http://www.clim-past.net/8/765/2012/cp-8-765-2012.pdfThe corresponding
95% confidence intervals have widths of 0.6 (two millennia
long reconstruction) and 0.4 C (500-yr long reconstruction)
for 50-yr smoothed values, thereby showing
that the residual noise-variance is relatively small compared
to the reconstructed low-frequency signal.
Our main conclusions are as follows.
– Our reconstructions indicate – in agreement with the
results of Moberg et al. (2005); Ljungqvist (2010), and
Loehle and McCulloch (2008) – that the first millennium
AD was generally significantly warmer than the
second millennium AD. The 17th century was the coldest
century during the last two millennia and most of
the LIA seems to have been colder than during the Dark
Age Cold Period ca. 300–800 AD. In general, our LOC
reconstructions show larger low-frequency variability
than previous reconstructions.
– Our two-millennia long reconstruction has a well defined
peak in the period 950–1050AD with a maximum
temperature anomaly of 0.6 C. The timing of
the peak of the MWP in our reconstruction is in agreement
with the reconstructions of Esper et al. (2002a)
and Ljungqvist (2010). The reconstructions of
Mann et al. (2008, 2009) show a longer peak warming
covering the whole period 950–1100 AD, and the reconstruction
of Moberg et al. (2005) shows a somewhat
later as well as longer peak MWP warming than in the
present paper. The level of warmth during the peak
of the MWP in the second half of the 10th century,
equalling or slightly exceeding the mid-20th century
warming, is in agreement with the results from other
more recent large-scale multi-proxy temperature reconstructions
by Moberg et al. (2005), Mann et al. (2008,
2009), Ljungqvist (2010), and Ljungqvist et al. (2012).