Arguments
Recent Comments
Prev 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 Next
Comments 33851 to 33900:
-
Tom Curtis at 14:20 PM on 23 September 2014The Wall Street Journal downplays global warming risks once again
JoeT @4, I misread what Koonin wrote and withdraw my post @8, no because it is wrong, but because it is no relevant to his claim. (There really are deniers who argue the position I rebut there, which contributed to my confusion.)
The "natural" greenhouse effect is the difference between the upward IR radiation at the Earth's surface (390 W/m^2) and the upward IR radiation to space from the top of the atmosphere (240 W/m^2). Of that 150 W/m^2 difference 27 W/m^2 is from CO2, a further 13.5 W/m^2 is from other will mixed greenhouse gases including methane and ozone. The remaining 109.5 W/m^2 comes from water vapour (61.5 W/m^2) and clouds (46.5 W/m^2).
Those values are for circa 1980 conditions, and hence include a significant portion of anthropogenic forcing already. Hence the scare quotes on "natural".
Based on RCP scenarios, by mid century greenhouse radiative forcing from anthropogenic sources is expected to increase by about 1.5 W/m^2, which is about 1% of the "natural" total greenhouse effect. However, to obtain that figure, you need to only consider the change relative to current values. If you consider the total anthropogenic forcing since 1760, that figure approximately doubles, and if you consider the business as usual forcing by the end of the century, it tripples.
Further, Koonan is carefull to only consider the "direct" effect. The effect of water vapour and clouds are actually feedbacks on temperature. If you drop temperature, they will fall, whereas if you increase it they will rise. The result is that increasing CO2 also increases the WV and cloud greenhouse forcing (but also decreases, ie, make more negative, the cloud albedo forcing). The effect is so strong that for a doubling of CO2, a 3.7 W/m^2 direct change in the total greenhouse results in a further 16.3 W/m^2 increase in water vapour and cloud greenhouse effect in feedbacks.
So, by mid century the direct increase may be only 1 or 2%, but the total increase as a result of that direct increase will be a 5 - 10% increase in the total greenhouse effect.
So, Koonan is not incorrect per se, but his claim is framed to cultivate confusion - and he fails to provide the explanation that would dissipate that confusion.
-
jwalsh at 14:06 PM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
PhilippeChantreau @97
I find it rather amsing that you'd adopt such snark toward Wikipedia but maintain deference for a buffoon like Monckton.
I am showing "deference" to Monckton by agreeing with a single thing the man said? I simply attributed the comment to him. I've read very little about, or by him, but happened to have done so recently enough. Should I? As for Wikipedia. Surely you know what it is. Wikipedia can be convenient for some things, but you almost always better check the references. The quality of information on it varies wildly. I usually avoid it for anything other than a starting point when possible. YMMV.
Perhaps you might point us to what you are precisely what you are implying but "relevant"? It seems you are yet again confusing sensitivity with attribution. Why do you continue to ignore the points the about OHC? Attribution is about sorting which cause created a particular change. Show us your evidence for another cause or stop trolling.
I've not once confused sensitivity with attribution. But if you change how much warming is assessed by CO2, it follows that the relative attribution of the warming is altered. I mostly ignored the points on OHC, because I am trying to stay on topic (attribution). OHC seems to me to be about where the heat is going, not what is causing it in the first place. Some are speculating issues with assumptions. And these "some" are many in the IPCC. Over-estimates of CO2 sensitivity could be one of those reasons. If there's nothing wrong with the attribution percentages, but only that the heat is all going into the ocean. That's fine, then the models have to be adjusted accordingly for the policy-critical estimates of surface temperatures. But I don't think there's complete agreement that that is indeed what we are seeing.
As for trolling. I am trying not to. If you don't understand the "why's" of those thinking somewhat differently, you stand little hope of convincing them, should you think that important.
-
Tom Curtis at 13:47 PM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
jwalsh @95:
1) I criticized you for using a regional proxy (GISP2) as though it were a global proxy. You implied your use was justified on the basis that tropical ice cores did not exist "they don't last so long". You now claim that you knew about them all along, which makes your original use of GISP2 simply dishonest.
2) I do not discuss the MWP or LIA with reference to those ice cores. Rather, I discuss the absense of evidence of evidence for a RWP or Minoan WP, which you claimed exist on the basis of GISP2. Clearly from the ice core data they were not global events - and changing the topic does not make them so.
3) From Marcott et al, we learn:
"The results suggest that at longer periods, more variability is preserved, with essentially no variability preserved at periods shorter than 300 years, ~50% preserved at 1000-year periods, and nearly all of the variability preserved for periods longer than 2000 years (figs. S17 and S18)."
If approx 50% of variability is preserved at 1000-year periods, >50% of a 1,200 year cycle would show up in the reconstruction. It is, however, not there. No amount of quoting Gavin Schmidt out of context will change that.
4) I criticized you for (in effect) taking the average of just one proxy as an indicator of changes in global mean surface temperature. You now respond by arguing that taking the average of eight such proxies is of dubious "scientific utility" and that it is a premise that is itself " itself is too absurd to bother" checking the maths. That you so argue in order to maintain that the data from the once proxy is a reliable guide to the timing and direction of trends in GMST (if not their magnitude) shows how absurd your position is, and how completely lacking in scientific merit.
As an aside, I did not credit the graph to wikipedia regardless of your misrepresentation. I sourced from wikipedia, and acknowledged the source as is required by copyright law (as they wave their copyright on condition that you credit the source). However, I cited Robert Rhode, the author of the graph. That you ignore that to play your empty rhetorical games is only to be expected from a troll.
-
scaddenp at 13:29 PM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
jwalsh - " Nothing to say about the IPCC experts on attribution downshifting estimates of future temperatures, setting aside temperatures at the mean or above from climate model projections as being unlikely? That would seem to be pretty relevant."
Perhaps you might point us to what you are precisely what you are implying but "relevant"? It seems you are yet again confusing sensitivity with attribution. Why do you continue to ignore the points the about OHC? Attribution is about sorting which cause created a particular change. Show us your evidence for another cause or stop trolling.
-
jwalsh at 13:29 PM on 23 September 2014Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
KR - Of course there's a lot of "selling" nonsense. Dangerously too much. It doesn't necessarily help to counter one with a different sales pitch. And I refuse to discuss "consensus without an object", whether it's by the Koch foundation or here! Any "consensus" needs to be clear about what exactly is being talked about. Not doing so is frustrating to people and will cause them to tune out. There is such thing as the charge on an electron. There isn't any such thing as "the science" with respect to the complex and chaotic system that is our climate.
I think educating the public on the actual science of AGW is a fine goal. I also think it's a largely irrelevant one. There wasn't any need to convince the public that the moon wasn't, in fact, made of cheese, to launch the Gemini and Apollo programs. You only needed to convince those funding the programs. And those people? They need more than vague information. They ask tough questions, and I wouldn't have it any other way. And yes, the money influence on politics is an enormous concern. There are indeed many industries and people not wild about their apple-carts being upset.
-
PhilippeChantreau at 13:04 PM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
Well, it seemed you did, kinda, or not, I'm not sure. I find it rather amsing that you'd adopt such snark toward Wikipedia but maintain deference for a buffoon like Monckton.
http://www.parliament.uk/business/news/2011/july/letter-to-viscount-monckton/
-
PhilippeChantreau at 13:01 PM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
Jwalsh, I note that you do not comment on any of Tom Curtis's arguments at #92, starting with the equatorial ice cores canard. I am unimpressed with your contribution so far.
-
jwalsh at 12:59 PM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
Tom Curtis @92
It goes tiresome correcting the errors, lack of evidence and outright falsehoods on which you base your "expert opinion". Never-the-less, here are the results of six near equatorial ice cores from high altitudes:
Then don't? You made the choice to reply to me at all or not. But if it's your job to do so, there are worse things to be doing, and every job can get tiresome at times. The six ice-cores mentioned come from Lonnie Thompson's paper. Interestingly, it's referenced as often by those wishing to show evidence of a LIA and MWP as often as it is to try to show a lack of both. Most that have looked at that the data have deemed it too noisy to say anything about either, which allows people to interpret it however they like. It's also trotted out as corroboration of a particular set of reconstructions, that seem to be moderated if mentioned, or critiqued in any way. I mentioned that I didn't want to delve too deeply into paleo reconstructions for the same reason. The existence or not of the LIA/WMP is a point of contention. Due to inconvenience, there are many trying to suggest that they were only European, or Northern Hemisphere, or didn't happen at all... etc. etc. There is evidence that both were global. And there is evidence that it wasn't. Part of the problem is that most studying it over the years seem to do so in the north. The NCDC of NOAA thinks the Greenland, Antarctic and other Arctic cores suggets both well enough. I wish we truly did have a great source of data spanning the globe and time with high precision.
As for Marcott 2013? I think Gavin Schmidt summed it up well.
http://www.realclimate.org/index.php/archives/2013/03/response-by-marcott-et-al/
"This is not the paper you should be interested in to discuss the details of medieval/modern differences. Given the resolution and smoothing implied by the age model uncertainties, you are only going to get an approximation."
And the vaunted academic source for all things climate "Wikipedia" (does Wm. Connolly still babysit it like a hawk on methamphetamines?) .... Hmmm. Not sure what the scientific utility is of averaging multi-proxy studies together. It gives rise to interesting features though. Such as it being cooler in 2004 than it was 8,000 years ago. I'd check the math myself, but the premise itself is too absurd to bother.
However, back to attribution. Nothing to say about the IPCC experts on attribution downshifting estimates of future temperatures, setting aside temperatures at the mean or above from climate model projections as being unlikely? That would seem to be pretty relevant.
-
pbdoc at 12:06 PM on 23 September 2014Newcomers, Start Here
Hey there, great website, thanks for all the great information.
A friend of mine is concerned about the earths magnetic fields and how they are affecting the climate. He sent me this, can someone comfortable with the climate science comment on this and if it something that has been studied or overlooked? Thanks.
http://phys.org/news/2014-05-earth-magnetic-field-important-climate.html
Moderator Response:[PS] Fixed link. The link only talks about changes in the "climate" of the upper atmosphere which, while important for many applications, isnt exactly what most people would think of in terms of climate change.
-
scaddenp at 11:48 AM on 23 September 2014Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
I believe the only goal of the consensus project was to counter the myth "there is no consensus". The importance of this is not for the science but because the consensus position is the only rational basis for making policy whether it is climate or chewing gum. If new data changes the consensus, then policy can be changed as well.
On the question of attribution, the data we possess supports the position that warming since 1970 is 100% anthropogenic, not 10%, 50% or 70%. If you are going to argue for another source of change, then present the data to support that position.
This is particularly so for OHC. Unless you also wish to challenge the consensus of the conservation of energy, you cant talk about unforced natural cycles changing OHC beyond minor wiggles from ocean/atmosphere exchange. I cant see how any amount of dickering about the uncertainties in the forcings can change the position that the warming is anthropogenic.
-
Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
jwalsh - There has indeed been a lot of "selling" on this topic; various and sundry attempting to convince the public that the science is unsettled, uncertain, that we don't know enough to make reasonable policy decisions. "Selling" by the "skeptics", following Frank Luntz's advice to falsely convince the public that no consensus exists, solely to prevent action. Political rhetoric, in other words.
Papers like Cook et al and discussions of the 'Consensus Project' are simply efforts to correct that misinformation, to bring public perception closer to reality. Efforts, I'll note, that you seem to object to strongly - IMO a position more of politics than reality.
-
jwalsh at 11:10 AM on 23 September 2014Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
Composer99 @355
(*) Recall that the scientific consensus - the degree of expert agreement - about AGW is a stand-in for the preponderance of evidence gathered regarding AGW, as outlined in (to pick a not-so-random-example) the IPCC reports.
One of the goals of the "Consensus Project" is to convince the public of the existence of a consensus. That this doesn't seem to be a goal of climate scientists themselves much, I would deem important too, but I don't believe the correct way to go about doing that is to be imprecise over just what the consensus is supposedly about.
Why? Because the natural inclination of people is to be skeptical and to sniff out "spin". They go their whole lives with people trying to sell them something or another. A famous example of this is an advertising claim made by a sugarless chewing-gum manufacturer. They made the claim that "Sugarless gum is recommended by four out of five dentists for their patients who chew gum." The more perceptive amongst the populace noted that, dentists should probably stick to maintaining and fixing people's teeth. And.. "Have you considered the benefit of NOT pestering dentists with ridiculous questions?" But people also noted that "for their patients who chew gum" was an important qualifier. And they also sensibly wondered "What does the fifth dentist recommend? Gum with sugar?" The answer of course was some variation of "Get out of my office.", or "That's a stupid question." or "Chewing sugarless gum is a habit with no discernible benefit one way or another to your teeth." The company made use of this by making a funny campaign that had the fifth dentist shouting "NO!" as a squirrel bit him on the nuts.
The more discerning public is going to wonder similar things about this consensus claim. The "fifth dentist here" either takes no position on their patients gum-chewing, and is in fact, closer to the 4/5. They'll take note of the logical weirdness of deciding that someone who acknowledges that greenhouse gases are a thing that can cause warning is "endorsing" anything meaningful. Particularly when someone who thinks CO2 is causing 49.9% of warming is an explicit rejection, the lowest part of the scale, and a person at 50.1% is an explicit endorsement, the highest of the scale. Fortunately, the vast majority of scientists wouldn't ever sign up to such a ludicrously precise number, and at best would put it as a range, if pressed, or not quantify at all. The "implicit endorsements" might place it at 10%, 100%, or "potato". We're not really sure. I think the question for any such consensus to be sold to the public needs to be clear, concise, and asked directly.
-
michael sweet at 11:06 AM on 23 September 2014Antarctica is gaining ice
Jetfuel:
I Googled "Antarctic ice loss" and found This link from June 2014. It says:
"Between 2010 and 2013, West Antarctica, East Antarctica, and the Antarctic Peninsula changed in mass by −134 ± 27, −3 ± 36, and −23 ± 18 Gt yr−1, respectively. In West Antarctica, signals of imbalance are present in areas that were poorly surveyed by past missions, contributing additional losses that bring altimeter observations closer to estimates based on other geodetic techniques. However, the average rate of ice thinning in West Antarctica has also continued to rise, and mass losses from this sector are now 31% greater than over the period 2005–2010"
Your suggestion that ice loss in the Antarctic is not increasing is incorrect. Perhaps if you Googled better you would be more up to date on your data. At least it is not doubling every five years.
-
Tom Curtis at 10:26 AM on 23 September 2014CO2 effect is saturated
rational being @284, the Earth's surface emits IR radiation upward at approximately 390 W/m^2. Absent IR absorbing molecules in the atmosphere, that IR radiation would radiate to space, making the total IR radiation to space from the Earth 390 W/m^2.
As it happens, some of that IR radiation is trapped by IR absorptive molecules, which then radiate based on their temperature. On average, IR radiation from water vapour radiates from an altitude of (very approximately) 4 km. At that altitude, temperatures are on average 26 K cooler than at the surface due to the lapse rate, so the IR radiation to space from water vapour is at (very approximately) 267 W/m^2. On average IR radiates to space from 10 km altitude, and hence from a temperature of 213 K. Consequently its IR radiation is at (very approximately) 116 W/m^2.
Combined across all factors, including the IR radiation from cloud tops, the IR radiation from the surface through the atmospheric window, and the differences in altitudes in radiation at different latitudes (along with the differences in surface temperatures), the total IR radiation to space averages at 240 W/m^2. That is, it very closely matches the incoming solar radiation averaged across the Earth's surface. Absent the IR active gases, however, it would radiate at the much higher level of the Earth's surface. That, of course, would create an energy imbalance leading to the rapid cooling of the Earth's surface until outgoing IR radiation matched incoming solar radiation again, with the Earth's average surface temperature near 255 K.
-
scaddenp at 09:38 AM on 23 September 2014Antarctica is gaining ice
Jetfuel, it remains completely unclear quite point you are trying to make.
Is it?
1/ Antarctica seaice is increasing, therefore Antarctic is getting colder
- not true as you have been shown. The paradox with seaice increase it that it happens while temperatures warm. Read the provided links/papers for why. Salinity decrease is only part of the story.2/ Antarctic sea-ice increase "makes up" for Arctic sea ice loss.
- Nope, as pointed out above, the increase is only 1/6 of the climatological effect from seaice loss in arctic.
3/?? What are else?
I would have say that it is statement of mighty hope to believe that ice sheet loss has decreased significantly since 2012. Cryosat-2 was measuring record loss rates in 2010-2013. Glacier movement rates were increasing in southern summer of 2013-2014. What do think has suddenly changed to give you that hope?
-
Tom Curtis at 09:34 AM on 23 September 2014The Wall Street Journal downplays global warming risks once again
JoeT @4, CO2 contributes only 1 or 2% to the downward IR radiation at the surface (back radiation). It contributes around 20% to the reduction in outgoing IR radiation to space relative to the upward IR radiation from the surface. Another 75% or so comes from water vapour and clouds, and constitutes the water vapour feedback which many deniers claim does not exist. It is the reduction in upward which constitutes the greenhouse effect, and the reduction in upward radiation that controls the energy balance equation that determines long term temperature trends. The back radiation is important for weather, but in principle its effects can be replaced by changes in the rate of convection. (There is, of course, no convection to space so that is not true of the outgoing IR radiation.)
So, at base Koonan's claim is based on a simple misunderstanding that shows he completely misunderstands the nature of the greenhouse effect, or that he is completely dishonest, or that he is simply parroting memes provided by others without understanding what the mean and what they are related to. The science really is settled on this one, so there is no fourth option.
-
Tom Curtis at 09:27 AM on 23 September 2014The Wall Street Journal downplays global warming risks once again
ubrew12 @12, jja is correct. Carrying the point through, however, only 55% of the emmissions, or 26 ppmv, are retained in the atmosphere. That corresponds to an additional 0.25 C warming on top of that from a 450 ppmv concentration (which seems inevitable from directly anthropogenic sources alone). That 0.25 C is based on the ECS, and for a short term response may be half of that.
A better way to look at it, however, is that it is estimated that we can emit a cumulative trillion tonnes of Carbon and still have a reasonable chance of avoiding dangerous climate change. We have already emitted 580 billion tonnes, so 100 GtC is 24% of our remaining allowance.
-
Tom Curtis at 09:14 AM on 23 September 2014Antarctica is gaining ice
jetfuel @270, the failure to acknowledge clear errors (such as your claim that "the Antarctic is well into unchartered territory in increased area covered by sea ice") shows your purpose in debate is not understanding, but purely rhetorical. Further, referring to data without providing a clear web address or link suggests you are hiding behind your interpretation of the data rather than relying on it.
More directly, the question is not the level of salinity, but the change in level of salinity. From your wording, your NASA site only shows the former. Here is the later, from Zhang (2006):
As you conveniently point out, the trend in Antarctic sea ice is 40 years long. Therefore the 1979-2004 data should provide the clue as to the cause of the increase in sea ice extent, for the sea ice extent was increasing over that period. We therefore notice that it is not due to changes in temperature, which was increasing over that period (panel e). Salinity, however, was decreasing over much of the Antarctic waters (panel d). Further, NASA accepts that data, and agrees that the decline in salinity is part of the explanation of increased ice extent.
-
The Wall Street Journal downplays global warming risks once again
ubrew12 @ 3
2.12 GT of Carbon is equal to 1ppmv of CO2 so 100GT of carbon from melting permafrost is equal to 47ppmv of CO2.
This means that the most agressive mitigation strategy through 2050, in attempting to stabilize at 450ppmv will significantly overshoot.
the reality is that permafrost carbon moves approximately 55% into the atmosphere in the form of CO2. So even this analysis is severely understated. It looks like even the most agressive mitigation strategy won't stabilize below 550ppm. This means that we have a significant job ahead of us removing CO2 from the atmosphere in an attempt to restabilize at 400ppmv. -
jetfuel at 08:36 AM on 23 September 2014Antarctica is gaining ice
Any data out there that shows Antarctic ice mass changes since Sept 2012 cannot be found by me. I understand that the -100 GT/yr number is floated around but there is no data to support this trend over the last 2 years. It is as though 2009 and 2010 data are currently on replay.
Per TomCurtis@268, Antarctic sea ice area is on the rise for almost 40 years as a general trend. With Nasa data showing ocean salinity as average surrounding Antarctica, as opposed to low salinity at the Amazon delta or Black sea, that salt dillution argument is weak as to why sea ice is unprecedented since the early 70's.
-
Tom Curtis at 08:35 AM on 23 September 2014Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
Russ R @350:
1) When I was young I had a biopsy on a lump on my knee which was poorly executed and kept me on crutches for several weeks (and provided a far larger and more gruesome scar than when my leg was ripped open by a wire while sliding down a hillock on cemment bags). Being on crutches for that period was a significant adverse impact. The more so because it caused me to favour one foot over the other (without my knowing) which has lead me to have ingrown toenails late in life. It was not by any stretch of the imagination catastrophic. Neither, for that matter were my three broken bones, said accident with the wire, or the various times I have bounced motorbikes of my knee as I hit the pavement (including the occassion that laid the skin back to reveal the patella. "Significant adverse consequences" does not mean "catastrophic", whatever your rhetorical needs to distort the language.
Of course, significant adverse consequences for a society are much larger than significant adverse consequences for an individual, but so also is the level of harm that is needed for the events to be called catastrophic.
Further, my clause (c) explicitly gave a probability indicator. The "significant adverse consequences" are likely, which allows that there is a real possibility that they will not happen, and even a very remote possibility that there will be net benefits. So at most your distortion should be Potentially Catastrophic AGW, which indeed I believe it to be although I do not think that is the consensus position.
2) Michael Sweet's comment about your marking yourself as a denier with the use of the term CAGW is entirely correct. So are his citations, although I would have preffered just the IPCC myself.
3) Bray and Von Storch (2010) asked a sample of climate scientists:
"22. How convinced are you that climate change poses a very serious and dangerous threat to humanity?"
In the responses, 78.92% were more than half responded 5 or higher on a 7 point scale where 1 was "not at all convinced" and 7 was "very much convinced". If you want to take that as the consensus level on clause (c), I have no problem. I do note, however, that "a very serious and dangerous threat to humanity" is a far larger level of harm than "cause significant adverse consequences". I further note that my clause (c) says only that the level of harm is likely, so that strictly even those who are 50/50 on the proposition (response 4, 10.81%) or even 43/57 (response level 3, 4.054%) should be considered part of the consensus on clause (3). That would lift the consensus level to 93.784%, ie, within error of 97%. The actual consensus on (c) is likely to lie in the 90% region, IMO (based on Bray and von Storch).
Regardless, while Cook et al do not investigate opinions on future impacts, it has been investigated in the "consensus literature" contrary to your claim. And in that investigation, the proportion of climate scientists who think there is no risk of "a very serious and dangerous threat to humanity" from AGW is only 1.162%
-
ubrew12 at 08:21 AM on 23 September 2014The Wall Street Journal downplays global warming risks once again
JoeT@4: There are people on these comments way more qualified to answer you than me, but just looking at the temperature effect, if 0ppm CO2 to 280ppm raises temperature by 60F (the greenhouse effect), then going up to 560ppm (a doubling) will only bring it up another 5F, or about 8%. I'm sure the way he's doing it is in Watts/sq in or something but who cares. It's severely disingenous. He's claiming that the basis for comparison of the effect of AGW is with a planet with no greenhouse effect (also known as a ball of ice). Well, sure, compared to such a planet, the effect of AGW is in the noise. And compared to the Sun, Earth is cool. So what? The Real point is: does that 5 F matter to us mere humans. Koonin excepted, apparently, yes it does.
-
jwalsh at 08:00 AM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
KR @89
1950-1960 is not when anthropogenic contributions become detectable in the climate record, but rather when they become dominant over natural forcings.
This would be a distinction without a difference for the purposes.
GISP2 is a local record, not a global one, recording temps at a single point on the Greenland ice cap. There is no evidence that I am aware of for 1200 year cycles, incidentally - that claim of yours appears to have materialized out of left field.
That the climate has varied wildly in the past is not "out of left field". It is considered to be more established scientific fact than most IPCC statements. The Minoan, Roman, and Medieval warm periods occurred at roughly 1200 year intervals. I acknowledge that the GISP2 is a local record. It is not, however, the only record. And a person would need to describe some proposed mechanism of extreme arctic warming and cooling cycles independent of the rest of planet earth to speculate that it was local. Could there be such a thing? I am not sure. I would be curious to hear one.
Negative anthropogenic forcings have a fairly high uncertainty - but the best estimate is for a climate sensitivity around 3C/doubling of CO2. Claiming that they are small and that correspondingly ECS is low (as you appear to) is a cherry-pick of but one low-likelyhood end of the PDF, and that isn't justified by anything other than wishful thinking.
Considering that there is strong observational evidence to support an ECS estimate of below 3, I am not alone. In fact, I suspect that a FAR greater percentage than 3% of the IPCC themselves would agree there. One need only pick through the IPCC expert reviewer comments to easily demonstrate a lack of clear agreement. I think that the PDF cobbled together from the 10.5 figure is getting an inordinate amount of attention. It would be similar to deciding that any particular PDF for climate sensitivity itself was the "correct" one. As observed my many, AR5 seemed to weight model methods of determination of ECS over observational ones with little justification. This would be, incidentally, in contrast to AR4 with no well-documented reasoning.
Temps have been running below (averaged) model projections for ~15 years - a statistically insignificant time period, while remaining in the 2-sigma model range. That means there has been no invalidation of the models to date.
If you'd like to discuss what is a statistically valid time period, that would be an interesting discussion. Certainly a great deal of ink has been made over the statistically much more "valid" 18 year period of 1980-1998. Do we really need to wait just a few years to consider an 18, 20, or 25 year trend? The IPCC thinks not. How many people have drawn trend lines over CRUT4 data or UAH satellite data? However, if 15 years is too short of a time period to consider making model adjustments, those actually doing so, such as those running them, are being hasty. And the IPCC themselves would be being "hasty" in using short term temperature data to alter their own 20-year temperature projections well below that of the model outputs. And they did exactly that in AR5.
It's worth noting here, that I don't think the IPCC attribution is "way off". Just minorly so. And for the record, I don't rule out climate sensitivity of "4" either, or indeed attribution of AGW of 120%. How would I know? As I said, greater effort would probably spent worrying about convincing the much smaller fraction of scientists who put it well below 50%.
-
Tom Curtis at 07:50 AM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
michael sweet @91, that is not a fair statement of the consensus. There are a significant core of climate scientists who do think that the IPCC, in general underplays the problem. There are also a substantial majority that think it gets it about right, and a large number who think it overestimates the problem by a small degree. Some of those (such as James Annan, and John Nielson-Gammon) are clearly very competent scientists who are following the science as best they understand it, as indeed are those on the other side of the coin. Further, some IPCC projections are clearly high including global temperature increase, which runs about 15% below projections even after accounting for ENSO. For other observations, IPCC projections are low (as with reduction of Acrtic Sea Ice extent, and sea level rise).
My problem with jwalsh is not that he thinks the IPCC has overestimated the problem, and more specifically the attribution level. His position is a consensus position. My problem is that he does so based on either no, or clearly misrepresented evidence. If you are going to disagree with the IPCC, you should do so scientifically, which clearly he does not.
-
Tom Curtis at 07:38 AM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
jwalsh @86:
"Yes, there's a tricky limitation with ice cores. The ones at the equator don't last nearly as long. I didn't say they were a perfect match to NH temps (or global). Evidence that the Greenland temperature swings were localized for some reason? None provided. Evidence of the Minoan, Roman, and Medieval warm periods from either historical records and other proxies? Hell yes. But sure, might not be as extreme in swing. Do you have a good explanation for the approximately 1200 year cycles?"
It goes tiresome correcting the errors, lack of evidence and outright falsehoods on which you base your "expert opinion". Never-the-less, here are the results of six near equatorial ice cores from high altitudes:
Here are three of the tropical or subtropical icecores along with three polar icecores:
And here the equivalent ice core (in blue, dO18) from Mount Kilimanjaro, which at 3 degrees, 3.5 minutes south, I think counts as being "at the equator":
You will notice that only Sajama has, what might be considered to be, your 1,200 year cycles. You will further notice the distinct hockey stick in the 6 ice core composite.
Further, I refer you again to the Marcott et al (2013) reconstruction of holocene temperatures, as displayed above along with eight temperature proxies and their arithmetic mean as constructed by Robert Rohde for wikipedia:
Again, the Roman Warm Period and the Minoan Warm Period, not to mention the 1,200 year cycles are only present in GISP2, and is distinctly not present in the global reconstructions.
The RWP and MWP are distinctly North Atlantic phenomenon, and have significant impact over European temperatures. That they do not have any discernible impact on global temperatures is a spear in the side of any theory that modulation of North Atlantic Temperatures is a significant, let alone a major cause of variance in global temperatures.
So:
"Evidence that the Greenland temperature swings were localized for some reason? None provided."
Evidence the sky is blue? None provided either, and none needed because it is assumed to be well known by anyone well informed on the topic as you claim to be.
"Evidence of the Minoan, Roman, and Medieval warm periods from either historical records and other proxies? Hell yes."
But exclusively restricted to NA (and immediately neigbouring land) proxies showing beyond doubt that they are regional, not global variations in temperature. As we are discussing impacts on global temperatures, your introduction of a known regional temperature proxy with poor correlation with other regional temperature proxies counts as a red herring at best - and is either proof that you are not well informed on the topic, or that you are intent on deception (if you are indeed well informed).
-
CO2 effect is saturated
rational being - I'm not entirely certain what your question is. CO2 at the top of the atmosphere radiates energy into space in the IR bands, with an effective emission altitude generally defined as where 50% or more of the emission escapes without absorption. That altitude is determined by the total amount of IR absorbing gases above that point in the atmosphere, and is rather directly related to the partial pressure of GHGs.
As CO2 levels increase, that effective emission altitude increases. Given the lapse rate, an increase in altitude means a decrease in temperature, hence a reduction in the IR energy radiated, an imbalance at the top of the atmosphere. That imbalance will persist as energy accumulates on the surface, warming the entire atmospheric column including the CO2 at the effective radiating altitude, until the energy radiated equals the energy incoming from the sun.
Summary: Increased GHGs -> increased radiating altitude thus colder radiating gases -> less energy leaves -> climate warms -> upper atmosphere warms as a result -> amount radiated equals amount received.
-
rational being at 07:03 AM on 23 September 2014CO2 effect is saturated
CO2 and similar assymetric species are necessary in order to radiate IR into space, for the same reason that they absorb IR.
IR frequencies are those of the bond-stretching modes and couple to the EM field via molecular dipoles (and molecular rotation to conserve angular momentum).
Suppose the upper atmosphere contained only N2 and O2. These molecules' bond motions cannot couple to the EM field [to 1st order] so cannot radiate IR. The heat would be trapped until the temperature rose enough to allow electron modes to radiate.
But there is CO2. And if the partial pressure of the CO2 is increased, that should provide more opportunities for the upper atmosphere to radiate, and so cool the upper atmosphere.
We already know that vertical heat transport in the lower atmosphere is dominated by convection [the IR "greenhouse effect is saturated there].
So doesn't that mean that extra CO2 in the upper atmosphere is an advantage to shedding IR into space?
I suspect that human changes to land use will turn out to be the dominant anthopogenic contribution to climate change.
-
JoeT at 06:52 AM on 23 September 2014The Wall Street Journal downplays global warming risks once again
In his article Koonin states,
"For example, human additions to carbon dioxide in the atmosphere by the middle of the 21st century are expected to directly shift the atmosphere's natural greenhouse effect by only 1% to 2%."
Anyone know what he is referring to when he says one to two percent? -
Composer99 at 05:59 AM on 23 September 2014Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
I believe, Russ R, that you should probably attend more to the goalpost-sized log in your own eye before getting so exercised about the mote in that of the current POTUS. (*)
I mean, your initial line of attack last week was that there were serious problems with Cook et al 2013, using a source that alleged fraud on the part of the Cook et al author team.
This week, without the slightest peep of acknowledgement that last week's criticisms were bogus, we're on to how President Obama is being misleading. That's practically a textbook example of moving the goalposts:
Person A: Cook et al is wrong [baldly stated or carefully insinuated] because reasons.
Person B: Those reasons are all rubbish. [Explanation demolishes reasons presented by Person A.]
Person A: Well, what about Obama's tweet, then?
(*) Recall that the scientific consensus - the degree of expert agreement - about AGW is a stand-in for the preponderance of evidence gathered regarding AGW, as outlined in (to pick a not-so-random-example) the IPCC reports.
So President Obama, at least, has a leg to stand on when he Tweets "climate change is real, man-made and dangerous", even if he is off the mark in referring to "ninety-seven percent of scientists" and providing a hyperlink to the Reuters article describing Cook et al 2013.
Moderator Response:[PS] Just a friendly reminder that political discussions are forbidden by the comments policy. Please dont let this discussion veer into politics.
Also, [RH] Russ is officially off this topic due to excessive repetition. You can find him on the It's not bad myth thread.
-
It's not bad
Russ, what you define as the "consensus research" never set out to measure consensus on the danger, so why complain about it? After all, the IPCC has already established a level of consensus in WG II, a report that summarizes much of the existing research on impacts (citing over 12,000 publications). How much more of a consensus do you want? Do you find that none of the WG II conclusions constitutes a significant adverse impact?
-
michael sweet at 04:27 AM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
jwalsh,
It is worth pointing out now that the IPCC positions are a consensus low amount of warming and/or damage. The majority of scientists in many fields think the IPCC projections are too low. None of the IPCC projections are thought to be too high. We use the IPCC projections here for debate because it gives us a reasonable starting point. Claiming without any data that they are much too high is a waste of time (trolling).
For example, sea level rise has always run at the very top of IPCC projections. Alternate methods of estimation of sea level rise are double the IPCC projections. Arctic sea ice has run ahead of almost all projections and is currently 50 years ahead of AR4.
Your suggestion that the IPCC is too alarmist without any data to support your claims is simply uninformed. Your posts have become longer and more disjoint. At the same time your claims have become even more extreme. Perhaps you need to rethink where you are getting your ideas and see if they have any data to suport your wild claims.
The LIA was a local event, not a global event. There is no trace of it in the reconstructions of global temeprature. You are incorrectly applying European and North American temperature records to the globe. You look uninformed when the only support you have for your claims is incorrectly applying a local event to a global discussion.
Claims made without data are easily dismissed. You are fortunate that Tom and MA Roger are so patient with you.
-
Russ R. at 04:23 AM on 23 September 2014Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
DSL & KR,
"None of the "consensus research" has investigated views on future impacts." That would be entirely incorrect."
"Huh? Are you saying that none of the research examined in Cook et al. spoke toward future consequences? Or are you saying that future consequences of rapid warming have not been examined by climate science in general? or what?"
No, (and sorry for not being clear) I'm saying that Cook's research paper didn't in any way measure or establish a "consensus" regarding dangerous impacts among the 12,000+ reviewed abstracts.
The "Consensus research" (as I'd put in quotations) consists of 4 studies that attempt to define and quantify a "consensus" in climate science: Oreskes (2004), Doran & Zimmerman (2009), Anderegg et al (2010) & Cook et al (2013).
They all looked for narrow AGW consensus on the questions "Is the planet warming" and "Is the warming manmade". Where did they ask anything about the future impacts of warming?
Extending the consensus to anything beyond "the planet is warming" and humans are causing it" is shifting the goalposts.
That's why it the Obama tweet was misleading. It's fine to say that Cook13 found a consensus that warming was real and man-made. But "dangerous"? The question of future impacts was never evaluated by the Cook study, so nobody can claim that the study showed a "consensus" on the matter of whether global warming is or will be "dangerous".
And, just for giggles DSL, my definition of "catastrophic" is exactly what Tom Curtis wrote @249. I don't intend to waste more time or bandwidth on the matter.
(-snip-)
Moderator Response:[RH] Snipped as off-topic, after having made a clear request to move to an appropriate thread. You can repost your comment on the "it's not bad" myth thread.
-
ubrew12 at 03:42 AM on 23 September 2014The Wall Street Journal downplays global warming risks once again
jja@2: does anyone know what 100Gt C translates into as temperature rise? I'm just curious.
As for the WSJ article, perhaps its time to call the bluff on what Koonin and others are doing: they are offering the public a false choice. To use an analogy, suppose you need to get downtown. Person A says take the road on the left. Person B says Person A is wrong. Now, the WSJ kicks in and says, "Let's be fair and balanced about this: is Person A right or is he wrong?" That is neither fair nor balanced: its a false choice. You still need to get downtown; the proper choice is the road on the left or another road. But Person B is not offering you a path downtown: he's just casting Doubt.
Koonin needs to tell us what the climate will be like by 2100. Failing that, he needs to get out of the way and let the experts on stage. Because 2100 is coming whether we like it or not. Koonin must know he represents the profound wishes of the most profitable corporate sector in the history of commerce. The fossils industries physically model everything they work with: oil fields, drilling rigs, refineries, coal deposits, trouble in the Middle East. To say they are simply incapable of developing a 'path downtown', i.e. an opinion of what future climate will look like if we keep using their product, is absurd on its face. They most certainly have an opinion, and just as assiduously want that opinion kept under wraps.
We still need to get downtown, and the false balance offered by rags like the WSJ aren't helping us one iota. Indeed, their primary purpose is to prevent the proper choice from ever being confronted. Koonin is either being paid to help them or is too egotistical to see how he's being used.
-
The Wall Street Journal downplays global warming risks once again
Under the RCP 8.5 most aggressive scenario, the spatial structure of variations in the carbon resources in the active layer is similar to the one obtained from the results of numerical modeling in experiment Cs–2 with the maxima in the southern regions of the cryolitic zone of Eurasia and North America (see Figs. 2c, 2b). According to this scenario, the resources of organic matter released as a result of thawing of longterm permafrost ground by the end of the 21st century exceed 100 Gt C.
LINKDOI: 10.1134/S1028334X14030234
Moderator Response:[RH] Hotlinked url.
-
The Wall Street Journal downplays global warming risks once again
Did you know that the RCP 8.5 temperature projections neglect to include positive feedbacks from methane and CO2 releases from melting permafrost?
-
Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
Russ R. - "None of the "consensus research" has investigated views on future impacts." That would be entirely incorrect. See the various IPCC WG2 reports on climate change impacts, such as AR5 Impacts, Adaptation, and Vulnerability, summarizing the literature on just those topics.
It's difficult to take your comments seriously if you make such outrageous claims.
Moderator Response:[RH] If this discussion is to continue, let's move Russ over to the It's not bad myth thread.
-
Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
Russ: "None of the 'consensus research' has investigated views on future impacts."
Huh? Are you saying that none of the research examined in Cook et al. spoke toward future consequences? Or are you saying that future consequences of rapid warming have not been examined by climate science in general? or what?
Also, just for giggles, what does "catastrophic" mean to you?
-
michael sweet at 01:45 AM on 23 September 2014Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
Russ,
The "C" in CAGW is completely made up by deniers and is never seen in the scientific literature. If you need to define that term it means you have been informed by deniers and are unfamiliar with the appropriate scientific terms. Tom's defination is generally accepted. Look at the recent position papers from the Academy of Science and AAAS.
-
Russ R. at 01:24 AM on 23 September 2014Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
Tom Curtis @348,
Specifically, "the AGW theory" is, in its simplest form, that:
a) humans have caused most of recent warming,
b) continuing as we have will result in a very significant warming, and
c) warming is likely to cause significant adverse consequences.
Citation needed.
What you've described above is more commonly known as CAGW theory, the "C" standing for "Catastrophic". And I'm skeptical.
In it's simplest form, AGW theory consists of exactly three things. Anthropogenic, Global, & Warming. i.e. that human activity causes the planet to warm. That's all. It's a theory which has an abundance of supporting evidence, and with which I am entirely in agreement. And that's the full extent of the "consensus" which has been tested and confirmed. None of the "consensus research" has investigated views on future impacts.
Moderator Response:[RH] This is off topic for this thread. Move it to an appropriate thread.
-
MA Rodger at 00:47 AM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
jwalsh @86.
You write:-
"I kind of agree with Lord Monckton that this appears to be somewhat of a universal "fudge-factor", varying wildly. I think it's over-estimated. And there's evidence that it was declining into the late 20th century."
I suppose I should be grateful that you implicitly agree to there being negative anthropogenic forcings. I know not what "kind of agree" is meant to men except when the difference between "kind of agree" and "agree" are made plain, something you fail to manage. But then it is dangerous ground being associated intellectually with the Viscount of Brenchley.
I would suggest that there is a contradiction hiding within something appering to be "...somewhat of a universal "fudge-factor", varying wildly." Of course, if it is "universal" I would assume that the Viscount of Brenchley has some use of it. And me. And you.
As negative anthropogenic forcings are not easily evaluated, their impact could easily be over-estimated as they could be under-estimated. And you say there is "evidence" of their decline. Where is that evidence? It appears to apply to a time "...into the late 20th century" which is a bit ambiguous but my interpretation suggests a period I haven't seen the slightest evidence for a decline, rather evidence for rapid rise.
And with that, I have dealt with less than 10% of your comment @86. I point out this proportion to demonstrate why some of the assertions within your comments will go without comment despite their complete lack of veracity.
-
The 97% v the 3% – just how much global warming are humans causing?
jwalsh - Several comments here:
1950-1960 is not when anthropogenic contributions become detectable in the climate record, but rather when they become dominant over natural forcings.
GISP2 is a local record, not a global one, recording temps at a single point on the Greenland ice cap. There is no evidence that I am aware of for 1200 year cycles, incidentally - that claim of yours appears to have materialized out of left field.
Negative anthropogenic forcings have a fairly high uncertainty - but the best estimate is for a climate sensitivity around 3C/doubling of CO2. Claiming that they are small and that correspondingly ECS is low (as you appear to) is a cherry-pick of but one low-likelyhood end of the PDF, and that isn't justified by anything other than wishful thinking.
Temps have been running below (averaged) model projections for ~15 years - a statistically insignificant time period, while remaining in the 2-sigma model range. That means there has been no invalidation of the models to date. Add in more accurate forcings (better than the ones used for CMIP5) such as discussed by Schmidt et al 2014, which clarify that short term internal variation is indeed negative right now, and there is every indication that the models are right on track.
---
The gist of your various Gish Gallops here seems to be that you disagree with the IPCC estimates of natural forcings, of indirect aerosols, of internal climate variability, and that you don't like the climate models. All because you "think the IPCC got that wrong". IMO your gut feeling simply doesn't measure up to the evidence.
-
Composer99 at 00:40 AM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
Ah, I clicked "Submit" before finishing, for which I apologise.
It is an excerpt from jwalsh's comment #86 that I have called out as incorrect in #87.
-
Composer99 at 00:37 AM on 23 September 2014The 97% v the 3% – just how much global warming are humans causing?
A combination of the two of these seem to be completely off-setting anthropogenic warming for the last decade and a half, and may have accounted for a good piece of the 1980-1998 warming.
The bolded portion is entirely incorrect.
-
jwalsh at 22:55 PM on 22 September 2014The 97% v the 3% – just how much global warming are humans causing?
Moberg 2005 trend from 1600-1850 - 0.08 C / Century.Moberg 2005 mean trend from start years between 1600 to 1700 inclusive through to 1850 - 0.09 C / Century
Moberg 2005 maximum trend from a start year between 1600-1700 inclusive to 1850 - 0.11 C / Century.
jwalsh overestimation factor 175-250%
Ahh. I see your error straight away. Yes, picking an end still at what is considered to be the end of the little ice age would indeed give a low estimate, and wrong just by inspection. The IPCC considers about 1950 as being the threshold period when anthropogenic causes start to be detectable in the record. Before then anthropogenic forcings just too small.
1600-1950 Moburg 2005 by my quick math : ABS(0.9-0.2 (deg. C approx))/35 decades = 0.02 deg C./decade .....exactly as I said. I should have specified a range. But it honestly didn't occur to me that someone familiar with climate would decide that 1850 at the end of the LIA was a sensible choice.
As for the troll discussion? I prefer to keep things on a mature and civil level or not at all. I'm funny that way. I think you'll find that it's not that easy to get a rise out of me though. I'm not so thin-skinned. Perhaps it's a relative age thing.
Standard troll attempt to mistake regional (Greenland) temperatures for global or NH temperatures by jwalsh - One to date.
Yes, there's a tricky limitation with ice cores. The ones at the equator don't last nearly as long. I didn't say they were a perfect match to NH temps (or global). Evidence that the Greenland temperature swings were localized for some reason? None provided. Evidence of the Minoan, Roman, and Medieval warm periods from either historical records and other proxies? Hell yes. But sure, might not be as extreme in swing. Do you have a good explanation for the approximately 1200 year cycles?
Firstly there are positive anthropogenic forcings of which CO2 is the biggest, and scariest because it is very long-lasting. The force of this first group can be evaluated with some accuracy.
Agree with that. Especially for the present and future.
Secondly is negative anthropogenic forcings.
I kind of agree with Lord Monckton that this appears to be somewhat of a universal "fudge-factor", varying wildly. I think it's over-estimated. And there's evidence that it was declining into the late 20th century.
The third category is natural forcings which can be evaluated with fair accuracy. There is no evidence to suggest they are very large. There is no evidence to suggest they are at present a positive forcing.
The fourth category is unforced internal variability of the climate system. There is no reasonable evidence to suggest this is a large effect.A combination of the two of these seem to be completely off-setting anthropogenic warming for the last decade and a half, and may have accounted for a good piece of the 1980-1998 warming. I think this is the IPCC's current biggest challenge. I have yet to see convincing a explanation for the 1910-1940 warming, and the above two reasons seem as likely as any other.
I see you missed my bit about the IPCC currently (and quietly) estimating temperatures at the the bottom range of model estimates (and even below). This appears to be an expert determination that the models are simply over-projecting by the IPCC. Perhaps you disagree with the IPCC on this. Your prerogative.
-
CBDunkerson at 21:31 PM on 22 September 2014Climate's changed before
schema, you can find general information on some of the methods of measuring global temperature anomalies here. Note that the 'fixed location' land-based temperature measurements you cite, and ocean buoy measurements for sea temperatures, have also been confirmed by weather balloon and satellite measurements. Numerous temperature proxies (e.g. tree rings, coral growth layers, ice cores, ocean sediment cores, et cetera) also match the various forms of direct measurement.
-
MA Rodger at 21:21 PM on 22 September 2014The 97% v the 3% – just how much global warming are humans causing?
Tom Curtis @80.
The graph you show from Dean et al (2014) gets me scurrying for the Houghton land-use emissions data which shows a pronounced kink in the emissions data, changing from 3.5Mt/yr/yr to 23Mt/yr/yr, at, you guessed it, 1950. How robust the Houghton data actually is, I know not, but the shift is quite profound (evidently, being x7) and well defined. I note Dean et al. make no comment on changing land-use emissions at that time, rather they stress the effect of FF emissions which of course have turned the biosphere from an increasing net CO2 source to a smaller CO2 net source/sink (which it had become by 1970). However the dramatic fall from an increasing source to a minor player occurred in the early 1950s. -
MA Rodger at 21:14 PM on 22 September 2014The 97% v the 3% – just how much global warming are humans causing?
jwalsh @81.
Down this comment thread, you have indeed been picking at the basis of the IPCC's Figure 10.5 but you have not until now reputed it in its entirety.
Yet if you were to get an answer to your questioning ("Where do you think attribution percentage is?"), that answer should be a lot more detailed than the likes of "Oh I see it at 110% ±10%." and such a fuller acount would very likely be a verbal Figure 10.5; something like this:-
Just like in Figure 10.5, things that affect global temperature can be placed into 4 catagories, all zeroed at AD1750.
Firstly there are positive anthropogenic forcings of which CO2 is the biggest, and scariest because it is very long-lasting. The force of this first group can be evaluated with some accuracy.
Secondly is negative anthropogenic forcings. These are not so easily evaluated. If their recent effect is very large, that is scary as it means climate is highly sensitive to forcings and potentially we could see some very large temperature changes if the negative forcings were to reduce. That is possible as they are not as long-lived as the positive ones. It is very unlikely that the negative ones are very small (and they cannot be negative) which means sensitivity cannot be very low so there is every reason to be worried by the size of the positive forcings.
The third category is natural forcings which can be evaluated with fair accuracy. There is no evidence to suggest they are very large. There is no evidence to suggest they are at present a positive forcing.
The fourth category is unforced internal variability of the climate system. There is no reasonable evidence to suggest this is a large effect.If somebody does wish to overturn Figure 10.5, they should really be indicating why - what within this description here is seen as wrong.
Judith Curry for instance, the subject of the post, believes the third category could contain "known unknowns" and even "unknown unknowns." However she does so on the unscientific-basis of zero evidence so jwalsh may well disageree with her give the acknowledgement of a "scientific education." Curry also has objections with the category 4 assessment that are a little better defined. Here she advocates the Stadium Wave, a highly dodgy use of a poorly defined hypothesis.
And on this unlikely basis Curry refutes Figure 10.5 with her unswerving 50:50 attribution alongside assertions of a low ECS. The reasoning for her position and how they link to her objections are not at all clear.Of course, while Curry has so obviously lost the plot, she actually does better than those whose argument gets no further than "No no no!!" which is my assessment of the position presented thus far by jwalsh.
-
Tom Curtis at 20:30 PM on 22 September 2014The 97% v the 3% – just how much global warming are humans causing?
jwalsh @81:
"So (presumably solar?) effects could be on the order of 0.12 degrees for 1950-2010."
Some more numbers, with data from the IPCC AR5 reconstruction of TSI as detailed here.
1951-2010_|_Forcing_|_7 Year mean_|_Units
Difference__|_-0.033__|___-0.064____|_W/m^2
Trend______|_-0.008__|___-0.0082___|_W/m^2/DecadeSo, a negative solar contribution magically becomes a positive contribution of 0.12 C (ie, with an effective Transient Climate Response of -13.45 Degrees K/W/m^2 all by the magic of an arbitrary and irrelevant invocation of GISP2.
No wonder jwalsh thinks the IPCC underestimates uncertainty. He is able to find contrary certainties whereever he looks.
-
Tristan at 19:02 PM on 22 September 2014Climate's changed before
Also, for future reference, after doing a basic level of Googling yourself, it's "Could someone please <request>?" or "I need help understanding <thing> and would really appreciate..."
-
Tristan at 18:55 PM on 22 September 2014Climate's changed before
Google didn't work?
http://en.wikipedia.org/wiki/Weather_buoy
Prev 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 Next
