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Comments 35901 to 35950:
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wili at 14:35 PM on 2 June 2014Global warming and the vulnerability of Greenland's ice sheet
chriskoz @#3: Thanks for your insights. But the last bit leaves me confused: "IS will not become dominant contributor for another 20y or so, even according to somewhat overestimated prediction by Hansen"
Your numbers for GIS and total Antarctic contributions (if I understand them correctly) add up to (.45mm/yr + .33mm/yr =) .78mm/yr, about the same as that from all glaciers, by your numbers, and about 80% of the contributions from thermal expansion.
If we take Hansens fastest doubling time (which, I agree, seems...ambitious) of 7 years, we would be getting about 6mm/year from ice sheets alone in about 20 years. Are you expecting the other factors to grow even faster during this period? If not, how is it that you say IS contributions would not be 'dominant'?
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scaddenp at 14:26 PM on 2 June 2014There's no empirical evidence
Razo, did you actually read the England et al papers that you quote? How come you have changed a slowing in the rate of warming into a cooling trend?
From the first "Here we show that a pronounced strengthening in Pacific trade winds over the past two decades—unprecedented in observations/reanalysis data and not captured by climate models—is sufficient to account for the cooling of the tropical Pacific and a substantial slowdown in surface warming through increased subsurface ocean heat uptake."
and the second...
"A variety of mechanisms have been proposed to account for this slowdown in surface warming" and "This hiatus could persist for much of the present decade if the trade wind trends continue, however rapid warming is expected to resume once the anomalous wind trends abate."
The papers conclusions do not appear to match your perception.
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Non-Scientist at 12:33 PM on 2 June 20142014 SkS Weekly News Roundup #22A
Re: "It's an angry beast that we've awoken".
Perhaps.
But have we awoken the Sheeple?
Moderator Response:[PS] Fixed link
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Tom Curtis at 11:47 AM on 2 June 2014There's no empirical evidence
Razo @203:
1) I did not put words into your mouth. I quoted you verbatim.
2) I am astonished that you do not know the meaning of "prima facie". As you do not, you need to learn it as it is a useful concept in understanding the practise of science. Of course, your intention was a rhetorical trick to allow you to criticize the OP without substance, so it may not help you.
3) Your precise words were:
"It also been all over the news now that temperatures have not risen in the last 15 years."
The paper for which you provide a link discusses the so-called "hiatus" since 2001, ie, the last 13 years. Thank you for indirectly confirming that you were exagerating the length of time involved. Further, to that, it is irrelevant how frequently a paper is echoed in the press.
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Tom Curtis at 11:24 AM on 2 June 20142014 SkS Weekly News Roundup #22B
grindupBaker @6, Wally Broecker's 1975 article only includes the term "global warming" in the title, and as such contains no definition of global warming. Further, the term was in use before 1975. The earliest use I have found was in 1972 (used three times in the article, but again without definition). However, I have no reason to think that was the earliest use.
The IPCC does not have a definition of "global warming". They do, however, define deglaciation as follows:
"Deglaciation/glacial termination Transitions from full glacial conditions
(ice age) to warm interglacials characterized by global warming
and sea level rise due to change in continental ice volume."The warming in deglaciation is more strongly characterized by reduced albedo than by increased greenhouse forcing. Given that, the use of the term here is inconsisent with the NASA definition.
The WMO defines global warming as follows:
"Global warming is an observed or projected increase in global average temperature."
The EPA defines it as follows:
"Global Warming
The recent and ongoing global average increase in temperature near the Earths surface."This is again inconsistent with the IPCC usage in that it is restricted to recent warming.
I consider the WMO definition to be best. It does not seem redundant to me to talk about recent global warming (as it would be with the EPA definition). Nor is it apparent that somebody claiming that the sun is the cause of recent global warming is contradicting themselves (as opposed to merely being in error) as they would be with the NASA definition.
The problem arises, however, that meanings are defined by usage. If the most common usage is of cases which are recent, and driven by anthropogenic green house gases, it is not clear the definition is not restricted to that use. It may be that the NASA or EPA defenitions are good descriptive accounts of the common meaning of "global warming". They are poor prescriptons for that meaning, however. Further, they are poor descriptive defenitions of my usage (which may only mean that I am idiosyncratic), or that by the IPCC or WMO.
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scaddenp at 08:22 AM on 2 June 2014Models are unreliable
Razo - these diagrams are from TAR, based on Stott et al 2000. I would agree there is an issue and I would hazard a guess the cloud-response to sulphate aerosols is exaggerated at low concentrations.
If you look at the corresponding diagram in FAQ 10.1, Fig 1 in latest report you will see that neither the CMIP3 nor CMIP5 model ensembles have this issue.
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Razo at 08:20 AM on 2 June 2014There's no empirical evidence
Hey Tom,
You're just putting words in my mouth. You wanna critisize me for not being exact, just Relax. FYI I do have a degree in a scientific field, I have bben published, and I didn't know what prima facie means.
Anyway, this is the article I was reffering to
http://www.nature.com/nclimate/journal/v4/n3/full/nclimate2106.html
They say they found a cooling trend. And is was in all the papers around February 10, 2014, such as
http://www.nature.com/nclimate/journal/v4/n3/full/nclimate2106.html
Thank you for the information about methane.Moderator Response:[JH] Pease tone down the rhetoric.
Please note that posting comments here at SkS is a privilege, not a right. This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.
Please take the time to review the policy and ensure future comments are in full compliance with it. Thanks for your understanding and compliance in this matter.
[PS] fixed links
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chriskoz at 08:16 AM on 2 June 20142014 SkS Weekly News Roundup #22B
grindupBaker@6,
Global warming: the increase in Earth’s average surface temperature due to rising levels of greenhouse gases.
(Broecker 1975) abstract:
If man-made dust is unimportant as a major cause of climatic change, then a strong case can be made that the present cooling trend will, within a decade or so, give way to a pronounced warming induced by carbon dioxide. By analogy with similar events in the past, the natural climatic cooling which, since 1940, has more than compensated for the carbon dioxide effect, will soon bottom out. Once this happens, the exponential rise in the atmospheric carbon dioxide content will tend to become a significant factor and by early in the next century will have driven the mean planetary temperature beyond the limits experienced during the last 1000 years
Note that (Leiserowitz 2014) definition questioned by yourself, agrees 100% with NASA's definitiond. So, do you implicitly argue that NASA's definiton is also "poor"? What do you find in Broecker's definition that makes it "better" than the other two ? Maybe a context "beyond the limits experienced during the last 1000 years"? Admittedly, a smart statement by Broecker, given it was written 22 years before (Mann et al 1997) - the hockey stick paper. But does the omition of that (now implicit in everybody's mind) context makes other definitions "poor"?
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villabolo at 07:11 AM on 2 June 20142014 SkS Weekly News Roundup #22B
@Moderator, #4.
Spencer Weart's book is titled "The Discovery of Global Warming."
Moderator Response:[JH] My bad. Thank you,
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grindupBaker at 04:42 AM on 2 June 20142014 SkS Weekly News Roundup #22B
Can somebody provide Wallace S. Broecker's 1975 definition of "global warming" because the definition given by Yale University researcher Anthony Leiserowitz, PhD in subject social-science paper "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" is a poor definition which renders much of the sks discussions a bit silly, even the ones that are excellent on the real topic, tautological at best. I'm going to stop using the phrase "global warming" entirely and invent a sensible one for myself unless somebody can provide Wallace S. Broecker's 1975 definition and I find it workable for the science. Thanks.
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Razo at 04:19 AM on 2 June 2014Models are unreliable
I find Fig. 1 of the respone curious.Figure 1a, the natural forcings, shows quite bad match with the climate model, especially for the 1850s. Fig 1b, the man made forcings, shows a great match in the 1850s, which is flat around zero. The model aslso shows a great match around the 80s and 90s, which is probably what it is calebrated to. In 1c, the combination of the two, the match is pretty good.
Even though its agreed that there is little effect of human activity in the 1860s, there is a significant correction in the model 1c at these dates. The poor modelling of natural forcing, doesn't say much for the model. This may best describe the error of the model, say .2C.The choice of calibration date appears to have a large effect on the results. I don't think AR4 models 'perturbate' calibration dates.
Its hard to understand the model to such detail, but it does appear that the models seem to only be able to predict recent warming.
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DSL at 01:38 AM on 2 June 20142014 SkS Weekly News Roundup #22B
MThompson, I'd guess that the current name was settled on because the assessment targeted climate change and not simply the primary driver of that change--global warming. The "IPCC" designation allows assessment of impacts and mitigation/adaptation.
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MThompson at 22:16 PM on 1 June 20142014 SkS Weekly News Roundup #22B
Regarding "Global warming vs. climate change" by science journalist Faye Flam:
Here is yet another article stimulated by the Yale publication that I have found objectionable and commented upon elsewhere in this prestigious blog. At least this time the author rightfully presses the responsibility of connotation upon journalists and not upon scientists.
Now, based on the theme of Ms. Flam's missive, I wonder how the IPCC in 1988 settled on the name of their august panel. Was there a consensus some 25 years ago that rejected IPGW as the moniker of the most important international body for the future of earth? I'm sure that within the vast experience range of SKS commenters someone can provide interesting history about this divisive nomenclature.
Moderator Response:[JH] The all-volunteer SkS team has a lot on its platter right now. You can probably find the answer you are looking for by perusing Spencer Weart's History of Global Warming. Also take a look at Wikipedia's entry for the "IPCC."
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chriskoz at 20:30 PM on 1 June 20142014 SkS Weekly News Roundup #22B
A bit of sad news from Auastralia. A bitter comment written by a young engineer who sees no future for himself is his home country:Science going back to dark ages
I note that it was written n May 28 but published on 20140531, per the link format.
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chriskoz at 20:22 PM on 1 June 20142014 SkS Weekly News Roundup #22B
U.S. Bishops call for reduction on carbon pollution
That news is a direct consequence of what Pope Francis said just a week ago: Causing Climate Change Is a "Sin", which itself should not be surprising to those who remember that Pope-emeritus Benedict expressed the same worry earlier.
It's worth noting that traditionally catholic church was very conservative, taking new science very cautiously. This latest news, especially Francis' latest statement, leaves no question as to where they stand with their preachings.
That leaves the conservative politicians in US and AUS on a very foolish position of not just science denial, but increasing alienation in their denial, as more and more influential organisations - traditional supporters - are not fooled anymore.
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scaddenp at 20:07 PM on 1 June 2014Models are unreliable
Well models from 30 year ago have been remarkably accurate. The Manabe model used by Broecker in the landmark paper 39 years ago nailed 2010 temperatures remarkably well. However, the model is too primitive to deal with much more than energy balance which is reasonably well understood. The inner workings of climate internal variability, regional difference etc are not captured at all. What exactly do mean by the comment?
That all models are wrong is trivial. The question is, are they skillful? Ie do they allow you to make better predictions of the future than doing it without a model. How would you make a prediction for future temperatures without a model.
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.
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chriskoz at 13:04 PM on 1 June 20142014 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.
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Tom Curtis at 12:06 PM on 1 June 2014There'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.
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MichaelK at 10:50 AM on 1 June 20142014 SkS Weekly News Roundup #22B
The link to "How will El Nino impact weather patterns?" returns a Not Found.
Moderator Response:[DB] Fixed; thanks!
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Tom Curtis at 09:22 AM on 1 June 2014There'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.
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John Hartz at 08:12 AM on 1 June 2014Models 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?
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DSL at 06:03 AM on 1 June 2014Models 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?
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MThompson at 05:02 AM on 1 June 20142014 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.
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Mike3267 at 02:55 AM on 1 June 2014Big 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
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ubrew12 at 02:40 AM on 1 June 20142014 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!!
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r.pauli at 02:07 AM on 1 June 2014Global 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
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Doug10673 at 02:01 AM on 1 June 2014The 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.
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Razo at 02:00 AM on 1 June 2014Models 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.
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Leland Palmer at 01:55 AM on 1 June 2014Rapid 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.
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Razo at 01:52 AM on 1 June 2014Models 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.
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Razo at 01:40 AM on 1 June 2014Models 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?
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DSL at 01:36 AM on 1 June 2014Models 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?
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Razo at 01:13 AM on 1 June 2014Models 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.
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Razo at 01:05 AM on 1 June 2014Models 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.
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Razo at 00:46 AM on 1 June 2014Models 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.
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Razo at 00:21 AM on 1 June 2014There'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.
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chriskoz at 23:14 PM on 31 May 20142014 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.
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chriskoz at 22:53 PM on 31 May 20142014 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
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LazyTeenager at 22:46 PM on 31 May 2014The 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%.
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dr2chase at 22:29 PM on 31 May 2014Global 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.)
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chriskoz at 22:25 PM on 31 May 2014Global 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.
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MThompson at 21:56 PM on 31 May 20142014 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?
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SeaHuck5891 at 21:09 PM on 31 May 20142014 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?
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Dean at 21:00 PM on 31 May 2014Global 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.
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wili at 06:29 AM on 31 May 2014Global 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.
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CBlargh at 04:17 AM on 31 May 2014Volcanoes emit more CO2 than humans
Your Moerner and Etiope and Kerrick links are dead.
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howardlee at 00:44 AM on 31 May 2014Rapid 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.
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Doug10673 at 20:54 PM on 30 May 2014The 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.
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Leland Palmer at 13:51 PM on 30 May 2014Rapid 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.
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mancan18 at 11:02 AM on 30 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Thanks howardlee
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