Recently, a Financial Times op-ed criticised the IPCC for having contributors and peers drawn from a narrow professional circle. I don’t think this is fair, unless one regards a whole discipline as ‘narrow’. Furthermore, recent public disclosure of both comments and response suggests a different story to the allegations in the FT op-ed of ‘refusing to disclose data and methods’. The IPCC has no control over the independent publication, but the disclosure of the comments and response at least enhances the openness for the synthesis of the report.
But it is pretty unusual in common scientific peer review that reviewer comments, such as those for the two first drafts of the IPCC Working Group I report (the scientific basis), are available on line – usually the reviewers’ comments are anonymous and the process concerning manuscript reviews are closed to the wider community. However, this does provide a good demonstration that the process leading up to the IPCC report has indeed been transparent and accountable.
For some, this release of reviewers’ comments may appear as a change of heart by the IPCC, and that it may look like the IPCC did not originally intend to do this. However, the fact that all the reviewers’ comments are available on-line, proves that all the information was indeed stored and organised for the benefit of the outside community (who ever they were intended to be). The proof of the pudding is in the eating.
An inspection of the comments shows that there has been a large number of reviewers. Much higher number than a paper review usually relies on (and don’t forget, the assessment is made of papers published in peer-reviewed literature and have already been reviewed for the individual journals).
One should also keep in mind that the main point of the reviewing exercise was to provide critical voices to the IPCC process. That is how science works and how it is supposed to work. Hence, it should not come as a surprise that one may find critical comments.
When comparing the IPCC process to normal peer-review, one should note that there are substantial differences: normal peer-review is not only anonymous but also non-public; in normal peer-review the reviewers do the whole paper not just bits; in normal peer-review the authors have a different balance of power with the reviewers.
Also the review process was very open – practically anyone could comment. There were a whole pile of comments from various government reviewers for the second round. In fact there is a lot to be said on the differences, however, this is not really the focus of this post.
Some have used these critical comments to create the impression that there are critical views to Al Gore’s film. Such framing displays a misunderstanding of the whole endeavour, since after all, it’s the final version of the report that really matters.
An important question is, however, how these critical comments were dealt with. There are several cases where obvious nonsense was rejected, but also plenty of examples where critical stuff was accepted.
The authors of the report used the input from the reviewers to improve the report. In some cases, the authors may disagree with the comments – after all, it is them who are the authors of the report; not the reviewers.
And finally, one should not forget that it is the final version that counts. In summary, the IPCC is indeed an open and transparent process and there is plenty of criticism from all quarters during the review process and the idea that it is just a closed forum is completely bogus.
Update: old link doesn’t work. Here is a new link.
What about being able to review the raw data when performing a peer review?
It is getting to the point where there is peer reviewed research published in journals that are on both sides of most every issue discussed in the IPCC. I have the impression that most of the authors of these chapters fall on the AGW side of the debate, so all of the other possible causes of the current warming are downplayed. This includes the cosmic ray flux theory, UHI, changes in areosol concentrations, and land use changes. I don’t think the IPCC has enough diversity in its authors to sort through all of the conflicting research in an unbiased way.
[Response: I would certainly disagree with your characterisation of the literature (look at the average table of contents of any of the mainstream journal or conference proceedings), and I don’t see why you think the IPCC reports don’t deal with the issues you raise. Look these things up – there is plenty of discussion of aerosol issues, land use and UHI. Even cosmic rays get a mention. If there was a huge debate in the serious literature, you’d see it in the reviewer comments. You don’t – and I doubt that is because people are shy. – gavin]
RE #1 (Robodruid): That doesn’t happen in my field (immunology). Why hold climate science to a different standard?
For which study? The raw data is for the studies that are in the footnotes, published in a great many different journals (the IPCC doesn’t do research, it reads research and draws conclusions).
Peer review means review by experts who know the area, for the journal, before the journal decides to publish an article.
It doesn’t mean that Lord Monckton gets to review it all, eh?
Re #3
It does in mine. (Analytical Chem)
Gavin, I read the short blurb on cosmic rays in the IPCC. The report described this theory “controversial” and didn’t attempt to quantify it in the list radiational forcing. I know of your debate with Roger Pielke Sr on the IPCC’s lack of consideration of land use changes on the radiational forcings. I also get the impression that the IPCC is concluding that the UHI effect is so small compared to the effect of greenhouse gases, that the UHI can be ignored. I’m not saying that greenhouse gases isn’t a player, but I’d like the IPCC and the climate community to work towards understanding the other potential causes of warming, before jumping to conclusions on the impact of greenhouse gases.
[Response: That’ s just the problem with the CR idea, no-one has done the work required to even get close to proper calculation of it’s radiative forcing. We detailed the ‘missing steps’ in an earlier post. IPCC is an assessment process, and they cannot assess what hasn’t been done. What is controversial are the conclusions drawn by some scientists involved, not the basic concept. However, even without a good calculation of the impacts, the lack of trend in any cosmic ray related index since 1960 rules out any role of CR changes in recent global warming. Coming to that conclusion is not ‘jumping’. It’s just concluding. – gavin]
I went through an entire PDF file and didn’t see what appeared to be a significant disagreement – a surprising number of comments resulted in partial to complete changes. In what section(s) is there an example of a climate scientist(s) who had material disagreement(s) with the report that went unheeded?
It makes me wonder whether IPCC press releases should come with a disclaimer explaining the IPCC process. The criticisms seem to neglect the fact that the IPCC is a review by a large panel of scientists of (already peer-reviewed) published literature that is then subject to a wide-open review by the community. What other research is subject to three levels of scrutiny? If anything, the resulting reports should be assumed to be conservative, since all multiple levels of review are likely to eliminate extreme views.
The challenging of the review process sounds like grasping at straws. If you can’t criticize the substance(the Report), then criticize the style, in this case the method of the review process. This is nothing new. Alexander Cockburn criticized the peer review of the IPCC ‘s 1996 report in the June 11,2007 edition of “The Nation”.
One of the big reasons for the inertia in accepting the reality of climate change is the belief that the changes involved in mitigating it are going to cost money. Almost everyone acknowledges that world temperature has increased about .6 or .7C in the last century or so, but balk at the human factor,as a cause, due to fear of the financial cost of changing over to alternative sources of energy. Actually, changing over to solar and wind power, for example, will create jobs, and add to the strength of our economy.
I have to ask Lawrence Brown (Gavin you are free to comment) this question. Of the .6 to .7 deg C warming, how much of it is due to greenhouse gases? 100 percent? 80 percent? How much is due to UHI? How much is due to direct and indirect solar processes? How much is due to lower areosol consentrations? How much is due to land use changes like deforstation? Even the IPCC admits that many climate forcings outside of greenhouse gases are poorly understood, and therefore, poorly modeled.
I came across this paper: Stanhill, G. 2007. A perspective on global warming, dimming, and brightening. EOS, Transactions, American Geophysical Union 88: 58.
It estimated that global dimming of solar energy due to aerosols was 20 w/m2…much larger than the response of greenhouse gases. While this paper was published in 2007, surely the IPCC had research available to them to consider? Can you understand my reservations of the IPCC conclusions when I see research published undermining the basis of their conclusions?
[Response: There’s no doubt that it can be confusing to outsiders and we spend a lot of time here going through the subtleties. The Stanhill paper confuses (and exaggerates) surface flux changes and compares them to radiative forcings – it just isn’t an appropriate comparison, and anyone writing the relevant IPCC chapter is aware of that (notwithstanding that there actually is a discussion of global dimming in the report). This is why assessment processes exist. You need experts in the field to cut through the confusion and put things into context. – gavin]
Re#9. The inertia isn’t about the money, its that a significant number of
rich and powerful people think that they should be able to live exactly like
they want to live. Drive huge moster 4WD (SUV to U.S. readers) vehicles and
live in 600 sq meter houses and coopt the entire realm of nature to their
service. Such people do not take kindly to being told they have to
change by a bunch of nerds with equations and computer models. And of course
plenty of nerds are telling them, no you don’t have to change, we will change
the technology and you can keep your lifestyle — just throw a few more
research dollars my way.
#3 Deech56 That doesn’t happen in my field (immunology). Why hold climate science to a different standard?
Because it’s wrong. Steve McIntyre shouldn’t have to file a FOI request to get data. I can understand 20 years ago when data might have had to have been shipped all over the world on magnetic tape. But with the internet, an important job of a journal should be archiving the data and source code used to arrive at conclusions in the article.
Where else should this job reside? We’ve seen from numerous requests with unsatisfactory answers that the researchers aren’t up to the task. I dont’ fault the researchers. With job changes, HDD crashes, etc, it’s too big of a task to put on the individual.
#11 Geoff Russell Re#9. The inertia isn’t about the money, its that a significant number of
rich and powerful people think that they should be able to live exactly like
they want to live. Drive huge moster 4WD (SUV to U.S. readers) vehicles and
live in 600 sq meter houses and coopt the entire realm of nature to their
service.
Whether you drive an SUV or ride the subway is irrelevent. The subway rider that lives in London is producing massive amounts of CO2, while the SUV driver that lives is Los Angeles is producing massive amounts + 10%. Note that the point of comparison for both is the simple farmer in China today.
In the end, both lifestyles lead to the tipping point once places like India and China begin to produce CO2 at rates that are 1/5 of what a Londoner might produce CO2 today.
I’m disappointed that the IPCC hasn’t responded to recent suggestions that the CO2 emissions scenarios they use may not be realistic. The case has been made by researchers in the US (Caltech) and Sweden. The key claim is that most alleged coal reserves cannot be profitably recovered under existing or potential technologies. Therefore a forcings timeline that shows increasing manmade CO2 after about year 2025 is arguable.
I think IPCC needs to respond to this, not just hope it goes away.
#1. The release of the comments was the result of several FOIA results made by memebers of
ClimateAudit. I have my response letter framed. The FOIA requests were made because the
IPCC refused to post the comments and instead put them in Harvard library, restricting access.
The whole tale is told on CA.
Several points:
1. The comments are still RESTRICTED. you cannot copy them or redistrubute.
2. Criticial comments in certain cases are ignored.
3. A page limited minority report would be more open and transparent.
#2. Comments are not data and methods. The IPCC could of course adopt a policy that it would only
rference studies that provided data and methods.
A report is only as transparent as its most opaque source.
Re #12: Obviously things that are legally public records need to be treated like that regardless of who’s requesting them, but the reason Steve McIntyre generally does not receive cooperation beyond that minimum is because his interest in these matters is not scientific. Even his use of the financial audit meme is fraudulent since financial audits don’t just cherry-pick small parts of a company’s operations. He’s a denialist, just smarter and more polite than the average.
Re #14: Links to that material?
Q.E.D
That you should write this shows either hubris or a profound misunderstanding about the difference between formal proofs and science. Science is always contigent. It is never Q.E.D
IF it were QED then consensus would be immaterial.
Theory is always underdetermined by the evidence which is why consensus is a consideration is the adoption ( not the truth) of a chain of hypotheses.
Here is a test. Reduce your steps to LOGICAL FORM.
then show each step with the appropriate logical rule that allws yu to move from one step to the next.
( eg Modus Tolens)
The you get to write QED grasshopper
I’m not at all surprised that the Financial Times would object. In the first place, they are journalists, alias innumerate [anumerate?] humanitologists. Since they have no idea what science is about, they may ascribe all sorts of irrelevant motives to scientists. They probably think that scientific opinion is just another opinion. See “The Republican War on Science” by Chris Mooney, 2005, Basic Books.
In the second place, the coal industry is a $100 Billion per year industry in the US alone. Being economics oriented, “Return On Investment” [ROI] is a really big thing with them. Thinking decades ahead is something they just don’t do. Most of their readers are also economics oriented and probably either investors or managers who would be upset if the Financial Times didn’t object.
The first problem could be overcome by requiring everybody in the country to get a degree in science………….
RE 16.
A smart auditor knows the most likely places to find
“shifty” business. Inventory evaluation for example.
and especially evaluation of prducts with a volitile
market value. They have caught cheats before so they know where to look.
Put differently. When we sample nature we sample randomly because we do not expect nature to hide from us on purpose. She has no intent. When we audit human organizations we do not randmly sample. We look in the places were Mistakes or deception have occurred before.
So, Mistakes: like y2k errors. Mistakes are all that has been found. This is to be expected because no human is omnscient and all science is contingent
[Response: The error was not a ‘Y2k’ bug in any traditional sense (nothing to do with two digit year codes, and wasn’t even a program bug) and so I’m unsure of your reasoning here. – gavin]
Therefore a forcings timeline that shows increasing Beyond mere guesses about quantity consumed, what does their timeline/projection assume about the development of clean coal?
Regarding comment #10 by VirgilM where he says in part:
“I have to ask Lawrence Brown (Gavin you are free to comment) this question. Of the .6 to .7 deg C warming, how much of it is due to greenhouse gases? 100 percent? 80 percent? How much is due to UHI? How much is due to direct and indirect solar processes? How much is due to lower areosol consentrations? How much is due to land use changes like deforstation? Even the IPCC admits that many climate forcings outside of greenhouse gases are poorly understood, and therefore, poorly modeled.”
Total forcings due to the increase of GH gases is 2.6W/m^2 ( Source “Global Warming,The Complete Briefing by John Houghton). A graph from the same source (fig. 3.8) for the period 1750 to 2000 shows that radiative forcings due to the GH gases,CO2,CH4,N2O,and the Halocarbons dominate all other forcings in the figure, which includes stratosphere ozone,tropospheric ozone,sulphates,land use,solar and other forcings.
I can’t answer (nor do I imagine anyone else can) with, certainty what percentage of the temperature change is due to GH gases. But I do know that this is the component that has changed the most in the last 250 years, CO2 in particular. So GH gases have to be
the primary suspect.
One problem is that the IPCC draws from the ranks of reputable, established, conservative, and conventional professionals. It does not recruit radicals. The IPCC recruits diplomats rather than people like me that just say what we think. The IPCC has established a paced, linear process for evaluating a potentially rapid nonlinear process. And, human nature being what it is, our leaders are waiting for that definitive answer before they take serious action.
Global warming is likely to unfold much faster than the IPCC can write its reports. It is not possible to report the progress of a highly non-linear process with 3-year old data. And, some of the folks on the IPCC panels are making a career out of global warming. They are more interested in a job for life than solving the problem as fast as possible. Any elected leaders that are waiting for those reports are in for a surprise.
Are we sure that the computer models are correct? I compare the various models projections of Arctic sea ice against actual sea ice and I see discrepancies. However, the sea ice projections in the models inform the other modules in the models, so if the sea ice projection is wrong, other things must also be wrong. For example, how many people did the computer models say would be affected by flooding this year? Now, the UN says the number of people affected by flooding is 500 million per year. That is a lot a of latent heat. That is significant.
Recently, gavin commented to me that N2O was not a greenhouse gas of global climatic importance. In fact, N2O is a powerful greenhouse gas, it is just cleared from the atmosphere more rapidly than CO2. I think that we should be looking for a whole group of small effects that we can sum together; so that we can fully explain why ice in the real world is melting faster than the ice in our computers.
Maybe there are some other things we should be doing. Maybe there are low hanging fruit that we can pick. (Both in modeling and in the real world to curb global warming.) For example, maybe everyone needs to operate under the Bay Area Air Quality Rules for N2O? Gavin’s baby could spit out the ROI for that in seconds. What else is cheap to fix? The only thing is: We better get this done faster than the IPCC writes reports.
“It doesn’t mean that Lord Monckton gets to review it all, eh?”
Touche! Look, either criticism is valid or not. What we have here as always, is an unacceptance of reality. And possibly a failure to communicate, but methinks to accept on one party.
RE 21…How can you say that CO2 is the primary driver in the climate system, when the effect of areosols and land use changes are poorly understood (so the IPCC says) and unquantified?
Virg, have you read Ruddiman’s book? What level of explanation do you need to start at?-
Even simpler — Virgil, did you read “Start Here” yet? The link’s at the top of the page; this is where it takes you, beginner questions:
https://www.realclimate.org/index.php/archives/2007/05/start-here/
I would like to know the approximate watts per meter produced from the daily burning of the Earth’s fossil fuels. If the burning of coal, methane and gasoline are added together, would the watts per meter of energy produced have a significant or miniscule effect on the global climate? The calculation seems easy enough if only the average daily energy released from fossil fuels is known.
Global warming newbie
I recently saw the ‘Global warming snowjob’ video on the website of the heartland institute. Three of Al Gore’s claims were refuted by lot of people. Can someone shed more light on Gore’s side of the argument ?
Claim 1 : Rising Co2 levels do not cause temperature rises but it is the other way round (rising temperatures cause increases in co2 levels).
[Response:See old post. There are feedbacks both ways, so that temperature/biological activity affects CO2 in the atmosphere and CO2 affects the temperature by perturbing the longwave radiative balance. -rasmus
]
Claim2 : Co2 is a very small component of greenhouse gases in comparison with water vapor and therefore is not responsible for global warming.
[Response: Although water vapour (H2O) carrys strongest weight, CO2 plays a non-neglegible role – see the most recent IPCC (AR4) report. While H2O has a short life time in the atmosphere (precipitates out) and varies strongly in time and space, CO2 is longlived and well-mixed. -rasmus]
Claim3 : Global warming will not raise sea level by 20 ft but by 23 inches.
[Response: There are large uncertainties around this issue. The sea level will depend largely on what happens to the ice sheets in the Arctic and Antarctic, but for sure, the thermal expansion of the oceans and melting glaciers alone gives a minimum estimate typically less than 1m. -rasmus]
[Response: I would add that Gore made no such prediction for 2100. – gavin]
Re #28 and Rasmus’ reply.
Claim3 : Global warming will not raise sea level by 20 ft but by 23 inches.
If nothing is done to stop the increase in the concentration of CO2, sea level rise will not stop at 20 ft. The Arctic sea ice has nearly gone. See http://www.abmcdonald.freeserve.co.uk/north.htm and when it does, the Greenland ice will follow soon after. Rasmus, when are you and the IPCC going to get real? Their prediction of only 23 inches for sea level rise is criminal.
Totally OT sorry, but would it be possible for a post on this paper?:
http://www.sciencemag.org/cgi/content/short/317/5839/796
“Improved Surface Temperature Prediction for the Coming Decade from a Global Climate Model
Doug M. Smith,* Stephen Cusack, Andrew W. Colman, Chris K. Folland, Glen R. Harris, James M. Murphy
Previous climate model projections of climate change accounted for external forcing from natural and anthropogenic sources but did not attempt to predict internally generated natural variability. We present a new modeling system that predicts both internal variability and externally forced changes and hence forecasts surface temperature with substantially improved skill throughout a decade, both globally and in many regions. Our system predicts that internal variability will partially offset the anthropogenic global warming signal for the next few years. However, climate will continue to warm, with at least half of the years after 2009 predicted to exceed the warmest year currently on record.”
It looks to me to be a very interesting new(? I see references to the approach in 2003 from Google) line.
NB I can’t read the paper as I don’t have a subscription.
[[I would like to know the approximate watts per meter produced from the daily burning of the Earth’s fossil fuels. If the burning of coal, methane and gasoline are added together, would the watts per meter of energy produced have a significant or miniscule effect on the global climate? The calculation seems easy enough if only the average daily energy released from fossil fuels is known.]]
Direct heating from fossil fuel use is on the order of 1013 watts worldwide. Solar energy input is on the order of 1017 watts. Therefore direct heating from fossil fuel use can be ignored.
Re#13. How do you calculate that a US SUV user uses 10% more than a UK
tube user? UK GHG emissions per capita = 11, US GHG emissions per capita =
24, from: http://www.carbonplanet.com/home/country_emissions.php
But a more relevant comparison is to compare the SUV driver with someone
who drives a smaller vehicle. To build and service a vehicle generates
about 17 tonnes ghg emissions per tonne of vehicle:
http://www.carbonneutral.com.au/rose_bj_2006._ghg-energy-calc_background_paper_august_2006.pdf
so 3 tonnes of Toyota Prado generates well over 50 tonnes of emissions
to build and service + 0.3kg per km to run. Which is about triple the total
emissions cost of any small vehicle.
Re 29 – the guardian (uk newspaper) have covered this paper:
http://www.guardian.co.uk/environment/2007/aug/10/weather.uknews
RE 19 Gavin,
Like it or not it will always be referred to as the “y2K” error. As SteveMc Noted early on he was not, and I am not, claiming it was a 2 digit coding error.
Had we be given access to the code produced at taxpayer expense it is highly doubtful that the error would have mislabelled as the “Y2K error” The lack of transparency at NASA has purchased a misleading moniker for the mistake.
Free the code.
Re #16
It does not matter who is asking for the data. Part of the scentific process requires tranparency in data collection and analysis.
No. 24. Hi Geoff. One question I would like an answer to is: Is it better to run an old and relatively inefficient car into the ground, or to scrap it and buy a newer, more efficient one?
Thanks.
What is all this hype going aroung the internet the 1934 is now the warmest year thanks to a “Y2k” bug in the nasa data that Mcintire exposed. They yahoos are rallying around this and trying to make the point that if Nasa does not allow other parties to check the data and see the original alogrithms, then NASA is keeping secrets.
It’s getting really rare to see a new or thoughtful question science here from new readers.
Is it possible to keep a ‘Roundup’ thread always at the very top of the main page, to capture those who feel they need attention so “post at the top” regardless of what topic’s recent?
Perhaps at the main top center a big link labeled “Climate Chatroom” that opens to say the Globalchange page, to direct people there who want to post “right at the top where everyone will see it” instead of looking for a relevant thread?
Adam wrote: “NB I can’t read the paper as I don’t have a subscription.”
Adam, you can read the abstract _and_ the extensive online supplementary material at http://www.nature.com, and you can go to any public library anywhere — most will have Nature available to read and any that don’t can borrow the copy for you free and easily.
Stephan: an old car run _rarely_ can last a long time yet not burn much gas. Check gas mileage and miles driven.
Re: #22 (Aaron Lewis):
I think you are confusing NOx and N2O. Gavin’s comment to you was about NOx, which is not a significant direct greenhouse gas, but has some indirect effects through ozone creation and methane lifetime: and because the ozone effects and methane effects are in different directions, and the non-linearity of the chemistry involved, it is not clear that a reduction in NOx will actually lead to a reduction in temperature (all else equal).
My guess is that the Bay Area Air Quality Rules apply to NOx and not N2O, because N2O isn’t really a traditional air pollutant.
N2O is produced in large part as a byproduct of fertilizer use in agriculture, though also some from adipic acid synthesis and some from combustion, and it is a long lived (120 year half-life) greenhouse gas, 3rd behind CO2 and CH4 in terms of anthropogenic contributions to well-mixed gas radiative forcing.
Re. Financial Times article. It seems while we’ve been busy with other things, many in the financial community have become so wealthy, they are now doing a daily commute to work from the planet Mars.
#39 Hank, thanks for that, but it’s not so easy for me to get to a library that has the subscription – not impossible but unlikely to happen soon or often. Also, just for reference, the paper was published in Science. I’ll keep an eye out for it elsewhere. Just for reference though, it’s published in Science (the abstract’s at the url I posted above). But thanks, I hadn’t seen the Nature article: http://www.nature.com/news/2007/070806/full/070806-10.html
Re 40
see http://www.eia.doe.gov/oiaf/1605/ggrpt/nitrous.html >> 18% from non-ag uses in US, much from mobile sources.
They had higher numbers in the days when I was at DOE. My guess is that for SE Asia the percentage is way higher than the current US what with our air quality rules.
#32 Geoff Re#13. How do you calculate that a US SUV user uses 10% more than a UK
tube user? UK GHG emissions per capita = 11, US GHG emissions per capita =
24, from: http://www.carbonplanet.com/home/country_emissions.php
The US is a big place. States like Wyoming are at 125 tons/per capita, while states like NYC are at 11 tons/capita. So I’d venture to guess that a New Yorker and a Londoner are very close to the same. I’m happy to be educated on that, however.
Now, NYC subway efficiency is around 3500 BTU per passenger mile, or 1.03 KWH/PM. For a place like the US that derived most electricty from coal, that means about 0.61 kg of CO2 per KWH delivered. So, to go 1000 miles on the NYC subway emits about 0.625 tons of CO2. I’m sure nuke-powered TRV is quite a bit better than this, but I suspect the older Tube is closer to NYC than TRV. Again, I’m happy to be educated.
A 2WD Ford Explorer, according to TerraPass, emits 0.496 tons of CO2 per thousand miles.
Now, if you are a soccer mom with two kids, and you have the option of taking mass transit to a destination OR your SUV, the you’d generate about 75% less pollution in your SUV. Weird, huh?
So, my statement that whether or not you drive an SUV is a very, very small part of your carbon footprint stands. There are so many other factors that matter much, much more.
Side note: building mass transit to reduce pollution is a scam. Cities would do much, much better to give hybrid cars to those that drive the most. Mass transit is very good at reducing congestion, however.
#24
(1) The Earth has been warming, implying a net positive radiative forcing. (2) The largest positive radiative forcing — by far — has been the one due to long-lived greenhouse gases, most notably, CO2. Thus, it is quite reasonable to say that the main cause for the warming has been the increase in these gases.
Jerry Steffens (#45) wrote:
… and GISS best estimates are that with 1880 as the baseline, positive forcings due to anthropogenic greenhouse gases have exceeded that of solar for the entire 20th century – although not by much in the earliest few decades.
Re 24. There are uncertainties in Quantum Theory as well, yet it has been a very successful accomplishment responsible for the many electronic wonders of our age. The Theory of Evolution has gaps and uncertainties, yet forms the basis of molecular biology.
The past 40 or 50 years of global warming can’t be explained without factoring in anthropogenic influences. Natural influences such as vulcanism and solar influences are sufficient to explain the first half of the twentieth century but they can’t alone explain the last half. Only including the net effect of human made greenhouse gases and aerosols, can the more recent decades be reproduced to match the actual record.( Parallel Climate Model/DOE/UCAR-Meehl,Washington,Ammann et al.Combinations of Natural and Anthropogenic Forcings in Twentieth Century Climate. Journal of Climate 17:3723,fig.2(d).
This looks, acts and quacks like a duck. Odds are that it’s a duck. You don’t need to get a DNA sample to remove all doubt.
re: 40
Marcus is correct: Bay Area Air Quality Rules include NOx and many others, but sets no limits on N2O.After all, N2O is “laughing gas”, and we need all the laughs we can get these days :-)
http://www.baaqmd.gov/dst/regulations/index.htm
Much of it comes from farming (of which not much is left in the Bay Area), and it is not so much a BAAQMD issue as a broader one, i.e., at least locally the California ARB is the relevant agency.
People are certainly discussing what to do about N2O: see Part III in “International Symposium on Near-Term Solutions for Climate Change Mitigation in California, march 5-7, 2007”,
http://www.arb.ca.gov/cc/030507symp/030507agenda.htm has many useful presentations.
#24
“How can you say that CO2 is the primary driver in the climate system, when the effect of areosols and land use changes are poorly understood (so the IPCC says) and unquantified?”
I must confess that I have a rather poor understanding of some of the charges on my monthly phone bill; yet I am reasonably confident in attributing the increase in my bank balance over the past year to my salary.
Re#44. Yes, it hit me a few hours after I posted that you were, effectively
comparing petrol (SUV) with electricity (London Tube), so I went digging.
“Total requirements of energy and greenhouse gases for Australian transport”
Transportation Research Part D 4 (1999) p.265–290, comes to similar
conclusions – there isn’t much difference between electric driven mass transit
and petrol motor vehicle — on average. But there are substantial differences between mass transit systems and between private motor vehicles and those
little differences add up in a mass transit system (hence the name “mass”) so
that 10 or 20% per passenger km adds up to one hell of a lot if lots of
people use it.
And yes, my mom was a soccer mum, but did it without an SUV — we walked.