Fig. 4 – Expanded plot of a short section of the GISP2 ice core laser-light scattering data (light line). The dark line, which corresponds to a four-year running average of the data, shows five complete dust modulation cycles that have an average period of ~11 years. Similar modulations are present throughout the GISP2 ice core dust record. These modulations are attributed to the solar cycle. Taken from Ram et al. (1997).