Dwa tysiące lat średniej temperatury powierzchni według różnych rekonstrukcji, każda zaokrąglona do skali dekadowej. Niezaokrąglona wartość za rok 2004 również oznaczona dla porównania. Na osi pionowej anomalia temperatury.
Expansion of the last 1000 years Temperature variations during the preceding 12000 years. Note that present day is placed at the left hand side This image is a comparison of 10 different published reconstructions of mean temperature 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 when they are historically believed to occur, though it is still disputed whether these were truly global or only 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 many reconstructions of past climate report substantial error bars, which are not represented on this figure. Reconstructions The reconstructions used, in order from oldest to most recent publication are: (dark blue 1000-1991): Error: journal= not stated. (blue 1000-1980): Error: journal= not stated. (light blue 1000-1965): Error: journal= not stated. Modified as published in Error: journal= not stated. (lightest blue 1402-1960): Error: journal= not stated. (light green 831-1992): Error: journal= not stated. (yellow 200-1980): Error: journal= not stated. doi:10.1029/2003GL017814. (orange 200-1995): Error: journal= not stated. doi:10.1029/2003RG000143 (red-orange 1500-1980): Error: journal= not stated. doi:10.1029/2004GL019781 (red 1-1979): Error: journal= not stated. doi:10.1038/nature03265 (dark red 1600-1990): Error: journal= not stated. doi:10.1126/science.1107046 (black 1856-2004): Instrumental data was jointly compiled by the w:Climatic Research Unit and the UK Meteorological Office Hadley Centre. Global Annual Average data set TaveGL2v [2] was used. Documentation for the most recent update of the CRU/Hadley instrumental data set appears in: Error: journal= not stated.