalent concentration. But don’t mistake this with reducing the CO2 concentration itself!
In my discussions in this post and the earlier one this week I have been discussing carbon dioxide concentrations only, not carbon dioxide equivalent. And for carbon dioxide, it is indeed the case that negative emissions (i.e., net of sinks) would be required to reduce concentrations on time scales of decades to centuries.
Does this make sense? Thanks.
September 14th, 2006 at 9:19 pm
“When I described _negative emissions_ that refers to a level less than the natural sink.”
“I seriously doubt that the Sierra Club or the Bush Administration are considering any such negative emission fantasies!”
The thing is that *no one* really has a clue what the world is going to look like even 60 years from now…let alone 100.
Have any of y’all read Ray Kurzweil’s work? What about Michio Kaku’s “Visions?”
Have you read and appreciated Jesse Ausubel’s work on “decarbonization?”
And (if you’ll pardon the immodesty) my own work on world economic growth in the 21st
century?
http://markbahner.typepad.com/random_thoughts/2004/09/second_thoughts.html
http://markbahner.typepad.com/random_thoughts/2005/11/why_economic_gr.html
Technological change and economic growth are ***accelerating*** and will continue to do so throughout the century. (Unless we all blow ourselves to Kingdom Come…in which case global warming will be the least of our worries.)
Solar power satellites? A world entirely powered by fusion? Photovoltaics far less expensive than grid power?
Those are all not simply remote possibilities, but even likely towards the middle to end of the century.
If that sounds weird to you, just think about it: What would it take to develop fusion enough to supply all our energy needs? $50 billion? $100 billion? $500 billion?
The same with photovoltaics. How much needs to be spent to bring those down in cost to other forms of electricity? $5 billion? $10 billion? $50 billion?
Well, much sooner than the end of the end of the century, there will be literally thousands of INDIVIDUALS with that kind of money. So forget about government…even INDIVIDUALS could finance complete development of fusion or photovoltaics.
http://markbahner.typepad.com/random_thoughts/2006/07/why_every_singl.html
In fact, Bill Gates might even be able to do that today. (But probably not the solar power satellites.)
September 14th, 2006 at 10:11 pm
Roger,
The current sink (mostly from atmosphere to ocean) is in the region of 3GtC/year. Obviously this number will vary depending on various things such as the actual atmospheric and upper oceanic concentrations, but a reduction in emissions to below this level would result in an immediate decrease in atmospheric CO2 concentration. Of course in the long enough term the level would start to rise again unless emissions actually went to zero (or at least to a low enough level that other slow processes start to have a significant effect).
I don’t see how any of this can be considered in any way debatable. What do *you* think would happen to the atmospheric CO2 concentration if emissions were held at 1GtC/y from next year onwards? Care to draw a graph?
I’d bet dollars to doughnuts that Bush’s plan (if it exists at all) is based on some overshoot scenario whereby we do virtually nothing for decades (and go well past 450ppm), and expect technology to come to the rescue in the latter half of this century. That is, no change to any actual concrete policies but some more politically acceptable words to dress them up in.
September 15th, 2006 at 1:35 am
Its hard to see why you’re being so obtuse over this Roger, other than having made an initial mistake and now clinging to it, to the point of redefining words (“When I described _negative emissions_ that refers to a level less than the natural sink”).
September 15th, 2006 at 5:55 am
James-
OK, I believe now you are now being a bit disingenuous with me.
1. Emissions net of the sink, using your math — 1GtC – 3GtC = -2CtC — is exactly what I have described as negative emissions. If you missed this in this discussion, then my apologies, but recognize that our differeneces are only semantic.
2. However, you pointed to a post at Real Climate that focuses on carbon dioxide equivalent, which has a downturn in equivalent concentrations which you characterized incorrectly as “actual atmospheric CO2 concentration”. Clearly the RC discussion, based on the DEFRA report, is NOT referring to “actual” CO2 concentration. This seems a bit more than semantic.
As I said to Coby, we probably have far more relevant issues to discuss than 1GtC levels of annual emissions this century.
Thanks.
September 15th, 2006 at 6:09 am
William-
By leaping to the semantic and invoking insults, (as you often do here) and ignoring my substantive response focused on Socolow and Pacala, you’ve added weight to my view that you are part of the nitpicking “gotcha gang” who seeks to derail substance here by hijacking posts with content-free arguments.
Please recognize that people from different disciplines often use similar terms to mean different things (cf. “mitigation”). When this occurs it does not mean that there is a mistake or someone is being misleading as you so often jump to conclude. It simply means that we have to work harder at communicating, and avoid the urge to be rude or nasty.
The notion of “negative emissions” is firmly established in the literature, such as by the IPCC.
http://arch.rivm.nl/env/int/ipcc/pages_media/SRCCS-final/SRCCS_WholeReport.pdf
In the future, I’d ask that if you have a semantic question, email me and lets see if we can discuss it offline. Otherwise, I will continue to conclude that you are simply trying to derail our discussions here.
Thanks.
September 15th, 2006 at 6:37 am
According to E&E Daily today:
“The White House does not intend to unveil a major global warming policy shift next week despite a recent media report indicating such a move is imminent, a senior Bush administration official said yesterday.”
September 15th, 2006 at 6:41 am
Roger – I fear the semantic wiggling is on your part. Recall that you began with “Absent some form of artificial direct air capture of carbon dioxide, once concentrations exceed 450 they will be there for centuries not decades as you suggest.” This isn’t true, as we all now seem agreed: CO2 can go over 450, and then reduce. This is the entire substance of the disagreement over the rumoured plan. You are using a meaning of the term “emisions” that has confused everyone here. James comment of September 14, 2006 10:11 PM seems the most likely explanation of this plan.
Which is why your “the fact that the effects of stabilization at a particular level are time invariant — that is, as far as the effects of carbon dioxide on climate change, the precise path to stabilization is not important, the time-integrated emissions are what matters because of the long atmospheric residence time of carbon dioxide.” is wrong. Since its likely (given the low threshold of 450 at a long date like 2106) that the “plan” involves exceeding 450 in the interim, the actual path matters as well as the final value.
September 15th, 2006 at 7:16 am
William-
Thank you much for reengaging on the substance. A few replies.
1. Lets get one thing out of the way up front. You say of my assertion, “This isn’t true.” We are not discussing truth or falsity here. My views on the ability of the world to reduce emissions below the natural sink is an _opinion_, as is everyone else’s perpective on emissions over 100 years. Let’s dispel of talking about the “truth” of such views. I find it implausible to think that annual CO2 emissions can be reduced below the level of the natural sink in the next 50-100 years, you disagree. Good. Time will tell. But for now we can certainly accept that we hold different opinions on this subject.
2. Going back to the first post on this thread, it makes little sense to try to divine the details of a plan that may or may not exist and for which we have no details. I’d much prefer to discuss something concrete, like Pacala and Socolow, as I did in an earlier post this week.
3. As far as the stabilization path mattering, I would agree that it does if we include methane and nitrous oxide, as well as other GHGs, as oppenheimer’s work argues and as discusssed in the DEFRA report. But discussing _CO2 only_ (which I have been doing all week), I do not believe that the exact path matters much if at all, as WRE 1996 argues. If you have a CO2-only citation that makes a different case on the importance of the stabilization path, please share it and I will read with interest. My current understanding of the science is that absent annual emissions dropping below the natural sink (which I completely discount, as I’ve said) or air capture (as I’ve argued), the effects of emissions reductions on stabilization will be minimal in any case.
Bottom line … debating the effects of reducing the final 2.5 GtC in annual emissions may be a fun theoretical exercise, but until there is evidence/reason to believe that the first GtC is going to be reduced, lets be clear that we are talking about angels on a pin.
Thanks.
September 15th, 2006 at 7:26 am
Roger,
You write, “As I said to Coby, we probably have far more relevant issues to discuss than 1GtC levels of annual emissions this century.”
Well…if you think that 1GtC of emissions this century is totally out of the realm of possibility, you probably should spend quite a lot more time studying energy technology and technological trends.
Let me give you an example. Currently, all energy sources (coal, oil, natural gas, nuclear, hydro, etc.) represent about 8% of the world economy. That’s from my memory of this seminar:
http://carolinafirst.unc.edu/ath/page18/page18.html
So…the current world economy is what…$60 trillion? (Again, from memory.)
So ALL energy is a $4.8 trillion business (again, that’s oil, coal, natural gas, nuclear, etc.).
Currently, photovoltaics is a $10 billion business, and growing at 40 percent per year. (From the announcement for the photovoltaics seminar I’m attending this afternoon.
)
So that’s $10B/$4.8T = 0.2% of world energy spending. That’s trivial.
Let’s say that trend in photovoltaics growth continues indefinitely into the future. What sort of numbers would be produced?
2010 = $27 B (trivial)
2015 = $150 B (still trivial)
2020 = $790 B (starting to be important)
2025 = $4.3 T (a monster!)
2030 = $23 T (essentially ALL energy in the world)
Now, this is an extremely crude assessment. But there is no *fundamental* reason (e.g. lack of sunlight, environmental or other public opposition) why photovoltaics could not supply ALL the world’s energy. And that *could* happen by midcentury, and *could easily* happen in the second half of the century.
Now, back to real work,
Mark
September 15th, 2006 at 9:07 am
All this discussion is academic. Injecting some reality that precludes any quantitative analysis here, we don’t know how much flora is going to spread (nor at what rate) due to increased CO2. All we know is that it will, correct? I don’t believe that is even considered by anyone here, also correct? That will increase natural sink by some unknown amount, so that 450 ppm may indeed be possible by mid century (assuming we actually get a handle on the reality of climate, and we still want to).
One tongue in cheek (maybe) comment though – this discussion is about the U.S. setting some arbitrary limit to atmospheric concentration. I guess that you are all assuming that the goal of Dubya is to take over the world, and that he will succeed…
September 15th, 2006 at 12:45 pm
Roger, I am going to assume you include me in the “gotcha gang” and defend myself.
There are two reasons that I often post about what I see as contradictions between your expressed beliefs and your exhibited reasoning. The first is that many of your post are of precisely this “gotcha” nature (tahis includes the current post and one that even used my own statements), and frankly what’s good for the goose is good for the gander. The second is that you hold other people to a much higher standard than you hold yourself. This thread being a compelling example.
You have seized on an isolated comment of David Hamilton’s about a hypothetical and ambiguous policy goal and tried to claim it shows something very base about his motives. I think that is pretty much the essence of a “gotcha”. When you are shown very clearly that there is nothing wrong with what he has said given one very reasonable assumption about what the unknown policy involves, you do not uphold the standard that you demand of others.
You may have more evidence that David Hamilton is simply anti-Bush no matter what Bush’s policies are, but you have definately not made your case here.
Best Wishes.
September 15th, 2006 at 1:40 pm
Coby-
Thanks for your comments. We welcome your input. I’ve got no problem with people arguing with me, criticizing my posts for their logic or even their tone. That is why we put ideas and arguments forward — to stimulate discussion and to learn from each other. All of this is fair game. Where it become counter-productive is when people begin focusing on trivialities (e.g., definition of “feature” anyone?;-) or start slinging insults, which I am sensitive to becuase in the past on this site they have gotten quite out of hand, and I won’t let that happen again.
If you honestly believe that I’ve treated Mr. Hamilton unfairly, then say so and explain why. Hijacking the post to prove a point is not productive in my view. In the end it is fine for particfipants here to agree to disagree and leave it at that!
From my perspective, Hamilton’s comments sill make no sense. And neither did your comment early in the post. When it was clarified that I, and the article I cited, were discussing carbon dioxide only and not a basket of gases, perhaps that cleared up the confusion in your comments about exceeding 450 for a few decades. This still doesn’t get Hamilton off the hook. Maybe he was misquoted. Maybe he thought the article was going to be about a basket of gases. Who knows? I still find the seeming reflexive opposition to policies not yet announced quite telling. I would think that if any president announced a commitment to 450 ppm at any timescale the environmental community would be dancing in the streets . . .
Thanks.
September 15th, 2006 at 5:24 pm
RE: Climate Scientists’ brief on Mass vs EPA
I suggest that interested readers should consider reading the Amici Curiae brief and determine for themselves if the discussion is about scientific knowledge and associated uncertainty, or whether it is a “disingenuous” “political” piece as Roger Pielke writes. Perhaps Prof. Pielke might carefully reread the brief. We labored hard to ensure that nothing in the brief carried political tone or intent. This brief is about risk, of what we know and what we don’t know, in relation to anthropogenic climate change.
The relevant section of the Clean Air Act is about risk too, that’s why Congress inserted the language “may be reasonably anticipated to endanger” as the trigger for regulation. It is a scientific judgement, not a political statement, as to whether greenhouse gas emissions pose that kind of risk. It is not “insincere or calculating” (the definition of “disingenuous”) for scientists to address this question–if not scientists, then who should do it?
The reader might be surprised that the brief connects CO2 reuglation most directly to the decision to remove lead additives from gasoline. At the time the ban was set into motion in the 1970’s, there was good scientific evidence of harm from lead emissions, but the impact was far from certain or precise. One could argue many different ways as to costs and benefits of leaded gasoline.
Only now, 30 years later when blood lead levels in the US have dropped by factor ~6, can the damages to health be clearly assessed. The net benefits of banning lead additives were many, many billions of dollars, plus better health and longevity for tens of millions of people. As noted in the article cited in the brief, the damage to health was far worse than thought at the time of the ban.
Climate change affects the whole globe and cannot be reversed in a decade like airborne lead pollution, in fact, reversal is essentially impossible. Does the reader think the risks of unrestrained emissions of greenhouse gases are bigger, or smaller, than for lead emissions?
September 15th, 2006 at 6:59 pm
Hi Steve,
You write, “All this discussion is academic.”
No, if technologies (such as solar cells and fusion) are truly capable of generating emission levels near 1-2 GtC before the end of this century, it would almost certainly limit the temperature rise in this century to approximately equal to or below 1 degree Celsius. (Unless the sun gets a lot stronger, which seems unlikely.)
“Injecting some reality that precludes any quantitative analysis here, we don’t know how much flora is going to spread (nor at what rate) due to increased CO2. All we know is that it will, correct? I don’t believe that is even considered by anyone here, also correct? That will increase natural sink by some unknown amount, so that 450 ppm may indeed be possible by mid century…”
Actually, we *do* have a very good idea how the natural sink is likely to behave in the next 50 years. We can simply look at how it’s behaved in the last ~50 years.
The airborne fraction of CO2 has averaged almost dead on 58% for the last ~55 years. So the natural sink has averaged almost dead on 42% of emissions for the last ~55 years. See slide #4 of James Hansen’s Keeling Lecture:
http://www.columbia.edu/~jeh1/keeling_talk_and_slides.pdf
So it seems very likely that natural sinks will average about 40-50 percent of emissions for the next 50 years.
It’s unlikely that the atmospheric CO2 concentration will be below 450 ppm in the year 2050. (I estimate the probability somewhere between 5 and 50 percent.)
http://markbahner.typepad.com/random_thoughts/2006/04/complete_set_of.html
Mark
September 15th, 2006 at 10:29 pm
SC Wofsy-
Thanks very much for commenting. (Though I think that this comment was intended for another thread.)
You write, “We labored hard to ensure that nothing in the brief carried political tone or intent. This brief is about risk, of what we know and what we don’t know, in relation to anthropogenic climate change.”
The submisison of an amicus curiae brief is fundamnentally a political act. There is nothing wrong with politics, it is how we get done the business of society.
Science becomes pathologically politicized when political acts are (mis)characterized as scientific. Judgments of value, which you have clearly and in my opinion convincingly made, are not something to pretend do not exist.
I do not have a problem with scientists serving as advocates. The problem is serving as an advocate but hiding behind science.
Thanks!
September 17th, 2006 at 4:11 am
If the White House does put forth a plan to reach 450ppm, it should be fairly easy to determine its realisticness by simply checking the date for maximum emissions. If it is something like 2012 or 2015, maybe it is in good faith. If it is closer to 2050, then obviously the plan is a con job.
Call me a cynic, but I doubt this administration’s ability to put together a realistic plan for anything.
September 18th, 2006 at 9:13 pm
Mark -
It is irrational to extrapolate the next 50 years of sink based on the previous 50 years. The distance from historic specific flora range and range made more robust by enhanced CO2 increases yearly, as flora can’t spread as fast as its potential range will allow – particularly around different obstacles like basins and ranges.
But, that’s all pretty much irrelevent to the question at hand as apparently few here save our host:
http://tinyurl.com/on9n8
understand that Dubya can’t do a *thing* about the future emissions of China and India et al.