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Comments 34101 to 34150:
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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?
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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.
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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.
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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.
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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.
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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?
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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.
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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?
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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..."
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Tristan at 18:55 PM on 22 September 2014Climate's changed before
Google didn't work?
http://en.wikipedia.org/wiki/Weather_buoy
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martinboas at 18:33 PM on 22 September 2014Climate sceptics see a conspiracy in Australia's record breaking heat
Hi, I'm new here. But what are Marohasy and LLoyd trying to say? Does anyone seriously think that dedicated career public servants would fiddle the record at Rutherglen to "prove" global warming? Or that these same people are part of some global conspiracy? The suggestion is ludicrous. If (as Jennifer claims) some-one should be sacked on the basis of all this, I'd suggest she look closely at her own motivation and scientific rigour. As for Lloyd, what more can be said; other than most of his employer's stable of newspapers studiously ignored the fact that tens of thousands of people marched (last weekend) to bring attention to climate change. His latest effort in the Weekend Australian, (on Antarctic sea ice) is yet another example of trying to muddy the water...rather than trying to inform us as to what is really going on.
Thanks for all the info. from contributors. It helps to know all is not lost.
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giulio8 at 18:06 PM on 22 September 20142014 SkS Weekly News Roundup #38B
Tom Curtis @6
Thanks for answering!
Let me just to complete your description with more updated news, when you write "He even, for three years, held an Assistant Professorship at Harvard":
Motl has *not* published a *single* paper there or anywhere else since 2007, when he split from Harvard, when he *lost* his job and has *not* held a university position since! From a better link:
http://rationalwiki.org/wiki/Lubo%C5%A1_Motl
It's important to be *honest* and clearly show the *incompetence* of this (climate change denier) blogger.
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schema at 17:44 PM on 22 September 2014Climate's changed before
Explain, precisely, how the temperatures are measured. I assume land-based temperatures have fixed locations. If so, how many are there, both in the United States and worldwide. How are temperatures obtained over the seas?
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Tom Curtis at 17:41 PM on 22 September 2014The 97% v the 3% – just how much global warming are humans causing?
jwalsh @81:
"MA Rodger @69
'Being as generous as I can , Figure 3 from Mann et al (2008) here shows perhaps 0.1ºC per century rise for the NH "since 1600 or so", about 7% of the 20th century rise. (Being less generous, note that some of the reconstructions are flat with zero warming.)'
I get roughly 0.02 per decade for Moburg. Which, while the outlier for that paper, there are others showing 0.03. Arguing over it would probably start a big paleo-climate discussion."
Running through some numbers:
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%
Percentage of trend from "1600 or so" that is unforced - no estimate by jwalsh, assumed to be 100% by his implicit argument.
Discussion of forcing history from "1600 or so" by jwalsh - zero.
Invocation of higher trends from unspecified data sets so that the numbers can't be checked - One to date.
Standard troll attempt to mistake regional (Greenland) temperatures for global or NH temperatures by jwalsh - One to date.
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jwalsh at 16:11 PM on 22 September 2014Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
"If you do not like the methods used by Cook13 then you are highly encouraged to create your own research and submit to peer review. We would be eager to see your results."
That strikes me as somewhat defensive, and unusual. I don't think I have ever seen that as a response to criticism of a paper elsewhere.
A person does not need to replicate research to comment positively or negatively on results and interpretation. The people who wrote the paper can choose to respond or not. They aren't obligated either way. I can write a criticism of a paper if I think they've interpreted something incorrectly, like an NMR or FT-IR spectra, or notice something they missed. Someone could suggest a different restriction enzyme or method in biochemistry, etc... etc... without doing the research again.
For instance, when I first read the Cook paper, and in particular, the author self-rated portion, I found myself curious about the people's thoughts on the question, even if they rated their own papers as not taking a position. And in the politics of it, "people" and "papers" seem to be interchanged cavalierly. I would note that because the issue of politics is a large one on the topic, a great deal of scientists (addressed with the drama effect discussion a little) might studiously avoid quantification, or even mentioning "global warming" or "global climate change" so as not to get dragged into defending their paper on a political, rather than scientific basis. I would think most scientists are interested primarily in the science, not the politics, and for them the question of consensus might be interesting, but less important. I think the lack of understanding of the rating system and what it means speaks possibly to a lack of clarity. I find myself wondering how well the raters themselves understood it (particularly in light of the 33% initial disagreement between them), or even the scientists invited to self-rate their papers. Maybe something to consider for follow-up, if any. And I can't for the life of me figure out why both the people and papers that didn't take a position, explicit or otherwise are considered not part of it. To a scientist, the answer "I'm not sure." is a perfectly valid answer, especially if they aren't actually sure. :)
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Rob Honeycutt at 13:59 PM on 22 September 20142014 SkS Weekly Digest #38
Well, the whole point is the NYC gathering is in response to the UN Climate Summit taking place in NYC.
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chriskoz at 13:43 PM on 22 September 20142014 SkS Weekly Digest #38
From Peru@2,
Latest estimates in NY are 400,000. However other cities gathered much less. Ten times less: 40,000 in London. In my city of SYD, the number was so miserable "around 300 protesters", that it's simply shameful to repeat that news.
Your district maybe smaller/less polluting than most Amer/Aus districts. With that perspective in mind, I consider SYD event an organisational failure because SYD, like NY is supposed to be one of the world most developed/biggest cities (i.e. the leading climate polluter) so having 3 orders of magnitude fewer demostration here is just disgraceful about its inhabitants.
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jwalsh at 13:28 PM on 22 September 2014The 97% v the 3% – just how much global warming are humans causing?
MA Rodger @69
Being as generous as I can , Figure 3 from Mann et al (2008) here shows perhaps 0.1ºC per century rise for the NH "since 1600 or so", about 7% of the 20th century rise. (Being less generous, note that some of the reconstructions are flat with zero warming.)
I get roughly 0.02 per decade for Moburg. Which, while the outlier for that paper, there are others showing 0.03. Arguing over it would probably start a big paleo-climate discussion.
And going to Greenland ice core data, there have been strong periodic shifts of roughly +- 1.0 deg C per millennia or so, which is more consistent with 0.02 than 0.01. And while the core trend shows an overall downward trend, that slope is much shallower than the millennial swings. So (presumably solar?) effects could be on the order of 0.12 degrees for 1950-2010. And they seem to be either strongly positive or strongly negative, not normally distributed around a mean on decadal scales.
Tom Curtis @68
Never-the-less it is interesting to note that your "estimate" of the anthropogenic contribution has a probability of 2.3% based on Fig 10.5, and that even if we inflate IPCC uncertainty so that there is a 5% chance of a 50% contribution or less, that probability rises to only 5.8%. Further, it is interesting to note that, as discussed above, your evidence for your preffered contribution is weak, ambiguous (at best) and does not in fact support your preferred value. However, if I ever decide to determine the anthropogenic contribution by inexpert ellicitation, I'll be sure to keep your wild assed guess in mind.
Tom, what you seem to keep forgetting is that someone who disagrees with the logic of the attribution assignment numbers and estimated uncertainties derived from models and summarized in 10.5 is that they think the IPCC got that wrong. So arguing probability estimates from 10.5 is a circular argument. They think those probability estimates are wrong as well.
And I like to think my opinion is at least an educated one. I derive my own thoughts on attribution from a scientific education, reading peer-reviewed papers on it since 1992 or so, and every IPCC report ever published. If there's a better way to come by climate information, I'd appreciate any tips. No, putting a lot of stock in the opinion of a random person on a blog, would certainly be an inadvisable approach. But I don't think the policy types would shift to that mode after ignoring the IPCC.... I mentioned it for context of my thoughts. Where do you think attribution percentage is? And did you come by your climate education guiding your own opinion any differently than I did?
One of the things about IPCC reports is that they sometimes lack self-consistency. The attribution experts within the IPCC seem to have issues with the model estimates for temperature and the under-lying assumptions as well, and in fact say so.
Figure 11.25b in Chapter 11 of AR5 (having issues with the new Firefox and Imgur), shows an expert-assessment of the IPCC of the next two decades. It shows "likely" warming of as low as 0.15 deg. C (this is below the 95% confidence range of the models) with a midpoint around 0.30 degrees per decade. The stated reasons for this are possible under-estimation of solar effects, other natural variabilities like ocean currents, and possible over-estimation of CO2 sensitivity and aerosol effects. What is unstated from a backing away from model predictions due to backing away from model assumptions, is that prior attribution of warming might be in need of adjustment. And this is even forgetting that the amount of warming is a little bit contentious. Taking the satellite data instead of CRUT4 for example gives an observed 1950-2010 warming of closer to 0.5, rather than 0.7.
But I think this is focusing on the wrong "enemies" in any case. Regardless of where attribution is now, it doesn't take a genius to follow the trend in carbon emmissions to realize that it's going to be most of a much higher number in short order in any case. And that's even forgetting that replacing a finite energy source is going to be necessary.
My 2 cents. Spent the weekend burning very little carbon, and no computer access up north. No electricity, roads, or land-line. :)
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Tom Curtis at 09:55 AM on 22 September 20142014 SkS Weekly News Roundup #38B
Wol @7, the important equation is ΔF = λΔT + ΔQ, where ΔF is the change in forcing relative to a particular time, λ is the climate sensitivity factor, with units of W/m^2 per degree Kelvin, ΔT is the change in temperature relative to that time, ΔQ is the change of heat flux into the earth system (of which 90% goes into the ocean). As ΔT appears in the equation as well as ΔQ, it is as important as ΔQ. The denier error is focussing on the change in temperature to the exclusion of the change in heat content. Infact, if anything you have the situation reversed in that in the short term temperature is largely irrelevant, wheras in the long term it controlls the response to changes in forcing. However, this is certainly correct at the moment:
"[The] denial side gets an easy ride on this point because any weather related scenario can occur regardless of the way the heat content of the planet itself is increasing."
Bear in mind, however, that up until 2008 the public presentation of climate science was itself focussed on temperatures and it was the deniers calling attention to ocean heat content due to misinterpretted and cherry picked attention to OHC results after 2004 and above 750 meters depth.
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2014 SkS Weekly News Roundup #38B
Deniers -either deliberately or through ignorance - confuse temperature (by which they usually mean atmospheric temperatures) with heat. Since the heat budget is what really matters in all but the short term, the denial side gets an easy ride on this point because any weather related scenario can occur regardless of the way the heat content of the planet itself is increasing.
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Tom Curtis at 08:30 AM on 22 September 20142014 SkS Weekly News Roundup #38B
giulio8 @4, Lubos Motl is "considered" a physicist because he has a PhD in physics and has made contributions to string theory. He even, for three years, held an Assistant Professorship at Harvard. None of that has any bearing on whether or not he is in denial about anthropogenic changes to climate.
On the other hand, he has political opinions so right wing that he wrote regarding the mass murder of young Norwegian members of the labour party:
"At any rate, I don't think that today, in 2011, there exists a problem in Europe that could even remotely justify the killing of dozens of this young people who attend a summer camp. ... I may speculate and I often speculate about the future in which tough decisions may have to be made to avert threats that are worse than anything we are seeing today but this mass murder didn't occur in the future. It occurred a few days ago and given this fact, it's unforgivable."
Do not over interpret that. He also wrote (in the space of the elipsis), "Sorry but this looks unforgivable to me - unforgivable at the level of a death penalty which doesn't exist in Norway" and earlier wrote:
"The mass murder itself remains shocking for me. It is both scary as well as incomprehensible. I just don't understand what the young people affiliated with the Labor Party who are having fun on some summer youth camp - and perhaps some random people on the street of Oslo - have to do with all the ambitious political plans. They were innocent children and young people, weren't they?"
So like any decent person he was shocked by Breivik's horrific acts. But not so shocked that he could not see a legitimate political role for them in the future.
I will state categorically that there is no political trajectory from any center left (or center right) party in Europe that would ever justify taking up arms against it; and no trajectory from any party ever that justifies murdering civilians as the primary target of the attack. Ever!
That Motl can contemplate current political trajectories in Europe as, in the future, justifying such acts shows him to be contemptible, and his thought on politically related matters (including on science that touches on politics) to be beneath contempt. As with Monckton, the fact that the climate denier community do not disown Motl shows how low they have sunk.
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Tom Curtis at 08:09 AM on 22 September 2014The 97% v the 3% – just how much global warming are humans causing?
MA Rodger @79, mindful of the context of the discussion, I will note that by 1700 there is already a significant ongoing decline in δC13, and hence already significant evidence of increasing anthropogenic forcings:
Indeed, the rate of decline of δC13 does not change significantly until at least 1900 although I very strongly suspect that conceals a switch from LLUC to fossil fuels as the primary source of emissions over that period.
With regard to Ruddiman's hypothesis, knocking out the declining δC13 does knock out a major evidentiary support for his theory making it far more controversial than I had supposed. He does, as you note, have an auxilliary hypothesis. That auxilliary hypothesis is plausible, and has some evidence in support in that Elsig et al 2009 does appear to use a low estimate of peat burial. Ruddiman et al (2011) write:
"A second argument for rejecting the early anthropogenic hypothesis has been the small amplitude of the negative δ13CO2 trend during the last 7000 years. This constraint was thought to limit total emissions of terrestrial carbon to the atmosphere (including those from anthropogenic sources) to at most 5 ppm. In compiling their carbon-isotopic mass budget, however, Elsig et al. (2009) chose a value for late-Holocene carbon burial in boreal peat deposits of 40 Gt, which falls below most published estimates. A new estimate of just under 300 GtC from Yu (2011, this issue) is close to earlier estimates by Gorham (1991) and Gajewski et al. (2001). This much greater carbon burial in boreal peat over the last 7000 years, combined with model-based constraints on carbon exchanges from other natural processes, requires much larger anthropogenic emissions to balance the δ13CO2 budget (Table 5)."
Taken at face value, that means human preindustrial emissions from the Holocene climactic optimum are in the order of 260 GtC, or approximately half of their emissions in the industrial era. That is consistent with an anthropogenic increase in CO2 of 20 ppmv over the last 8000 years to 1750. (For those not familiar with the carbon cycle, over periods of thousands of years, only 10-30% of emissions remain in the atmosphere depending on the amount of emissions.)
Returning to the context of the discussion above, my take on Ruddiman's hypothesis is that the basic idea must be true in principle, in that humans did start about 10,000 years ago undertaking activities which increased CO2 and CH4 emissions such that they increased atmospheric concentrations relative to what they would otherwise have been. What is being argued about is whether that increase amounts to 5% or 100% of the increase in CO2 over that time. Therefore the assumption that preindustrial changes in temperature are entirely natural is unwarrented. However, I must revise down my current estimate of how much anthropogenic factors reduce the millenial scale cooling trends since about 8000 years ago.
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From Peru at 07:53 AM on 22 September 20142014 SkS Weekly Digest #38
310 000 people in New York ....
... 4 orders of magnitude less people in my district.
I hope that elsewere in my city (Lima, Peru) there were better results.
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giulio8 at 07:25 AM on 22 September 20142014 SkS Weekly News Roundup #38B
correcting the above link: http://disq.us/8k6vfe
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giulio8 at 07:23 AM on 22 September 20142014 SkS Weekly News Roundup #38B
How can a denier like Motl be considered a physicist
and continue insulting people aware of the greenhouse effect?
Look at his ignorant reply to my comment -
MA Rodger at 05:58 AM on 22 September 2014Antarctica is gaining ice
jetfuel @266.
It is difficult to know when you talk of "the turn around in the Arctic" whether you are proposing the reversal of the trends of the last 30 years or that the winter freeze has arrived.
This "number of days in the year when sea ice area was increasing at both poles" you talk of - why do you pick on 1994? Indeed, why this annual statistic? A quick bash at the SIA data shows those 'numbers of days' are not very relevant to levels of SIA & SIE for those years. Why then do you feel the statistic is worthy of the diodes recording them?
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MA Rodger at 05:47 AM on 22 September 2014The 97% v the 3% – just how much global warming are humans causing?
Tom Curtise @78.
Perhaps we use the word "controversy" differently. When a theory has a whole list of stuff to overcome (like Rudiman's theory gets in AR4 Section 6.1.5.2), that is when I would consider aspousing such a theory "controversial."
I was of the understanding that the isotope data (eg from Elsig et al 2009) was a problem for Ruddiman's case was as yet unresolved. Elsig et al. Figure 1. of data from Dome C cores shows no fall in C13 as required for biosphere emissions. Ruddiman in his 2011 paper did respond with a peatland argument but that draws the whole early Holocene carbon cycle into the equasion rather than put the matter to rest. I note Ruddiman's latest presentation of his theory (Ruddiman et al 2014) remains silent on any isotope issue.
My sympathy for the Ruddiman theory perhaps rests on not knowing how agriculture developed. I tend to find the human population (gu)estimates are quoted with more credence than they deserve and feel a low figure is worthy of more consideration. A small population is one of the things leveled at Rudimman. How can so few illiterate prehistoric humans armed with only a stone axe be so much more effective at CO2 emissions than the illiterate 4x4 owners today? I think due consideration would show it is far from impossible for a small population using fire and perhaps even hunting to make a big impact on CO2 emissions (averaging 30 MtC over the period) and which appear to be up to speed very quickly as sedentary agriculture had only just begun.
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John Hartz at 02:41 AM on 22 September 20142014 SkS Weekly Digest #38
The New York Times is providing continuous coverage of the Climate Change March in New York City via the following article:
Climate Change March Begins in New York City
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Jeremy C at 01:12 AM on 22 September 20142014 SkS Weekly News Roundup #38B
Its very interesting that in Australia (apologies for this post being Aus-centric) before this news came out about 2014 the deniers have been running this ruse that Australia's Bureau of Meteorology weather station records can't be trusted. Its almost as if they knew they wouldn't be able to keep up the ruse about the world not warming for the past how-many-years and this latest ruse is very well timed to blunt any data coming out about rising temps.
You might call me paranoid but if I was a denier its what I would do. -
Tom Curtis at 00:43 AM on 22 September 2014The 97% v the 3% – just how much global warming are humans causing?
MA Rodger @77, if his case were established "beyond ... controversy" I would have called it an overwhelming case. IMO, the chief points in Ruddiman's favour are that CO2 levels have risen while global temperatures have fallen from the HCO. Absent significant emissions into the atmosphere from a terrestial source, that is not possible (as colder water absorbs more CO2). Further, at the same time deltaC13 has also risen indicating the the excess CO2 has come from plants:
The mechanisms whereby humans can cause such a change, deforestation, increased rice agriculture (leading to increased methane production from C12 enriched sources), and increased cattle grazing (same as rice production) definitely have that effect. The question is whether they have been sufficient to account for a significant proportion of the effect, or whether natural deforestation (as with the Sahara) or increases in wetlands are to blame. I think the case for the former is significantly stronger than the later, in part because while interglacials can vary, it would be a remarkable coincidence for this interglacial to vary on just this point immediately following the invention of agriculture.
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Tom Dayton at 00:28 AM on 22 September 2014We're heading into an ice age
The link to Archer 2005 is stale. Here is a new location of that paper: http://geosci.uchicago.edu/~archer/reprints/archer.2005.trigger.pdf
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Tom Curtis at 00:22 AM on 22 September 2014Antarctica is gaining ice
jetfuel @266 says:
"Meanwhile, The Antarctic ice level far surpasses the level at this time at 10, 20, and 30 years ago. Since the turn around in the Arctic has already happened so Ice area is increasing there too, while the Antarctic is well into unchartered territory in increased area covered by sea ice, ..."
It is true that the Antarctic Sea Ice anomaly is greater than at any time in the last thirty years, but even my history goes back longer than that - let alone the Antarctics. So, let's look at the charted sea ice extent from the HadISST database, as plotted by Tamino:
Of course, that is a little out of date. The current data (Sept 20th, 2014) is at 20 million square kilometers. Uncharted for the satellite era, certainly - but uncharted simpliciter? That you choose to forget history does not mean it does not exist.
Or we might compare the August 2014 sea ice extent to a 1904 estimate of winter sea ice extent, which is shown extending as far north as South Georgia:
So, Antarctic sea ice extent is in uncharted territory, but only if you are carefull not to look at charts that might bust your pet theory.
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MA Rodger at 23:53 PM on 21 September 2014The 97% v the 3% – just how much global warming are humans causing?
Tom Curtis @72
Some interesting points being made in recent comments here (I always enjoy a good AMO discussion) but I was surprised to read "Ruddiman mounts a very convincing case..." I didn't think his case has established itself beyond being an interesting controversy.
I'm not averse to the idea that a few hundred thousand humans in pre-history could have been responsible for CO2 & CH4 levels by some means as Ruddiman suggests they did and that the Holocene ice cores yield data that looks a lot different to the Eemian and other interglacials.
But surely the "means" suggested do remain speculative and interglacials are not expected to be carbon-copies of each other. Or have I missed something? -
Tom Curtis at 23:50 PM on 21 September 2014Deciding who should pay to publish peer-reviewed scientific research
Ashton @15, I don't know which Tom Curtis you are responding to, but it is certainly not me. I suggest you read my post @14, which you probably did not see before posting your comment. It makes it quite clear, however, that you are arguing against a strawman. Specifically, I do not disagree with open access. Indeed, I am strongly in favour of it. What I disagree with are specious arguments that we, as taxpayers, are already entitled to open access without having made specific legislative and funding provision to support it.
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Tom Curtis at 23:14 PM on 21 September 2014The 97% v the 3% – just how much global warming are humans causing?
michael sweet @75, the change in CO2 is a drop from approx 282 ppmv to 274 ppmv, which would entail a negative forcing of 0.15 W/m^2, which would correspond to a 0.06-0.18 C temperature influence over centenial scales, with a 0.12 C influence for a climate sensitivity of 3, taking about 200 years to approach the full impact. That in turn is about a fifth of the total temperature change from the MWP to the LIA.
It is a matter of scientific dispute as to the cause of the decrease in CO2. I lean to the theory that it is temperature related. That is, as global temperatures fall, oceans absorb more CO2 thereby lowering global atmospheric CO2 concentration. Such a process would make little change to the C13/C12 ratio in atmospheric CO2. I have only read the abstract, but this article appears to support such a cause for the fall in CO2 levels. However, other causes have been proposed, including increases in wetland areas, and, as you mention, depopulation in the Americas due to disease brought by European colonists (for which I cannot find a suitable reference).
Against the last proposal, I would note that the Americas are only one part of the world and deforestation was occuring in Europe and potentially other places in the world at the time; and further, the lost farmlands had not denuded the forest as with modern agriculture, but formed a patchwork within the forest so that the impact may have been less than suggested.
However, I cannot claim to be well informed on this topic so beyond noting that there are alternative theories, I do not think I can really help you.
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Antarctica is gaining ice
jetfuel, what are you trying to dance around? Do you have a point?
Btw, Arctic sea ice area minimum for 2014 is less than SIA minimum for 2013 (3.554m km2 vs. 3.483m km2). If you're going to use a one-year change to claim "recovery," then what do you do when the next one-year change reverses the sign? The summer minimum linear for Arctic SIA from 1979-2006 (the year before the 2007 collapse) is -47,592 km2. The same for 1979-2014 is -69,590 km2. Between 1979 and 2013, there are 15 years where SIA exceeds the preceding year. Most importantly for the sake of your dance, reality is about 50 years ahead of model expectations for Arctic decline. Call me when the ten-year linear is positive. Maybe I'll listen.Also, if you don't think wind patterns, wind speed, and salinity have anything to do with Antarctic sea ice growth, by all means provide the physical mechanism through which these forces are rendered powerless.
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jetfuel at 22:40 PM on 21 September 2014Antarctica is gaining ice
Scaddemp, In your rebuttal to my comment about 2012 conditions being used as a rebuttal to what is happening today in the Antarctic, you point to articles written in 2012 about what happened in 2011. Further removed from recent happenings.
Meanwhile, The Antarctic ice level far surpasses the level at this time at 10, 20, and 30 years ago. Since the turn around in the Arctic has already happened so Ice area is increasing there too, while the Antarctic is well into unchartered territory in increased area covered by sea ice, I expect another very cold winter just south of the Great Lakes. The Arctic turn back up of ice area happened already and did so only 3 days later than last year.
In combining the number of days in the year when sea ice area was increasing at both poles at the same time, this happened for 41 days in 1994 (20 years ago). So far this year, it has been happening for 36 days and surpassing the 20 years ago mark looks easy considering 6 more days will do it. All totalled, there was about 980,000 km sq more sea at these times in 1994 than today, out of 27M, that is less than 4% less. This .98M difference is falling each day, as The Antarctic just passed 20M with a half million increase just in the last week. The vaguery of "shifting wind patterns" is proposed as the reason why we are about to have more sea ice than 20 years ago even though the oceans are supposedly the warmest since 1900. All this while state legislatures fight over sea level rise extrapolation methods that amount to less change in 1000 years than an annual but rare moon caused tidal change that happened this summer.
Sea ice data from nsidc charctic
Moderator Response:[Rob P] - Perspective is important here. A back-of-the-napkin calculation by myself, using middle-of-the-road estimates, shows that the annual average rate of global ice volume loss over the last decade is around 50 times greater than the increase in Antarctic winter sea ice. So the fact that Antarctic sea ice is increasing doesn't challenge our observations that the world is warming in a largely coherent manner - which we would expect given the increasing greenhouse effect.
Trends in Antarctic sea are very patchy though, strong losses in some areas, but overcompensated by gains in other areas. Indeed, the growth areas appear to be in the vicinity of the Weddell and Ross Sea polar gyres - where divergence at the surface pulls cold water up from the deep. This will likely weaken when the Interdecadal Pacific Oscillation (IPO) switches to its positive phase in the coming years. So it will be interesting to see how the gyres respond, and what effect this has, when this phase switch occurs.
The image below is from Maksym et al (2012):
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John Hartz at 22:05 PM on 21 September 20142014 SkS Weekly News Roundup #38B
nigelj:
Also see:
El Niño is Kinda Sorta Maybe Here by Brian Kahn, Climate Central, Sep 18, 2014
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michael sweet at 21:56 PM on 21 September 2014The 97% v the 3% – just how much global warming are humans causing?
Well if you want to get schooled in the data on a subject just make a comment to Tom!
Thank you for the data on long term forcing. It appears that over centuary spans natural forcings exceed human forcings.
Do you know if data supports the claim that the decrease in CO2 around 1550 (from your post 72) was caused by the collapse of Native American Indian populations due to the introduction of European diseases (and subsequent reforestation of their farmlands)? How much did this decrease in CO2 change the temperature (if the sensitivity is 3.0) over the next 250 years before the CO2 concentration rose again?
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