Monday, October 29th 2012, 6:15 AM EDT
Figure 5. Temperature reconstructions created using the 650-tree (‘alltrw’ data) TRW chronology (a) and the 130 tree (‘S88G1112’ data) MXD chronology (b). Chronologies were created using two RCS curves and were regressed against the Bottenviken mean May–August monthly temperature over the period 1860 to 2006. The shaded areas show two standard errors (see SI15, available online, for details) plotted either side of the mean where standard errors were scaled to fit the temperature reconstruction.
The TRW and MXD temperature reconstructions of (a) and (b) are compared in (c) after they were normalised over the common period 600 to 2008 and smoothed with a 10 year spline. The lower two panels compare the reconstructions using the TRW chronology (d) and MXD chronology (e) with the mean of May to August monthly temperature from Bottenviken over the period 1860 to 2006.
Look at graph 5c, and you’ll see 20th century warmth matches peaks either side of the year 1000, and that for the TRW chronology 20th century warmth is less than the spike around 1750. This puts 20th century (up to 2006 actually) warmth in the category of just another blip. There’s no obvious hockey stick, and the MWP returns, though approximately equal to 20th century warmth rather than being warmer.
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