Re: We have had lessons about this park
Posted by Harold Ericsson on June 16, 2004 at 10:38:06:
In Reply to: Re: We have had lessons about this park posted by Owens lake dust pic 1 on June 15, 2004 at 16:46:36:
Pollution Shifting Rain Patterns in Sierra, Worldwide
By Don Thompson
The Associated Press
Thursday 10 June 2004
Sacramento - As he flew high above the snowy Sierra Nevada this
spring, atmospheric scientist Veerabhadran Ramanathan saw
confirmation of what he'd both hoped and feared to see: Big, dark
storm clouds that weren't producing any rain.
Air pollution appears to be altering rainfall patterns in the
Sierra and around the world, said Ramanathan of the Scripps
Institution of Oceanography in La Jolla.
It's the latest fallout from an exploding human population that
over the last half-century has pushed untold tons of smog, soot and
ash into the atmosphere, he said Thursday at the nation's first state-
sponsored global warming research program.
The vast sprawl of Los Angeles, with its millions of cars pumping
greenhouse gases into the air, are in effect driving away the very
rainfall its population needs to survive as pollution forces rain to
fall outside the state. Instead of accumulating as snow in
California's Sierra, a smaller amount lands in neighboring Nevada.
Ramanathan co-led a 1999 study that reported the existence of a
vast "brown cloud" of pollution, dust and chemicals that he believes
is slowing solar evaporation from the oceans and leading to a net
reduction in world rainfall.
It's part of a band of pollution encircling the globe, helping
produce a 10-20 percent reduction in the amount of sunlight reaching
the earth over the last 50 years. The phenomenon cools the earth's
surface, but heats the middle atmosphere.
Minuscule flecks of black carbon make up perhaps only 10 percent
of the pollution cloud, but play a dominant role in altering the way
the atmosphere behaves, Ramanathan said.
The dark particles absorb solar radiation and scatter sunlight,
helping produce that characteristic haze that today coats not only
cities like Los Angeles but once-pristine areas like Yosemite
National Park downwind.