Climate variability and sustained change presage far-reaching transformations across America’s West, an expanse dominated
by immense mountain ranges and interspersed with important urban centers. These mountains provide the region’s life
blood—water that courses through its streams and runs out its faucets, power that fuels its industries and lights its cities, and
natural resources that feed its economy and provide many of its jobs. The West is a land where life is written in water—from
vast ranchlands and farmlands, to large densely populated urban areas—and the communities of the West are intricately tied
to it.
Why should we be concerned about how climate change is affecting the mountains? Despite their imposing grandeur and
apparent fortitude, the mountains contain highly sensitive environments that support delicately balanced physical and
natural systems. A warming of only a few degrees has major implications for mountain regions—for the integrity of the
seasonal snowpack, the extensive forests that western mountains support, and for the people who make their home
there. Such changes are already affecting water supply, energy availability, fire severity, and recreational opportunities.
Continuing climate change may significantly alter the western landscape, where one encounters distinct ecological
communities as successive layers from the lowlands to the high peaks. Each of these ecosystems has specific requirements
for temperature and precipitation. As climate variability increases and global warming continues, complex changes in
montane plant and animal communities will occur, increasing vulnerability of species to dramatic shifts in distribution and
local extinctions.
