Have
You Heard of "Global Dimming"?
If
you know of somebody who has not heard of the phrase “global warming,”
ask her how she keeps the world from intruding on her happiness.
The
flip side of global warming is “global dimming.”
On April 23, 2008, I caught a “Nova” documentary about global
dimming, on PBS station KOCE. According
to the documentary, there is evidence that particle pollution in the
Earth’s atmosphere is cutting sunlight up to 10%, turning clouds into
mirrors which reflect sunlight back into space.
Like global warming, global dimming can affect rainfall, creating
drought.
In
the early 21st century, it's become clear that air pollution can
significantly reduce the amount of sunlight reaching Earth, lower
temperatures, and mask the warming effects of greenhouse gases. Climate
researcher James Hansen estimates that "global dimming" is cooling
our planet by more than a degree Celsius (1.8°F) and fears that as we cut
back on the pollution that contributes to dimming, global warming may
escalate to a point of no return. Regrettably, in terms of possibly taking
corrective action, our current understanding of global dimming has been a
long time in the coming, considering the first hints of the phenomenon date
back to 18th-century observations of volcanic eruptions. In this slide show,
follow a series of historic events and scientific milestones that built the
case for global dimming. ....—Susan K. Lewis
From
http://www.pbs.org/wgbh/nova/sun/dimming.html.
If
you answer the multiple-choice questions below and e-mail to lessonanswers@mymontebello.com
with “Lesson answers” in the subject field, you will be credited toward
a “certificate of recognition in community affairs” to be awarded in
2008 by a local nonprofit organization.
1.
What is global dimming?
(a) Less sunlight
reaching the Earth.
(b) People using fewer
lights at night.
2. What should we do if
global dimming slows global warming?
(a) Pollute more, to
keep sunlight away from the Earth.
(b) Do the right thing:
reduce our carbon emissions quickly and dramatically.
July 3, 2008