Not so long ago I republished a letter from 60 ‘global warming skeptics’ who wrote to the new Prime Minister of Canada asking for more public consultation on climate change issues and explaining that climate change can be natural, click here to read the blog piece.
Now 90 ‘global warming believers’ have written to the PM of Canada:
An Open Letter to the Prime Minister of Canada on Climate Change Science
April 18 2006
The Right Honourable Stephen Harper, P.C., M.P.
Prime Minister of Canada
Ottawa, ON K1A 0A3
Dear Prime Minister:
As climate science leaders from the academic, public and private sectors across Canada, we wish to convey our views on the current state of knowledge of climate change and to call upon you to provide national leadership in addressing the issue. The scientific views we express are shared by the vast majority of the national and international climate science community.
We concur with the climate science assessment of the Intergovernmental Panel on Climate Change (IPCC) in 2001, which has also been supported by the Royal Society of Canada and the national academies of science of all G-8 countries, as well as those of China, India and Brazil. We endorse the conclusions of the IPCC assessment that “There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities” and of the 2005 Arctic Climate Impact Assessment that “Arctic temperatures have risen at almost twice the rate of those in the rest of the world over the past few decades”.
Climate variability and change is a global issue and the international IPCC process for assessment of climate science, with its rigorous scientific peer review processes, is the appropriate mechanism for assessing what is known and not known about climate science. Many Canadian climate scientists are participating in the preparation of the IPCC Fourth Assessment Report which will be completed in 2007.
The following points emerge from the assessments and ongoing research by respected Canadian and international researchers:
• There is increasingly unambiguous evidence of changing climate in Canada and around the world.
• There will be increasing impacts of climate change on Canada’s natural ecosystems and on our socio-economic activities.
• Advances in climate science since the 2001 IPCC Assessment have provided more evidence supporting the need for action and development of a strategy for adaptation to projected changes.
• Canada needs a national climate change strategy with continued investments in research to track the rate and nature of changes, understand what is happening, to refine projections of changes induced by anthropogenic release of greenhouse gases and to analyse opportunities and threats presented by these changes.We have supplied justification and more detail for each of these points in the accompanying documentation.
We urge you and your government to develop an effective national strategy to deal with the many important aspects of climate that will affect both Canada and the rest of the world in the near future. We believe that sound policy requires good scientific input.
We would be pleased to provide a scientific briefing and further support, clarification and information at any time.
Yours sincerely:
Signed by 90 Canadian climate science leaders from the academic, public and private sectors across the country.
For a list of the science leaders and also supporting background information click here.
And there is editorial comment at CNC, click here and more opinion at Canada’s National Post, click here.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
I enjoy your even-handed posts on climate change and other science matters, Jennifer. But I can’t believe the sheer hatred directed towards you in earlier comments threads. Amazing.
Jen – its not about the numbers of scientists it is about the scientific accuracy of the letters in question. This one makes no bold claims and is in agreement with most of the world’s climate scientists including the 1500 or so that participated in the IPCC 2001 report and are participating in the 4th assessment.
Is OK to remain skeptical personally however if asked to give an answer professionally as a scientist you would have to give one that most represented the views of the scientific community. This is what this letter does.
If asked you must present your own views or research, if they differ from the scientific majority, with the caveat that these do not represent the views of the majority of scientists. This is what the other letter did not do. It presented claims as truths with reservation. This letter presents claims as the best possible advice from the worlds climate scientists.
Ender, you just said “its not about the numbers of scientists” then said that a professional scientist must provide an answer “that most represented the views of the scientific community”.
If its not about numbers then who is in the majority?
rog – what I meant is that 90 does not trump 60. Generally theories that have the support of more than 95% of the world scientific community for many years like AGW then this is accepted as the majority.
I would agree that 90 does not represent a majority.
Yes but how many of them are experts in the field of climate?
How many are publishing scientists in this area?
I’m somehow guessing that this time the signatories won’t be slagged anywhere near as much as the last letter signing experts.
Let’s see……..
jim – yes well that is because this group is presenting the ideas that most of the scientific community share.
Ender says
Is OK to remain skeptical personally however if asked to give an answer professionally as a scientist you would have to give one that most represented the views of the scientific community.
Me
Ender, I distinctly recall one/two (can’t recall exact number) medical research scientist(s) receiving a nobel prize for figuring out that most digestive ulcers are caused by bacteria. This went right against accepted medical practice and “knowledge” of the mainstream medical profession. In fact thye were both taken as idiots.
Do you wish to retire the comment you made? Science is not swinging the bat the way everyone else does.
FROM Crikey.com about 5th October 2006:
As the media, politicians and the Australian medical research sector rush to congratulate our newest Nobel laureates – and to bask in their reflected glory – it is worth reflecting on the truth of the long and, at times, lonely journey Barry Marshall and Robin Warren have taken to reach this point.
Rather than welcoming and supporting the work of “local heroes,” many Australian gastroenterologists were highly critical and disbelieving of Marshall and Warren’s (ultimately) Nobel Prize-winning work, and continued for many years to stubbornly deny that Helicobacter pylori had much, or indeed any, role in the pathogenesis of ulcer disease.
Barry Marshall was made to feel quite uncomfortable when he attended specialist conferences – he was regarded by many as a maverick and even a loony, especially when the story of his drinking “swampwater” in order to infect himself got around. Worse still, this lack of acceptance was often blamed on Marshall’s personality (he has been described as “brash”) or justified as a response to him apparently seeking publicity and glory. It certainly didn’t help that he was not a gastroenterologist by training.
Given Marshall and Warren’s pioneering work, Australia should have been the first place in the western world to accept the full H. pylori story. But, shamefully, it was not. Although a Working Party reported to the 1990 World Congress of Gastroenterology (which incidentally was held in Sydney) that H. pylori was definitely an important cause of ulcer disease, many prominent leaders of the gastroenterology specialty in Australia continued to deny its importance, or to claim that it was a cause of only a small minority of cases of ulcer disease, well into the mid-1990s. As examples:
In 1991, Parke Davis got scant support from local “opinion leaders” when it brought an international speaker (and member of the Working Party) to Australia to discuss H. pylori eradication as an approach to treating ulcer disease.
In a drug company-sponsored 4-page educational publication for GPs published in Australia in 1992, only the last two paragraphs mention H. pylori, and only in the context of how this company’s anti-acid drug might one day have a role – in combination with antibiotics – in eradicating the bacterium. It was only 4-5 years later, when such combinations were shown to be effective in eradication, that education and promotion to GPs about the role of H. pylori in ulcer disease really started to pick up momentum.
Marshall’s work was much more readily accepted internationally than locally, and so he spent what may perhaps have been his most productive years as a researcher overseas. Medical journalist Melissa Sweet gave some of the back-story in this article in the SMH in 1997, as reproduced on Barry Marshall’s personal website.
joe “Ender, I distinctly recall one/two (can’t recall exact number) medical research scientist(s) receiving a nobel prize for figuring out that most digestive ulcers are caused by bacteria. This went right against accepted medical practice and “knowledge” of the mainstream medical profession. In fact thye were both taken as idiots.”
Yes however by good science they put their case through peer reviewed science and because their science was solid it was accepted.
It bears no relation to the present AGW case. Scientists 40 years ago struggled against a skeptical scientific community with similar peer reviewed science and convinced the present majority of scientists that the science of AGW is sound.
Science by nature changes however it very rarely changes with media released psuedo science that has been characteristic of climate change skeptics especially the team put together from the pro smoking campaign by vested interests.
Please joe read something other than money and look at this history of AGW.
http://www.aip.org/history/climate/co2.htm
Ender, you did just say “if asked to give an answer professionally as a scientist you would have to give one that most represented the views of the scientific community”
Given that statement Marshall and Robin were wrong to go against the majority view of the scientific community in spite of the fact that they had, as you put it, “their science was solid”
Ender:
I really, really do think you are a thoughtful and decent person, hell, I even think Phil is too. I know I have sometimes gone over the top with my criticisms of you, while sometimes I have tried to be light hearted about it.
Let me tell you what I feel is wrong in your thinking from a trader’s perspective.
In my job stilted and one side thinking means death. In fact the people I have seen in my history, the ones that fail, are the people who are dogamtic in their thought processes.
I used to be a denier when it came to AGW. However I spent a little time reading up on it and came away with thinking there is a possibility that it may be happening. Yes, I opened the gate to the possibility and look it as such. However I will never close the door on the other more likely set of scenarios.
I think your approach to this issue is dogmatic in the extreme and it would be good for you to open up to the possibility that we are at this stage onny beginning to understand climate science. It is not any easy subject to get ons teeth around.
Scientist need a lot more time to figure out this complicated stuff. Quite a few seem to be what (i call) married to their position. You need to as well.
Please don’t take it the wrong way as I am expressing these fellings with all the best intentions.
Ender says:
“Science by nature changes however it very rarely changes with media released psuedo science that has been characteristic of climate change skeptics especially the team put together from the pro smoking campaign by vested interests.”
It’s statements like this the kid of reaffirm my views about you being married to your position.
You know full well that junk science and scary stuff is been coninually put out by the warmers as well. Tim Flannery, someone not schooled in climate science, is a great example of what I mean.
http://www.thecrimson.com/article.aspx?ref=512890
This is what a lot of us mean.
Tin Worstal has an interesting piece in TCS, I’ll select a few paras;
There’s good news, more good news and then, unfortunately, some bad news, on the subject of climate change.
+ for a doubling of CO2 a climate sensitivity of only 3 degrees C is reasonable
+ estimates of how much of a rise in CO2 emissions we are going to see are also too high
+ the IPCC isn’t going to take any notice
Read it all on
http://www.tcsdaily.com/article.aspx?id=041106A
Thanks for your analogy, Jennifer. It’s an excellent illustration that science isn’t democratic. The majority is often completely wrong. As for “if asked to give an answer professionally as a scientist you would have to give one that most represented the views of the scientific community”, this is just breathtakingly anti-science.
rog – “Given that statement Marshall and Robin were wrong to go against the majority view of the scientific community in spite of the fact that they had, as you put it, “their science was solid””
No they would have said professionally before their work was accepted something like this:
“The current thinking in stomach ulcers is that that it is caused by acid however we have done some research that shows that it is in fact caused by bacteria”
Once their research had been peer reviewed and accepted as it has now it becomes the majority view.
joe – “I think your approach to this issue is dogmatic in the extreme and it would be good for you to open up to the possibility that we are at this stage onny beginning to understand climate science. It is not any easy subject to get ons teeth around.
Scientist need a lot more time to figure out this complicated stuff. Quite a few seem to be what (i call) married to their position. You need to as well.”
Joe I appreciate your comments however you are quite wrong. I think that there is every chance that AGW could be wrong. You are correct that the science in uncertain and there have been celebrated cases of every scientist in the world being wrong.
In science there is nothing really certain. If you asked a scientist of say 1890 that if you banged 2 pieces of metal together you would get an explosion the size of 10 000 tons of TNT he/she would have said you are mad. It would have been pointed out that this is against thermodynamics and there could not be enough energy in the metal to do this. However we know better now because of discoveries in nuclear physics.
The point is that tomorrow there might be a discovery that renders this whole discussion mute and shows AGW to be a whole load of hot air.
Right at the moment however all the best scientific evidence tells us, if you listen, that AGW is happening and could cause some degree of climate change that could have effects on our society. We may be the same as the 1890 phyisist however how can we know this? In 1890 should they have not built any coal power plants because nuclear plants were 40 years away? We have to act now on the best advice we have, we cannot anticipate future discoveries.
joe – “There’s good news, more good news and then, unfortunately, some bad news, on the subject of climate change.
+ for a doubling of CO2 a climate sensitivity of only 3 degrees C is reasonable
+ estimates of how much of a rise in CO2 emissions we are going to see are also too high
+ the IPCC isn’t going to take any notice”
The only minor problem with this it that it is almost totally wrong. The IPCC range of climate sensitivity is 1.4 deg to 4.5 degrees. This is almost bang centre in the range of the IPCC projections. This study confirms that quite dangerous warming is consistant with past climate changes.
Upper limit 3 deg.
60 better than 90? Well it depends who they are. I’m sure you could find 90 people with PhD’s to sign just about anything.
I did note the following things about these signatories, all of which are a contrast to that other letter:
– they are all from Canadian institutions
– they are all working in climate science fields
– they are unfamiliar names to me, ie busy doing their jobs rather than PR
I think that is significant and commendable.
An interesting tidbit I came across and would like to share with your readers, Jennifer. It seems at least one of the signatories, Dr. Gordon E. Swaters, says he was tricked into signing! He does not doubt that climate change is real and he is recanting and wishing he had never signed “that damn petition”.
These professional denialists are a nasty, tricksy, wicked bunch!
(Information from a post on DesmogBlog.com that came to my attention via a RealClimate comment
http://www.desmogblog.com/signatory-bails-on-anti-climate-science-petition )
To clarify, Dr Swaters signed the first letter that denied climate change is established or a threat. Sorry for the confusion.
Ender, You are correct that the paper discussed by Tim Worstal (a recent paper by Annan & Hargreaves that was published in Geophysical Research Letters) arrives at a climate sensitivity which is very similar to the IPCC range. It puts the most probable level at 2.9 deg.C, compared with the 3.0 deg.C midpoint of the IPCC range. The ‘good news’ in the A&H paper is that they argue against the possibility of very high sensitivities: in their view, there is a high probability that climate sensitivity is in the 2 – 4 deg.C range. Most if not all of the models used the IPCC are in this range.
Worstal’s second point relates to CO2 emissions. Here he says correctly that Diewert, Quiggin, Castles and Henderson are agreed that the IPCC scenarios should be redone.
Unfortunately Worstal’s link is to the original version of Erwin Diewert’s note on John Quiggin’s website, and not to the revised version which Professor Diewert asked JQ to post a fortnight ago. This means that those who get access to the Diewert note via the Quiggin site do not learn of the important work of the Australians Stegman & McKibbin on the convergence issue, or of any of the three papers containing the extended Castles & Henderson critique. (In his posting ‘Diewert on Quiggin, Castles and Henderson’, Quiggin refers to an earlier set of documents, which we had ourselves described as ‘a contribution, albeit rough and ready, to an important debate which was already under way’, as our ‘main paper’).
I’ve posted the link to the revised note as it appears on Professor Diewert’s website, and also the text of the Diewert to Quiggin letter detailing the changes made in that version, on the Richard Tol thread on this blog.
Tim Worstal’s third point – that the IPCC isn’t going to take any notice – relates to the emissions scenarios, not to climate sensitivity. It appears that Worstal has access to the draft of AR4, which shows that they’ve used the SRES scenarios again. I think that they had to do so, because many of the research results reported in the WGII Contribution rely on the flawed SRES projections.
So as Richard Tol pointed out, one should worry about the fact that the IPCC, first, made a very basic error and, second, is unable to admit that and correct it. He also pointed out that if one is interested in climate impacts or regional climate change, the Castles and Henderson critique does matter. The Stegman & McKibbin critique also matters.
Ian, I’ve found the Erwin Diewert comment, for others the link is: http://www.econ.ubc.ca/diewert/quiggin.pdf .
Also, here is the IPCC report that says it is going to persist with the http://www.ipcc.ch/meet/othercorres/ESWmeetingreport.pdf including that “These scenarios have been developed in a four year
process with many scientists involved in the writing and the review process. The SRES scenarios
played an important role in the Third Assessment Report (TAR) of the IPCC and will be used in the
upcoming Fourth Assessment Report (AR4).”
So what will this mean in terms of recommendations and predictions in AR4?
Ian, it’s hard to see into these muddy waters. Back in 2003 when the runs for AR4 were being put together, the IPCC decided there wasn’t enough time to redo the scenarios (seems to be correct on resources required) and so they used selected scenarios from TAR.
It seems that the ones that were picked were a high, middle and low scenario (A2, A1B, and B2) so that the spread was covered. The climate modellers seem to be saying the SRES criticism issue is a red herring as the spread is nevertheless covered.
A question then – for the record, does any criticism of the scenarios significantly change the usefulness of the climate modelling for that spread?
I should have perhaps added to my last comment – apart from the fact that the IPCC evidently cares little about due process and getting the detail correct if it is prepared to ignore you, Quiggin, Tol and Diewert.
Thanks Jennifer. The need to use converters based on PPPs rather than exchange rates in making international comparisons of GDP is a specific requirement of the System of National Accounts, which was published in 1993 by the United Nations, the World Bank, the IMF, the OECD and the Commission of the European Communities after being welcomed and unanimously approved by the UN Statistical Commission at its meeting in New York in February/March 2003.
I was the Australian member of the Commission at the meeting, in the course of which the European Union successfully argued for changes to the draft System as previous agreed. The approval of the System was a valid exercise of my functions as Australian Statistician under the Australian Bureau of Statistics Act 1975, section 6 (1) of which provides that the functions of the Bureau include ‘to provide liaison between Australia, on the one hand, and other countries and international organizations, on the other hand, in relation to statistical matters.’
The failure of the IPCC to ‘endeavour to achieve consistency with the 1993 SNA’ is in breach of the Panel’s obligations pursuant to UN Economic and Social Council resolution 1993/5 of 12 July 1993.
The IPCC’s claim that PPP-based GDP projections are reported for some of the scenarios is incorrect, as I have repeatedly shown both in papers co-authored with Professor David Henderson and in my written submission to the House of Lords Committee Inquiry into the Economics of Climate Change.
Even if the IPCC’s contention was correct, the Panel would still be in breach of its obligations because the SNA is explicit that conversions must NOT be made using MER-converters. A company could not justify presenting false and misleading information in a prospectus on the grounds that some of the information was also presented correctly in another part of the document.
In addition to criticising the scenario projections themselves, David Henderson and I have also pointed to other statistical errors both in the SRES (e.g., in misdefining ‘gross national product’) and in other IPCC reports.
Neither the IPCC nor the lead authors have at any time acknowledged that statistical errors were made in any of its reports, although in their first response to Castles and Henderson the SRES Team blamed Cambridge University Press for mistakenly using the word ‘prediction’ in the short text on the back of the jacket of the SRES.
According to these 15 authors, ‘Mr Castles and Mr Henderson have focused (at tedious length) on a ‘problem’ that does not exist.’ In a subsequent media release which was specifically and exclusively devoted to brushing aside our critique, the IPCC said that ‘disinformation has been spread questioning the scenarios’; that ‘Criticism of IPCC’s work has been mounted by so called ‘two independent commentators’ Ian Castles and David Henderson’; and that ‘the economy does not change by using a different metrics (PPP or MEX), in the same way that the temperature does not change if you switch from degrees Celsius to Fahrenheit.’
You mention Tol, Diewert, Quiggin and me as agreeing that the SRES exercise needs to be redone. In addition, the Committee on Economic Affairs of the House of Lords has unanimously recommended that ‘there is an urgent need for a wholesale reappraisal of the emissions scenario exercise.’ Others economists who have objected to the use of MER-based measures in the SRES include Professors William Nordhaus of Yale, Sir Partha Dasgupta of Cambridge, Alan Heston of the University of Pennsylvania, Warwick McKibbin of the ANU and Angus Maddison, the world’s leading scholar in the field of international comparisons of GDP over time. Then there is the submission to the Stern Review by nine economists including (in addition to those already mentioned) Sir Ian Byatt and Professors David Henderson, Ross McKitrick, Julian Morris, Sir Alan Peacock and Colin Robinson.
I will send a separate post in response to your question ‘So what will this mean in terms of recommendations and predictions in AR4?’, but in the meantime I want to point out one example of the waste and confusion that is occurring as a result of the IPCC’s failure to follow the internationally-agreed standards for the measurement and reporting of GDP.
As part of the arrangements under the United Nations Framework Convention on Climate Change (UNFCCC) for the monitoring of greenhouse gas emissions, countries make regular reports (‘national communications’) on their economies and on progress in containing such emissions. In the case of Annex I countries, these national reports are then subjected to an ‘in depth review’ by an international team that visits each reporting country and prepares a further report after discussions with officials and scientists, visits to power plants and so on.
For example, a team from China, Bolivia, Russia, UK, the OECD and the UNFCCC secretariat visited Australia between April and June 2004 and had discussions with officials from national, state and territory governments, academia and business and environmental NGOs. (All of the teams preparing in depth reports include at least one representative from the UNFCCC secretariat: this is not noted separately in the lists of countries and organisations providing experts which are given in the succeeding paragraphs).
The first main table in each of the ‘in depth reports’ is headed ‘Main macroeconomic indicators and GHG emissions’, and includes lines showing the GDP and the ‘GHG emissions per GDP unit’ for the country concerned. But, encouraged by the IPCC dictum that ‘it’s like Celsius and Fahrenheit’, THE DEFINITION OF GDP VARIES FROM ONE IN-DEPTH REPORT TO ANOTHER, and the definition of GHG emissions per unit of GDP varies as a necessary consequence.
The European Community produces its own regular communications to the UNFCCC, and the latest such communication was reviewed by a team from China, Poland, the United States, and the IEA. Not surprisingly, this in depth report used PPPs to calculate the Community’s total GDP and GHG emissions per unit of GDP because, as noted above, the EC is one of the five sponsoring organisations of the System of National Accounts.
However, the report on Germany, prepared by a team from Malaysia, Uganda, Armenia and Belgium, included the statement that ‘In terms of gross domestic product (GDP), the German economy ranks third in the world (after the United States and Japan).’ This is of course untrue; if correctly measured according to the internationally agreed definition, Germany’s economy is far smaller than those of China and India. But German politicians (like British and French politicians) are fond of telling themselves and their electorates that the country’s economy is bigger than that of any country outside Europe (the US and Japan excepted). The UNFCCC reporting team then used MER-converted figures for Germany’s GDP and GDP per unit of output in the first table. Because the DM is a strong currency, this makes it look as if Germany’s GHG emissions per unit of output are low.
Then there’s France, a permanent member of the Security Council. It helps to justify the country’s position in this context if it continues to claim that its economy is bigger than India’s, and its GHG emissions per unit of GDP look low if the wrong converter is used. The wrong converter IS used: the in depth report on France, prepared by a team from Morocco, Senegal, Switzerland and the OECD, presents the macroeconomic measures in terms of MER-converted GDP.
Netherlands has one of the best statistical offices in the industrialised world, so it’s not surprising that the in depth report of the team from India, Kazakhstan, Croatia and Finland used PPP measures to report GDP and emissions per unit GDP for that country. Belgium has one of the weakest statistical offices, which could be the reason why the team from Burundi, Indonesia and Ireland reported that country’s macroeconomic indicators in MER terms.
Spain’s latest in depth review, by a team from Cuba, Peru and Portugal used MER-based measures; but Portugal’s review, prepared by a group from Brazil, China and France, used PPPs. Finland’s review, by a group from Colombia, Latvia and France used MER-based measures but Sweden’s review, by a team from Albania, Brazil, Latvia and Denmark used the correct PPP-based measures.
For Annex 1 parties other than the EC members, a similar pattern emerges. Russia’s in depth review, by a team from Ecuador, Hungary, the European Community and the IEA used MERs; but the review of Belarus, by a team from the Kyrgyz Republic, Russia, and Greece used PPPs. The group that travelled to Switzerland from Kenya, Lesotho, and the Czech Republic used MERs – but the group that travelled to the Czech Republic from Togo, Slovenia and Greece used PPPs. The team that went to Japan also included a representative from the Czech Republic, as well as experts from Pakistan, Canada, Korea and the OECD: they reported the country’s GDP and emissions per unit GDP in yen, but also provided the yen/$US exchange rate (but not the PPP rate).
These in depth review procedures are effectively training experts from developing countries in the statistical tricks that are played by countries which should know better (and in fact do know better).
Ian you’ve talked at length about obligations and good statistical procedure in using MER v’s PPP and revisiting the issue of whether or not MER or PPP assumptions are used. We’ve previously covered much of this on this blog. You also raised other errors in definitions etc and discussed the approaches of various countries. This is informative, but doesn’t address the question that I asked. I gather that you wrote the above in response to Jennifer, and you seem to have overlooked my question so I’ll now repeat it in the hope that you’ll respond directly:
Ian does any criticism of the scenarios significantly changes the usefulness of the climate modelling for that spread?
Thinxy, I have no knowledge of what the IPCC has done or intends to do other than what has been made available in the public domain. I don’t have access to the draft of AR4.
You tell me that in 2003 the IPCC selected the A2 scenario as a high and the B2 scenario as a low scenario ‘so that the spread was covered.’
That’s the first that I’ve heard of this but if it’s true I’m surprised that the Co-chair of IPCC Working Group II, Professor Martin Parry, did not know of the decision.
Yet the studies reported in ‘An assessment of the global effects of climate change under SRES emissions and socio-economic scenarios’, published in a special issue of ‘Global Environmental Change’ (GEC, edited by Professor Parry) in May 2004 with an introduction by Professor Parry, are based at the high end on the A1FI illustrative scenario and at the low end on the B1 marker scenario.
The ‘high’ in the GEC studies, expressed in terms of cumulative CO2emissions between 2000 and 2100, is 2.34 times the ‘low’ in these studies. In the case of the scenarios that you say were selected by the IPCC in 2003, and assuming that the ‘high’ and ‘low’ for these scenarios is represented by the A2 and B2 marker scenarios, the corresponding range of cumulative emissions is 1.65. In the case of the full suite of the SRES scenarios, the range in cumujlative CO2 emissions from the highest (A1C AIM) to the lowest (B1T MESSAGE) is 3.56 (i.e., over twice as great as the range of cumulative emissions between the highest and the lowest in the scenarios that you say that the IPCC selected).
The B1T MESSAGE scenario is in one of the families of convergence scenarios which, in the view of the IPCC, ‘cannot be ruled out, even if they are certainly very challenging from the perspective of recent growth in a number of regions’ (SRES, p. 196).
In my paper of 4 February 2003 (IPCC emissions scenarios: The case for a review”), I gave ‘a number of reasons for believing that the B1T MESSAGE scenario does not by any means establish a reasonable lower bound.’ I said that ‘lower emissions levels can be projected on the basis of assumptions that are fully defensible.’ Neither the IPCC nor the SRES Team have commented on my reasons for this view.
Professor Diewert agrees with the view of Stegman & McKibbin that the assumptions underlying the convergence scenarios are ‘pretty questionable’.
I am not sure that I have understood the meaning of your question. But if the question is, ‘does any criticism of the scenarios significantly change the usefulness of the climate modelling for projecting plausible levels of mean global temperatures?’, the answer is ‘yes’.
More emissions tedium. What about the other side – that most studies now agree that future feedback from the biosphere means that CO2 levels are likely to be higher than a simple constant-airbourne-fraction would suggest. Or are you only interested in guesses on the low side?
William Connelley, According to the TAR, ‘Uncertainties, especially about the magnitude of the climate feedback from the terrestrial biosphere, cause a variation of about -10 to +30% around each scenario. The total range is 490 to 1260 ppm (75 to 350% above the 1750 concentration).’
In those far-off days, back in 2001, the TAR authors chose to report the uncertain range of variation as a proportion (-10 to +30%) of projected concentrations in the absence of feedback. If that is the case, it is all the more important that the emissions projections be realistic.
Do any of these new studies find that future emissions levels are irrelevant to the future climate? Governments would be disappointed if scientists were now to decide that reining back emissions is a pointless exercise.
Sorry, but what is kimerikas?
Jane.
Sorry, but what is kimerikas?
Jane.
Sorry, but what is kimerikas?
Jane.