Scientists Iris Stewart and colleagues examined snowmelt in western North American streams and suggest that climate fluctuations are driving changes in the timing of snowmelt, which is increasingly becoming triggered earlier in the season.

• Stewart, Iris T et al. "Changes Toward Earlier Streamflow Timing Across Western North America." Journal of Climate 18(8): 1136–1155. April 2005 at ams.allenpress.com/amsonline/?request=get-toc&issn=1520-0442&volume=18&issue=8

The scientists examined streamflow from 1948 through 2002 for more than 300 stream systems and provide evidence that the early onset of snowmelt is characteristic of a much larger portion of the region's streams than initially anticipated. Of the snowmelt-dominated gauges, which totaled 241 in number, two-thirds had an early spring onset date of more than three days.

Implications: Snowmelt supplies water to western North American rivers and will impact many communities (e.g. drinking water availability, hydroelectric utilities, and agricultural lands will be affected) and ecosystems that rely on these water sources. Early melting may lead not only to increased intensity of spring-time flooding, but also of summer droughts when meltwater is not available at all.