The role of the sun on Earth's climate variability is still much debated. Here we present an ice core oxygen isotope record from the continental Siberian Altai, serving as a high-resolution temperature proxy for the last 750 years. The strong correlation between reconstructed temperature and solar activity suggests solar forcing as a main driver for temperature variations during the period 1250–1850 in this region. The precisely dated record allowed for the identification of a 10–30 year lag between solar forcing and temperature response, underlining the importance of indirect sun-climate mechanisms involving ocean-induced changes in atmospheric circulation. Solar contribution to temperature change became less important during industrial period 1850–2000 in the Altai region.