SW-NCA-color-FINALweb

90 assessment of climate change in the southwest united statesand Brown 2001; Cook et al. 2004; Cook et al. 2009; MacDonald 2007; MacDonald andTingstad 2007), seasonal and annual precipitation (Grissino-Mayer 1996; Ni et al. 2002;Touchan et al. 2010), April 1 snow-water equivalent (Woodhouse 2003; Tingstad andMacDonald 2010; Pederson et al. 2011), as well as annual streamflow in many basins(see below). All of these reconstructions extend back at least 350 years, and some up to2,200 years. The annual paleodrought information from tree rings is complemented bycoarser-resolution information derived from oxygen isotopes in lake sediments (Benson1999; Anderson 2011), renewed movement of sand-dune fields (Muhs et al. 1997), lowstands of lakes (Stine 1994), and speleothems (Asmerom et al. 2007).Figure 5.8 History of drought in the West. Percent area affected by drought (PDSI