million people will live in Washington, Oregon, Idaho, and Montana.
That is like adding another state the current size of Oregon, or moving
everyone in the cities of Chicago and San Francisco to the Pacific
Northwest even as the water supply continues to shrink.
Looking at his figures, Mote notes that from 1950 through 1992,
the amount of water contained in snowpack fell steadily throughout
the region. All but four of the 145 sites studied had less water in its
snowpack, as measured on April 1 of each year. Most declined by at
least one-quarter. Nine sites—eight in Oregon and one at Hurricane
Ridge on Washington’s Olympic Peninsula—had a drop of 60 percent
or more. Notably, all of this happened by 1992—before the globe espe-
cially heated up. The 1990s became the warmest decade of the millen-
nium, and 1998, 2001, and 2002 were three of the hottest years ever
recorded, according to the Pew Center on Global Climate Change. But
Mote’s snowpack study stops at 1992.
Most of the decline Mote saw traces to higher temperatures that
cause the snowpack to melt earlier. At the nine sites with the sharpest
decreases, the cause was a combination of rising temperatures and
declining precipitation. “The losses generally decrease with elevation,
especially in the Cascades, which is consistent with a temperature
effect,” says Mote, who later presented his findings at the American
Meteorological Society’s annual meeting in Long Beach, California.
“The way that I would portray it is that over the observed period, we
have gradually shifted from a fully natural climate regime to one in
which humans have a growing influence. That’s why we can say that
this decline in snowpack points the direction to where we’re headed—
giving us a glimpse of where we’re headed.”
But there is more bad news. Not only is snow drier. Not only are
glaciers shrinking. An even bigger impact of a warming climate is this:
Expect less snow, more rain, with dangerous disruptions of the water
supply. Less snow will fall in the first place, and higher temperatures
will turn more of that precipitation into rain. Winter rains will melt
more accumulated snow earlier in the season, aggravating flooding
and affecting drinking water supplies, as well as having a profound
economic impact on ski resorts and other snow-dependent businesses.
148 Sally Deneen