Dust Storms, Snowpack and the American West
June 10, 2013
Jason Neff
According to a new study from CU-Boulder, there's a lot more dust being
blown across the landscape now than a few decades ago. Increasing dust
storms can have a number of negative impacts. When dust blows on an
existing snowpack, for example, the dark particles better absorb the sun's
energy and cause the snowpack to melt more quickly, says CU-Boulder's
Jason Neff, associate professor of geology and coauthor of the study.
CUT 1 “On average, the dust is accelerating snowpack by somewhere between
two weeks and a month. So it’s a really substantial change. (:09) It exposes
the ground more, it reduces the amount of water that actually makes it to the
Colorado River drainage. It changes the timing of the snowmelt, so you get a
bigger pulse off the mountains early in the season, which then means you
have to mange the water differently.” (:24)
The amount of dust — which may be due to the interplay of several factors,
including increased dust storm activity in the desert southwest, drought cycles
and changing land use patterns – has increased over the last 17 years, says
Neff
CUT 2 “What we know is that there are a lot of dust storms, and if you ask
people in Colorado, especially on the Western Slope, if you ask people in
Utah or Arizona, what you’ll often here is them say is, ‘Yeah, I did grow up in
this area. I don’t remember it ever being like this before.’ And now, all of a
sudden, there are all these dust storms.” (:19)
Hearing that there were more dust storms is one thing, says Neff, but
knowing how much of an increase of dust in the air was another matter.
That’s because dust has not been routinely measured over long periods of
time. They needed another way to measure for dust. So they looked at
decades of records from the National Atmospheric Deposition Program - a
program that analyzes rainfall to better understand acid rain.
CUT 3 “When we don’t have a direct measurement of the dust then we look
for what we call proxy measurements — something that comes from the dust
but is not the actual dust itself. (:09) What we found is calcium in rainfall.
What you find out is that most of that calcium around here is coming from
soils. (17) And so, if we see that calcium in the rainfall then we can pretty
reasonably or safely assume that that calcium is coming from soil that’s been
blown into the air and become dust.“ (:29)
And Neff says the escalation in dust emissions has implications both for the
areas where the dust is first picked up by the winds and for the places where
the dust is put back down.
CUT 4 “What happens when you make dust is basically you’re losing surface soils
— you’re losing topsoil. And that topsoil is what contains a lot of the nutrients that
support plant growth. It’s more of a problem in the deserts where the erosion
occurs. (:12) There’s a flip side, which is that all those nutrients then travel up into
the mountains, and they functionally fertilize the soils. (:19) It’s one of the reasons
we have beautiful alpine flowers now today in Colorado.” (:26)
Neff says the majority of the large dust storm events happen in the spring – March,
April and May are the times when the state get’s huge deposits of dust.
-CU-