Fig. 4.

δ¹³C (‰) contour maps for the Last Glacial Maximum (LGM) (A and B) and the mid-Holocene (C and D), together with modern mean annual precipitation (A and C) and temperature (B and D) over 51 y (1951–2001). The contour maps were constructed using δ¹³C data from the 21 sites in this study (solid circles; Figs. 1 and 2) and four additional sites in Liu et al. (14) (solid triangles; Fig. 1). All of the δ¹³C data used in this paper were obtained from the same laboratory by identical methods, thereby minimizing interlaboratory variability.