Lake sediment pore water has been proposed as a noble gas archive for paleoenvironmental reconstruction, but appropriate experimental techniques have not been available until recently. Here we present noble gas concentrations measured in the sediment pore water of Lake Issyk-Kul (Kyrgyzstan) which demonstrate for the first time the value of the sediment pore water archive for paleoclimate reconstruction. The noble gas profiles in the sediment indicate that the salinity of the lake water during the mid-Holocene was more than twice its present value of 6.0 g/kg, implying a 200-m lower lake level.