File:2000 Year Temperature Comparison.png

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Summary[edit]

Expansion of the last 1000 years
Temperature variations during the preceding 12000 years.

This image is a comparison of 11 different published reconstructions of changes during the last 2000 years. More recent reconstructions are plotted towards the front and in redder colors, older reconstructions appear towards the back and in bluer colors. An instrumental history of temperature is also shown in black. The medieval warm period and little ice age are labeled at roughly the times for which they have been postulated, though it is under dispute whether these should be considered global or merely regional events. The single, unsmoothed annual value for 2004 is also shown for comparison. (Image:Instrumental Temperature Record.png shows how 2004 relates to other recent years).

For the purposes of this comparison, the author is agnostic as to which, if any, of the reconstructions of global mean temperature is an accurate reflection of temperature fluctuations during the last 2000 years. However, since this plot is a fair representation of the range of reconstructions appearing in the published scientific literature, it is likely that such reconstructions, accurate or not, will play a significant role in the ongoing discussions of global climate change and global warming.

For each reconstruction, the raw data has been decadally smoothed with a σ = 5 yr Gaussian weighted moving average. Also, each reconstruction was adjusted so that its mean matched the mean of the instrumental record during the period of overlap. The variance (i.e. the scale of fluctuations) was not adjusted (except in one case noted below).

Except as noted below, all original data for this comparison comes from [1] and links therein. It should also be noted that scientific challenges to methodology and data used in several of the references have been substantiated and reconstructions of past climate report substantial error bars, which are not represented on this figure.

Reconstructions[edit]

The reconstructions used, in order from oldest to most recent publication are:

  • (dark blue 1000–1991): P.D. Jones, K.R. Briffa, T.P. Barnett, and S.F.B. Tett (1998). "High-resolution Palaeoclimatic Records for the last Millennium: Interpretation, Integration and Comparison with General Circulation Model Control-run Temperatures". The Holocene 8: 455–471. doi:10.1191/095968398667194956
  • (blue 1000–1980): M.E. Mann, R.S. Bradley, and M.K. Hughes (1999). "Northern Hemisphere Temperatures During the Past Millennium: Inferences, Uncertainties, and Limitations". Geophysical Research Letters 26 (6): 759–762.
  • (light blue 1000–1965): Crowley and Lowery (2000). "Northern Hemisphere Temperature Reconstruction". Ambio 29: 51-54. Modified as published in Crowley (2000). "Causes of Climate Change Over the Past 1000 Years". Science 289: 270–277. doi:10.1126/science.289.5477.270
  • (lightest blue 1402–1960): K.R. Briffa, T.J. Osborn, F.H. Schweingruber, I.C. Harris, P.D. Jones, S.G. Shiyatov, S.G. and E.A. Vaganov (2001). "Low-frequency temperature variations from a northern tree-ring density network". J. Geophys. Res. 106: 2929–2941.
  • (light turquoise 831–1992): J. Esper, E.R. Cook, and F.H. Schweingruber (2002). "Low-Frequency Signals in Long Tree-Ring Chronologies for Reconstructing Past Temperature Variability". Science 295 (5563): 2250–2253. doi:10.1126/science.1066208.
  • (green 200–1980): M.E. Mann and P.D. Jones (2003). "Global Surface Temperatures over the Past Two Millennia". Geophysical Research Letters 30 (15): 1820. doi:10.1029/2003GL017814.
  • (yellow 200–1995): P.D. Jones and M.E. Mann (2004). "Climate Over Past Millennia". Reviews of Geophysics 42: RG2002. doi:10.1029/2003RG000143
  • (orange 1500–1980): S. Huang (2004). "Merging Information from Different Resources for New Insights into Climate Change in the Past and Future". Geophys. Res Lett. 31: L13205. doi:10.1029/2004GL019781
  • (red 1–1979): A. Moberg, D.M. Sonechkin, K. Holmgren, N.M. Datsenko and W. Karlén (2005). "Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data". Nature 443: 613–617. doi:10.1038/nature03265
  • (dark red 1600–1990): J.H. Oerlemans (2005). "Extracting a Climate Signal from 169 Glacier Records". Science 308: 675–677. doi:10.1126/science.1107046

Copyright[edit]

The original version of this figure was prepared by Robert A. Rohde from publicly available data, and is incorporated into the Global Warming Art project.

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Notes[edit]

  1. Data from Moberg et al. was taken directly from the supplemental information accompanying the Nature article.
  2. Data for Oerlemans was provided by William M. Connolley.
  3. Esper et al. reported only fluctuations in "arbitrary" units, so the variance in this record was rescaled to match the variance during the period of overlap with the instrumental record.
  4. When a paper included multiple reconstructions, the global annually average temperature data was used. If this was not reported, then Northern Hemisphere annually averaged data was used.
  5. Four records appearing at [3] were not used in preparing this graph for the following reasons:
    1. Mann et al. 98 was not included because Mann et al. 99 extended and updated that record.
    2. Briffa et al. 98 was not included because Briffa et al. 2001 extended and updated that record.
    3. Pollack et al. 98 was not included because the reported data was not found to be in a form that allowed for easy replotting.
    4. Mann et al. 2000 was not used because it did not include an original reconstruction covering at least the Northern Hemisphere.

External references[edit]


Dragons flight's Temperature Record Series
This figure is part of a series of plots created by Dragons flight to illustrate
changes in Earth's temperature and climate across many different time scales.
Time Period: 25 yrs | 150 yrs | 1 kyr | 2 kyr | 12 kyr | 450 kyr | 5 Myr | 65 Myr | 500 Myr
For articles related to this topic see: Temperature record

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Date/TimeThumbnailDimensionsUserComment
current19:07, 27 May 2018Thumbnail for version as of 19:07, 27 May 20181,449 × 1,088 (316 KB)Dragons flight (talk | contribs)Same material but the instrumental time series is continued to 2016.
22:51, 17 December 2005Thumbnail for version as of 22:51, 17 December 2005600 × 443 (39 KB)Saperaud~commonswiki (talk | contribs)*'''Description:''' [[en:Image:{{subst:PAGENAME}}]]
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