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Open Letter by Netherlands Scientists on IPCC and Errors in 2007 Climate Change Report

In response to the ongoing discussion about the reliability of the UN IPCC and the climate reports, a group of 55 leading Dutch scientists working in the field of climate change, energy and the environment wrote an open letter. The letter, which follows below, was published in several Dutch media on 10 February.

Open letter (10 February 2010) to Netherlands parliament by Netherlands scientists on climate change and IPCC

Errors in the IPCC climate change report are being seized by some to discredit climate science. In the Netherlands parliament climate scientists have recently been depicted as “swindlers” and “climate mafia”. Such allegations are not supported by the facts and are unwarranted. The fact that IPCC is not infallible does not make its key findings untrue or biased. Still, IPCC should become more generous in acknowledging errors rapidly and openly.

With this open letter from the Netherlands scientific community, we aim to adjust the image that has emerged. We ask to keep the public debate more in accordance to the facts. We discuss the key messages from climate science, the IPCC procedures and the quality control mechanisms of the IPCC. Finally we explain what we will do next to contribute to improvement of the IPCC practice and to the restoration of the tarnished trust in climate science.

The climate problem

Since 1990, our knowledge on human made climate change and the understanding of its urgency have rapidly increased. Within the natural sciences, the major components of the climate system are well understood. It is a well established fact that the amount of anthropogenic greenhouse gases in the atmosphere has increased rapidly since the industrial revolution. The major influence of greenhouse gases in the atmosphere on the temperature on the ground is a matter of elementary physics. The increasing amounts of anthropogenic greenhouse gasses in the atmosphere change the heat radiation balance of the earth, which very likely leads to higher temperatures on the ground. Measurements consistently show a world wide temperature increase of about half a degree Centigrade over the past century. The measured temperature increase lags several decades behind the changes in atmospheric composition: with present day greenhouse gas concentrations the temperature is expected to further increase by at least 1 °C in the coming decades.

The increase in greenhouse gas concentrations is mainly caused by the way in which coal, oil and natural gas are being used and by deforestation. Major uncertainties exist regarding future greenhouse gas emissions and their impacts. Studies by reputable research groups show that projected emissions of greenhouse gases may lead to a further warming of 1.1 to 6.4 °C by the year 2100 (relative to the period 1980-1999). Given the fact that the climate system exhibits tipping points, this may lead to partly unpredictable and possibly far reaching and irreversible impacts on society and nature. The Copenhagen Accord acknowledges that dangerous human interference with the climate should be prevented. For that reason governments agreed that global warming should be limited to 2 °C at maximum (compared to the preindustrial climate). Research has shown that this is economically and technically feasible with emission reduction measures and changes in consumption patterns.

The IPCC and the Fourth Assessment Report

In 1988 the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) established the Intergovernmental Panel on Climate Change (IPCC) with the aim to provide policy makers regularly with abalanced overview of the state of knowledge on climate change. IPCC is an open network organization in which renowned scientist from all over the world collaborate. These scientists are mainly from universities—including most of the Dutch universities—and research institutes such as in our country the Royal Netherlands Meteorological Institute (KNMI), the Energy Research Centre of the Netherlands (ECN) and the Netherlands Environmental Assessment Agency (PBL). At present 194 countries participate in the IPCC, including the Netherlands.

IPCC publishes an assessment report every six years. The most recent was published in 2007. This report comprises three volumes: The Physical Science Basis (Working Group I); Impacts, Adaptation and Vulnerability (Working Group II) and Mitigation of Climate Change (Working Group III). The 2007 report has been authored by about 44 writing teams with a total of 450 lead authors. These authors have been selected on the basis of their expertise. All 194 countries have a say in this selection. Another 800 scientists have contributed texts on specific aspects. The whole process is supported by four Technical Support Units (TSUs) with 5 to 10 employees each.

Errors in the Fourth Assessment Report

We took cognizance of the commotion surrounding the errors that were found in the IPCC fourth assessment report, in particular in volume II. The wrong year for the projected disappearance of the Himalaya glaciers and the wrong percentage “land below sea level” of the Netherlands are examples of errors that need be acknowledge frankly and need be rectified properly. However, they do not alter the key finding that human beings are very likely changing the climate, with far reaching impacts in the long run.

In heated debates that emerged around these errors, questions have been raised regarding the quality and integrity of the IPCC. The quality control procedure of IPCC has shown not to be watertight. But the suggestion that scientific data have deliberately been manipulated is not supported by the facts.

Also we strongly contest the impression that the main conclusions of the report are based on dubious sources. The reference list of the approximately three thousand page report refers to about 18,000 sources, the large majority being studies published in peer-reviewed scientific journals. The IPCC has transparent procedures[1] for using non-published and non-peer-reviewed sources in their reports. In the Himalaya case these procedures have not properly been followed. In the writing of new reports the compliance with the procedure requires extra attention.

Quality control within the IPCC

The impression that the IPCC does not have a proper quality control procedure is mistaken. The procedure for compiling reports and its quality control are governed by well documented principles.[2] These principles are reviewed regularly and amended as appropriate. On a website all steps of each chapter can be traced: the First Order Draft, the comments by many scientist on that draft, the Second Order Draft in which the comments are incorporated and the comments by experts and country representatives on that revised version. In the case of the Fourth Assessment Report, 2,500 reviewers provided together about 90,000 comments on the 44 chapters. For each comment it is documented how and why the comment has or has not been used in the revision. Review editors guarantee that each comment is treated properly and honestly in the revision of the chapter texts. As completion of the procedure, once they are satisfied with the result, review editors sign a statement in this regard.

The IPCC principles also govern how authors have to treat non-published and non-peer reviewed sources. These procedures acknowledge that in peer reviewed scientific journals little information can be found regarding matters such as the emission reduction potential in a given industrial sector or in a country or regarding vulnerabilities of sectors and countries with regard to climate change. Such information can often only be found in reports from research institutes, reports of workshops and conferences or in publications from the industry or other organizations, the so-called gray literature. The IPCC procedure prescribes that authors are obliged to critically assess any gray source that they wish to include. The quality and validity of a finding from a non-peer reviewed source needs to be verified before the finding may be included in a chapter text. Each source needs to be completely traceable. In case unpublished sources are used, a copy needs to be made available to the IPCC secretariat to guarantee that it is available upon request for third parties.

We conclude that the IPCC procedures are transparent and thorough, even though they are not infallible. The writing of IPCC reports and its quality control remains the work of humans. A guarantee for an error free report is an unachievable ideal, however much an error free report is highly desired. It is however essential to continuously evaluate the IPCC principles and procedures and to amend them where appropriate and learn from errors that occurred.

What next?

Meanwhile, as a consequence of the impression that has emerged from the—in our view—disproportionate commotion, public trust in the scientific underpinning of climate policies is now tarnished. This is worrying because the climate change issue is serious and urgent. Despite the errors found, the robust key conclusions of the IPCC Fourth Assessment Report that we sketched above, remain valid.

IPCC should become more generous in acknowledging errors rapidly and openly. To this end, IPCC should put an erratum on its website that rectifies all errors that have been discovered in the text after publication. In doing so, a clear distinction needs to be made between errors and progressing knowledge. Progressing knowledge is published in new scientific journal articles and used in the next IPCC climate report; this information should not be in the errata.

Climate research and the IPCC reports on the state of knowledge provide a scientific foundation for climate policy making. We consider the quality of and balance in the knowledge delivered and the explicit communication of uncertainties to be of paramount importance, as IPCC does. Given the recent commotion we find it important to seek for ways to find a solution and restore trust in the climate change community. We will do our best to make sure that a critical evaluation of the IPCC procedure will take place—where possible in close consultation with the Royal Netherlands Academy of Arts and Sciences (KNAW). This should lead to both a better prevention of errors in IPCC reports and a mechanism for adequate rectification of errors found after publication.

[1] and

The undersigned

  1. Prof. Wim Turkenburg, Utrecht University
  2. Prof. Rik Leemans, Wageningen University
  3. Prof. Hans Opschoor, Institute of Social Studies, Den Haag
  4. Dr. Bert Metz, European Climate Foundation / former co-chair IPCC Working Group III
  5. Prof. Rien Aerts, Free University of Amsterdam
  6. Prof. Theo Beckers, Tilburg University
  7. Prof. Frans Berkhout, Free University of Amsterdam
  8. Prof. Frank Biermann, Free University of Amsterdam
  9. Prof. Kornelis Blok, general director Ecofys, Utrecht / Utrecht University
  10. Prof. Henk Brinkhuis, Utrecht University
  11. Dr. Stefan Dekker, Utrecht University
  12. Prof. Peter Driessen, Utrecht University
  13. Prof. Klaas van Egmond, Utrecht University
  14. Prof. Nick van de Giesen, TU Delft
  15. Prof. Joyeeta Gupta, Free University of Amsterdam
  16. Prof. Jan Hendriks, Radboud University Nijmegen
  17. Dr. Ton Hoff, chairing director ECN, Petten
  18. Prof. Bert Holtslag, Wageningen University
  19. Prof. Jef Huisman, University of Amsterdam
  20. Dr. Gjalt Huppes, Leiden University
  21. Prof. Bart van den Hurk, Utrecht University / KNMI
  22. Prof. Ekko van Ierland, Wageningen University
  23. Dr. Ron Janssen, Free University of Amsterdam
  24. Prof. Pavel Kabat, Wageningen University
  25. Prof. Gert Jan Kramer, Eindhoven University of Technology
  26. Prof. Carolien Kroeze, Wageningen University / Open University Netherlands
  27. Prof. Maarten Krol, Wageningen University
  28. Dr. Lambert Kuijpers, Eindhoven University of Technology
  29. Dr. Lucas Lourens, Utrecht University
  30. Prof. Pim Martens, Maastricht University
  31. Prof. Arthur Mol, Wageningen University
  32. Prof. Henri Moll, University of Groningen
  33. Prof. Paul Opdam, Wageningen University
  34. Prof. Paquita Perez Salgado, Open University Netherlands
  35. Dr. Ad Ragas Radboud University Nijmegen
  36. Dr. Max Rietkerk, Utrecht University
  37. Prof. Lucas Reijnders University of Amsterdam
  38. Prof. Jan Rotmans, Erasmus University Rotterdam
  39. Prof. Paul van Seeters, Tilburg University
  40. Prof. Anton Schoot Uiterkamp, University of Groningen
  41. Dr. Appy Sluijs, Utrecht University
  42. Prof. Geert de Snoo, Leiden University
  43. Prof. Gert Spaargaren, Wageningen University
  44. Prof. Jef Vandenberghe, Free University of Amsterdam
  45. Prof. Anne van der Veen, Twente University
  46. Prof. Pier Vellinga, Wageningen University
  47. Prof. Herman Verhoef, Free University of Amsterdam
  48. Dr. Pita Verweij, Utrecht University
  49. Prof. Martin Wassen, Utrecht University
  50. Prof. Pieter Winsemius, Tilburg University
  51. Prof. Ernst Worrell, Utrecht University
  52. Prof. Sjoerd van der Zee, Wageningen University
  53. Prof. Bert van der Zwaan, Utrecht University

In addition two signatures were received just after closing time:

  1. Dr. Rob Swart, Wageningen University
  2. Prof. Karsten Kalbitz, University of Amsterdam


Stan Peterson

Tranlation: We want the grant money flow tp continue, unabated. We advise putting fine print in that says so.
For example:

GloBaloney... can be more properly spelled as... Global Bologna.

Thomas Lankester


These particular scientists appear to be tenured academics so it seems unlikely that they have a huge amount to gain by collectively conspiring and lying, which seems to be what you are implying. That seems to be a terribly rude slur on, what I suppose, are a bunch of people you have never met. If you have personal knowledge that any of these people is dishonourable then say so and back up your post.

Applying Occam's Razor, I have another interpretation of these scientists.
If I was living below sea-level and was aware of the observed 3mm/yr sea-level rise and that this rate of rise has increased in the last decade - I would similarly speak out.

Nick Lyons

I am frankly puzzled by the climate change deniers, the neo-Luddites of the early 21st century. Do they have no children, no stake in the future? Do they think that by shutting their eyes tight an unwanted reality will just go away? Are they just so resentful of science that they will take any opportunity to try and discredit the work of all scientists based on a few minor errors? Or is it the fact that overcoming the climate change challenge will require cooperation, organization and regulation--in other words, government. Is it the failure of unregulated markets to prevent the crisis that makes them so rabid?

Different strokes for different folks, I suppose. For the sake of my children and theirs, I hope that reason prevails and we can work together for the common good.


@ Nick:

You probably give humanity far more credit than it deserves, i warrant.


The nice thing about capitalism at this point in society, if there is anything good about it, is that the collective effect of the selfishness of all its component persons so far outweighs any other system going - and that system does well based on technological advances and consumerism -- when taken, promoted, and advanced together can solve about almost anything technical. Further, i think it is reasonable to assume that technology got us all into this anthropomorphic emissions mess - and it can also get us out of it. The key is to believe that the technology being developed expensively (i.e. at the government's support) is the technology we will all have to run out and buy to transform the energy use, manufacturing, and consumption system we feverishly support, while overcoming emission-gluttony - given that we are unlikely to cut back on any of these things anytime soon, we might as well make them clean. So, continue being stubborn, gluttonous, and selfish - but just do it in a pro-green way. Its all society has got going for it - whether you believe the timelines of the IPCC or not.

richard schumacher

"GloBaloney". Haw haw! That's a real thigh-slapper. I wish all your stuff was that clever.

Aaron Turpen

Hey, I'll be honest when you are, Mr. Tenured Scientist dude who needs the government grant cash to keep your position relevant.

I have an idea: since your computer models have thus far predicted jack squat, how about you use real science and stop pretending your computers aren't anything more than GiGo machines?

Right. Sorry, that'll affect your ability to get headlines and BBC specials about climate catastrophes, but hey, we all have to make sacrifices for humanity. Eh?

Meanwhile, I'll go back to looking at actual data from both ground and satellite (without "homogenizing it") and see that... oh, wow, no significant change in 20 years. Then I'll think about Medieval Warm periods and that 800 year gap and whatnot.

Feel free to join in for some real climate change science rather than hokum based on Al Gore and the IPCC's need for relevance.

As a side note: I see that nothing has been said here on Green CAR Congress about Climategate, Glaciergate, etcgate. Probably because those things don't have anything to do with C A R S. Unlike stuff like this story, which obviously has a lot to do with cars.

In case the Green CAR Congress people forgot what CAR means: car (n) 1. an automobile.
2. a vehicle running on rails, as a streetcar or railroad car.
3. the part of an elevator, balloon, modern airship, etc., that carries the passengers, freight, etc.
4. British Dialect. any wheeled vehicle, as a farm cart or wagon.
5. Literary. a chariot, as of war or triumph.
6. Archaic. cart; carriage.

Hmm... nothing about CLIMATE, GLOBAL WARMING, or CO2 in any of those definitions.


"Meanwhile, I'll go back to looking at actual data from both ground and satellite (without "homogenizing it") and see that... oh, wow, no significant change in 20 years. Then I'll think about Medieval Warm periods and that 800 year gap and whatnot."

Aaron you are full of crap. That's what ticks me off about deniers like you and Stan is that they're spectacularly badly informed about the state of climate science but have no qualms about spouting inasne, unsubstantiated rubbish on internet forums.

One more definition for you:

/griːn/ adj
relating to the protection of the environment

But you anti-science lot are arrogantly content to condemn our world to a chaotic future just because you're scared of change.



"Further, i think it is reasonable to assume that technology got us all into this anthropomorphic emissions mess - and it can also get us out of it."

You're not far off. What many greens are missing is the great opportunity to build awareness even after AGW has fully collapsed. At that point the "pro-green" way that you suggest will work fine. And, we will discover that a vast majority of people will even go along with the rational ideas behind greenness (energy independence, clean air, domestic jobs etc.) They won't be buying the cap and trade or one world government schemes.

So, we will see the ringleaders of climate fraud going off to the big house and the little castles, fiefdoms and mobs running science in government will be dismantled. But in its place will be a far more open form of peer-review, publishing and discussion.

And even the hard core conservatives will see the value in installing energy and COST saving LED/CFL light fixtures. And driving a car that uses no OPEC oil.

Aureon Kwolek

Cure the Cause Not the Symptom

Climate Scientists knew that some glaciers were receding and some were advancing. But they either downplayed advancing glaciers or ignored them altogether. Because that didn’t give them the outcome they were looking for - to blame CO2 and label it as a universal global pollutant. That would establish a basis for a global carbon tax, for their purse strings.

What the false claim of all Himalayan glaciers melting by 2035 brought to light was much more – The real cause of melting glaciers is migrating Black Carbon Soot (BCS), forming solar thermal layers on snow and ice. That blows the global CO2 agenda. When you have some glaciers receding and some glaciers advancing, then you don’t have universal global warming or climate change. You have a “Pollution Migration Effect” caused by the soot, that routinely travels from a concentrated source, hundreds or thousands of miles, to where it causes the effect.

A one degree rise in average air temperature is Not going to melt a glacier. Layers of Sulfurous Black Carbon Soot will.

Migrating Ozone is another example of “Pollution Migration Effect”: “In springtime, pollution from across the hemisphere, not nearby sources, contributes to the ozone increases above western North America. When air is transported from a broad region of South and East Asia, the trend is largest.” Owen R. Cooper, Ph.D., lead author. (Green Car Congress: “Study Links Springtime Ozone Increases above Western North America to Emissions in Asia”) This is Not Global Warming or Climate Change. It’s “Pollution Migration Effect”.

Prior to this revelation, Scientists measuring ozone levels on the West Coast had no idea that it was originating thousands of miles away, in Asia. So they may have assumed that spikes in ozone were caused locally by something else.

That brings up another issue. Where are scientists taking their measurements? Are they are suppressing measurements upwind or in rural locations, where the effect is not present? Or, are they taking them down wind of urban centers, where pollutants are more concentrated? With weather events and air masses constantly changing, how reliable can these measurements be?

IPCC science is not just flawed. It’s entirely disoriented. Global Warming or Climate Change, whatever you want to call it, is Not Universal and Not Uniform. It can’t be, if some glaciers are receding while others are advancing. And it can’t be uniform, because the “Real Pollutants” - the Causal Factors - are much more concentrated around urban centers, power plants, industrial zones, major highways, shipping lanes, airports and flight paths, sewage disposal plants, landfills and burning dumps, and downwind of concentrated sources of pollutants. Take one measurement upwind and another one downwind, and you may have data that varies dramatically, even within 100 miles or less. ‘Same thing for pollutants deposited on ocean currents and shipping lanes.

One effect occurs while pollutants are suspended and migrating in the air. (2) Another effect occurs when these migrating masses of pollution, such as Sulfurous Black Carbon Soot, ozone, or what have you - fallout on land, water, snow and ice. (3) And, another effect acidifies water run-off into streams, lakes, rivers and oceans, with Sulfurous Black Carbon Soot a big factor. Yet recent studies make the false assumption that oceans are being acidified only by excess CO2 in the air.

We know that the ocean naturally absorbs CO2, in cycles, especially more so in the colder waters of northern latitudes. And the ocean also expels CO2, especially in the warmer waters of the Tropics. So where did scientists take their acid measurements to blame CO2 in the air? The timing and the location is everything. Ocean current is another big factor that could influence ocean acidification. Prevailing winds, shifting winds, and major weather events, for example, can also dramatically cause data to vary. Because masses of migrating pollutants, although they may originate in the same place, are not always deposited in the same place. So the effects and the data will naturally be inconsistent.

Climate Scientists typically claim that Global Warming or Climate Change is uniform, when it’s Not. They falsely advocate that the problem, which they have thus far failed to accurately measure and describe, can be solved universally by controlling CO2.

Instead, we need to cast out all political agendas and get the science right. And we need to create specialized local programs to mitigate specific pollutants where they originate. In other words, cure the Causal Factor, not the CO2 symptom.


"Smoke'um if you got'um - police the area (pick up cigarette butts) if you don't" is how I began smoking in the Army.

After a couple years of smoking tobacco, smokers don't need global studies to know smoking is deadly - despite a tobacco industry still blowing decades of lies and smoke.

After a couple decades, anyone can see increasing ocean levels, receding glaciers, decreasing polar ice, and other global trends visible by satellite.

Those denying global warming are still smoking the petrol and blowing the smoke..

Thomas Lankester

@Aaron Turpen
>>Hey, I'll be honest when you are, Mr.
>>Tenured Scientist dude who needs the
>>government grant cash to keep your
>>position relevant.

Again, there seems to be this assumption of dishonest behaviours by the authors of the letter. As these are specific, named individuals that are being called into question, some specifics of their dishonesty should be provided. Otherwise, this attack on their integrity is simply insulting and rather poor form.

The comment about computer models prediction indicates a fundamental misunderstanding of the (limited) role that computer modelling play in the debate. Computer models cannot prove anything but they can disprove theses. Various climate driving mechanisms (e.g. solar activity) can be proposed and their effects tested to 'see if they add up'. Only when there are computer models that can match the observations is there any point in attempting to make predictions.

And where did the article even mention computer models? In fact it stated that the scientists are from a range of disciplines. As for looking at the actual observations from ground and satellite, please explain how a 3mm/yr rise ( over the last couple of decades indicates 'no significant change'. With GRACE observation it is even becoming possible to separate out the components due to thermal expansion (steric sea-level change) and due to mass contribution from melting ice (

The comment about "homogenizing" the observations also suggest a lack of understanding. Inter-calibration of satellite sensors / instruments is standard practice and not for any underhand reasons. No two sensors or even instruments will show the same signal response even on the ground, let alone in the harsh environment of space. It is therefore essential that successive missions are flown for an overlap period to ensure that the measurements are cross calibrated.

The Medieval Warming Period is a term applied regionally and is not evidenced by a global, synchronous warming event. Trotting out MWP in this way is a classic FUD tactic.

The definition of 'car' provided is somewhat odd.
'British Dialect' – indeed!

The GREEN element of Green Car Congress however is clearly pertaining to a concern for environmental issues. Articles such as this, that provide the environmental context, would seem to fall quite naturally within this remit.

It should be noted that as GCC provides a free service then its visitors should act like guests. If I was the guest in someone's house, it would certainly be extremely bad manners for me to loudly criticise how my host arranged their own home.

Thomas Lankester

@Aureon Kwolek
I lot of the points you make seem to depend on straw men.

>>Climate Scientists typically claim that
>>Global Warming or Climate Change is uniform,
>>when it’s Not.

I have never heard that claim in 25 years of following the debate. In fact, climatologists normally take great pains to emphasis that effects will vary from one place to another. Some areas will cool whilst others warm. One of he greatest challengers for those involved in the modelling side is to try to resolve regional effects and it is not an easy task. A classic example is the concern (now receding) that the North Atlantic halo-thermal conveyor might shut down imminently. This would plunge Europe into a huge drop in temperature even as the world, as a whole, warmed.

Similarly, any glaciologist will tell you that some glaciers will grow whilst others melt (e.g. in the Eastern Antarctic where increased snow fall from warmer, more moist air is frequently predicted. You cannot base your assessment of what the scientific community really says on sound-bite laden / nuance deprived headline reporting.

>>They falsely advocate that the problem,
>>which they have thus far failed to
>>accurately measure and describe,
>>can be solved universally by controlling
Again, this is the headline news but as soon as you look under the surface there are a raft of anthropomorphic emissions that are know to have greenhouse potential - CO2 may be the biggest contributor but methane CFCs, HCFCs and the albedo effect of carbon soot are all openly discussed. There has even been finger pointing at the Europeans for their use of diesel cars which reduce CO2 emissions but generate more of the carbon soot that you correctly highlighted as an issue.

As for the admitted and corrected Himalayan glacier error, this was not make by group 1 but by group 2 of the IPCC. Group 2 are not the specialist in the area and the reference they used and openly published was not peer reviewed. They should have check with Group 1 and Group 1 should have had enough time to review Group 2. It did not happen and this error slipped through. The day I can guarantee that I won't make mistake in a customer delivery under pressure, I will point the finger at the IPCC. For sure, IPCC report 5 will be subject to tighter internal quality checks after this escapade!

Should we stop instead of learning from mistakes? If the US and NASA had done so after the Apollo 1 fire then they would never have reached the moon.

At GCC we should be able to handle the nuances, accept there will always be uncertainties and errors.


Well said Thomas!


This spells it out:


Well yes, a blog about an article in a conservative, British TABLOID newspaper certainly spells out... something.

BTW The Daily Express is currently owned by a pornographer - Richard Desmond.

At least a former owner[Lord Beaverbrook] was more up front about this rag, he said "I run the paper for the purpose of making propaganda and with no other motive."


Professor Jones has reportedly conceded the possibility that the world was warmer in medieval times than now – suggesting global warming may not be a man-made phenomenon.
And that for the past 15 years there has been no ‘statistically significant’ warming.


He only answered the questions he was asked. He was not asked if he thought the solar minimum we just went though might have something to do with there being 'no statistically significant warming for the past 15 years.'

And conceding the possibility that the world was warmer in medieval times than now is not news; there's always been that possibility, it's just not a high probability. Either way Professor Jones didn't suggest "global warming may not be a man-made phenomenon," he pointed out that although past warmings could be explained by natural phenomena - the more recent warming could not. The suggestion was the tabloid's.


What is the relevance of him "only answering the questions he was asked"?
Professor Jones may not be suggesting "global warming may not be a man-made phenomenon," but it is obvious WE can.


In his own words;
"As for the two periods 1910-40 and 1975-1998 the warming rates are not statistically significantly different (see numbers below).
I have also included the trend over the period 1975 to 2009, which has a very similar trend to the period 1975-1998.
So, in answer to the question, the warming rates for all 4 periods are similar and not statistically significantly different from each other.
Here are the trends (Deg C per decade) and significances for each period:
Period . . . . Yrs . . . Trend - Significance
1860-1880 . 21 . . . 0.163 - Yes
1910-1940 . 31 . . . 0.150 - Yes
1975-1998 . 24 . . . 0.166 - Yes
1975-2009 . 35 . . . 0.161 - Yes

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