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Composer99 at 01:59 AM on 13 November 2014More research confirming large methane leakage from shale boom
I have a longer follow-up prepared, however global methane concentration is off-topic for this particular thread.
Any suggestions as to an appropriate thread? One of the 'IPCC models vs observations' threads, perhaps?
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bcglrofindel at 01:52 AM on 13 November 2014IPCC overestimate temperature rise
Tom Curtis,
I believe responses like yours just drives away skeptics. A question as simple as how do the IPCC projections from 1990 compare to the instrumental record today nearly 25 years later seems a fairly honest starting point. To summarize the correct response to such a query as declaring the very question as "inappropriate" is terrible.
IMHO, the correct responses are one of:
The actual is hotter, and here is why.
The actual is cooler, and here is why.
The actual is very close, and here is why.
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bcglrofindel at 01:44 AM on 13 November 2014IPCC overestimate temperature rise
scaddenp,
We are talking about the 1990 IPCC report, so the current record is about 25 years out and closing on the 30 years you suggest quickly. I also don't think it's the best argument to just tell people well the answer doesn't matter, or is just a strawman. The IPCC temperature projections ARE described in th executive summary as BEST guess changes. The IPCC executive summary IS being used to inform policy changes. When I see someone claiming that the IPCC temperature projections, in ALL scenarios, estimated higher actual temperatures than we see today on actual record I don't feel like telling them it's irrelevant is a strong argument.
More over, my underlying and overarching question was if there is anywhere one can simply go to point out the truth or falsity of such a claim? We have the instrumental temperature record available all over the place online, but referencing it correctly to the IPCC FAR fig6.11 is tricky without the actual data underlying the FAR projections.
My question more simply is if someone claims that the IPCC F(irst)AR overestimated temeprature compared to actual measurements are they making a false statement? If I say that isn't true, am I lying?
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Russ R. at 01:30 AM on 13 November 2014More research confirming large methane leakage from shale boom
Composer99,
No... I'm saying the IPCC has overestimated either CH4 emissions, or residence time, or both. The observed methane concentrations (with uncertainty of ±4 ppb as of 2011) are sufficient evidence of this.
Here's the link to the figure:
- http://www.ipcc.ch/report/graphics/images/Assessment%20Reports/AR5%20-%20WG1/Chapter%2001/Fig1-06.jpg
And the chapter:
- http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter01_FINAL.pdf
And the data table:
- http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_AnnexII_FINAL.pdf
Enjoy.
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Composer99 at 01:04 AM on 13 November 2014More research confirming large methane leakage from shale boom
Russ R:
You're the one asserting that (1) the IPCC has underestimated CH4 emissions and that (2) the degree of underestimation is significant or meaningful in some vague, ambiguous, can't-quite-spell-it-out-can-you kind of way.
So it's incumbent upon you to provide sufficient evidence to support your assertion.
So instead of playing rhetorical silly buggers, how about providing the figure number or section of the report that the graph appears in.
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Russ R. at 00:37 AM on 13 November 2014More research confirming large methane leakage from shale boom
Composer99,
You should address your question abut uncertainty bars to the IPCC, since it's their chart. Amusing how all of a sudden you grasp at any prospect of uncertainty to avoid accepting a completely obvious conclusion.
What's the word for that sort of thing?
Moderator Response:[JH] Keep it civil or loose your privilege of posting on SkS.
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Russ R. at 00:36 AM on 13 November 2014More research confirming large methane leakage from shale boom
gws,
"Some work to do."
It appears we agree on this point.
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bcglrofindel at 00:34 AM on 13 November 2014IPCC overestimate temperature rise
@Bob Loblaw,
Thanks for that. I'm Canadian and so yesterday was remembrance day and thus I was out visiting family and not back in till now.
My background is comp sci, so I very much understand that the original FAR models assumptions matter to the results they plotted and if scenario baseline assumptions aren't met that results will differ. I agree with all of that as self evident. It's also IMHO a very big and broad subject to try and get into.
My question that I still only have a fuzzy yes/maybe/no answer to is about how actual measured temperature compares to the published FAR temperature projections in Fig6.11. I totally understand that those projections had massive spreads within themselves because of the broad number of scenarios and unkowables they were working from. That doesn't stop people I've seen from posting the claim that ALL the FAR Fig6.11 projections are higher than current actual temperatures. I don't have a problem articulating the reasons that would be 'ok' or not a disprove of underlying theory. I can argue for and against that well enough. What I don't know is if that base claim is even remotely true. The best I can do is try and see from the graphs in Fig6.11 what temp increase from 1990 through 2014 the graphs show, which is extremely rough and not in anyway pursuasive. Additionally, if anyone has access somewhere to the actual raw data used for Fig6.11, then it should be trivial to show how actual temperature has tracked to the Fig6.11 scenarios, no? Yes, I know the scenarios Fig6.11 used with radically high assumptions will be too high, and we all know to expect that. I just want to know if people that claim all scenarios in Fig6.11 exceed modern temp can be called liars? More over, if I call them liars, am I actually the one lying?
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MA Rodger at 20:30 PM on 12 November 2014More research confirming large methane leakage from shale boom
gws @4.
Absolutely. Rough-and-ready to the power N. I had a go at the numbers with no idea what the result would be. If anything, I expected it to be far higher than 6%. However, that result does perhaps allow some sort of consideration of an upper limit to fugative leaks from fracking. True, the atmospheric CH4 balancing act does contain some big players and they will be noisy. But the numbers do suggest that some of the larger percentages for leaks being talked about (The leakage rates found for Bakken and Eagle Ford in the study discussed here is 9% &10%.) would make fracking itself one of those big players.
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Stephen Baines at 16:45 PM on 12 November 20142014 SkS Weekly News Roundup #45C
Here's an article in the NYT by Piers Sellers describing how Rep. Stockman from Texas completely abused Sellers' honest description of the science regarding ice ages and climate change to confuse congressional testimony on the issue. Sellers sets the record straight.
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Tom Curtis at 15:25 PM on 12 November 2014We must manage global warming risks by cutting carbon pollution, top scientists conclude
Regardless of where austrartsua should have posted, his elimination of a vast literature which is reduced to (apparently) just one study by the parroting of a phrase (which it is questionable as to whether austrartsua understands). Just one sample from that literature:
"Bush-era tax cuts are scheduled to expire at the end of 2012, leading to interest in raising revenue through a carbon tax. This revenue could be used to either cut other taxes or to avoid cuts in Federal programs. There is a body of economic research suggesting that such an arrangement could be a win-win-win situation. The first win—Congress could reduce personal or corporate income tax rates, extend the payroll tax cut, maintain spending on social programs, or some combination of these options. The second win—these cuts in income taxes would spur the economy, encouraging more private spending and hence more employment and investment. The third win—carbon dioxide (CO2) pollution and oil imports would be reduced. This analysis uses the MIT U.S. Regional Energy Policy (USREP) model to evaluate the effect of a carbon tax as part of a Federal budget deal. A baseline scenario where temporary payroll cuts and the Bush tax cuts are allowed to expire is compared to several scenarios that include a carbon tax starting at $20 per ton in 2013 and rising at 4%. We find that, whether revenue is used to cut taxes or to maintain spending for social programs, the economy is better off with the carbon tax than if taxes remain high to maintain Federal revenue. We also find that, in addition to economic benefits, a carbon tax reduces carbon dioxide emissions to 14% below 2006 levels by 2020, and 20% below by 2050. Oil imports remain at about today’s level, and compared to the case with no carbon tax, are 10 million barrels per day less in 2050. The carbon tax would shift the market toward renewables and other low carbon options, and make the purchase of more fuel-efficient vehicles more economically desirable."
(Rausch & Reilly, 2012, emphasis added)
As the bolded sentence makes plain, there is a body of economic research on the topic (not a single study). In fact, my search on google scholar found 22,800 results (excluding citations and patents).
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dana1981 at 15:19 PM on 12 November 2014We must manage global warming risks by cutting carbon pollution, top scientists conclude
There is a link in the above post to a discussion of the economic benefits of a revenue neutral carbon tax. It is one study - feel free to reference any evidence to the contary. I don't think any exists.
Also, a revenue neutral carbon tax does make carbon fuels more expensive. In most households those costs are offset by the resulting rebate, but who wants to turn around and give that money right back to the oil companies? Higher prices are still a motivator even if the funds are returned to the taxpayers.
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One Planet Only Forever at 14:49 PM on 12 November 2014We must manage global warming risks by cutting carbon pollution, top scientists conclude
Trevor_S,
I would suggest that a start towards increased acceptance of the science and the policy requirements it irrefutably leads to would be for 'people who understand and accept the science and acknowledge that CO2 emissions need to be dramatically reduced' to stop repeating made-up claims that the people who try to deliver messages to encourage better understanding are excessively travelling in damaging ways to spread their message.
The real problem is the people profiting from damaging unsustainable activity who abuse their wealth to fund the creation and dissemination of such made-up claims.
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We must manage global warming risks by cutting carbon pollution, top scientists conclude
austrartsua - Did you post on the thread you intended to? There's no mention of taxes in either the opening post or any of the comments until yours.
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austrartsua at 14:14 PM on 12 November 2014We must manage global warming risks by cutting carbon pollution, top scientists conclude
Dana is falling for a bad case of "single-study syndrome" when he makes the claim that a revenue-neurtral carbon tax could be beneficial for the economy. This one study seems pretty dubious to me. It also seems odd, basic economics tells you if you want people to stop using fossil fuels, you have to make them more costly. If a carbon tax is truly revenue-neutral, no one would change their behavior. They'd put up with higher energy costs because they are getting a subsidy from the gov.
The study seems hard to believe.
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Composer99 at 13:44 PM on 12 November 2014More research confirming large methane leakage from shale boom
Russ R:
Where are the uncertainty bars on the observed methane concentration time series?
Absent those, you can't really say that observed concentrations are below projected ones, since you can't exclude the possibility that the observed and projected spreads overlap.
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Riduna at 12:44 PM on 12 November 2014More research confirming large methane leakage from shale boom
Fugitive emissions from fossil fuel mining are undoubtedly increasing and contribute to some as yet unquantified extent to rising atmospheric CH4. Another bit in the jigsaw which represents the quasi methane budget espoused by the IPCC’s 5AR?
There is no reason to believe that scarcity of tropospheric –OH radicals has anything to do with growth in the level of CH4. Perhaps ongoing increase in the level of atmospheric CH4 has something to do with emissions associated with ocean warming and degradation of permafrost, particularly in Siberia?
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Miguelito at 12:39 PM on 12 November 2014More research confirming large methane leakage from shale boom
All I have to say is, Jesus Farking Christ, is industry sloppy.
The only bright light in that study is that the area over the Haynesville Shale shows no emissions bullseye despite that it grew into one of the largest gas fields in the U.S. over the period of the study. Too bad the study authors didn't calculate leakage rates for it too. It would have made an interesting contrast with the Bakken and Eagle Ford, where operators aren't after the gas, but oil and condensate instead.
All in all, it only makes it more urgent for the EPA's methane regs to be implemented sooner rather than later and for those regs to be expanded from gas wells to all wells. Of course, industry will sue, because that's what industry does.
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gws at 10:33 AM on 12 November 2014More research confirming large methane leakage from shale boom
Russ, your question was addressed by me here. If you read the papers I just linked above, you will also find that the methane budget bottom-up estimates, which underlie the IPCC's projections (not predictions), tend to be higher than the top-down estimates (derived from atmospheric measurements), and that difference has not been reconciled yet.
Some work to do.
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Trevor_S at 10:28 AM on 12 November 2014We must manage global warming risks by cutting carbon pollution, top scientists conclude
No edit,
I forgot to include the link to Professor Kevin Andersons comments and the typos above.. forgive me.
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Trevor_S at 10:24 AM on 12 November 2014We must manage global warming risks by cutting carbon pollution, top scientists conclude
So is CO2 fertilization really that strong of an effect in the short run?
I read this in the Australia "Land" today (online edition, agricultrual Newspaper owned by Fairfax)
CO2 a nutrient, not pollutant: Moore
of particular interest where the comments... sigh
eg
Finally this paper writes something that is truthful about CO2 and the climate change fiasco
There is "little" hope (99% wide agreement) of structural change at a national level and virtually "none" at an international level (99.9% confidence, wide agreement) to ensure efficacy of emissions reductions with any chance of keeping under the 2 C target... over to you Professor Anderson
- At current (2014) emission levels, the 1000Gt will be consumed in less than 23 years.
- But with CO2 certain to rise over the coming few years, then, at the likely 2020 emission level, there will be ~13.5 years until the full 2°C carbon budget will have been consumed; i.e. full decarbonisation of energy before 2034.
I know you guys keep going on with the evidence but as this study in to anti vax indicates, you may actually be doing more harm than good ?
researchers found that while they were able to teach parents that the vaccine and autism were not linked, parents who were surveyed who had initial reservations about vaccines said they were actually less likely to vaccinate their children after hearing the researchers messages.
Which brings me to my question :) Where the sites advocating actions that are effective, something akin to here ? I know we have people like Naomi Klien etal flying all over the Planet, flogging product, telling us not to fly all over the Planet and flog product but there must be some sites with a little more "integrity" ? or is the reason we don't hear from these people because they just live a low emissions lifestyle themselves ? eg Joan Pick's / Ted Trainer's etal of this world
Perosnally I think encforced penury is the only true solution, emisisons dipped with the global economic crisis and I know when I quit my job (no welfare) and moved remotely off grid to lower my emissions, having no money enforced a low emissions lfestyle but am interested in debate on this issue .
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Russ R. at 10:10 AM on 12 November 2014More research confirming large methane leakage from shale boom
For all this extra methane being released into the atmosphere, why has its concentration so stubbornly lagged model predictions?
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gws at 08:48 AM on 12 November 2014More research confirming large methane leakage from shale boom
Bit too "rough & ready" ...
The atmospheric increase is based on an imbalance between sources and sinks. The historic imbalance was probably ending in the late 80s and it took 2-3 decades, based on methane's atmospheic lifetime, to reach a new equilibrium, about ten years ago. The new imbalance is still being researched, and while it is tempting to prescribe the shale boom as its cause, evidence from atmospheric background stations, shown by Ed Dlugokencky at AGU last December, and available as Nisbet et al. (2014), is mixed. Methane rise in northern mid-latitudes was strong in 2008-09, then again in 2012-13, but not in between.
Even if the 12 Mt/yr CH4 were correct, and that is closer to the current estimate of total US emissions including all sources, that does not necessarily mean that that is the answer just because it matches the global atmospheric increase.
There is a recent review paper here that may be useful to digest for those who want to learn more, and in detail .... Quote:
We show that a rise in natural wetland emissions and fossil fuel emissions probably accounts for the renewed increase in global methane levels after 2006, although the relative contribution of these two sources remains uncertain.
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Mike3267 at 08:32 AM on 12 November 20142014 SkS Weekly Digest #45
Regarding the cartoon, neither the major oil companies nor most religions deny human caused climate change. We will be much more likely to win over still skeptical Americans if we point this out, rather then promoting stereotypes. Even the World Coal Association supports action to reduce GHG emissions. I am not saying these statements can always be taken at face value, but that they undermine and discredit the deniers.
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Don9000 at 08:31 AM on 12 November 2014We must manage global warming risks by cutting carbon pollution, top scientists conclude
wili@3
Remember too that yields have been increasing due to modern agricultural practices. In other words, there are negative and positive forces and trends at work when it comes to crop yields.
Re. the old frog story:
There's nothing apocyrphal about it. I used to rescue frogs from a hot tub at my old apartment complex in Florida during rainstorms--at least those I reached in time. They would hop in and quite peacefully hang out as they heated up to the point of no return, which in a 40 degree C hot tub wasn't more than about ten minutes. On several occasions, particularly on warm rainy nights in the spring, if the tub wasn't running, I had to clear an assortment of dead and living frogs from it. The living ones were always acting like climate change deniers--they were oblivious to the threat.
If a frog jumped in when the tub was running (and of course thus rather foamy), anyone who wasn't squeamish joined in the rescue efforts. Those who were squeamish usually exited the tub quite rapidly.
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MA Rodger at 07:29 AM on 12 November 2014More research confirming large methane leakage from shale boom
tmbtx @1.
A very rough & ready back-of-fag-packet calculation. By 2007, man-made CH4 emissions were 282Mt(CH4) resulting in an increase of 12000ppb. Since 2007, atmospheric CH4 has risen ~50ppb, which would simplistically require an increase in emissions of ~12Mt(CH4) pa. US fracking (2013) produced 10.33 tcf CH4 /48.700 = 212Mt(CH4). So (assuming no decimal point slippage in these calcs) leakage of about 6% production would yield the 12Mt(CH4) pa increase in atmospheric CH4.
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jja at 05:43 AM on 12 November 2014More research confirming large methane leakage from shale boom
Equally unsurprising is the front group's repeated attack on the seminal publication by Howarth, Santoro and Ingraffea, as if the claimed refutation of its results somehow invalidates all subsequent findings of high methane emissions. The parallels to Global Warming denial are all too obvious.
This technique is called a "dog whistle" where the heavily indoctrinated key into an entire litany of misrepresentative arguments upon hearing key terms like "Mann" or "hockey stick". It is a dog whislte, because only the heavily indoctrinated have the pavlovian response to a signal that is not heard by rational, interested parties.
If they could marshall enough propaganda dissemination outlets to besmirch the name of "Howarth" as they have Michael Mann, they would be very, very happy about that. Because all later analyses would be jumbled into the first (e.g. Marcott). -
tmbtx at 01:48 AM on 12 November 2014More research confirming large methane leakage from shale boom
Just an observation at this point, but the atmospheric methane curves had somewhat flattened until about 2007. What began in 2007 at the same time the curve started up again? The shale boom.
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Bob Loblaw at 01:43 AM on 12 November 2014IPCC overestimate temperature rise
A word to bcglrofindel, who I hope is still following this thread:
One of the SkS comments policies is "no dog-piling", which is intended to avoid having one poster have to deal with a whole bunch of comments from several people. It can be overwhelming.
In this thread, you've now had several people respond. In your last comment @21, you indicated that you still inidcate a desire for a simple graph, even though there have been several comments saying why this is difficult - some directed to you, some in response to jsmith's earlier graph.
If you still can't see why the graph jsmith provided is misleading, it would help if you told us why you feel that the responses don't explain it well. Please engage in a conversation about these explanations. If the number of responses is too much for the moment, tell us that you wish to discuss one aspect of things, and engage on that aspect. Refrain from introducing new issues until the discussion on that aspect is complete.
Regulars here wil lose patience if they feel that their responses are being ignored. A simple acknowledgement of "OK, I see that now" (as suggested by Tom @ 26), will go a long way in terms of encouraging a productive discussion.
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One Planet Only Forever at 01:20 AM on 12 November 2014We must manage global warming risks by cutting carbon pollution, top scientists conclude
wili,
Unfortunately what is going on is likely far more sinister than the simple frog in warming water scenario. The regions expected to momentarily improve the ability to grow food are mainly in the already well developed and wealthy nations that must make the biggest reduction of their per-capita impacts.
So what is going on is that the leaders who try to appease popular opinion in those wealthy powerful developed nations are essentially putting the less developed regions of the planet into a pot and keeping the burner going, while the people in the pot understand exactly what is going on but are unable to stop it. And caring and considerate bystanders outside the pot are equally unable to stop it because of the power of popular opinion driven by profitable damaging ultimately unsustainable pursuits.
It will be interesting to see what the future generations think of leaders who did not vigorously fight to improve the better understanding of what is going on. Made-up unsustainable appearances of success and affluence eventually fall apart.
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wili at 21:07 PM on 11 November 2014We must manage global warming risks by cutting carbon pollution, top scientists conclude
So if not CO2 fertilization, is it just the added heat and moisture that helps increase yeilds?
It all reminds me again of the (apocryphal?) anecdote about the frog in slowly warming water--at first it just seems like its just getting nicer and nicer as it warms, so why jumpt out? But by the time it starts to boil, all ability to react adequately (jump out) has been lost.
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wili at 20:34 PM on 11 November 20142014 SkS Weekly News Roundup #45C
Here is a link to an article that discusses some of the strategies being employed in Sao Paulo to avert catastrophe. They all seem like great things to have been planned and implemented years ago. Now it feels like too little too late.
Sao Paulo Announces Measures Against Worst Water Crisis in History
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One Planet Only Forever at 15:32 PM on 11 November 2014We must manage global warming risks by cutting carbon pollution, top scientists conclude
wili,
I'm not sure that CO2 fertilization is expected to be a big booster of food production.
I can't quickly find a specific online reference, you can check the references listed in the IPCC report, but I recall reading several articles on the issue that implied that the expected near-term climate changes may marginally improve growing conditions in already established farming regions. However, the continued changes after those near term changes would make many of those regions less reliable for food production.
An unfortunate twist could be that areas not currently cleared and usable for growing food with appropriate infrastructure will rapidly shift to having more favorable conditions then shift to not being so favourable. The changes to regional climate could be too quick and difficult for those trying to adapt to predict and effectively adapt to. The result could be a fruitless chase after regions with better growing conditions that are hoped to last.
The 'good news' is that such a wild-goose-chase would only be for as long as the rapid changes occur. Eventually the ones who make it through the tough decades (or centuries) would have a decent chance to figure out the better places to grow food and live using the hopefully dramatically improved ability to understand what is going on and the ability to keep the less concerned people, those who only care about a better present day existence for themselves, from creating more future problems.
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Tom Curtis at 14:40 PM on 11 November 2014IPCC overestimate temperature rise
KR @25, I have not assumed bcglrofindel does not have valid concerns. I have addressed his concerns by showing why a direct comparison is simply misleading (on numerous grounds). He is quite welcome to respond by showing that he now gets why it is inappropriate.
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IPCC overestimate temperature rise
Tom Curtis - Note that bcglrofindel didn't insist that modeling was invalidated by differences between past projections of climate versus emission expectations, but presented a query as to why a simple comparison might look off. While there are a lot of climate trollers who pass by, I would prefer to treat everyone as sincerely interested in a discussion unless/until proven otherwise.
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wili at 12:45 PM on 11 November 20142014 SkS Weekly News Roundup #45C
Thanks, OPOF.
On the Sao Paulo situation, a poster on another site says local sources there are talking about major projects to start cycling used sewage water back into the system to be filtered and reused, as is done to varying degrees in a number of cities around the world. I'm not sure if or how they can get that kind of a system up and running in time to avert major catastrophes in the mean time.
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wili at 12:40 PM on 11 November 2014We must manage global warming risks by cutting carbon pollution, top scientists conclude
So it looks like the proverbial stuff hits the fan starting about 2030 for crop yields? I'm surprised there isn't more of a negative effect till then.
I had heard something about a ten percent loss in global yield for every degree C of GW, and that made it sound like a rather steady, lock-step relation. But as with much else, there seems to be a lag between the basic change and the full negative consequences of the change.
Kind of unfortunate, since we will not get a clear signal from this vital sector of the economy till we have already commited ourselves to truly catastrophic levels of GW. And we seem to need many very stron signals to even begin to get our attention.
So is CO2 fertilization really that strong of an effect in the short run? If not, what exactly accounts for this lag till 2030 for something like the full negative effects of GW to start hitting the ag sector?
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Tom Curtis at 11:44 AM on 11 November 2014IPCC overestimate temperature rise
bcglrofindel:
1) In the estimates made using the energy balance diffusive model, the IPCC assumed a radiative forcing for doubled CO2 of 4 W/m^2 rather than the actual 3.7 W/m^2. The more accurate value was determined by Myhre et al (1998), and included in IPCC reports since the Third Assessment Report (2001).
2) The radiative forcing for the BAU scenario in 2015 for the energy balance diffusive model of IPCC FAR was 4 W/m^2 (Figure 6, Policy Makers Summary, IPCC FAR). For comparison, the current radiative forcing is 3 W/m^2 (IPCC AR4 Technical Summary, Table TS.7), 25% less. To properly test the actual model used in making the predictions, you would need to run the model with accurate forcings. An approximation of the prediction can be made by simply scaling the values, so that the IPCC 2030 predictions would be 0.83 C (0.53-1.13 C).
3) The reasons for the high value of the projected BAU forcings are:
a) The high estimate of radiative forcing for a doubled CO2 concentration already mentioned;
b) The fact that the model did not project future temperature changes; but the effect on future temperature changes based on changes in GHGs alone; and
c) A failure to predict the break up of the former Soviet Union, and the consequent massive reduction in emissions growth.
Factors (a) and (c) explain the discrepancy between the projected BAU forcing for GHG alone (4 W/m^2 for 2015) and the current observed forcing for GHG alone (3.03 W/m^2). From that, it is easy to calculate that there is a 16.75% reduction in expected (BAU) forcing due to reduced industry in the former Soviet Block (plus unexpectedly rapid reduction in HFC's due to the Montreal Protocol).
Thus insisting on a comparison of the actual temperature trend to the actual BAU projections in order to determine the accuracy of the model used by IPCC FAR amounts to the assumption that:
A) The IPCC intended the projections as projections of actual temperature changes rather than projections of the expected influence of greenhouse gases, contrary to the explicity statement of the IPCC FAR;
B) The IPCC should be criticized based on their use of the best current science rather than the scientific knowledge gained 8 years after publication, and 16 years prior to the current criticism (Myhre et al, 98); and
C) The failure of the IPCC to project the break up of the Soviet Union invalidates its global climate models.
The last leaves me laughing. I look forward to your produceing quotes from the critics of the IPCC dated 1990 or earlier predicting both the break up of the Soviet Union and a huge reduction in CO2 emissions as a result to show that they were wise before the event. Better yet would be their statements to that effect in peer reviewed literature so that the IPCC can be shown to be negligent in not noting their opinion. I expect confidently zero evidence of either (due to their not existing).
I am also looking forward to your defence of those three assumptions, as you seem to consider the direct comparison (rather than a comparison with the forcings of the model adjusted to observed values) to be significant. Failing that defence, or your acknowledgement that the assumptions are not only invalid but unreasonable, I will consider you to be deliberately raising a strawman.
4) Despite those issues, the 30 year trend to 2013 of the GISS temperature series is 0.171 C per decade, just shy of the 0.175 C per decade for the lower value. That it is just shy is entirely due to short term variation due to ENSO. The 30 year trend to 2007, for example is 0.184 C per decade, just above the lower limit. Further, that is a misleading comparison in that it treats the trend as linear, wheras it the projection in fact accelerates (ie, we expect a lower than 0.175 C trend in the first half of the period). Ergo, not withstanding all the points raised above, the IPCC FAR projections have not in fact been falsified - even without adjustments to use historical forcing data, and even ignoring the fact that it was not intended as a projection of future temperatures (but only of the GHG impact on future temperatures).
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scaddenp at 09:22 AM on 11 November 2014IPCC overestimate temperature rise
" Isn't it trivial to plot actual temperature against the 3 projections the IPCC gave in Fig 6.11?"
But doing that comparison would be falling for a straw man fallacy. The IPCC does NOT predict that actual measured temperatures will follow those lines. However, it would expect 30-year trends to follow those lines. It is interesting that skeptic make dance that actual temperature is below ensemble mean (its natural variation), but werent worried when in earlier decades suface temps were running hotter (also natural variation). Trends in surface temp shorter than 30 year are weather not climate.
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IPCC overestimate temperature rise
bcglrofindel - I would have to agree that the chart is quite difficult to parse. But that's not uncommon when overlaying so much data, and frankly the TAR/SAR/FAR models and projections, while interesting as historical documents, are far from state of the art in resolution, in incorporated components of the climate, and perhaps most importantly in the more recent forcing histories.
Hence, while I personally would have preferred to have just the overlaid ranges and not individual model runs plotted there, I'm not surprised that AR5 spent very little time and graph space on the previous reports.
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bcglrofindel at 07:31 AM on 11 November 2014IPCC overestimate temperature rise
Thanks KR, my trouble is still actually seeing what the FAR range actually is on that graph. I've hunted around for the actual underlying data for the graph but can't find it anywhere. Regrettably, the shading of all 4 AR onto the same graph leaves the FAR virtually completely hidden for the entire time the instrumental record is plotted :(.
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IPCC overestimate temperature rise
bcglrofindel - You certainly can find such a plot. I would suggest looking at the AR5 Technical Summary, in particular Fig. TFE.3:
JSmith's graph suffers from selecting a single timepoint offset, rather than a multi-year average that cancels out short-term variations, and hence is a misleading presentation.
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bcglrofindel at 06:57 AM on 11 November 2014IPCC overestimate temperature rise
Maybe more simply, I want to add the red line below where the red line is actual instrumental temperature record:
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bcglrofindel at 06:53 AM on 11 November 2014IPCC overestimate temperature rise
I wa referring to the temperature projections from the IPCC first assessment report, Chapter 6. In Figure 6.11 they have 3 graphs for three different temperature sensitivities. It's also notably the ONLY temperature predictions posted in the first assessment report, isn't it? I'll post the image a second time below. What I am told is that actual instrumental temperatures are colder than all of the predictions in Fig 6.11 from the IPCC F(irst)AR. Can someone not simply graph instrumental temperatures against the IPCC projections below and demonstrate the truth? Shouldn't it be a simple enough task? Unfortunately the only examples I can find are like JSmith's that are declared inaccurate.
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Bob Loblaw at 06:40 AM on 11 November 2014IPCC overestimate temperature rise
bcglrofindel:
I can't sort through just exactly what your issue is with the IPCC projections. To begin with, exactly which projection are you selecting, why are you selecting that one, and what data are you using to compare?
Each IPCC projection has some assumptions in it, with respect to the growth of atmospheric CO2 (emissions scenario) and the temperature response to that change in CO2 (climate sensitivity).
With four emissions scenarios and three climate sensitivty values, that gives 12 projections "on display". Note that these projections are not "predictions", because the IPCC is not claiming that one (or any) of these is "the one". When comparing to observations (i.e., testing the projections as if they were predictions), you have to do the following:
- if one of the 12 scenarios is a good match choose it
- if none match well, adjust the results from the projections to take into account the difference in assumptions - i.e., interpolate or extrapolate from the published scenario results.
Note that the choice of an approriate scenario is based on the closeness of the assumptions, not the closeness of the temperature trend.
Let's take a trivial model as an example. Let's assume that we have a linear model that states:
T = A + B*CO2(t)
where T is temperature at time t, as a function of the concentration of CO2 at time t (CO2(t)), and A and B are parameters. If I want to make a projection (not a prediction) of temperature into the future, I need three things:
- I need a scenario to tell me the value of CO2(t).
- I need the sensitivity parameter B (the slope, in linear-equation-speak)
- I need the inital value A (the intercept, in linear-equation-speak)
I will have uncertainties in my CO2(t) values, and in my sensitivity B. As a good scientist, I will try several values of each, based on my understanding of what is reasonable or possible, and I will publish results of those several projections. This is what the IPCC did (with models a little more complex than the linear example here!).
Now, after several years, I want to compare the actual observed T to my model results. I need to determine:
- did one of my CO2(t) assumptions fit reality?
- do I have any better information to tell me what value of B is best?
...and, most importantly...
- what is an appropriate value of A to use to start things off?
Once I have all that, I can start to compare the model to observations. I may need a new CO2(t) time series, and I may need to use different values of A and B from my earlier projections. Note that this does not mean that I'm changing my model: I'm just changing input parameters.
jsmith's graph has the mistake of choosing an inappropriate value for A. The observations contain a lot of "noise", which causes annual variation that is not a function of CO2 concentration. If jsmith's graph were repeated using 1992 as a starting point, the results would be very different. This lack of a robust result ("robust" means that the analysis is not highly dependent on a particular assumption) is an indication that the result is unreliable. This is what Dikran points out in comment #10.
By contrast, if you averaged observations over several years and matched that to the average of the model over the same years, and used that to determine the value of A, you would likely discover that the value of A did not change much if you chose different periods (near the start of the comparison). This would be a robust result, because you could say "I chose this period, but the results are pretty much the same if I choose another period".
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bcglrofindel at 05:46 AM on 11 November 2014IPCC overestimate temperature rise
KR,
You still aren't giving a simple apples to apples comparison. The claim I see people making is that the published IPCC trends from 1990 are too high compared to actual measured temperature. Isn't it trivial to plot actual temperature against the 3 projections the IPCC gave in Fig 6.11? That would easily do away with all the hedging and confusion and end the matter, no? Why can't I find such a simple plot anywhere? All the places I find such a plot, like JSmith's in thread, it's called out as inaccurate. Can't 3 simple plots done on excel in about a half hour clear this up and silence skeptics?
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IPCC overestimate temperature rise
bcglrofindel - In short, short term variability. GCMs are intended to project (not predict) average climate over the long term, and there has never been a claim that they could accurately predict short term variations that cancel out over several decades.
See this post examining how recent short term variations have affected longer term projections. Or this thread comparing various projections (including 'skeptic' ones) against actual temperatures, although that only goes to 2011.
Quite frankly, even the earliest IPCC projections are quite good. Certainly when compared to those from people in denial of climate science...
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scaddenp at 05:06 AM on 11 November 20142014 SkS Weekly News Roundup #45B
"groupthink takes hold and dissident voices are treated with contempt"
Deliberate distortions of the truth are treated with contempt. Published analysis and new data are not. "Blog science" type analyses that somehow dont get published are generally because they are rubbish that playing to a gallery that uncritically accepts anything that conforms to their desire. I would love AGW to be proven false but I am not so stupid as to my wishes ignore data.
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Ashton at 02:57 AM on 11 November 20142014 SkS Weekly News Roundup #45B
Thanks for that Tristan (and JH too) I had no idea what piling in meant. I would hope no one would refuse to acknowledge information but as they say information is not knowledge, knowledge is not understanding and understanding is not wisdom. I'm probably somewhere between knowledge and understanding on climate change.
I hope this doesn't get axed as I'd like to thank SkS for giving me a very fair go on this post
Moderator Response:[JH] As long as your posts conform to the SkS Comments Policy, they will not be deleted.
My sense is that English may not be your first language. Is that the case?
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bcglrofindel at 02:54 AM on 11 November 2014IPCC overestimate temperature rise
If JSmith's methods were wrong can you not at least address his core concern? Your article doesn't show the actual IPCC first assessment predictions for temperature, but adjusts them prior to comparison to observed temperature. The IPCC first assessment summary states in Chapter 6 that for 2030 they see "a predicted rise trom 1990 of 0.7-1.5°C with a best estimate of 1.1C". If I'm not mistaken, we currently are very much on track to be under 1.1C warmer than 1990 in the next 15 years?
If JSmith made mistakes or inaccuracies in matching the observed temperatures to the 1990 IPCC predictions as they were published below, don't just settle for saying he did it wrong. Graph the actual observed temperatures against the actual published predictions of the IPCC from 1990 as shown below. I'm afraid all my efforts to match recorded observations to them only seem close to matching the very coldest 1990 predictions and I'd love to see a graph that can more clearly show me where I'm going wrong.
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