Global warming & CA's Water system

[Tim Bousquet <chicoexaminer@xxxxxxxxx>]

Does anyone know anything about these scientists? Are
their projections credible, or is this a ploy to
justify the building of more dams, relaxation of
environmental regulations, etc., or both?

Tim

Global warming may ruin state water system, scientists
say
San Jose Mercury News - 6/21/01
By Frank Sweeney, staff writer

LOS ANGELES -- Within 60 years, global warming could
wreak havoc with California's delicate water system,
drying up the supply for millions of people and
limiting protection from the natural extremes of flood

and drought, scientists warned Wednesday.

Warmer temperatures would shrink the annual Sierra
snowpack, throwing off the seasonal flow of water
through the state's gargantuan network of dams and
canals.

``More rain, less snow, earlier runoff, earlier
depletion of the snowpack,'' said Dan Cayan, director
of the climate research division at Scripps
Institution of Oceanography in La Jolla.

Cayan and others discussed the potentially grim
scenario at a meeting
of the State Water Advisory Committee, a 60-member
panel helping the
state Department of Water Resources devise a new
master plan for
California's plumbing system.

This was the first time the state's water planners
felt the need to consider the disruption that climate
change could cause to the state's economy and people.

Half of the Sierra Nevada snowpack, which provides
drinking water for two-thirds of California's
residents and irrigates millions of acres
of farmland, could disappear by the end of this
century, the experts
said.

The potential effects are staggering. It could mean
declining water
supplies and hydropower production. The threat of
major floods could
increase as rainfall runoff rushes down the mountains
early in winter
to overwhelm dams and reservoirs rather than being
locked up in snow
to melt and flow down slopes in a slower, more orderly
way later in
spring and summer.

Over the past century, California has invested
billions of dollars in
huge control systems that store and deliver water
nearly the length
of the state, from the Northern Sierra to arid
Southern California,
where a majority of the state's residents live. Santa
Clara County
gets half of its water from the Sacramento-San Joaquin
River Delta,
which is fed by Sierra snowmelt.

Water agencies should look at their systems now ``to
see how
vulnerable they are to climate change,'' said Maurice
Roos, chief
hydrologist for the state Department of Water
Resources. Although
precipitation prediction models are not very reliable,
he said,
``warmer would mean more evaporation and more
precipitation. If
warming occurs, one thing is sure -- the snow levels
in the mountains
will rise and the snowpack will decrease.''

A 4-degree Fahrenheit average temperature increase --
the high end of
the range that scientists say could result this
century from global
warming -- would push snow levels about 1,500 feet
higher, to about
4,500 feet in the northern Sierra, which feeds the
Sacramento River,
and to 6,000 feet in the southern Sierra, where the
peaks are higher
but the snowpack smaller, Roos said.

In the Sacramento River system, Roos said, ``Only a
quarter of our
current snowpack would remain.''

Overall runoff from Pacific storms probably would be
much the same as
today, but much more of it would be in the form of
rain earlier in
winter, which could trigger much greater floods than
the Central
Valley has experienced in the past century, Roos said.

All of which leaves water managers in a classic bind:
If they operate
their dams to catch this water rushing toward the sea
instead of
being locked up in the snowpack early in winter, they
will have less
room in their reservoirs to capture floodwaters later
in spring that
might inundate downstream regions.

``There's a very strong consensus that climate change
is here, and
some of it may be unavoidable no matter what we do,''
said Peter
Gleick, president of the Pacific Institute for Studies
in
Development, Environment and Security in Oakland. ``We
better start
thinking about dealing with the impacts.''

Gleick called on water agencies to begin a
``systematic
re-examination of engineering designs, operating
rules, contingency
plans and water allocation policies. The past is no
longer a good
guide to the future,'' he said. Flood risk, for
example, might be
reduced if the systems are operated differently.

``It's too early in the learning curve to deal with
possible
solutions,'' said Jonas Minton, deputy director of the
state water
department. And the ability to operate water projects
``is very
highly constrained'' by environmental laws, flood
control
requirements and a host of other regulations.

``The system is currently so inflexible to deal with
this,'' Minton
said, that rules will have to be changed. ``We're not
jumping to any
conclusions, but we have to think about the potential
impacts,'' he
said. ``We do not have any expectation of quick
answers.''

Cayan, the Scripps scientist, said the Earth's
atmospheric
temperature is expected to rise 2 to 4 degrees
Fahrenheit over the
next century ``because of the overwhelming impact of
what man has
done to the atmosphere.'' Natural fluctuations on top
of that, such
as El Niño, he added, ``could be the straw that breaks
the camel's
back, when we really notice change.''#



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