PALEO PERSPECTIVES ON EXTREME CLIMATIC VARIABILITY IN THE MOUNTAINS OF
WESTERN NORTH AMERICA
GRAY, STEPHEN T. (1); BETANCOURT, JULIO L. (1); WOODHOUSE, CONNIE A. (2); MEKO,
DAVID M. (3) AND GRAUMLICH, LISA J. (4)
(1) USGS Desert Laboratory, Tucson, AZ 85745, (2) NOAA Paleoclimatology Program, Boulder,
CO 80305, (3) Laboratory of Tree-Ring Research, Univ. of Arizona, Tucson, AZ 85721, (4) Big
Sky Institute, Montana State Univ., Bozeman, MT 59717
Evidence from a growing network of paleoclimatic reconstructions emphasizes that strong,
persistent droughts- some outside the range of instrumental era events- are a common feature of
Western climate. On the other hand, extended wet periods that coincided with the economic and
social development of the West were, in some cases, anomalous events. Here we explore how
droughts and pluvials of the 20th century have shaped natural resource management and growth
in the region. We then use a combination of paleo archives to place the last 100 yrs in a longterm context, and explore how persistent hydroclimatic anomalies affect the structure and
function of natural systems. These results show that droughts and pluvials are likely to be a
primary driver of future environmental change. Widespread droughts and pluvial regimes can
also promote types of ecological and hydrologic change that may be difficult to predict using
current forecast methodologies. Overall, better knowledge of the geographic and temporal
aspects of extreme hydroclimatic variability must inform how we manage natural resources and
plan for the effects of global change.