Skeptical Science Forum

Posted on 24 April 2011 by Hoskibui

With regularity, you might hear skeptics mentioning a website called CO₂Science and its Medieval Project. It is a front for a research center called Center for the Study of Carbon Dioxide and Global Change and their goal is to distribute:

…factual reports and sound commentary on new developments in the world-wide scientific quest to determine the climatic and biological consequences of the ongoing rise in the air's CO₂ content.

The website is run by the Idso family (Craig, Sherwood, Keith and Julene).

Medieval Project

One of the Idsos' main projects is to collect references that shows temperature reconstructions of the Medieval Warm Period (MWP). The website lists a large number of sources and diagrams that purportedly show local warming during the MWP, along with the Idsos' interpretations of those. Its main conclusion is that current warming is not unprecedented since there was a lot of warming during that time at various sites.

One of the commonly used methods of "skeptics" is to flood the discussions with large sets of references that supposedly support their point of view, regardless of what the studies in that reference list actually say. It is usually the quantity, not the quality, that counts. This is probably done with the confidence that few of the readers will bother, or have the time or ability, to scroll through the entire list of references to point to problems with the website's interpretation of the studies.

The CO₂ Science also has a powerful interactive map where you can find the locations of the studies in their database. By clicking on the dots on the map you get to a page where a summary of that study is displayed - or rather the CO₂ Science interpretation of the study.

Figure 1: Interactive map from CO₂ Science, part of the Medieval Project.

CO₂ Science has also been a useful resource for other skeptics, see for example the Science Skeptical Blog which has also available an interactive map (pictured below):

Figure 2: Picture of an interactive map from Science Skeptical Blog. It refers to CO₂ Science.

This interactive map is useful in its purpose: to view the alleged global warming during the MWP in graphical form. It has the feature that if you click on the images, then it shows a temperature reconstruction (or other proxy, see below). There you can also find sources for each graph, with abstracts (actually, the abstracts sometimes tell a different story line than the documents - see below).

Interaction for healthy skeptics?

For people with healthy skepticism these interactive maps are quite good. When I say healthy skepticism I am referring to those who have skeptism for both sides of the argument, not just skeptism about studies that can be interpreted as pro-AGW theory.

So it is crucial that those maps are viewed with a critical mind. On Skeptical Science (as opposed to Science Skeptical Blog) we have looked before at common graphical tricks and the Medieval Warm Period that include the following tricks:

Hide the temperature scale and/or the temperature values
Pick one area or location of the world
Cut out or ignore recent warming

The total effect of those maps, like the one on Science Skeptical Blog - is what is most effective for the casual reader. All of the selected articles on the map show at some point a period that can be interpreted as "Medieval Warming". The quotation mark is because in some cases the research is only about the MWP itself - but not the temperature. For example we can find graphs showing changes in precipitation, like, Zhang et al 2003 - study from Tibet, by which it states in the abstract (emphasis mine):

High-resolution climate proxy records covering the last two millennium on the Qinghai-Tibetan Plateau are scarce yet essential to evaluation of the pattern, synchroneity and spatial extent of past climatic changes including those in the Medieval Warm Period (MWP) and the Little Ice Age (LIA). Here we present a 2326-year tree-ring chronology of Sabina Przewalskii Kom for Dulan area of northeastern Qinghai-Tibetan Plateau. We find that the annual growth rings mainly reflect variations in regional spring precipitation. The greatest change in spring precipitation during the last two millennia seems to occur in the second half of the 4th century. The North Atlantic MWP was accompanied by notable wet springs in the study region during AD 929–1031, with the peak occurring around AD 974. Three intervals of dry springs occurred in the period of the LIA. Our tree-ring data will facilitate intercontinental comparisons of large-scale synoptic climate variability for the last two millennia.

This research is not only notable for the fact that it contains a proxy for precipitation and not for temperature, but also because here the skeptics freely use a tree ring proxy - which they consider mostly unusable (well, unless it can be used to make a point contradicting AGW theory).

Few of the graphs shown in figure 2 show the temperature like it is today; in addition, one trick frequently used is to have the MWP ill-defined. Usually the MWP is the period between 950-1250, but when you look at the graphs you see some inconsistency. It seems that it doesn´t matter for the maker of those websites if it is warm during 800 AD, 1100 AD or even 1400 AD; that warming is - by their opinion - indication of a global warming during the MWP.

If you take graphs from two separate locations you can see some difference. One graph shows a proxy for temperature in Greenland and the other one for New Zealand:

Figure 3: The Medieval Warm Period in Greenland, according to Johnsen et al. 2001, was quite strong around 1000 AD.

Figure 4: The Medieval Warm Period in New Zealand, according to Wilson et al. 1979, was strongest between 1300 and 1400 AD.

Looking at those two graphs it is clear that the warming is not at the same time.

Another flaw is evident when looking at those graphs: the insistence on using old data. Much of the data is old and outdated. It is difficult to imagine that there are no better and newer data on paleoclimate in New Zealand then a study of oxygen isotopes from the year 1979.

There is also a tendancy to ignore corrected version of data. In the case of this map, they use for example Loehle 2007 instead of Loehle 2008 (See Kung-fu Climate).

CO₂ Non-Science

The above description above can be used for CO₂ Science - and for what can be seen on Science Skeptical Blog. The map on the Science Skeptical Blog actually is better because it links directly to the abstract of the relevant article - while CO₂ Science only show their own interpretation of the studies.

As an example, there is research from the Alps (Mangini et al 2005) which CO₂ Science interpret in a weird way and conclude that the MWP was warmer than today. The CO₂ Science summary of the study says:

… at three different points during the MWP their data indicate temperature spikes in excess of 1°C above present (1995-1998) temperatures of 1.8°C.

In contrast, it states in the abstract:

…maxima during the Medieval Warm Period between 800 and 1300 AD are in average about 1.7 °C higher than the minima in the Little Ice Age and similar to present-day values.

Another misinterpretation of data can see by looking at the sea temperature data from the Indian Ocean (Oppo et al 2009).

The CO₂ Science interpretation reads:

Reconstructed SSTs were, in their words, “warmest from AD 1000 to AD 1250 and during short periods of first millennium.” From the authors' Figure 2b, adapted below, we calculate that the Medieval Warm Period was about 0.4°C warmer than the Current Warm Period.

Then they change the image 2b from the article and make it look like the medieval warming was 0.4 ° C higher than the current warming:

Figure 5: Graph from CO₂ Science - derived from the Oppo, et al. 2009, which is said to show that MWP was 0.4 ° C higher than now.

The original graph can be seen below:

Figure 6: Graph from Oppo et al 2009. Figure 2b in the center indicate that the current warming is greater than the Medieval Warm Period (graph from Nature).

As is evident from the 2b in figure 6 above, the mean annual SST for 1997-2007 was higher than the rest of the graph.

It is interesting when these maps point to the data that should show that the medieval warming is unique and greater than the current warming - and use the articles and graphs, as of Paulsen et al 2003 to confirm it:

Figure 7: Medieval Warming in central China, Paulsen et al. 2003.

Here you see a brief Medieval warming around the year 1400 AD. Current warming is pretty clear.

Conclusion

There are some substantial problems with CO₂ Science and its sister site Science Skeptical Blog. Various tricks are used to confuse the reader into accepting that the MWP was global and even warmer than the current warming.

For reference geek like me, it is still a goldmine. It has a large collection of articles about paleoclimate - still with the downside that we can't trust the conclusion or the graphs that we see, because of many misrepresentations.

The story is half-told by pointing at a large set of data. Some scientists have actually used some of this data to make comparisons between current warming and the past (Mann et al 2008):

Figure 8: The new hockey stick (Mann et al. 2008). Temperature proxys for the last 1800 years. The red line shows direct measurements and various indirect measurements (ISPs) are in different colors.

Indeed, one point that people forget when they try to make the most of the MWP: if its temperature was greater than scientists generally believe, there is more warming in the pipeline than scientists expected (see What does past climate change tell us about global warming). That means that the climate sensitivity is greater - and consequently, global warming caused by increased greenhouse gases will be greater. Therefore those arguing that there is no worry about the future of climate change should avoid arguing for a warmer MWP.

Medieval project gone wrong

Posted on 24 April 2011 by Hoskibui

…factual reports and sound commentary on new developments in the world-wide scientific quest to determine the climatic and biological consequences of the ongoing rise in the air's CO₂ content.

The website is run by the Idso family (Craig, Sherwood, Keith and Julene).

Medieval Project

One of the Idsos' main projects collects temperature reconstructions of the Medieval Warm Period (MWP) that claim to show local warming and then posts them on their website with the Idsos’ interpretation. They conclude that current warming is not unprecedented since there was a lot of warming during in the past at various places.

The site is flooded with lots of references, but do the references say the same thing as the Idsos? CO₂ Science has a powerful interactive map and by clicking on the dots on the map you get to a page where a summary of that study is displayed - or rather the CO₂ Science interpretation of the study.

Figure 1: Interactive map from CO₂ Science, part of the Medieval Project.

CO₂ Science has also been a useful resource for other skeptics, see for example the Science Skeptical Blog which has also available an interactive map (pictured below):

Figure 2: Picture of an interactive map from Science Skeptical Blog. It refers to CO₂ Science.

This interactive map is useful to view the alleged global warming during the MWP in graphical form. You can click on the images and see a temperature reconstruction (or other proxy, see below) of that location. There you can also find sources for each graph, with abstracts.

Interaction for healthy skeptics?

For people with healthy skepticism these interactive maps are quite good. It is crucial that those maps are viewed with a critical mind. On Skeptical Science (as opposed to Science Skeptical Blog) we have looked before at common graphical tricks and the Medieval Warm Period that include the following tricks:

Hide the temperature scale and/or the temperature values
Pick one area or location of the world
Cut out or ignore recent warming

The total effect of those maps is what is most effective for the casual reader. All of the selected articles on the map show at some point a period that can be interpreted as "Medieval Warming". The quotation mark is because in some cases the research is only about the period itself - but not the temperature. For example we can find graphs showing changes in precipitation, like, Zhang et al 2003 - study from Tibet, by which it states in the abstract (emphasis mine):

... We find that the annual growth rings mainly reflect variations in regional spring precipitation. The greatest change in spring precipitation during the last two millennia seems to occur in the second half of the 4th century. The North Atlantic MWP was accompanied by notable wet springs in the study region during AD 929–1031, with the peak occurring around AD 974. ...

Few of the graphs in figure 2 show the temperature like it is today; in addition the MWP is rather ill-defined. Usually the MWP is the period between 950-1250, but when you look at the graphs you see some inconsistency. In it you see a warm period during 800 AD, 1100 AD or even 1400 AD; that warming is - by their opinion - indication of a global warming during the MWP. For example if you take graphs from two separate locations you can see some difference. Here we have one graph with a proxy for temperature in Greenland and the other one for New Zealand:

Figure 3: The Medieval Warm Period in Greenland, according to Johnsen et al. 2001, was quite strong around 1000 AD.

Figure 4: The Medieval Warm Period in New Zealand, according to Wilson et al. 1979, was strongest between 1300 and 1400 AD.

Looking at those two graphs it is clear that the warming is not at the same time.

Another flaw is evident when looking at those graphs: the insistence on using old data. Many of the articles used has data that is old and outdated. It is difficult to imagine that there are no better and newer data on paleoclimate in New Zealand then a study of oxygen isotopes from the year 1979. There is also a tendancy to ignore corrected version of data. In the case of this map, they use for example Loehle 2007 instead of Loehle 2008 (See Kung-fu Climate).

CO₂ Non-Science

On CO2 Science the problem is not just the way they pick the graphs, but how they change them and interpret them. As an example, there is research from the Alps (Mangini et al 2005) which CO₂ Science interpret in a strange way and conclude that the MWP was warmer than today. The CO₂ Science summary of the study says:

… at three different points during the MWP their data indicate temperature spikes in excess of 1°C above present (1995-1998) temperatures of 1.8°C.

In contrast, it states in the abstract of the paper:

…maxima during the Medieval Warm Period between 800 and 1300 AD are in average about 1.7 °C higher than the minima in the Little Ice Age and similar to present-day values.

Another misinterpretation of data can see by looking at the sea temperature data from the Indian Ocean (Oppo et al 2009).

The CO₂ Science interpretation reads:

Reconstructed SSTs were, in their words, “warmest from AD 1000 to AD 1250 and during short periods of first millennium.” From the authors' Figure 2b, adapted below, we calculate that the Medieval Warm Period was about 0.4°C warmer than the Current Warm Period.

Then they change the image 2b from the article and make it look like the medieval warming was 0.4 ° C higher than the current warming:

Figure 5: Graph from CO₂ Science - derived from the Oppo, et al. 2009, which is said to show that MWP was 0.4 ° C higher than now.

The original graph can be seen below (see graph b and the line representing the 1997-2007 mean annual SST):

Figure 6: Graph from Oppo et al 2009. Figure 2b in the center indicate that the current warming is greater than the Medieval Warm Period (graph from Nature).

As is evident from the 2b in figure 6 above, the mean annual SST for 1997-2007 was higher than the rest of the graph.

Conclusion

Both CO₂ Science and its sister site Science Skeptical Blog use various methods or tricks to make the case for a global warm period during the medieval times. As can be seen with a critical lookat the original papers and graphs, their conclusion don't hold water. In those pages we have a large collection of articles about paleoclimate and we can't trust their conclusion or the graphs that we see, because of many misrepresentations.

The story is half-told by pointing at a large set of data. Some scientists have actually used some of this data to make comparisons between current warming and the past (Mann et al 2008):

Figure 7: The new hockey stick (Mann et al. 2008). Temperature proxys for the last 1800 years. The red line shows direct measurements and various indirect measurements (ISPs) are in different colors.


2011-04-17 04:25:07	Post about the Medieval Project
Hoskibui hoskibui@gmail... 85.220.127.116	My first post here on Skeptical Science is now waiting for comments and more. There seems to be some problems that I will need to fix regarding images for example.. but feel free to comment - I would rather have nasty comments from you rather then later on the front page of Skeptical Science :) Medieval project gone wrong
2011-04-17 04:40:41
Hoskibui hoskibui@gmail... 85.220.127.116	I seem to have lost the url to the figures - does anybody know how to find those urls? Edit: found a way around it - working on it.
2011-04-17 07:25:43
Daniel Bailey Daniel Bailey yooper49855@hotmail... 97.83.150.37	Fixed your links and images. Check 'em to make sure I didn't miss any. Will give it a read-through later.
2011-04-17 08:18:43	comments
dana1981 Dana Nuccitelli dana1981@yahoo... 69.230.97.203	"One of the larger project of the website " => One of the Idsos' main projects "There are The website lists a large number of sources and diagrams that purportedly show local waming during the MWP" "One of the common used methods of "skeptics" is to flood the discussions with large set of references that supposedly support their point of view" "Most Much of those data has have been, undoubtedly, updated" <= I'm not sure we can safely say this. It might just be better to say the studies are old and may be outdated. "while CO2 Science only show their own interpretation of the researches studies." "As an example, there is a research from the Alps (Mangini et al 2005) which CO2 Science interpretate in a weird way and conclude that the MWP was warmer then than today. The summary of CO2 Science summary of the study says:" "The CO2 Science interpretation reads:"
2011-04-17 08:32:04
Hoskibui hoskibui@gmail... 85.220.127.116	It is a temptation to give the regular posters (dana1981, Bailey, logicman and more?) a full permission to edit the text, won´t it save time? Just a suggestion, maybe a silly one :)
2011-04-17 08:54:29
Daniel Bailey Daniel Bailey yooper49855@hotmail... 97.83.150.37	I wouldn't presume to force any suggested changes down your throat, Hoskibui. Fixing links & URLs is one thing; making editorial content decisions without your input is another. But if you're swamped for time or having issues with the WYSIWYG editor, let us know via leaving a message here to that effect. Someone will step in to help at that point.
2011-04-17 09:04:20
Hoskibui hoskibui@gmail... 85.220.127.116	No, it's okey - I have enough time, I was thinking about you guys. I mean, english is your language, so it´s kind of a default that your suggestions are the correct one. It looks like it takes time correcting - like the strikethrough and colouring (as dana1981 does so well). But my time is not that importent, have a lot of time- at least over this weekend :)
2011-04-17 09:16:12	edits
dana1981 Dana Nuccitelli dana1981@yahoo... 69.230.97.203	I'd be happy to go in and edit any other minor english mistakes before we publish it, Hoskibui.
2011-04-17 09:22:30
Hoskibui hoskibui@gmail... 85.220.127.116	Very good, thank you dana1981. I think it will be better for others to read over the post, if the english is correct :)
2011-04-17 11:06:47
Andy S skucea@telus... 66.183.165.122	Hi Hoskibui I think that this will make a good post but it needs a fair bit of work, especially in sharpening up the English. I'll try to help out with this later. For now, one substantive point: In your Figure 7 you seem to have used different y-axis scales for the Mann data and the Oppo data. You have exaggerated the Mann data by a factor of two, without any explanation and I don't think that this is admissible. Of course, I may have misundestood something and that wouldn't be the first time.
2011-04-17 21:37:39
Hoskibui hoskibui@gmail... 85.220.127.116	Thank you Andy - good question. It´s been more than a year that I did the post in Icelandic - so I´m not completely sure about everything in the post (that should make you skeptical ;) But in this case I got the figure in a post from Oxford Kevin.It says on his web page that the figure is from the press release - but I thought it was a figure from the article itself (2,000-year-long temperature and hydrology reconstructions from the Indo-Pacific warm pool) but I didn´t have access then (I do now see link). The article has some similar figures, but nothing identical. It then seems like it is from the press release. Vhat can we do to find out?
2011-04-18 20:19:52
Hoskibui hoskibui@gmail... 194.144.161.27	dana1981 - I have corrected according to your comment. --- Andy - I looked at the article again (another and a better link to the article) and it says for example: The hemispheric and global temperature difference between the early AD 1900s and themodern era is similar to the difference in mean annual SST at our core site (Supplementary Notes), so the greater amplitude of Makassar Strait SST than Northern Hemisphere temperature variability (note different axis scaling in Fig. 3a) may be related to the hypothesized changes in G. ruber seasonality. Do you think we will have to explain it - or maybe just take it out all together? --- Somebody raised question over if it was right to use this sentance in the medieval post: The website s run by the Idso family (Craig, Sherwood, Keith and Julene). They don't hide the fact that they get money from financially strong businesses, for example from Exxon among others. Any comments about that?
2011-04-18 21:06:06
nealjking nealjking@gmail... 84.151.44.233	There's nothing wrong about a business being financially strong. The issue is that they have an incredible degree of investment in the fossil-fuels industry.
2011-04-19 04:02:06
Andy S skucea@telus... 66.183.165.122	Hoskibui Thanks for the clarification, although I would have to read the whole Oppo paper carefully before I could claim to understand what's going on with the different temperature scales; even after that, no guarantees ;-) If it was my article, I wouldn't include a figure unless I could explain it to the intended audience in terms I would expect them to understand. If that's not possible, then it might be best to take it out unless it is critical for making your main point. One tactic might be to take it out and later insert it in a comment should a relevant (excellent) question come up. In that way you could still make the point in your Figure 7 without cluttering up your main article. I learned from giving business presentations that a "Good" question was a question that you had an answer to, an "Excellent" question was one that you had a reserve PowerPoint slide for.
2011-04-19 08:51:25
Hoskibui hoskibui@gmail... 85.220.127.116	Thank you, took up on your advise. So if somebody is reading this after deleting fig 7, then there is a new fig 7 :) I appreciate all your efforts and please continue - fire away :)
2011-04-21 16:26:48
Rob Painting Rob paintingskeri@vodafone.co... 118.92.111.75	Hoskibui, - Figure 6 - it ain't clear to me at all that the current warming is higher than the MWP (Oppo 2009) - Delete any mention of "tricks" and the Idso's affiliation with oil companies. Hey, we know they're a bunch of lying, scheming psychopaths, but keep the tone neutral for casual readers. - Conclusion - I'm not sure that a warmer MWP necessarily means greater climate sensitivity (using the recognised defintion of that term) but it sure shows we can expect some surprises in the future as the Earth re-organizes the circulation of heat and water around the planet. I think this should be left out (a subject for a later post?) and the conclusion summarize the Idso's ploy - throw a whole bunch of references out there in the expectation that people won't actually read the studies, when you do, one finds the Idso's have misrepresented the facts, their MWP jumps back and forth in time like Doctor Who's tardis!. And lastly, peer-reviewed studies that have looked at all the data (Mann etc), find that the current warming is exceptional compared to the last few millenia (Ye olde hockey stick) Great topic and post, just needs a few touch-ups here and there.
2011-04-22 05:48:47
Hoskibui hoskibui@gmail... 85.220.41.229	Thanks Rob Painting: -About figure 6 - it is not clear unless you see the horizontal line indicating the current temperature is higher (1997-2007). If it is not clear (or wrong) - any idea how to fix it or make it more clear? -I agree, I have now deleted connections with oil companies and toned down somie mentions of the tricks and deceptions :) -Let me think about the conclusions a bit, I might be inclined to shorten it a bit - any more input? After all this input above it is allready much better post - still it need some fixing :)
2011-04-22 06:32:22
Daniel Bailey Daniel Bailey yooper49855@hotmail... 97.83.150.37	Took the liberty of tweaking grammar & tense (revised copy shown below): Medieval project gone wrong Posted on 24 April 2011 by Hoskibui With regularity, you might hear skeptics mentioning a website called CO₂Science and its Medieval Project. It is a front for a research center called Center for the Study of Carbon Dioxide and Global Change and their goal is to distribute: …factual reports and sound commentary on new developments in the world-wide scientific quest to determine the climatic and biological consequences of the ongoing rise in the air's CO₂ content. The website is run by the Idso family (Craig, Sherwood, Keith and Julene). Medieval Project One of the Idsos' main projects is to collect references that shows temperature reconstructions of the Medieval Warm Period (MWP). The website lists a large number of sources and diagrams that purportedly show local warming during the MWP, along with the Idsos' interpretations of those. Its main conclusion is that current warming is not unprecedented since there was a lot of warming during that time at various sites. One of the commonly used methods of "skeptics" is to flood the discussions with large sets of references that supposedly support their point of view, regardless of what the studies in that reference list actually say. It is usually the quantity, not the quality, that counts. This is probably done with the confidence that few of the readers will bother, or have the time or ability, to scroll through the entire list of references to point to problems with the website's interpretation of the studies. The CO₂ Science also has a powerful interactive map where you can find the locations of the studies in their database. By clicking on the dots on the map you get to a page where a summary of that study is displayed - or rather the CO₂ Science interpretation of the study. Figure 1: Interactive map from CO₂ Science, part of the Medieval Project. CO₂ Science has also been a useful resource for other skeptics, see for example the Science Skeptical Blog which has also available an interactive map (pictured below): Figure 2: Picture of an interactive map from Science Skeptical Blog. It refers to CO₂ Science. This interactive map is useful in its purpose: to view the alleged global warming during the MWP in graphical form. It has the feature that if you click on the images, then it shows a temperature reconstruction (or other proxy, see below). There you can also find sources for each graph, with abstracts (actually, the abstracts sometimes tell a different story line than the documents - see below). Interaction for healthy skeptics? For people with healthy skepticism these interactive maps are quite good. When I say healthy skepticism I am referring to those who have skeptism for both sides of the argument, not just skeptism about studies that can be interpreted as pro-AGW theory. So it is crucial that those maps are viewed with a critical mind. On Skeptical Science (as opposed to Science Skeptical Blog) we have looked before at common graphical tricks and the Medieval Warm Period that include the following tricks: Hide the temperature scale and/or the temperature values Pick one area or location of the world Cut out or ignore recent warming The total effect of those maps, like the one on Science Skeptical Blog - is what is most effective for the casual reader. All of the selected articles on the map show at some point a period that can be interpreted as "Medieval Warming". The quotation mark is because in some cases the research is only about the MWP itself - but not the temperature. For example we can find graphs showing changes in precipitation, like, Zhang et al 2003 - study from Tibet, by which it states in the abstract (emphasis mine): High-resolution climate proxy records covering the last two millennium on the Qinghai-Tibetan Plateau are scarce yet essential to evaluation of the pattern, synchroneity and spatial extent of past climatic changes including those in the Medieval Warm Period (MWP) and the Little Ice Age (LIA). Here we present a 2326-year tree-ring chronology of Sabina Przewalskii Kom for Dulan area of northeastern Qinghai-Tibetan Plateau. We find that the annual growth rings mainly reflect variations in regional spring precipitation. The greatest change in spring precipitation during the last two millennia seems to occur in the second half of the 4th century. The North Atlantic MWP was accompanied by notable wet springs in the study region during AD 929–1031, with the peak occurring around AD 974. Three intervals of dry springs occurred in the period of the LIA. Our tree-ring data will facilitate intercontinental comparisons of large-scale synoptic climate variability for the last two millennia. This research is not only notable for the fact that it contains a proxy for precipitation and not for temperature, but also because here the skeptics freely use a tree ring proxy - which they consider mostly unusable (well, unless it can be used to make a point contradicting AGW theory). Few of the graphs shown in figure 2 show the temperature like it is today; in addition, one trick frequently used is to have the MWP ill-defined. Usually the MWP is the period between 950-1250, but when you look at the graphs you see some inconsistency. It seems that it doesn´t matter for the maker of those websites if it is warm during 800 AD, 1100 AD or even 1400 AD; that warming is - by their opinion - indication of a global warming during the MWP. If you take graphs from two separate locations you can see some difference. One graph shows a proxy for temperature in Greenland and the other one for New Zealand: Figure 3: The Medieval Warm Period in Greenland, according to Johnsen et al. 2001, was quite strong around 1000 AD. Figure 4: The Medieval Warm Period in New Zealand, according to Wilson et al. 1979, was strongest between 1300 and 1400 AD. Looking at those two graphs it is clear that the warming is not at the same time. Another flaw is evident when looking at those graphs: the insistence on using old data. Much of the data is old and outdated. It is difficult to imagine that there are no better and newer data on paleoclimate in New Zealand then a study of oxygen isotopes from the year 1979. There is also a tendancy to ignore corrected version of data. In the case of this map, they use for example Loehle 2007 instead of Loehle 2008 (See Kung-fu Climate). CO₂ Non-Science The above description above can be used for CO₂ Science - and for what can be seen on Science Skeptical Blog. The map on the Science Skeptical Blog actually is better because it links directly to the abstract of the relevant article - while CO₂ Science only show their own interpretation of the studies. As an example, there is research from the Alps (Mangini et al 2005) which CO₂ Science interpret in a weird way and conclude that the MWP was warmer than today. The CO₂ Science summary of the study says: … at three different points during the MWP their data indicate temperature spikes in excess of 1°C above present (1995-1998) temperatures of 1.8°C. In contrast, it states in the abstract: …maxima during the Medieval Warm Period between 800 and 1300 AD are in average about 1.7 °C higher than the minima in the Little Ice Age and similar to present-day values. Another misinterpretation of data can see by looking at the sea temperature data from the Indian Ocean (Oppo et al 2009). The CO₂ Science interpretation reads: Reconstructed SSTs were, in their words, “warmest from AD 1000 to AD 1250 and during short periods of first millennium.” From the authors' Figure 2b, adapted below, we calculate that the Medieval Warm Period was about 0.4°C warmer than the Current Warm Period. Then they change the image 2b from the article and make it look like the medieval warming was 0.4 ° C higher than the current warming: Figure 5: Graph from CO₂ Science - derived from the Oppo, et al. 2009, which is said to show that MWP was 0.4 ° C higher than now. The original graph can be seen below: Figure 6: Graph from Oppo et al 2009. Figure 2b in the center indicate that the current warming is greater than the Medieval Warm Period (graph from Nature). As is evident from the 2b in figure 6 above, the mean annual SST for 1997-2007 was higher than the rest of the graph. It is interesting when these maps point to the data that should show that the medieval warming is unique and greater than the current warming - and use the articles and graphs, as of Paulsen et al 2003 to confirm it: Figure 7: Medieval Warming in central China, Paulsen et al. 2003. Here you see a brief Medieval warming around the year 1400 AD. Current warming is pretty clear. Conclusion There are some substantial problems with CO₂ Science and its sister site Science Skeptical Blog. Various tricks are used to confuse the reader into accepting that the MWP was global and even warmer than the current warming. For reference geek like me, it is still a goldmine. It has a large collection of articles about paleoclimate - still with the downside that we can't trust the conclusion or the graphs that we see, because of many misrepresentations. The story is half-told by pointing at a large set of data. Some scientists have actually used some of this data to make comparisons between current warming and the past (Mann et al 2008): Figure 8: The new hockey stick (Mann et al. 2008). Temperature proxys for the last 1800 years. The red line shows direct measurements and various indirect measurements (ISPs) are in different colors. Indeed, one point that people forget when they try to make the most of the MWP: if its temperature was greater than scientists generally believe, there is more warming in the pipeline than scientists expected (see What does past climate change tell us about global warming). That means that the climate sensitivity is greater - and consequently, global warming caused by increased greenhouse gases will be greater. Therefore those arguing that there is no worry about the future of climate change should avoid arguing for a warmer MWP. Further reading Even though there are lot of misrepresentation in the web sites in question, they can be quite helpful in finding the right references, with the good help of Google Scholar for example. Other reviews of CO₂ Science and its false interpretations can be found at Climate Shift, on Kevin Oxford and Climate Feedback
2011-04-22 20:56:58
MarkR Mark Richardson m.t.richardson2@gmail... 134.225.187.197	My advice (as always!) is to shorten it if you possibly can! I did a session on science communication this week and their first suggestion was to 'halve it, then halve it again'. You can do it without losing any of the points you want to make and it might just encourage a few more people to read it. e.g. the chunk after the first title of 3 paragraphs could be halved in length like this: "One of the Idsos' main projects collects temperature reconstructions of the Medieval Warm Period (MWP) that claim to show local warming and then posts them on their website with the Idsos’ interpretation. They conclude that current warming is not unprecedented since there was a lot of warming during in the past at various places. The site is flooded with lots of references, but do the references say the same thing as the Idsos? CO₂ Science has a powerful interactive map and by clicking on the dots on the map you get to a page where a summary of that study is displayed - or rather the CO₂ Science interpretation of the study."
2011-04-23 02:31:44	agreed
dana1981 Dana Nuccitelli dana1981@yahoo... 64.129.227.4	I agree with Mark, it would probably be helpful to shorten this one a bit.
2011-04-26 23:19:03
Hoskibui hoskibui@gmail... 194.144.161.27	Thanks Daniel for the grammar corrections (and more). Agreed with Mark and dana1981 - will try to shorten it - will give it a thought as soon as I have time. Cheers.
2011-04-27 07:56:52	Shorter and shorter :)
Hoskibui hoskibui@gmail... 85.220.124.174	Here is a shorter version - and with a changed conclusion (which might have added some errors in grammar or spelling). ------------------------------------------------------- Medieval project gone wrong Posted on 24 April 2011 by Hoskibui With regularity, you might hear skeptics mentioning a website called CO₂Science and its Medieval Project. It is a front for a research center called Center for the Study of Carbon Dioxide and Global Change and their goal is to distribute: …factual reports and sound commentary on new developments in the world-wide scientific quest to determine the climatic and biological consequences of the ongoing rise in the air's CO₂ content. The website is run by the Idso family (Craig, Sherwood, Keith and Julene). Medieval Project One of the Idsos' main projects collects temperature reconstructions of the Medieval Warm Period (MWP) that claim to show local warming and then posts them on their website with the Idsos’ interpretation. They conclude that current warming is not unprecedented since there was a lot of warming during in the past at various places. The site is flooded with lots of references, but do the references say the same thing as the Idsos? CO₂ Science has a powerful interactive map and by clicking on the dots on the map you get to a page where a summary of that study is displayed - or rather the CO₂ Science interpretation of the study. Figure 1: Interactive map from CO₂ Science, part of the Medieval Project. CO₂ Science has also been a useful resource for other skeptics, see for example the Science Skeptical Blog which has also available an interactive map (pictured below): Figure 2: Picture of an interactive map from Science Skeptical Blog. It refers to CO₂ Science. This interactive map is useful to view the alleged global warming during the MWP in graphical form. You can click on the images and see a temperature reconstruction (or other proxy, see below) of that location. There you can also find sources for each graph, with abstracts. Interaction for healthy skeptics? For people with healthy skepticism these interactive maps are quite good. It is crucial that those maps are viewed with a critical mind. On Skeptical Science (as opposed to Science Skeptical Blog) we have looked before at common graphical tricks and the Medieval Warm Period that include the following tricks: Hide the temperature scale and/or the temperature values Pick one area or location of the world Cut out or ignore recent warming The total effect of those maps is what is most effective for the casual reader. All of the selected articles on the map show at some point a period that can be interpreted as "Medieval Warming". The quotation mark is because in some cases the research is only about the period itself - but not the temperature. For example we can find graphs showing changes in precipitation, like, Zhang et al 2003 - study from Tibet, by which it states in the abstract (emphasis mine): ... We find that the annual growth rings mainly reflect variations in regional spring precipitation. The greatest change in spring precipitation during the last two millennia seems to occur in the second half of the 4th century. The North Atlantic MWP was accompanied by notable wet springs in the study region during AD 929–1031, with the peak occurring around AD 974. ... Few of the graphs in figure 2 show the temperature like it is today; in addition the MWP is rather ill-defined. Usually the MWP is the period between 950-1250, but when you look at the graphs you see some inconsistency. In it you see a warm period during 800 AD, 1100 AD or even 1400 AD; that warming is - by their opinion - indication of a global warming during the MWP. For example if you take graphs from two separate locations you can see some difference. Here we have one graph with a proxy for temperature in Greenland and the other one for New Zealand: Figure 3: The Medieval Warm Period in Greenland, according to Johnsen et al. 2001, was quite strong around 1000 AD. Figure 4: The Medieval Warm Period in New Zealand, according to Wilson et al. 1979, was strongest between 1300 and 1400 AD. Looking at those two graphs it is clear that the warming is not at the same time. Another flaw is evident when looking at those graphs: the insistence on using old data. Many of the articles used has data that is old and outdated. It is difficult to imagine that there are no better and newer data on paleoclimate in New Zealand then a study of oxygen isotopes from the year 1979. There is also a tendancy to ignore corrected version of data. In the case of this map, they use for example Loehle 2007 instead of Loehle 2008 (See Kung-fu Climate). CO₂ Non-Science On CO2 Science the problem is not just the way they pick the graphs, but how they change them and interpret them. As an example, there is research from the Alps (Mangini et al 2005) which CO₂ Science interpret in a strange way and conclude that the MWP was warmer than today. The CO₂ Science summary of the study says: … at three different points during the MWP their data indicate temperature spikes in excess of 1°C above present (1995-1998) temperatures of 1.8°C. In contrast, it states in the abstract of the paper: …maxima during the Medieval Warm Period between 800 and 1300 AD are in average about 1.7 °C higher than the minima in the Little Ice Age and similar to present-day values. Another misinterpretation of data can see by looking at the sea temperature data from the Indian Ocean (Oppo et al 2009). The CO₂ Science interpretation reads: Reconstructed SSTs were, in their words, “warmest from AD 1000 to AD 1250 and during short periods of first millennium.” From the authors' Figure 2b, adapted below, we calculate that the Medieval Warm Period was about 0.4°C warmer than the Current Warm Period. Then they change the image 2b from the article and make it look like the medieval warming was 0.4 ° C higher than the current warming: Figure 5: Graph from CO₂ Science - derived from the Oppo, et al. 2009, which is said to show that MWP was 0.4 ° C higher than now. The original graph can be seen below (see graph b and the line representing the 1997-2007 mean annual SST): Figure 6: Graph from Oppo et al 2009. Figure 2b in the center indicate that the current warming is greater than the Medieval Warm Period (graph from Nature). As is evident from the 2b in figure 6 above, the mean annual SST for 1997-2007 was higher than the rest of the graph. Conclusion Both CO₂ Science and its sister site Science Skeptical Blog use various methods or tricks to make the case for a global warm period during the medieval times. As can be seen with a critical lookat the original papers and graphs, their conclusion don't hold water. In those pages we have a large collection of articles about paleoclimate and we can't trust their conclusion or the graphs that we see, because of many misrepresentations. The story is half-told by pointing at a large set of data. Some scientists have actually used some of this data to make comparisons between current warming and the past (Mann et al 2008): Figure 7: The new hockey stick (Mann et al. 2008). Temperature proxys for the last 1800 years. The red line shows direct measurements and various indirect measurements (ISPs) are in different colors. Further reading Even though there are lot of misrepresentation in the web sites in question, they can be quite helpful in finding the right references, with the good help of Google Scholar for example. Other reviews of CO₂ Science and its false interpretations can be found at Climate Shift, on Kevin Oxford and Climate Feedback
2011-04-27 08:29:43
Alex C coultera@umich... 67.149.101.148	"As can be seen with a critical lookat the original papers and graphs" [near end] >>>"As can be seen with a critical look at the original papers and graphs" [space added] "In those pages we have a large collection of articles about paleoclimate and we can't trust their conclusion or the graphs that we see, because of many misrepresentations." [near end as well] >>>"In those pages we have a large collection of articles about paleoclimate, and we can't trust their conclusion or the graphs that we see because of many misrepresentations." [comma shift] Perhaps also some links to the studies you quote? Such as Mangini et al 2005 and Oppo et al 2009.
2011-04-27 18:16:05
Hoskibui hoskibui@gmail... 194.144.161.27	Cheers Alex - fixed, with plenty of references :)
2011-04-27 19:43:18	Current version
Hoskibui hoskibui@gmail... 194.144.161.27	Current version can be found here: Medieval project gone wrong I appreciate any input, hopefully it will make it finally as a post on skeptical science :)
2011-04-28 02:01:39	post
dana1981 Dana Nuccitelli dana1981@yahoo... 64.129.227.4	Yeah I think it looks good. We can publish this in the next few days. One question though, when you say "few of the graphs in figure 2 show the temperature like it is today" Do you mean they don't show it as warm as today?
2011-04-28 02:06:08
Riccardo riccardoreitano@tiscali... 192.84.150.209	right after Mangini et al quote: "Another misinterpretation of data can see by looking" did you mean "can be seen"?
2011-04-28 05:42:30
Hoskibui hoskibui@gmail... 85.220.124.174	dana1981 - I mean it doesn´t show temperature during the last few decade, how can I make it more understandable? Riccardo - yes, fixed - thank you :)
2011-04-28 07:53:00
dana1981 Dana Nuccitelli dana1981@yahoo... 64.129.227.4	That's a good way to put it. Or something like "few of the graphs in Figure 2 contain temperature data past the mid-20th Century, and thus do not reflect current temperatures"
2011-04-28 08:11:42
Hoskibui hoskibui@gmail... 85.220.124.174	dana1981 - I used your version, thank you :)
2011-04-29 03:42:20
Rob Honeycutt robhon@mac... 98.207.62.223	An interesting note: Check out who runs the CO2 Science site. It's a father and two sons, Drs Idso. They're funded by Exxon. They also have a staff of 8. How would you like it if SkS had a full time staff of 8, John? ;-)
2011-04-29 03:46:06
Daniel Bailey Daniel Bailey yooper49855@hotmail... 97.83.150.37	If you're taking volunteers to add to the payroll, then I'm in! (Understood that paychecks will be in Monopoly money UFN)
2011-04-29 03:46:30
Rob Honeycutt robhon@mac... 98.207.62.223	Correction: They have a board that consists of 8 members. Not staffers. http://www.exxonsecrets.org/html/orgfactsheet.php?id=24 http://www.sourcewatch.org/index.php?title=Craig_Idso
2011-04-29 22:54:55	Suggested minor revisions
James Wight jameswight@southernphone.com... 121.79.21.179	A few more English corrections: “common graphical tricks and the Medieval Warm Period that include the following tricks” --> “common graphical tricks used to exaggerate the Medieval Warm Period, which include the following” “study from Tibet, by which it states in the abstract” --> “a study from Tibet, which states in its abstract” “their conclusion don’t hold water” --> “their conclusions don’t hold water” or “their conclusion doesn’t hold water” “Temperature proxys for the last 1800 years” --> “Temperature proxies for the last 1800 years” Also maybe you should clarify that the “Science Skeptical Blog” is no relation to us!
2011-04-30 00:47:48
Hoskibui hoskibui@gmail... 194.144.161.27	Cheers James, used your corrections. About the similarities in names I added this under Figure 2: * Note: despite similarity in names, Science Skeptical Blog has nothing to do with Skeptical Science. How is that?
2011-04-30 01:57:45	good
dana1981 Dana Nuccitelli dana1981@yahoo... 64.129.227.4	I think this post is good to go. I'm going to publish it.
2011-04-30 03:07:38
oslo borchinfolab@gmail... 90.149.33.182	Thanks for the article Hoskibui, I think it is very good and to the point! co2science should really be prosecuted for spreading all the BS imo, but having good information is very helpfull!
2011-04-30 03:51:40
Hoskibui hoskibui@gmail... 85.220.124.174	Cheers - it was sudden, I heard it was posted on facebook :)
2011-04-30 07:02:00
Hoskibui hoskibui@gmail... 85.220.124.174	I'm a bit slow in answering questions at the blog post - I will be busy tonight (it is evening on the 29th. here in Iceland) but tomorrow I will try to answer some questions. Looks like I don't have to worry - there have appeared some answers allready :)
2011-05-01 01:08:42
Rob Painting Rob paintingskeri@vodafone.co... 118.92.113.216	Cheers Hoskibui, glad someone finally got around to covering this topic. Don't want to see it languish, so thumbs up from me too.

Medieval project gone wrong

Posted on 24 April 2011 by Hoskibui

Medieval Project

Interaction for healthy skeptics?

CO2 Non-Science

Conclusion

Further reading

Medieval project gone wrong

Posted on 24 April 2011 by Hoskibui

Medieval Project

Interaction for healthy skeptics?

CO2 Non-Science

Conclusion

Further reading

CO₂ Non-Science

CO₂ Non-Science