Fig 1. Location and climate of the Callitris tree-ring site.

(a) Location of the Callitris site in the Pilbara region of northwest Australia; semi-arid and arid areas of Western Australia are shown in white; the temperate south-west and tropical north of Western Australia are shaded grey. (b) Long-term (1901–2012) mean monthly precipitation (bars) and maximum temperature (line) of the northwest region (i.e., CRU version 3.22 data area-averaged over 117–122°E, 21–26°S, see methods for details). (c) The tree ring site; a shallow, south-facing gully in the Hamersley Range. Dark green/grey trees visible in the centre of the image are Callitris columellaris, lighter-coloured trees are Eucalyptus leucophloia, and grasses in foreground and along the slopes are predominantly Triodia spp.