National Geographic: Snowpack-which essentially serves as a water tower for the western United States-produces vital meltwater that flows off the mountains each spring. Like a time-release capsule, snowpack refills streams and reservoirs and waters crops and cities through the dry summer in this largely semiarid region.
But the snowpack is becoming more like a snow gap, as temperatures in the Cascades and Sierra Nevada become too warm for the snow that replenishes the ecosystem each winter. Temperatures in the West...