Figure 3: Many groundwater hydro-refugia persist through even precessional orbital climate cycles.

Modelled frequency of springs that are still active (that is, flow rate still above 1,000 m³ y⁻¹) at the driest part of climate changes over a range of timescales under gradual or sudden boundary condition changes (ENSO—El Nino—Southern Oscillation; IOD—Indian Ocean Dipole; DO—Dansgaard–Oeschger). Recharge is assumed to vary between the modern day value to a minimum value of 1 mm y⁻¹. Sensitivity of persistence to the recharge occurring at the driest point in a climate cycle is explored in Supplementary Fig. 1.