Figure 4

Variations in four of the longest tree-ring reconstructions of summer temperature. The reconstructions are for northern Fennoscandia (April to August; thick line, Briffa et al., 1992a; thin line, Briffa et al., 1990), northern Urals (May to September, thick line, Briffa et al., 1995; June to July, thin line, Graybill and Shiyatov, 1992), Tasmania (November to April; Cook et al., 1992), and northern Patagonia (December to February; thick line (Rio Alerce, Argentina), Villalba, 1990; thin line (Lenca, Chile), Lara and Villalba, 1993). Variations are shown in degrees Celsius after application of a 20-year low-pass filter (upper panel) and a 100-year low-pass filter (lower panel). For all series the zero line is 1901 to 1960.