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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Recent article on this here.

If you are trying to imply that AGW is dependent on models, then please try reading the IPCC WG1 report first so we can have a more informed discussion.

chriskoz at 13:04 PM on 1 June 2014

2014 SkS Weekly News Roundup #22A

MThompson@9,

That's the clarification I was expecting from an honest person. Thank you!

I have a bit different opinion to yours about emotional aspect of "Global Warming vs. Climate Change" but I don't think this topic is worth discussing here, so I concede it.

Tom Curtis at 12:06 PM on 1 June 2014

There's no empirical evidence

Sorry, I mistyped the HadCRUT4 trend for the last 15 years as 0.66 C/decade rather than the correct 0.066 C per decade.

MichaelK at 10:50 AM on 1 June 2014

2014 SkS Weekly News Roundup #22B

The link to "How will El Nino impact weather patterns?" returns a Not Found.

Moderator Response:

[DB] Fixed; thanks!

Tom Curtis at 09:22 AM on 1 June 2014

There's no empirical evidence

Razo @200:

"...all the research in global warmimg would not be necessary if this rebutttal was indeed proof"

First, the rebutal is an attempt at science communication, ie, to present scientific information in a readilly digestible form. No matter how good it is at that, it can be no substitute for scientific research.

Second, the evidence summarized in this post establishes a prima facie case that the current warming is anthropogenic. Scientists are not happy with prima facie cases, and test them rigorously as they should. The prima facie case was established in a fairly rigourous form by the mid 1960s, and all the testing since then has failed to falsify it. Indeed, it continues to be tested, because that is what scientists do, but the vast majority of climate research is now focussed on expanding on less well established aspects of climate science. This is something Raz would know if he knew anything about the scientific method, or climate science. He is either making a case from his own ignorance, or (at best) being deliberately obtuse for rhetorical advantage.

It is, however, very kind of him to so prominently flag that his an AGW denier intent on publishing talking points rather than a genuine enquirer or person interested in reasoned debate.

"The question is 'what impact does man's CO2 producction have' and thus 'emperical evidence of his impact on climate change'."

Harries (2001) (as shown in the intermediate version of the OP) directly addressed that issue, and showed the following differences in IR brightness temperature:

The first thing to note is that the increase in concentration of all the listed gases is anthropogenic in origin, so that even if methane had more effect it would be irrelevant.

The second thing to note is that the area of reduced emission due to methane is slightlly larger than that of CO2. That, however, is misleading on two counts. First, the spectrum shown does not show the full CO2 band, showing, in fact, only one wing (see spectrum below). With the full CO2 band shown, the impact of CO2 would be approximately double that shown. Second, the graph shows the "brightness temperature". The brightness temperature is the emission spectrum so scaled that black body curves are shown as straight lines parallel with the x-axis. Because the region of the spectrum in which methane is active has much less IR activity at Earth temperatures than does the area in which CO2 is active, that greatly inflates the area in the Methane portion of the spectrum relative to the CO2 portion. We can see from the spectrum shown below, that approximately doubles the apparent impact of methane. Combined these factors inflate the apparent effect of methane by a factor of four. Correcting for this it is very apparent that CO2 has an impact around 4 times that of methane over the time period covered by the chart (27 years). That short time scale further inflates the apparent effect of methane, which is oxidized to form CO2 plus water over about a thirty year time frame in the atmosphere. Thus while Harries (2001) shows near the full forcing effect of methane since the preindustrial, it shows only a fraction of the effect of CO2.

"...methane is heavy, and would stay near the surface."

Methane (CH4) has a molecular mass of 16, ie, half the molecular mass of oxygen (O2), and 36% of that of CO2. The claim that it is heavy is the opposite of the truth. Further it is irrelevant, in that atmospheric motion is sufficient to keep even the heavy CO2 in near constant mixing ratios (within 10-20 ppmv) up to the meso-sphere.

"It also been all over the news now that temperatures have not risen in the last 15 years."

The HadCRUT4 OLS for the last 15 years (Jan 1999-Dec 2013) was 0.66 +/-0.13 per decade. That is, it was positive, but not statistically significant. It is similar if we take it from May 1999 to April 2014. Indeed, all major global temperature series are positive (but not stastically significant) over that period. Clearly Razo has accidentally cherry picked the wrong interval.

Perhaps he really meant the last 16 years. That would have included the 2nd largest (SOI) or largest (temperature based ENSO indices) El Nino as the start year, but alas the trend remains positive but not statistically significant if you do.

To get a negative trend, you have to reduce the trend to 13 years, starting in Jan 2001, which gives you a HadCRUT4 trend of -0.011 +/- 0.145 C per decade, though it remains stubornly positive in temperature series that actually include the entire globe such as Gistemp. Even then, and cherry picking our temperature indice to get a negative, trend it is misleading to say "the temperature has not risen" in the last thirteen years. The trends to Dec 2007, or Dec 2010, are both positive. Ergo, the temperature has risen, then fallen back. Specifically, it has fallen back in 2008 (due to a strong La Nina and a solar minimum some solar experts consider to have been as low as the Maunder Minimum), and in 2011-2012 (due to the strongest La Nina on record based on the SOI index). It appears not to be as usefull to Razo to say that two recent short term cooling events have temporarilly wiped out a decades worth of global warming, so he chooses a less accurate form of expression.

John Hartz at 08:12 AM on 1 June 2014

Models are unreliable

Razo: You really should do some homework before piously pontificating about climate models. The Intermediate version of the OP has a Reading List appended to it. If you read the first Spncer Weart article, you will discover that the first General Circulation Model was created in the mid-1950s. Would six decades of model development and enhancement satisfy your rather vague time criteria?

DSL at 06:03 AM on 1 June 2014

Models are unreliable

Razo, pointing out that modeling is "not as perfect as it may seem" is a no-brainer. Who has been saying it is? Are you suggesting that climate modeling is useless? Where is your comment going? Or is that the extent of it?

MThompson at 05:02 AM on 1 June 2014

2014 SkS Weekly News Roundup #22A

Thank you, M. Koz for your kind invitation to clarify my post on line 5. After reading your comment on line 7, I learned that my comment, while clear in my own mind, could be vague to other readers. After reviewing Ms. Pappas' blog article in preparation for my clarification, I discovered an egregious mistake on my part. When I wrote my original comment I believed that the blogger had made the pronouncement that “Scientists … should be aware that the two terms generate different interpretations among the general public and specific subgroups.” This is an honest mistake on my part because I believed that Yale researchers would never deign to instruct scientists on what terminology they should choose when reporting the results of their research. Especially when the implication is that scientists could elicit different emotional responses from their colleagues and readers. It turns out Ms. Pappas was correctly quoting the authors’ of the study: Leiserowitz, A., Feinberg, G., Rosenthal, S., Smith, N., Anderson A., Roser-Renouf, C. & Maibach, E. (2014). What’s In A Name? Global Warming vs. Climate Change. Yale University and George Mason University. New Haven, CT: Yale Project on Climate Change Communication. So I do owe her an apology. Notwithstanding, I must confess shock and dismay that Yale researchers would presume to press upon climate scientists the methods of marketers, entertainers and politicians. Are climate scientists supposed to be “aware” of the connotations in order to avoid criticism, or in order to promote a noble cause? Which one is it? Who gets to choose?

Thus as you have correctly surmised, the integrity of the blog article is intact, and the author has accurately recapitulated the content of the original scientific publication. I should not have been taken in by the sensational headline (probably not attributable to the writer), and I find that the concept of invoking fear or “scarier” is found nowhere else in the blog or the original cited work.

Mike3267 at 02:55 AM on 1 June 2014

Big Oil and the Demise of Crude Climate Change Denial

Hi. It is ExxonMobil not Exxon, and your link to their statement is broken. I could not find the exact statement you quote, but a similar one can be found here:

http://corporate.exxonmobil.com/en/environment/climate-change

ubrew12 at 02:40 AM on 1 June 2014

2014 SkS Weekly News Roundup #22A

John Hartz@3. I'm going to 'double down' on my criticism. The West Antarctic is now in unstoppable collapse. With that as context, what are we to make of "men are 12 percent more likely to believe that 'global warming' is happening versus 'climate change.' "? I'll tell you what I make of it: Run For Your Lives!!

r.pauli at 02:07 AM on 1 June 2014

Global warming and the vulnerability of Greenland's ice sheet

This is like the spectator sport of global warming climate destabilization. A very big deal, everybody should be watching closely.

Thanks

Doug10673 at 02:01 AM on 1 June 2014

The Wall Street Journal denies the 97% scientific consensus on human-caused global warming

Rob P. Thank you for your response. I always stress to people that it's a very high bar to meet, to distinguish man made climate change, from natural forcings, and that a significant percent of the 3% or so of scientists who don't think the bar has been met, don't reject the possibility. When you focus on the 3% it has the effect of putting those who deny the science on the defensive. Something they are always trying to get us to do.

Razo at 02:00 AM on 1 June 2014

Models are unreliable

DSL, I think my argument is sufficiently objective to allow for critism of failure in all directions? (I'm not sure what you mean). I talk about the equations, the procedure, and give examples of approximations. I also gave examples from solid mechanics, a different feild after all. Numerical integration applies to all fields. I was trying to illustrate that modelling is not as perfect as it may seem, for both experts and to the layperson. Also that it takes decades to develope good models.

This is site is for skeptics. So to your question "Let's imagine that the sign of the alleged failure was in the other direction. Would you still make the comment?", unless you disagree with my content, so what.

Leland Palmer at 01:55 AM on 1 June 2014

Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.

Hi howardlee, thanks for the reply and information.

Yes, the triple point hydrates may be a minor player in the whole scenario- nobody knows. Each extinction event may be different, but follow the same general theory. The rate of onset and the magnitude of the triggering event necessary for massive hydrate dissociation might depend on the total hydrate inventory, and whether there is a large region of methane hydrates near the poles or subsea permafrost that is shallow enough to be abruptly triggered. Our own East Siberian Arctic shelf seems particularly vulnerable. And hydrate inventories could be high, since we are coming out of a series of ice ages with low bottom water temperatures, although water pressure also factors in, and ocean levels are low. So, we could have more total hydrates than average, and in fact our "methane capacitor" could be fully charged and ready to be triggered.

The good news, if there is any, about the high salt triple point hydrates is that these pinnicles will have their salt concentrations diluted as the hydrates dissociate into methane and fresh water. The high salt hydrates might be important in the early phase of the extinction events, adding mostly to ocean acidification in the early stages, with little methane escaping into the atmosphere. But, along with melting permafrost, and other carbon sinks turning into carbon sources, they might act as a bridge to the destabilization of the greater hydrate mass.

Later on, as the extinction scenario unfolds, the amount of methane released could start to overwhelm the local oxidation capacity of the ocean. Basin scale anoxia and acidification will likely occur, if the modeling done by the IMPACTS group at the national labs is any indication of real events. IT should be noted, however, that the modeling done by Reagan et al does not take into account the high salt hydrates:

Basin Scale Assessment of Gas Hydrate Dissociation in Response to Climate Change

According to this modeling, the northern Pacific will be more severely affected than the well ventilated Arctic Ocean. The sea of Okhotsk, that most Americans have never heard of, could create a plume of anoxic deep water stretching all the way across to Alaska, down the west coast of North America, all the way to Baja California, wandering out into the Pacific, then continuing down the coast of South America in diluted form.

It scares me too, howardlee. It sure would be nice to be wrong about this stuff, wouldn't it?

But, I don't believe it. The whole theory hangs together too well, and explains too much geological information. The theory of flood basalt triggered methane catastrophes has too much predictive ability, too much explanatory ability, too much unifying ability, and it too consistent to be basically wrong, I think.

Razo at 01:52 AM on 1 June 2014

Models are unreliable

DSL, I think my argument is sufficiently abstract to allow for critism of failure in all directions? (I'm not sure what you mean. I also gave examples from solid mechanics, after all. I was trying to illustrate that modelling is not as perfect as it may seem, for both experts and to the layperson.

Razo at 01:40 AM on 1 June 2014

Models are unreliable

So a question: if we had the GCM of today 30 years ago, would we be having the same conversation? how would it be different?

DSL at 01:36 AM on 1 June 2014

Models are unreliable

Razo, if you find the models failing, what practical conclusions do you draw from it? In other words, so what? Let's imagine that the sign of the alleged failure was in the other direction. Would you still make the comment?

Razo at 01:13 AM on 1 June 2014

Models are unreliable

Although, to be complete, theses solutions ^, do get tested and conditioned to work reasonably well under normal circomstances, ie hindcasting. However this is the mathematically equivalent of rigging it with duct tape. Certainly for highly non linear equations, like NSE, this is not good for extrapolation.

Razo at 01:05 AM on 1 June 2014

Models are unreliable

Reduced integration techniques are a good example of how researchers can BS themselves for years, just to get papers published (which I will eplain). So the analytical solution is a series of sines and cosines. One tries to approximate the solution using a third order polynimial, obviously in small segments to reduce the error. They use three gausss points (? i dont remeber) for each axis to integrate their equations. Their results are crap. So they just remove a Gauss point and say it has ceratin advantages. Another resaercher removes another Gauss points and says it has some advantages and some problems. They create word like 'shear locking' or 'zero energy mode'--how about 'wrong solution'? This goes on for 20 years and thousands of papers. Meanwhile the pile of paper of what you have to learn gets higher and these methods are put in commercial programs. The next generation of people have fanciful intellectual musings on what a 'zero-energy' mode is, because the pile of paers is so full of crap and the fact that its the 'wrong solution' is lost.

Razo at 00:46 AM on 1 June 2014

Models are unreliable

Saying that models are mathematically representative of interactions in the climate, is far to simple a statement. As I understand, they basically numerically integrate Navier Stokes Equations (NSE). While NSE are quite complete, integrating them is no simple minded task. Grid size, time steps, and most importatnly boundary and starting condidtions have a big effect on the model's results. Also there are many constants, linear and non linear, that may only be described in limited or aproximate way, or omitted.

Hindcasting is of course a practicle method of checking all the assumption, but it does not guarantee results. It is entirely possible that thousands of papers can be written all using limited and poor models for constants and make bad assumptions, only refering to the work of another reseacher. For example, people numerically intgrate equations that describe reinforced concrete. They describe cracks as a softening and ignore aggregate interlock. Engineers forget when the limits of these assumtions are reached; normally they just add more steel to be safe.

It also been all over the news now that temperatures have not risen in the last 15 years.I realize the oceans are storing heat, and their are trade winds, and that this post started years ago, neverthess average tempratures are not rising. Also early models could not predict trade winds! What, they don`t have oceans either? We have waited now 20 years and the models are wrong. So it seems that although tested with hindcasting on data that showed increasing temperatures, the models could not predict the temperatures staying constant.

Moderator Response:

(Rob P) - The news, in general, is hardly a reliable source of information. Some news media organizations seem little concerned with things such as facts.

Yes, the rate of surface warming has been slower in the last 16-17 years, but it has warmed in all datasets apart from the RSS satellite data - see the SkS Trend calculator on the left-hand side of the page.

As for hindcasts see: Climate Models Show Remarkable Agreement with Recent Surface Warming.

Razo at 00:21 AM on 1 June 2014

There's no empirical evidence

Few deny CO2 is a greenhouse gas, or that the atmosphere traps heat, or that people produce CO2 (i don't care if some do it doesn't matter in analyzing the science). Thats not the question. It seems to me what is presented here is justification to propose the hypothesis, not emperical proof that man is causing climate change. I think this is all basic science of many years ago and all the research in global warmimg would not be necessary if this rebutttal was indeed proof. The question is 'what impact does man's CO2 producction have' and thus 'emperical evidence of his impact on climate change'. So the rebuttal doesn't answer the question.

A couple other points, the graph shows methane as not being less significant. I have heard otherwise recently; that CH4 is 10 times worse than CO2. But Im a little confuced about the methan arguement, becasue methane is heavy, and would stay near the surface.

The question also implies the issue of quality of numerical models. Saying they are mathematically representative of interactions in the climate, is far to simple a statement. As I understan they numerically integrate Navier Stokes Equations (NSE). While NSE are quite complete, integrating them is no simple minded task.

It also been all over the news now that temperatures have not risen in the last 15 years.I realize the oceans are storing heat, and their are trade winds, and that this post started 4 years ago, neverthess average tempratures are not rising.

chriskoz at 23:14 PM on 31 May 2014

2014 SkS Weekly News Roundup #22A

MThompson@5,

I believe the blog writer is somewhat confused about the difference in the terms 'Global Warming' and 'Climate Change'

Really? The definition of the terms in the article:

"Global warming refers to the increase in the Earth's average surface temperature since the Industrial Revolution, primarily due to the emission of greenhouse gases from the burning of fossil fuels and land-use change," Yale University researcher Anthony Leiserowitz and colleagues wrote in the new report, "whereas climate change refers to the long-term change of the Earth's climate, including changes in temperature, precipitation and wind patterns over a period of several decades or longer."

Sounds correct and perfectly clear to me. What's wrong with that definiton, or where is the "confusion about the difference", according to you?

Maybe, judging from the rest of your post, you disagree about the interchangeable use of the two terms rather that their definitions. But in that case, it's just your opinion which has no bearing on the integrity of the aticle and its author. Please clarify.

chriskoz at 22:53 PM on 31 May 2014

2014 SkS Weekly News Roundup #22A

SeaHuck5891@4,

You're correct that this is "distraction from Arctic collapse". But it is not distortion. Antarctic is indeed gaining sea ice but the gain has no "colling effect" at all, and in fact it is paradoxically, partially related to the melting of AIS...

http://www.skepticalscience.com/arctic-antarctic-sea-ice.htm

LazyTeenager at 22:46 PM on 31 May 2014

The Wall Street Journal denies the 97% scientific consensus on human-caused global warming

Weeeelll , I think we should defer to the expertise of Anthony Watts. Just compare the number of peer reviewed papers he asks his minions to disparage, to the number of peer reviewed papers he asks them to applaud. I am taking bets the ratio is close to 97%.

dr2chase at 22:29 PM on 31 May 2014

Global warming and the vulnerability of Greenland's ice sheet

The problem with the IPCC reports is that they are biased to be too conservative. If they were literally, mathematically unbiased, half the time they would hit high, half the time they would hit low. We don't see that. Three obvious reasons are that humans tend to be biased in the conservative direction, the scientific process is biased in the conservative direction (default assumption is that nothing new is happening), and that for reasons of credibility in the face of "skeptics", I think the IPCC attempts to never overpredict. This sort of cascaded filtering is nothing new; there are examples of companies that failed because a CEO inclined to "shoot the messenger" successfully created his own little bubble of misinformation, till reality intruded.

But if the IPCC was literally and accurately unbiased, about half their predictions would fall short as new data arrived. There's things where we can look and say "that won't happen" — we know the ice caps won't melt quickly in place, because physics tells us so pretty directly. But otherwise, it would be nice to see predictions that were based on sound science, yet not artificially muted by pervasive conservatism. (I assume this is what we're getting from Hansen, which is why he sounds so much more alarmed than the IPCC.)

chriskoz at 22:25 PM on 31 May 2014

Global warming and the vulnerability of Greenland's ice sheet

wili@1,

The study in question does not try to quantify the GIS contribution to SLR nor the prediction of its contribution (in the abstract and press releases I only have access to).

The Antarctic study you're most likely referring to (McMillan 2014), quantifies the current total Atntarctic contribution from recent satelite altimetry as 160Gt/y, equiv. to 0.45mm (central value). Recalling the AR5 number for Antarctic ice sheet contribution: 0.27mm/y, we can clearly see that AR5 has been substantially outdated as (McMillan 2014) increases it by some 70%. We know that IPCC findings about SLR outdate quickly, so no surprise here.

I think the increase of AIS loss rate comparing to AR5 is nothing new, considering e.g. (Hansen 2012) who predicted sustained doubling of icesheet melt rate every 7-10 years with SLR up to 5m by 2010. I think Hansen based his prediction on GIS data but I don't know the recent GIS melt data, apart its contribution is just slightly higher (0.33mm/y by AR5). AIS melt rate in (McMillan 2014) seems to be somewhat slower than (Hansen 2012) prediction, if it can be a bit of consolation. That is just my very rough interpolation: in order to verify if Hansen 2012 was correct, we need to wait a couple decades (if we are young enough).

To put the current IS melt contribution to SLR in perspective, it's worth remembering they are still quite behind the main contributors:

- thermal ocean expansion due to warming: 1.1 (0.8 to 1.4) mm/y

- glaciers: 0.76 (0.39 to 1.13) mm/y

and based on that numbers, IS will not become dominant contributor for another 20y or so, even according to somewhat overestimated prediction by Hansen.

MThompson at 21:56 PM on 31 May 2014

2014 SkS Weekly News Roundup #22A

Regarding 'Global Warming' scarier than 'Climate Change,' surveys find, I believe the blog writer is somewhat confused about the difference in the terms. Do you believe that these two are synonymous? I think that the consensus of commenters on this site is that both are happening, both are quantifiable and both portend catastrophe. Even so, these concepts are not the same thing, though the belief is that they are linked. The aforementioned article's blogger does a disservice to the climate-concerned community by suggesting at the end of the article that scientist should be aware of the different responses elicited by the different terms. I would infer that the preferred terminology would be "global warming," in order to "scare" the most people. Is this an intentioned implication, and should climate scientists make sure to be as scary as possible in their publications? If so, then they should also clearly state in their abstract that the results of the study support the consensus belief that global warming is accelerating and that is being caused primarily by human emissions of carbon dioxide?

SeaHuck5891 at 21:09 PM on 31 May 2014

2014 SkS Weekly News Roundup #22A

Saw this article floating around social media the other day. My guess is it is a distortion, or at the least a distraction from Arctic collapse, but is there a more scientific response someone can point me to?

Dean at 21:00 PM on 31 May 2014

Global warming and the vulnerability of Greenland's ice sheet

I think this shows a few problems with the IPCC reports and using them as THE reference for assessments. First, new research is coming out fast, changing previous conclusions (as above) and 7 years is a long time. Then (and related) the ESLD effect might have affected estimates of ice sheets and sea level rise. IPCC AR4 was quite far off at the low side but also IPCC AR5 gave a lower value than the average expert: www.realclimate.org/index.php/archives/2013/11/sea-level-rise-what-the-experts-expect/ and www.glaciology.net/Home/Miscellaneous-Debris/comparisonofsealevelprojections

OK, that estimates are changing with time is in principle a normal part of the scientific progress and not in itself a proof of any bias. But the tendence has been that new (dynamical) effects are added with time, increasing estimates, which is the problem with bottom-up approaches. And IPCC AR5 dismissed the semi-empirical approaches in favour of the process-based, but they now seems to be the more realistic.

wili at 06:29 AM on 31 May 2014

Global warming and the vulnerability of Greenland's ice sheet

Thanks lots for posting this. Do we have any idea about how much this particular dynamic might increase the rate of sea level rise in the next few decades? A little? A lot? Not at all?

If even a little, how does this, plus what we have learned about WAIS change our understanding of likely sea level rise in the next few decades and by the end of the century? This is a questions of vital concern to the hundreds of millions living in directly vulnerable areas, and really, to everyone one on earth, since nearly all will likely be affected one way or the other by the wrenching changes needed to deal with the evacuations of these areas.

So any light anyone can throw on these questions would be most welcome.

CBlargh at 04:17 AM on 31 May 2014

Volcanoes emit more CO2 than humans

Your Moerner and Etiope and Kerrick links are dead.

Moderator Response:

[DB] Mörner and Etiope is here. Kerrick is here. A nice chapter on geologic methane by Etiope is here.

howardlee at 00:44 AM on 31 May 2014

Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.

Leland @30 - I know that conventionally volcanic CO2 is not considered sufficiently isotopically light to explain the strong -ve Carbon isotope excursions. So hydrates are commonly pointed to as a likely source of light carbon. Others point to the geothermal baking of organic-rich sediments releasing high volumes of light carbon. Still others point to crustal melting and mixing with plume magma generating the volumes of light carbon. We also know that the geochemistry of these deepest-mantle-derived magmas is a little different from more shallow-melted magma.

Personally, I'm slightly skeptical of the hydrate idea as the initial driver of the ancient global warming events because the rapid, strong warming points to the initial atmospheric buildup of carbon (CO2/methane) faster than surface ocean/biosphere can buffer the changes (ie centuries to a few millennia at most). IPCC AR5 points to uncertain but expected slow (millennial-scale) release of hydrates, then slow subsequent release of methane from the sea to the atmosphere (see p 531 of the report - warning large pdf). Also recent observations suggest that microbial metabolism would mitigate ocean methane release somewhat.

The "tripple point" shallow hydrates you refer to may indeed be more responsive, and affect the same shallow ocean reservoir that would be saturated by volcanic CO2 and geothermal methane/CO2.

Given the magnitude of the temperature changes observed for these ancient events and the difficulty in resolving dates under about 2,000 years, it seems likely that a cascade of knock-on effects unfolded after the initial perturbation of the system. Hydrates and permafrost methane release would - in my personal view - be triggered as a response to the initial volcanic/geothermal carbon-shock global warming. I recall somewhere related to the Permian extinction that there are multiple isotopic kicks in a very expanded geological exposure which supports the idea of various carbon reservoirs being released in sucession, but I can't find the paper right now. There was also a good paper suggesting that the Eocene hyperthermals after the PETM were driven by permafrost melting at orbital pacing (ie a long tail feedback, long after the initial carbon shock of the PETM - which I am personally convinced was triggered by the North Atlantic LIP).

The suggestion that such huge and long-lasting feedbacks could be triggered by an initial carbon-shock of sufficient rate and magnitude (at rates similar to or slower than today) is truly scary to me.

Doug10673 at 20:54 PM on 30 May 2014

The Wall Street Journal denies the 97% scientific consensus on human-caused global warming

Of the two or three percent of climate scientists that don't "believe" in man made global warming, how many of them don't deny it, but instead just don't think there's enough evidence yet to make the claim? In other words, we always assume that the two of three percent firmly reject man made global warming, but is that really the case? Perhaps the figure is much lower than the already very low two or three percent, that categorically reject manmade global warming. There may be a very high percentage within the two or three percent, that believe we may be behind the warming. Perhaps Skeptical Science should do a post on that.

Moderator Response:

(Rob P) - See The Consensus Project (TCP) at the top of the page. Those classified as rejections include papers which minimize the role of humans in global warming and therefore ascribe the bulk of warming to other unexplained forces.

Leland Palmer at 13:51 PM on 30 May 2014

Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.

howardlee @26-

Wow, that's a great list, thanks. Best I've ever seen. :)

So there are isotope excursions at a coincident time and in the correct direction to fit the flood basalt erruption / methane and CO2 release / oceanic acidification and anoxia general theory of most mass extinction events.

It appears now that there is a subclass of methane hydrates that might be dramatically less stable than most methane hydrates are - high salt "triple point" hydrates.

DYNAMICS OF SHALLOW MARINE GAS HYDRATE
AND FREE GAS SYSTEMS- Xaoli Liu (Thesis)

"We show that the hydrate system at South Hydrate Ridge is already
everywhere at the three-phase boundary, and therefore it is highly sensitive to changes in ambient conditions, offering a mechanism for rapid release of methane from gas hydrate deposits." [page 2]

Other scientists including Peter Flemmings are starting to write about these high salt hydrates. Models of the high salt hydrates tend to confirm Xaoli Liu's predictions.

These hydrates appear to be at the triple point of the hydrate/methane gas/sea water system. This would result in extreme temperature sensitivity and gas phase transport of methane within the high salt region. These high salt methane hydrate deposits, in combination with albedo change from loss of sea ice and permafrost rotting, could act as a bridge between mild CO2 based warming and massive hydrate dissociation.

The high salt concentrations in these sediments would normally be diluted out by diffusion into surrounding sea water and low salt sediments. The salt is generated by the well known "purification by crystallization" process in which the methane hydrates tend to exclude salt from their crystal structure when they crystallize out, leaving the salt behind in the sediments. So, a continuous flow of methane gas from deeper in the deposit is necessary to sustain these high salt triple point hydrates, before the salt diffuses away.

The need for a continuous flow of methane tends to put the high salt deposits in pinnacles at the top of the hydrate formations - in deposits at the top of the hydrate stability zone. So the relative shallowness of these deposits may make them more vulnerable to temperature changes.

These high salt deposits are in principle detectable by seismic mapping - there is a blank looking "wipeout zone" created by free diffusion of gas beneath a methane producing pinnacle.

So, just by looking again at existing sonic mapping data, we could in principle discover just how common these high salt methane hydrate deposits are, and determine how likely they are to push the climate system past tipping points into low level (?) runaway global warming.

mancan18 at 11:02 AM on 30 May 2014

Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.

Thanks howardlee

Joel_Huberman at 09:57 AM on 30 May 2014

Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.

Thanks to billthefrog @ 11 and howardlee @12 for their helpful, informative responses to my comment about the Snowball Earth web site @ 10. And thanks to everyone @1-27 for a wealth of fascinating information about paleoclimatology!

John Hartz at 09:44 AM on 30 May 2014

2014 SkS Weekly News Roundup #22A

ubrew12: You seem to have missed the point of the article and the purpose of the two surveys it summarizes.

scaddenp at 07:09 AM on 30 May 2014

The Wall Street Journal denies the 97% scientific consensus on human-caused global warming

Kernos - Wikipedia has a list here. You will note a preponderance of non-climate scientists in that list as well as a large no. who have "gone emeritus". Inside that list, I would say only Lindzen, Spenser, Christy, and Chylek have any scientific chops in the field worth considering. I dont think any of these 4 are into denying physics, though some of the "natural causes" arguments push Conservation of Energy pretty hard. I also do not think that they have published hypotheses that have not been discredited in the published literature. Corrections welcome.

ubrew12 at 06:31 AM on 30 May 2014

2014 SkS Weekly News Roundup #22A

Reading that LiveScience article ('Global Warming' scarier than 'Climate Change,' surveys find) I got the distinct image of people rearranging the deck chairs on the Titanic.

Anthony10658 at 06:17 AM on 30 May 2014

The Wall Street Journal denies the 97% scientific consensus on human-caused global warming

What bothers me is the lack of common sense in the people who argue against global warming. They either hide behind kindergarden reasoning, "we had the coldest winter on record" or contrariantism for the sake of it. CO2 is created added to our atmosphere. As that happens the atomsphere gets warmer. Let's say in the old days most CO2 came from animal farts, decomp and lightening strike forest fires. Well clearly since the industrial revolution, we (humans and our by-product industries) have been contributing a lot more CO2 year after year. If you want to argue that it is to late to stop, or that we will be just fine if oceans rise, great. But why disagree with the obvious?

BojanD at 05:57 AM on 30 May 2014

John Oliver's viral video: the best climate debate you'll ever see

Tom, your last point is excellent. I've just checked the robustness of the consensus figure by flipping numbers between 3rd and 4th category and they are indeed very stable and well above 90% even in most extreme cases.

The discussion about operational definition is not so compelling to me, though. I'm not even sure where the alleged problem of exclusion comes from, but I admit the methodology of such studies is not my bag. If the goal is to get a lower bound of a consensus I don't see an inconsistency. Cook et al. found an upper bound and that was my problem, but since this figure is very inelastic, that's ok for me. Looks like I've given the guy I was discussing with too much credit. ;) Thx for clarification.

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