"The Arctic will retain its power to amaze for a long time. Yet it is now changing beyond the usual regional and annual variations in sea-ice formation, glacier melt and so forth. The Arctic is clearly melting. Its floating ice cap is shrinking and thinning and its glaciers are retreating. By the end of this century, maybe much sooner, there will be frequent Arctic summers with almost no sea...
Temperature Anomalies Index 1400-1980 for Northern Hemisphere Average Temperature
Figure 7. Temperature anomalies index (deg C) 1400-1980 for Northern Hemisphere average temperature construction from (top) Mann et. al. (1998); and (bottom) based on this work using corrected and updated data as outlined in text.
This is a supporting graph from the study that casts doubt on the "Mann Hockey Stick".
"The data set of proxies of past climate used in Mann, Bradley and Hughes (1998, "MBH98" hereafter) for the estimation of temperatures from 1400 to 1980 contains collation errors, unjustifiable truncation or extrapolation of source data, obsolete data, geographical location errors, incorrect calculation of principal components and other quality control defects. We detail these errors and defects. We then apply MBH98 methodology to the construction of a Northern Hemisphere average temperature index for the 1400-1980 period, using corrected and updated source data. The major finding is that the values in the early 15th century exceed any values in the 20th century. The particular "hockey stick" shape derived in the MBH98 proxy construction - a temperature index that decreases slightly between the early 15th century and early 20th century and then increases dramatically up to 1980 - is primarily an artifact of poor data handling, obsolete data and incorrect calculation of principal components."
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