File talk:2000 Year Temperature Comparison.png

message: Where is the legend to this chart? The lines are not described and therefore they mean nothing really. There is no information what the red, yellow, blue, green and so on line means and it gives reader nothing but feeling of confusion. How one can guess what are these lines when they are not named? If you'll give me source of these data I will do it properly and professionally.
88.108.234.195 (talk) 20:16, 15 October 2016 (UTC)
thread_title: Legend

message: I remember this graph with error margins for the past of the same magnitude as the hockey stick in the end  —Preceding unsigned comment added by 87.162.210.217 (talk) 21:03, 5 August 2008 (UTC)
thread_title: Error margins 

message: This is great work: both in research and in editing.  This is what an image page should be.  Kudos — Clarknova 05:19, 1 December 2005 (UTC)
thread_title:  Appreciation 

message: Why not take the COLDEST year from 1900 to 2010 and Hockey Stick the thick black line based on that?  Would be just as accurate as this chart which chooses to pick one of the warmest years.  While they are it, why don't they take a reading from the Mojave desert in July 2009 and just HOCKEY STICK the whole graph up based on that?  It would look much more dramatic and be equally irrelevant and misleading.     —Preceding unsigned comment added by Afenic (talk • contribs) 04:16, 7 December 2009 (UTC)
replies: text: Variation. Fair point - but a difficult one. Sometimes they measure different things. Or different methods of reconstruction. There is (ahem) some slight controvery over this issue. And why does the modern data series leave all of the others behind? - for the obvious reason: its got warmer. Error bars: I don't think they all come with error bars. Some individual series do - MBH for example William M. Connolley 22:56, 4 December 2006 (UTC)
replies: text: The black line represents instrumental data and putting it together with reconstructed data is just dishonest. The two are apples and oranges. Yet the way the graph is constructed it leads the reader to believe the black line somehow updates the reconstructed data. Kauffner (talk) 09:25, 8 July 2010 (UTC)

text:  I would presume that not all these samples came from the same geographic location, and that there was some level of local variation in temperature.  This could account for the discrepancies between samples. --Saforrest 04:48, 2 November 2007 (UTC)

text: Not all of the methods are capable of predicting temperatures. As an example, tree-ring data is obviously not available before the tree has grown. Also, it is worth noting that the uncertainties are smaller for more recent data ( since ways to measure it has improved ). 85.224.77.212 (talk) 18:58, 14 December 2007 (UTC)

text: Just for fun... you might want to read urban heat island. Meanwhile: you're *sure* that current temperature records are unreliable, but you're also *certain* that Global mean temperatures were highest during this current interglacial period during the heyday of the Roman empire - based on, what? The extensive records of the time? Perhaps you'd care to tell us: what was the temperature of, say, Australia during this period? This is a common skeptic misunderstanding William M. Connolley (talk) 07:46, 29 April 2010 (UTC)
thread_title:  Criticism 

message: What is the zero set at for this chart? Rmhermen 21:19, 10 February 2006 (UTC)
replies: text: The instrumental data (which is what all the other records are keyed to) is anomalies from 1950-80 - see . William M. Connolley 22:00, 10 February 2006 (UTC)

text: It's relative to an average of temperatures over thirty years - based on the assumption that temperatures are mean reverting over the medium-long term (i.e. excluding ice ages) any variation of temperature from this mean could be considered an "anomaly". Sorry for the answer that is probably more basic than you needed - but I didn't understand what a "temperature anomaly" was at first. --Dilaudid 21:25, 4 December 2006 (UTC)

text: It is apparent that the average temperature of all of the data points in not the average of what is displayed. Since most of this data is a swag, the zero point should be the average of all of the models. Cvairin 18:36, 5 February 2007 (UTC)
thread_title: Zero

message: It seems to me that this image needs to be updated.  9 of the 10 reconstructions lack data from the last 15 years.  With the exception of the black line (the shortest set, covering only 13% of the span), only one set has data up to 1995.  Yet the graph terminates at 2000, giving the false impression that the data is somehow even 7 years recent, and there is one lone single-value plot for 2004 that is represented with a prominent asterisk and label.  --Magoon (talk) 16:34, 20 December 2007 (UTC)
replies: text: Do we have the source data for this image?  After reading the archived "no change" section and this whole talk I still don't know what data sets the individual colors come from.  I know that people are strongly defending the image so it would be nice to be able to recreate the original and just update it with more recent data. Cubbieco (talk) 21:15, 21 December 2009 (UTC)
replies: text:  I'm puzzled. There is a list of papers, one for each colour. Is there a colour that you don't know which paper it comes from? As for the update, see divergence problem. Only the instrumental data gets updated William M. Connolley (talk) 23:07, 21 December 2009 (UTC)
replies: text:  LOL The the thick black line IS hiding the decline! The divergence is concealed, the instrumental line should be grey and behind all reconstructions. The highlighted 2004 value is useless as all spaghettis in the graph are smoothed values. NB I won't be editing the graph, as I know my edits wouldn't survive 10 minutes.   Hans Erren (talk) 13:41, 24 December 2009 (UTC)
thread_title:  Expired:  Is this image obsolete? 

message: In the article Temperature record, this graph is descibed as:
:Comparison of many reconstructed proxy temperature studies covering last 2000 years
in the article Medieval Warm Period, it is described as:
:Northern Hemisphere temperature reconstructions for the past 2000 years.
The first implies a global temperature record, the second implies that the MWP was North-Atlantic constrained. Which is correct? Which one should be changed? --naught101 (talk) 09:09, 14 December 2008 (UTC)
thread_title:  MWP North-atlantic only or global? 

message: http://www.ncdc.noaa.gov/paleo/pubs/pcn/pcn.html might be useful William M. Connolley (talk) 23:19, 22 December 2009 (UTC)
thread_title:  http://www.ncdc.noaa.gov/paleo/pubs/pcn/pcn.html 

message: Has anyone thought of using the Google Chart API (that page needs work) to produce the plot? It tends to produce very appealing graphs, not to mention being editable on-the-fly. If I understand correctly, the data is publicly available. Just throwing the idea out there. --Alibubba7 (talk) 01:41, 23 December 2009 (UTC)
thread_title:  Plot using Google's Chart API 

message: This is reconstructed by climate models and is not actual fact. This needs to be stated somewhere.--92.28.135.31 (talk) 18:45, 7 January 2010 (UTC)
replies: text: No it isn't William M. Connolley (talk) 20:10, 7 January 2010 (UTC)
thread_title:  Remind people this is not factual data. 

message: Why isn't there an updated plot which includes 2009 as the final data point?  —Preceding unsigned comment added by Mjspe1 (talk • contribs) 04:41, 4 March 2010 (UTC)
thread_title:  Updated data 

message: Why is the black line thicker than the other lines? (I copied the image and pasted it in Paint without stretching or compressing it, and the black line as at least 1 pixel thicker than the others) It is hiding where the other lines are and where they end. Why is it even black when the others are coloured? Shouldn't it be something that is more like the other coloured graphs, like pink, maybe? Can we have it thinner and in a different colour, please? --Joshua Issac (talk) 16:39, 9 April 2010 (UTC)
replies: text: This is Wiki's version Mike Mann's famous "hide the decline" trick. The graph is labeled "Reconstructed temperature", yet the line colors and thickness cause the reader to focus on the instrumental data. If the idea is to compare the instrumental and reconstructed temperatures records, then time period should be the same. Reconstructed temperature records do not normally show a massive upswing in recent years, which is what a casual reader would think looking at this graph. What's up with the asterisk for 2004? There is no other single year value on the graph. Everything else is smoothed. It encourages the reader to mentally connect the asterisk to the black instrumental line, which is totally invalid. Kauffner (talk) 08:25, 1 June 2010 (UTC)
thread_title:  The thick black line 

message: Is there any way that the reconstruction from "Correction to: A 2000-YEAR GLOBAL TEMPERATURE
RECONSTRUCTION BASED ON NON-TREE RING PROXIES" by Craig Loehle could be added to the graphic?
http://farm3.static.flickr.com/2666/3914214320_261cba1cf2_o.png  —Preceding unsigned comment added by Nursebhayes (talk • contribs) 16:03, 28 May 2010 (UTC)
replies: text: With a proper source, it might be possible (though the Loehle paper has been heavily criticised). But why would you bother? It has basically the same as before, except it is truncated so doesn't show the recent warmth William M. Connolley (talk) 16:20, 28 May 2010 (UTC)
replies: text: The most likely reason is the main focus of this graph is to cover an event that happened hundreds of years ago, so I don't see what covering the last decade will achieve in this situation.--174.93.163.194 (talk) 04:01, 3 December 2013 (UTC)
replies: text: Ops I thought that this was about its inclusion in the medieval warm period page specifically.--174.93.163.194 (talk) 04:04, 3 December 2013 (UTC)
thread_title: Loehle, 2009

message: This image is marked as having "little importance", and is the subject of some reasonable criticism. Yet it prominently appears as the primary, otherwise unquestioned representation of global temperature by Wikipedia. And by the uninitiated, it may be inferred as the prominent modern view of the internet and/or world at large. It appears on over 150 pages, in over 50 languages.
This is problematic for the following reasons, completely aside from the controversial "hockey stick" portion from the late 1900s.
The graph excludes error and uncertainty ranges, and disregards the credibility (or lack thereof) of the underlying data sources (by their inclusion, each is given equal authority). The image itself has no legend, description, or caveats. Yet even then, taken as a whole, with the limits representing an overall uncertainty, the data can be interpreted in any number of ways. The same is true depending on whether you take the graph as a whole, or one or more individual sources as authoritative, and how much smoothing is applied.
For example, did the Medieval Warm Period and Little Ice Age exist, and if so, when did they happen and how severe were they? Has the average global temperature risen, fallen, or stayed the same between AD 0 and 1000, and 1000 and 1900? What is the general trend for the last 2000 years? From -0.6 to 0.4, or -0.2 through -0.2, or something else? How does the data correlate with carbon emissions, solar activity, and other atmospheric phenomena? Which peaks and valleys display trends which are unnatural, alarming, or otherwise significant?
I don't consider myself any kind of meteorologist, statistician, or scientist. And yet what does it say about the credibility of Wikipedia when the average reader finds such glaring flaws in such an important image?
I guess the next question is how should such issues be addressed. But I don't really have an answer, because I don't know of any climate change data set which is the "most authoritative/accurate" and which doesn't contain an error margin so large as to make its credibility questionable. I suppose the next best solution would be to simply add a disclaimer to the image itself, stating that it is an amalgam of several sources with several discrepancies, and should not be used to make any conclusions. Then again, if this is true, why does such a dubious image exist to begin with? 174.20.161.214 (talk) 05:27, 29 December 2016 (UTC)
thread_title: General Issues