Michael E. Mann, Raymond S. Bradley and Malcolm K. HughesComplete Scientific Reference
Summary:The Mann et al. reconstruction of annual northern hemisphere temperature is perhaps the most exhaustive and statistically rigorous reconstruction yet produced. Paleoclimate records from more than 100 sites were used. As in the work of Jones et al. (1998) and Overpeck et al. (1997), a "multi-proxy" approach (in this case using ice cores, corals, tree rings, historical records, and long instrumental records) was used which allowed the research team to make sure their results were not biased by potential problems with any one proxy source.
Mann et al. also investigated the role of different hypothesized climate forcing mechanisms in influencing hemispheric temperatures through time. They conclude that variations in the sun, volcanic eruptions, and human-induced increases of greenhouses gases (CO2 in particular) all played a role in generating the observed patterns of climate change over the last 600 years. They also conclude that greenhouse gases were the dominant forcing during the 20th century.
As with other state-of-the-art temperature reconstructions published in the last couple of years, the Mann et al. reconstruction indicates that the 20th century is the warmest of the last 600 years, and that 1998 is the warmest year of the last 600 years. This research has been updated in Mann et al 1999. Expanded reconstructions of Northern Hemispere temperature strongly suggest that the 1990s were the warmest decade and 1998 the warmest year of the past millennium.
Proxy records do not extend to the present day; for this reason the red star (located on the graph) marks approximate 1999 Northern Hemisphere Temperature.
For larger viewing version of graph, please click here or on the graph.
Year by year maps of reconstructed climates have been produced for the last 260 years. The maps were produced for a scientific paper by Mann et al., 1998. Click here for complete scientific reference. To view animated maps of climate reconstructions, click here.
Link to Mann Data and FTP information...
Link to Mann et al 99 Data and FTP information...
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