Figure 1

(a) Millennial-scale variation of precession index (blue), obliquity (red), and eccentricity (black) between 31 ka BP and 1 ka AP. (b) Solar insolation (W m⁻²) in July at 15°N (orange) and 65°N (red) between 31 ka BP and 1 ka AP. Isotope changes in the collected proxy records listed in Table in (c) 5 ka BP compared with 10 ka BP and (d) 27 ka BP compared with 32 ka BP (see identification in the “Materials” section). Red circles (black dots) correspond to the wet-to-dry (dry-to-wet) changes. Green contour lines denote that the climatological mean summer (May–September) precipitation is equal to 1 mm day⁻¹ in 1 ka AP. Monsoon precipitation is also marked by shadings, identified when local summer precipitation is larger than 1 mm day⁻¹ and exceeds 55% of annual total (similar to identification in Wang, et al.⁴⁷). The software GrADS Version 2.1.1.b0 (http://cola.gmu.edu/grads/grads.php) was used to generate the figure.