The 20th century hydroclimatology of northwestern North America has been linked to naturally recurring large-scale climate patterns such as the Pacific Decadal Oscillation (PDO) and the El Niño-Southern
Oscillation (ENSO). Few observed hydroclimatic records from this region exceed in length the w60-year
periodicity of the lower frequency climate oscillations; however, tree-ring proxy data from semi-arid
western North America document natural hydroclimate variation over centennial to millennial scales.
We reconstructed the summer Palmer Drought Severity Index (PDSI) over the western Canadian Prairies,
providing a record of drought for the past 600 years.
