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Tom Curtis at 08:08 AM on 21 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
Mark Bahner @23,
First, this point is an obvious attempt at distraction from the fundamental disanalogy within your example - ie, the estimated probability of the event within the next 100 years.
The difference between the devastation of an asteroid impact, and that of global warming is that the former is localized while the later is global. Thus, quoting the peak energy release is not a relevant comparison.
Consider a 1.6 km iron asteroid hitting Earth at 30km/s and an angle of 45 degrees.
It will release 1.84 million megatonnes energy. Never the less, at 1000 km, the most severe immediate effect will be to shatter glass. Its ejecta is likely to also cause a short lived episode of very cold years. Of course, within 600 km radius, devastation is almost complete.
In addition to providing almost total devastation to 0.2% of the Earth's surface, the devastation of a 1.6 km impactor would be very limited in time, with direct effects being over within days and indirect effects excluding damage.
An ocean impact is in many ways worse, with the tsunami at 1000 km being 11 to 22 meters, and an impact midway between the US and Europe causing a tsunami of about 3 to 6 meters on both shores. It does so, however, with 14 hours notice, so the actual loss of life should be minimal (4 hours at 1000 km). Further, the effect would only ever by felt in one ocean basin (indeed part of any single ocean basin)
It is ambiguous whether you are saying 1 billion would be killed by a 2 km impactor, or a 1 km impactor, but the extreme localization of the events make such estimates very dubious. A 1.6 km impact in Germany, for example, would kill almost everybody in Germany, and a significant population near Germany, but residents of Spain, Britain and Greece would be effectively untouched. The death toll would be 100 to 200 million. In contrast, an impact in the Antarctic would have a death toll only in the 100s. The 1 billion is clearly the upper end of a large probability range.
For comparison, the upper end of the probability range for AGW is currently about 6.25 billion. The lower end of the probability range is around 500,000 (approximately 3 times the estimate of the current annual death toll from global warming). The reason for the high potential death toll from global warming is that, unlike the very localized effects of a 1 km impactor, global warming is ubiquitious.
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joeygoze9259 at 07:51 AM on 21 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
Tom Curtis - actually I am making the opposite argument, that the consensus argument is a worthless conversation and the paper that claimes the 97% consensus is suspect in anycase. The abstract from the paper (http://iopscience.iop.org/1748-9326/8/2/024024/article) states, "We find that 66.4% of abstracts expressed no position on AGW, 32.6% endorsed AGW, 0.7% rejected AGW and 0.3% were uncertain about the cause of global warming. Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming." So out of ~12,000 papers that were looked at, 66.4% take NO position (~7,970 papers). Only ~32% of the papers (~3,840 papers) that took a position happened to take a positive position that manmade CO2 is driving climate change. In looking at the set of 12,000 papers, that looks to fall short of what I would think someone would define as a consensus. Also, papers that took NO position, what were the results. Did they suggest something else was driving climate changes aside from CO2, and if so, what? This type of study is not Black and White and we as much as the other side should be just as critical of things if the science looks dodgy.
KR - You are certainly fine to disagree but stop crying about public misperceptions because of some lobbying effort from the other side. Maybe our messaging must be better? (-snip-)
Moderator Response:[DB] Sloganeering snipped.
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BillyJoe at 07:39 AM on 21 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
@Bay Bunny #5
"You seem to be suggesting AGW isn't dangerous."
Nope.
I'd just like to clarify what the J Cook paper actually says about the consensus
(I'm not sure what is causing the formatting errors in my post???)
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BillyJoe at 07:35 AM on 21 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
@John Haetz #4
"Exactly how do you distinguish between "dangerous AGW" and "AGW"?"
AGW could just be an interesting fact.
Dangerous AGW requires action.
If even Andrew Watts and Christopher Monckton agree that AGW is happening, then concluding that 97% of climate scientists agree that AGW is happening doesn't say much. If these same 97% agree that action is required to mitigate its effects, then that is saying something meaningful.
Nobody here seems to want to address my question...
What exactly does J Cook's paper conclude ?
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Tom Curtis at 06:58 AM on 21 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
joeygoze @6, given the concerns you have raised, you no doubt have examples from the scientific literature of scientists arguing that a concensus of climate scientists agree with AGW, and that therefore AGW is true. Absent such examples, you are clearly raising a straw man. So, could you please list even one such article.
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Bulletin of the Atomic Scientists: Closing the Consensus Gap
joeygoze - You appear to be ignoring the majority of my last comment. The public perception of expert opinion is incorrect, distorted by mis/dis-information. And that public perception drives public policy.
The science is just fine, with papers finding acceptance or dropping into irrelevance based on the data. The public perception of agreement on the science, however, is incorrect, and that leads to poorly considered policies. Nobody is arguing about the science in this particular discussion - that's a red herring in regards to public perceptions and policies. I have to consider diverging to various papers as wholly off-topic on your part.
Again - you appear to be arguing to allow public misperceptions to continue, misperceptions fueled in part by extensive lobbying. And I disagree.
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joeygoze9259 at 05:42 AM on 21 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
KR - The public policy must be driven from the science and proper scientific process. Not a bunch of people agreeing with each other.
I would have to understand what you define as "misinformation". For example, is a scientific paper that is peer reviewed but has conclusions that you disagree with automatically misinformation?
Would a paper such as this: (http://www.worldscientific.com/doi/abs/10.1142/S0217979213500732) which looks at solar radiation and CFCs as a major driver of global warming be considered "misinformation" to you?
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Bulletin of the Atomic Scientists: Closing the Consensus Gap
joeygoze - Do you feel it desirable or appropriate for the public to be misinformed regarding what is an important policy issue affecting everyone? Because currently, they are.
This is a its core a public policy issue, not a climate science issue. Public policy as an input incorporates public perceptions of expert opinion - perceptions which (due to a great deal of disinformation) are currently quite distorted. Your position would appear to be allowing those misconceptions to persist, letting disinformation go unchecked - I would have to disagree.
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Bulletin of the Atomic Scientists: Closing the Consensus Gap
joeygoze - Correct, science doesn't work by consensus, rather consensus is the result of the majority of scientists being convinced by evidence. It's an outcome, not a starting point.
Public policy, on the other hand, is entirely driven by public consensus - and understanding and trusting the experts is a significant part of public opinion. Currently there is a large gap between the public understanding of the consensus in science and what that consensus actually is (fueled in no small part by lobbyists, disinformation, false 'balance' in mass media presentations, and a considerable pile of money).
Claiming a lack of consensus is a delaying tactic that has been used by the tobacco industry, over the ozone hole and DDT, mercury pollution, on and on, and now by those potentially impacted by climate action. Far better that the public should understand the expert opinions, and develop political will and action along factual lines rather than lobbying slogans.
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Harperdog at 03:52 AM on 21 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
joeygoze, it was deniers who first started claiming there was no "consensus" among climate scientists, therefore no reason to take the science seriously. Now deniers are trying to move the goalposts, saying that consensus isn't important. I am old enough to remember the same tactics about science showing that smoking causes cancer. Different topic, but same strategies.
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shoyemore at 03:43 AM on 21 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
Actually, Professor Richrd Tol pointed out quantitatively what is meant by Dangerous Climate Change - it is 2C above pre-industrial global average temperature, a figure internationally agreed, by others including President Obama, and signed off by him in Copenhagen.
There should be no doubt then about what the President meant.
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joeygoze9259 at 03:23 AM on 21 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
The groups that push the concept of "consensus" as some kind of proof for the reality of AGW are actually the ones that are disregarding scientific process. Science does not work by consensus, you don't get 1000 scientists in a room and if they all agree about something, then it is true. Scientific process is Hypothesis, Experimentation, Results and Conclusion. Just focus on the data for AGW, not the number of people that believe in AGW. When one does that, you are moving from the realm of science to the realm of faith.
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Bay_Bunny at 02:54 AM on 21 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
@BillyJoe #2 - You seem to be suggesting AGW isn't dangerous. Perhaps you would like to investigage that notion elsewhere on this very site:
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bibasir at 02:53 AM on 21 August 20132012: One of the 10 Warmest Years on Record
The fact that every year in the new century was hotter than every year except 1998 says that warming has not stopped as deniers claim.
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Mark Bahner at 02:41 AM on 21 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
In contrast, at least 80% of relevant scientists (see my post @17) think it very likely that AGW will cause devastation on a similar scale to the asteroid impact within the next 100 years.
Please name 10-20 of these "scientists", because the statement that AGW could cause "devastation on a similar scale to the impact of an asteroid (1-2 km in size) in the next 100 years" is patently ridiculous. Here are some projected effects of a 1 km asteroid hitting earth:
1) Energy release of 46,000 megatons of TNT. (Comparable to the explosive power of all the nuclear weapons on earth exploding at once.)
2) A crater 14 km in diameter. (In contrast, Meteor Crater in Arizona is only 1 km in diameter.)
3) An 18-meter tsunami at a distance of 1000 km from an ocean landing site (and 8 meters at 3000 km from the landing site).
And the effects are much more devastating for a 2-km asteroid. Estimates for that size asteroid are that more than 1 billion people would be killed.
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John Hartz at 00:55 AM on 21 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
@BillyJoe #2:
Exactly how do you distinguish between "dangerous AGW" and "AGW"?
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MA Rodger at 00:48 AM on 21 August 20132012: One of the 10 Warmest Years on Record
Klapper @6.
It might have been a wiser move to check the source document rather than faff about on your own. On the PDF's page 28 it says:-
Globally-averaged, 2012 ranked as the eighth or ninth warmest year since records began in the mid-to-late 1800s, according to four independent analyses (NASA-GISS, Hansen et al. 2010; HadCRUT4, Morice et al. 2012; NOAA-NCDC, Smith et al. 2008; JMA, Ishihara 2006). The year was 0.14°C–0.17°C above the 1981–2010 average, depending on the dataset considered, which provides some estimate of “measurement uncertainty” (Table 2.1)
And Table 2.1 gives Land, Ocean & Land/Ocean thus:-
Table 2.1. Temperature anomalies (°C) for 2012 with respect to the 1981–2010 base period. For ERA-Interim, the values shown are the analyzed 2-m temperature anomalies for both land and ocean. Note that the land values computed for HadCRU used the CRUTEM4 dataset, the ocean values were computed using the adSST3 dataset, and the global land and ocean values used the HadCRUT4 dataset.
Global Land & Ocean
+0.17 NASA-GISS+0.15 HadCRU
+0.16 NOAA-NCDC
+0.14 JMA
+0.16 ERA-Int
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Lou Grinzo at 00:33 AM on 21 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
Bert points out an interesting, if painful, truth: The more valuable a contribution is to the discussion, the more it helps people (particularly newcomers) realize what's going on re:CC, the more viciously it will be attacked. If the deniers keep it up, QtC might someday achieve the exalted status of the hockey stick.
I have to respectfully disagree about the deniers having any sort of public conversion. I think that be far the most likely outcome is that they will dwindle in numbers and influence (even as their claims become ever more shrill and absurd, their tactics ever more outrageous) until they're just another group that's widely recognized for being, shall we say, excessively colorful in their views. Other examples would be vaxxers, the HIV/AIDS deniers, the moon hoaxers, and the people holding out hope that Elvis is still alive.For comparison, consider all the people who were adamant that Y2k was going to be TEOTWAWKI (Google it) and were convincing people to buy remote property stocked with tuna and sacks of beans, guns, diesel generators, etc. When Y2k was a non-event (because we fixed it, not because it wasn't a problem), these people simply disappeared or moved on to other things.
I also expect to see the highest profile deniers, like our friends in right-wing radio, suddenly pivot and blame the scientists for "not making a sufficiently compelling case." The sound of heads exploding at that point will be deafening. -
CO2 effect is saturated
basnappl - scaddenp has an excellent point; 7 years is a very short time in terms of CO2 increase, and given little GHG change we can but expect little spectral change over such a short period. But _all_ of the Harries papers provide solid support for the accuracy of LBL models.
As I noted above, I believe some of the response to Stealth involves the fact that he repeated unsupported assertions of uncertainty in LBL models after and through multiple pointers to the data. IMO - It's one thing to discuss a point in question, another entirely to ignore responses.
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julienx2k2 at 00:22 AM on 21 August 2013There's no tropospheric hot spot
First of all, hi again to everyone, I've been silent for several years but reading you almost on a daily basis :)
Just bumped into this blog post - is it me or Spencer cherry picks exactly the tropical hot spot region where observational data is doubtful to prove the "epic failure" of GCMs??
http://www.drroyspencer.com/2013/06/still-epic-fail-73-climate-models-vs-measurements-running-5-year-means/
Thx again
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Klapper at 23:25 PM on 20 August 20132012: One of the 10 Warmest Years on Record
@ianw01 #4:
I checked the latest versions of all the datasets, July 2013, using HadCRUT4 SAT, GISS SAT, NCDC SAT, RSS TLT and UAH TLT to make my assertions. As I see it none of these datasets are truly independent, the TLT ones being less so. Maybe the NOAA comment meant land temperature only, which would include Berkeley. However if so their comment is misleading.
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scaddenp at 23:23 PM on 20 August 2013CO2 effect is saturated
Reading that paper I see: "In Fig. 8, both the observations (Obs) and simulation
(NCEP) show a rather flat difference spectrum, close to zero except in the 2
band of H2 O. This would be expected, since in the short time interval between 1997
and 2003 little growth of greenhouse gases occurred" Note Obs and simulation showing little difference.On the other hand, the paper is yet another (using new instruments) showing that the real atmosphere very much behaves in accordance with the models. Skepticism is good, but it seemed to me in the end, Stealth was determined to misunderstand, more like someone looking desparately for a reason to dismiss climate science rather than understand it.
The fact remains -the observational evidence from multiple sources supports the contention that LBL models are very accurate. The errors in estimating CO2 forcing from change in GHG are very small compared to errors in estimating feedbacks so I struggle to understand the hang-up.
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Klapper at 23:21 PM on 20 August 20132012: One of the 10 Warmest Years on Record
@StBarnabas #2:
I doubt any of the datasets are accurate to .001C degrees but if you want to rank them that's the number of significant digits required. Are you suggesting that NOAA only ranked by 2 significant digits and then awarded any ties with 2012 to 2012?
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BillyJoe at 23:06 PM on 20 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
Does the J. Cook paper say that there is a 97% consensus regarding AGW or a 97% consensus regarding dangerous AGW. I'm still not clear a bout this.
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ianw01 at 22:55 PM on 20 August 20132012: One of the 10 Warmest Years on Record
@Klapper: Sorry - I just returned and saw your last paragraph! It will be interesting if anyone can cite the datasets used.
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ianw01 at 22:52 PM on 20 August 20132012: One of the 10 Warmest Years on Record
@Klapper: You seem to be jumping to conclusions.
The article says "Four major independent datasets show 2012 was among the 10 warmest years on record, ranking either 8th or 9th, depending upon the dataset used."
Presumably you just picked a different one than the four they did. It seems you should be quibbling with the issue of which data set is better, rather than inccorectly declaring "not true" based on a data set of your chosing.
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Rob Painting at 18:22 PM on 20 August 2013What makes ice sheets grow and shrink?
BC @ 22 - The graphic above is of the Thermohaline Circulation, whereas the SkS post, A Looming Climate Shift: Will Ocean Heat Come Back to Haunt us?, was focused on the wind-driven ocean circulation. The two circulations are not really separate, but a distinction between the two is necessary for the purpose of explaining the main features of the ocean circulation. SkS has some upcoming posts explaining the wind-driven ocean circulation in more detail, and why the deep oceans are warming.
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StBarnabas at 17:47 PM on 20 August 20132012: One of the 10 Warmest Years on Record
@Klapper
I presume the Global SAT anomaly in in oC. do you know the error on these figures? Is it truely 0.001 degree or less?
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grindupBaker at 17:07 PM on 20 August 2013A grand solar minimum would barely make a dent in human-caused global warming
This post opens the topic of somebody's question "How can the ocean below 700 meters be heated up, without the upper ocean warming" but does not give the simple blindingly-obvious answer. It's because the deep ocean (the majority of it) is colder (often far colder) than the upper few hundred metres at most places. If the ocean was same temperature surface to sea bed it would be impossible to raise temperature of the lower part from above without raising the temperature of the upper part, but it ain't, so it is.
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basnappl at 16:37 PM on 20 August 2013CO2 effect is saturated
Hello KR,
In post 234, I quote Harries 2007 paper (Griggs, J. A., J. E. Harries, 2007: Comparison of Spectrally Resolved Outgoing Longwave Radiation over the Tropical Pacific between 1970 and 2003 Using IRIS, IMG, and AIRS. J. Climate, 20, 3982–4001.)
Regarding Stealth's "unsupportable" comments: It seems to me that at least part of his question is to what extent are lab models of radiative transfer representative of what is actually occurring in the atmosphere. I think this is a fair question. He did add a perhaps unneccessary bit of opinion but I took that as supplying context for why he might feel compelled to post here at all. Essentially, I think, he's saying that he has a lot of experience with applying non-climate physics based models to the real world and that this experience, along with Dyson etc's statements and what appears to be variability in a pretty foundational number (CO2 forcing), has led him to be skeptical about climate models.
It bothers me that his skeptisism wasn't greeted more warmly. I understand that this is an enormously complex system and it must be tedious for those that know a lot about it to try to bring others up to speed. I imagine it doesn't help when those asking questions start with the hypothesis that this is all a bunch of hooey (which I don't think Stealth was). But, that's the way it is with climate science. There's no denying it's been politicized and lots of people who have no business voicing an opinion do. That's not (as far as I can tell) what the case was with Stealth. Bear in mind, the entire purpose of this website is at least partially political. It wouldn't make much sense for me to make a skepticalscience page regarding high-temperature superconductors even though it's an open, important problem. This site is, in part, meant to be a political counterbalance to non-science. I think that's a good thing, but I also think that attacking people is an ineffective way to change their minds.
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Klapper at 14:08 PM on 20 August 20132012: One of the 10 Warmest Years on Record
"...ranking either 8th or 9th, depending upon the dataset used..."
Not true. As I pointed out on an earlier story, in the NCDC dataset 2012 is actually #10 and here are the numbers to prove it:
Rank Year Global SAT anomaly 1 2010 .658 2 2005 .651 3 1998 .633 4 2003 .623 5 2002 .612 6 2006 .597 7 2009 .595 8 2007 .589 9 2004 .578 10 2012 .575 These numbers come from
ftp://ftp.ncdc.noaa.gov/pub/data/anomalies/monthly.land_ocean.90S.90N.df_1901-2000mean.dat The rank for 2012 in the RSS TLT dataset is 11th. No current dataset for atmospheric temperature shows 2012 to be 8th so the range is 9th to 11th. The NOAA is victim of the incessant corrections to these datasets I guess.
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chriskoz at 14:08 PM on 20 August 2013A grand solar minimum would barely make a dent in human-caused global warming
Tom@4,
Thanks for your insightful (as usual) comment.
So, the "atmosphere absorbtion" part of solar (67 W/m2 in Kiehl and Trenberth, 1997) is mainly UV absorbtion by the ozone layer 20-50k above surface. With such facts, it's worth to note that the proclaimed impending Maunder Minimum, although having little effect on AGW, will have a positive effect on the ozone hole: if the lower level sun activity is confined to essencialy UV spectrum, then ozone will be depleting at lower rate, giving it a chance to recover quicker. But I don't know how signifficant that latest effect would be.
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CO2 effect is saturated
basnappl - "...in Harries et al's more recent publication, no significant difference in absorption for CO2 is observed between 1997 and 2003"; a reference please? I am not aware of such a paper.
Chen and Harries et al 2007, "Spectral signatures of climate change in the Earth’s infrared
spectrum between 1970 and 2006" clearly indicates the same top of atmosphere (TOA) spectral changes as predicted by LBL models and described in Harries 2001.Speaking for myself, some of the strong responses were due to Stealth dismissing (repeatedly) the accuracy of well supported LBL spectral calculations by inappropriately considering them to have the uncertainties associated with far more complex global circulation models (GCMs). Those are not equivalent, and his comments thereof were unsupportable.
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basnappl at 13:31 PM on 20 August 2013CO2 effect is saturated
I've returned to see what discussion followed the questions I asked a while back and have a few comments.
First, I would like to say that I have enjoyed reading the questions posed by Stealth. I am six years into a graduate program in physics and appreciate that even some of the most "basic" phenomena can be hard to model.
That said, I would like to point out that Stealth comes across to me as a true skeptical scientist. A quick Google of define:skeptical yields:
- Not easily convinced; having doubts or reservations.
- Relating to the theory that certain knowledge is impossible.
As I was reading the responses to his questions, I also felt they were needlessly "combative". Some of them, I think, would certainly qualify as "ad hominem"...
Whatever. Just sort of disappoints me when I see the response to a well-thought out question on a website that intends to teach is criticism of the asker. That said, the parts of the responses that were science I liked.
Back to the original topic (and my prior question), it is true that the measured outgoing spectra and the atmospheric temperature profile are coupled. It is also true that, in Harries et al's more recent publication, no significant difference in absorption for CO2 is observed between 1997 and 2003. The original post here uses the observed difference as definitive proof that CO2 absorption is not saturated. Should the conclusion be changed to something like "Assuming the validity of the temperature profiles resulting from simulations to match the outgoing spectra, CO2 absorption is not saturated."?
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chriskoz at 12:34 PM on 20 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
Rob@21,
There would be no incentive for the "impact denial" movement, unless the asteroid was made of gold, or some rare earth mineral, or some other substance proclaimed to be a miracle homeopathic remedy that can extend your life to 1000s y.
Your WUWTA would've been just secondary hub of "impact denial" associating those who believe in the miraculous properties of the asteroid.
The primary hub would exist of those who, even if knowing the signifficance of potential damage to the civilisation, they have claimed the exclusive rights to the asteroid, and make money by trading their claims on the stock market. Those primary "impact denialists" would rather make sure the asteroid hits the Earth, because that would increase the value of their wealth on the stock market.
I'm sorry if this quasi-sober & entertaining vision goes off topic.
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Bert from Eltham at 12:01 PM on 20 August 2013Bulletin of the Atomic Scientists: Closing the Consensus Gap
This is why John Cook's refereed paper 'Qualifying the Consensus' is so important! It is also why it is attacked with the most spurious inane analyses.
The anti science brigade will always do damage to the rest of us. The anti vaccination mob against preventable diseases are a good example of a subset of deniers that fear an outcome that has no basis in scientific reality. Yet when there is a lethal outbreak of whooping cough these deniers line up in droves.
I look forward to all the deniers having a 'road to Damascus' conversion. The comments on denial sites seem to me to be now only the most fervent ignorati. Cherry picking has become such an art, that the Japanese would categorise it as a 'National Treasure'!
Bert
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scaddenp at 10:47 AM on 20 August 2013What makes ice sheets grow and shrink?
William, if clathrates beneath the ice sheets are a significant part of the feedback, then this would imply a few things:
1/ Should see more than CO2 is atmosphere than is explainable from other earth system feedback.
2/ If straight methane is important, then should see enough in ice bubbles to match the supposed forcing.
3/ The methane in ice bubbles should show a d13 signature consistant with significant clathrates.
What does observation say?
1/ is not easy to constrain, but it will be interesting to see AR5 models on this.
2/ Methane rises in ice core, but not to levels of significant forcing
3/ What's been looked at so far (eg Petrenko at al 2009) suggest swamp methane is far more important than clathrates.
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Rob Honeycutt at 10:44 AM on 20 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
Actually, the statements would be comparable if we were currently staring down a large asteroid. 97% of scientists might say, "Yup, that sucker is big enough to destroy civilization and there's a high likelihood it's on target to hit us."
You would also likely see 3% of scientists still saying the asteroid is clearly there, but it's too small to do significant damage and might not hit us anyway.
Then you'd have people on the internet running websites called WUWTA (What's up with that asteroid) running articles of people saying thing like:
"Asteroids are likely made of spongy material." and...
"Asteroid impacts are a natural event." and...
"The asteroid is clearly going the other direction." and...
"Asteroids are missing other planets, so this one will likely miss us." and...
"Asteroid projection are done with computer models and thus can't accurately estimate the true track." and...
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Tom Curtis at 09:35 AM on 20 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
Mark Bahner @19, the two statements are obviously not comparable. That is because while it is true (I suppose) that 97% of scientists think that an asteroid impact could be "serious and dangerous" they do not think it likely in any given short time frame. According to NASA, "... an impact by an asteroid larger than 1-2 kilometers could degrade the global climate, leading to widespread crop failure and loss of life. Such global environmental catastrophes, which place the entire population of the Earth at risk, are estimated to take place several times per million years on average." Taking "several" to mean 10 (it is likely to be less), that means in any given century there is a 0.1% of such a cataclysmic impact (and a 1% chance in the next thousand years). So, that means that around 97% of relevant scientists believe there is a 0.1% chance of so devestating an impact in the next century.
In contrast, at least 80% of relevant scientists (see my post @17) think it very likely that AGW will cause devastation on a similar scale to the asteroid impact within the next 100 years.
Further, your claim that the statements are "not actionable" represent a ridiculous rhetorical ploy. The statements by themselves with no further context do not inform us as to which are, and which are not reasonable policies, ie, "are not actionable". But the statements are not made shorn of context. There is a massive context of further facts summarized by the IPCC on which we can draw, and which can certainly guide policy.
Given that your point depends on:
1) comparing two disparate probabilities as though they were approximately equal (despite knowing better); and
2) deliberately ignoring a host of further available information,
it strikes me as nothing beyond vacuous rhetoric.
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Mark Bahner at 08:41 AM on 20 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
"97% of scientists agree that global warming may be severe."
This is not an actionable scientific statement...any more than a statement that, "97% of scientists agree that an asteroid could destroy human civilization" is an actionable scientific statement.
Obviously, 97% of scientists agree that an asteroid could destroy human civilization. (And that outcome would be pretty "severe.") But it means nothing from public policy standpoint.
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william5331 at 06:48 AM on 20 August 2013What makes ice sheets grow and shrink?
In the first 1.5m years of the present ice age, the glacial-interglacial cycle was about 41,000 years, in sinc with obliquity (one of the Milankovitch cycles). It is still in sinc but only every third or so nudge melts the ice. Clathrates sequestered under the ice sheets plus the fact that the deeper the ice sheet, the more unstable it is, may, at least, partially explain this.
http://mtkass.blogspot.co.nz/2011/09/continental-glacier-meltdown.html
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franklefkin at 05:50 AM on 20 August 2013Levitus et al. Find Global Warming Continues to Heat the Oceans
KR,
Thanks, its been a long day and I knew the answer was something simple like that.
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Levitus et al. Find Global Warming Continues to Heat the Oceans
franklefkin - Keep in mind the difference between relative humidity (the percentage of how much water air at a particular temperature can hold without saturation) and absolute humidity (the mass of water in an air volume) - these are very different numbers.
Relative humidity, including over the oceans, has changed very little globally, meaning that the 'evaporation thermostat' hypothesis is not supported by the data. Evaporation/precipitation drives any heat loss, and while regional effects have been strong, they to a large extent cancel out globally, with only a small and difficult to detect mean global increase (Zhang 2007).
Absolute humidity, on the other hand, has been increasing - and with each 1C increase in temperature trapping an additional 2 W/m2, meaning that increased water vapor with temperature has an overall positive feedback, not a negative/cancelling one.
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franklefkin at 03:55 AM on 20 August 2013Levitus et al. Find Global Warming Continues to Heat the Oceans
KR,
Are you sure of this number?
Evaporation is controlled by both temperatures and by local relative humidity. Relative humidity worldwide has changed less than 0.6% worldwide over the last 30 years (Dai 2005), so this continues to act as a limiting factor - the atmosphere can only hold so much moisture at any temperature.
0.6% is pretty low. According to another SkS thread, it is expected that each C increase should increase humidity levels by 6 - 7.5% (H2O is most important GHG). If temps have risen by ~ 0.5 C over the past 30 years, humidity should have risen by 3 3.75% over that time, not 0.6%.
Tell me if I have mixed up percentage increases and percent point increases, please.
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Levitus et al. Find Global Warming Continues to Heat the Oceans
dvaytw - Evaporation is controlled by both temperatures and by local relative humidity. Relative humidity worldwide has changed less than 0.6% worldwide over the last 30 years (Dai 2005), so this continues to act as a limiting factor - the atmosphere can only hold so much moisture at any temperature.
Even more importantly, though, is that water vapor is a powerful greenhouse gas. Additional water vapor (absolute humidity) given by the same relative humidity at higher temperatures means more IR trapped, a warming feedback rather than a cooling one (Atmospheric Infrared Sounder data).
Last but most certainly not least, the data regarding IR driven skin layer gradients controlling heat loss from the oceans shows, over a long enough period for any evaporative feedback, that evaporative effects do not override the gradient effects. In other words, such claims are flatly contradicted by the data.
In general, as several people have commented, the claims that "evaporation will stop warming" are just another "single-cause" argument, not considering other contributing factors, much as in discussions of CO2 without considering other forcings. And as such, they are incorrect.
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dvaytw at 01:39 AM on 20 August 2013Levitus et al. Find Global Warming Continues to Heat the Oceans
Bob Loblaw thanks for that!
And sorry to be a pest, but I was wondering if anyone could give me a good analogy to explain why my opponent is wrong on the issue of evaporation. Something along the lines of, "If what you're saying was true, it would mean..."
In general terms I get what you guys are saying, but I don't get it well enough to analogize, and a nice analogy always makes a point stick better.
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What makes ice sheets grow and shrink?
There was a recent SKS article talking about the PDO and ocean gyres and how with a La Nina surface ocean currents flow from east to west across the Pacific, which slows or stops with an El Nino. I don't understand how these surface flows (eg La Nina and the gyres) relate to the warm surface flows shown in the diagram in this article. Anyone help?
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Leland Palmer at 17:15 PM on 19 August 2013Toward Improved Discussions of Methane & Climate
Correction for spelling- That's the sea of Okhotsk, in the last paragraph.
One of their papers shows a severe anoxic region in the northern Pacific, extending down the Alaskan and Canadian west coast.
I live in California, near the ocean.
Are my wife and I going to have to worry about clouds of toxic hydrogen sulfide gas drifting in from the Pacific, if this anoxic region extends as far south as northern California?
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Leland Palmer at 16:58 PM on 19 August 2013Toward Improved Discussions of Methane & Climate
The Department of Energy and national labs IMPACTS group is attempting to quantitatively model sudden climate change scenarios, including methane hydrate release.
Here are some links to one of their papers, doing basin scale modeling of the next hundred years of methane hydrate release, and also a slide show based on that paper:
BASIN-SCALE ASSESSMENT OF GAS HYDRATE DISSOCIATION IN RESPONSE TO CLIMATE CHANGE -Scientific Paper
Basin-Scale Assessment of Gas Hydrate Dissociation in Response to Climate Change
The second link is to a slide show, based on the scientific paper linked to by the first link.
Their assumptions are troubling in some respects, at least to me. They use slab models- one dimensional models projected over a two dimenstional surface- and suggest that their modeling confirms that the dissociation process will be gradual and orderly. But the use of slab models dictates that the process will be orderly, I think, which seems like circular reaoning to me. Will it really be an orderly process, and what are we willing to risk to confirm that?
I believe that they are assuming a total methane hydrate inventory of around 4000 cubic kilometers of methane hydrate. I wonder, myself, what their modeling would tell us if they were to use the higher global methane hydrate inventory estimates of around 80,000 cubic kilometers.
But, still, it seems like a good first effort, I think.
Their modeling seems to show some interesting or perhaps terrifying things. Their conclusions?
• Shallow hydrates can release significant methane rapidly, with significant methane fluxes regulated by coupled thermo-hydrological processes
• Methane is relevant to ocean (and atmospheric!) chemistry, not just as a contributor to total atmospheric CO2
• 1-D models averaged over depth/temperature/area can estimate basin-scale release potential
• The vast majority of deep hydrates are stable, in the short term, but the methane release potential is still large
• Limited instability/release can feed biochemical/chemical changes in the ocean and atmosphere, before climate effects are considered
• Resource limitations overturn assumptions about methane oxidation
• New coupled seafloor-ocean-atmosphere calculations under way (with plume physics, extended biochemistry, higher resolution) leading to a coupled global model… and better estimates.Their conservative modeling, which postulates an orderly process, shows significant Arctic Ocean anoxia after 30 years of methane releases from the hydrates, with one figure suggesting a 60% direct transfer to the atmosphere through these anoxic waters. Their conservative modeling arrives at numbers like an additional 800 ppb of methane in the tropics, rising to an additional 1,800 ppb in the Arctic, after 30 years of methane release. So,assuming that methane concentrations, mostly from other sources, rise to about 2000 ppb in 30 years, that would mean methane concentrations of about 2800 ppb at the equator, increasing to 3,600 ppb in the Arctic.
But I don't think that their modeling takes into account increased warming from the methane itself, and a subsequent higher methane release rate. I don't think that their modeling takes into account what would happen if the global methane hydrate inventory turns out to be 80,000 cubic kilometers of methane hydrate, rather than 4,000 cubic kilometers. I don't think that their modeling takes into account atmospheric chemistry effects predicted by Isaksen's modeling, increasing methane lifetime and so increasing its greenhouse effect. Their modeling suggests an orderly top down methane release process- but what if that projected order is an artifact of their use of slab models?
Their modeling also does not consider shallow permafrost bound hydrates- for example those contained in the East Siberian Arctic shelf.
One of their papers shows a huge anoxic area- not in the Arctic Ocean, but in the northern pacific in the region of the Sea of Othosk. Their modeling suggests that the Sea of Othosk is particularly vulnerable to sea water warming, and could "light up like a candle".
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Jose_X at 10:00 AM on 19 August 2013Andrew Dessler on Why It's Stupid not to Act on Climate Change
Mark Harrigan #5, the video addressed costs by saying we are going to have to move to renewables whether we like it or not.
I wonder how the people whining about making changes now would behave if they were born 100 years into the future instead and had to deal with society running up against real fossil fuel supply limitations. We can't risk paying $6/gallon in the US tomorrow -- no, way Jose -- but our great grand kids should not mind $60/gallon if the whiners around the world today have their way with policy?
scaddenp #14, yup.
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