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Fig. 1


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A comparison of solar activity and northern hemisphere climate from AD 800 to AD 2016. Top: Sunspot number, from direct telescopic observations (black; Lockwood et al., 2014) and reconstructed on the basis of 14C concentrations in tree trunks (red, with pink 1-sigma uncertainty band; Usoskin et al., 2014). Taking a threshold smoothed sunspot number of 20 (dashed black line), the MM spans 1637–1719. Bottom: Northern hemisphere temperature anomaly, ΔT, (relative to the 1961–1990 mean) for paleoclimate reconstructions, as presented in the IPCC fifth assessment report (Masson-Delmotte et al., 2013). Colours, from white through red, show the probability density function (PDF), while the white line shows the PDF maximum value (or mode). The blue line shows ΔT from the instrumental record (HadCRUT4; Morice et al., 2012). All data have been smoothed using an 11 year running mean. Taking thresholds of ΔT = −0.25 K, −0.37 K and −0.55 K (dashed grey lines) defines LIAs, LIA1, LIA2 and LIA3, respectively.

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