Hockey stick graph (global temperature)

Common card · No. 395755

Hockey stick graphs present global or hemispherical mean global surface temperatures of the distant past, as shown by quantitative climate reconstructions based on climate proxy records, in relation to instrumental temperature records which only go back to around 1850. These reconstructions have consistently shown a slow long term cooling trend changing into relatively rapid warming in the 20th century, with earlier temperatures exceeding the instrumental temperature record by 2000. The term hockey stick graph was popularized by the climatologist Jerry Mahlman, to describe the pattern shown by the Mann, Bradley & Hughes 1999 (MBH99) reconstruction, envisaging a graph that is relatively flat with a downward trend to 1900 as forming an ice hockey stick's "shaft" followed by a sharp, steady increase corresponding to the "blade" portion. The reconstructions have featured in Intergovernmental Panel on Climate Change (IPCC) reports as evidence of global warming. Arguments over the reconstructions...

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