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Mysteries
of ozone depletion continue 25 years after the discovery of the Antarctic ozone
hole
DENVER, Aug. 29, 2011 — Even
after many decades of studying ozone and its loss from our atmosphere miles
above the Earth, plenty of mysteries and surprises remain, including an
unexpected loss of ozone over the Arctic this past winter, an authority on the
topic said here today. She also discussed chemistry and climate change,
including some proposed ideas to “geoengineer” the Earth’s climate to slow
down or reverse global warming. The talk happened at the 242nd
National Meeting & Exposition of the American Chemical Society (ACS), being
held this week.
In a Kavli Foundation Innovations
in Chemistry Lecture, Susan Solomon, Ph.D., of the University of Colorado,
Boulder, said that the combined efforts of scientists, the public, industry and
policy makers to stop ozone depletion is one of science’s greatest success
stories, but unanswered questions remain. And ozone is still disappearing.
“We’re no longer producing
the primary chemicals — chlorofluorocarbons (CFCs) — that caused the
problem, but CFCs have very long lifetimes in our atmosphere, and so we’ll
have ozone depletion for several more decades,” said Solomon. “There are
still some remarkable mysteries regarding exactly how these chlorine compounds
behave in Antarctica — and it’s amazing that we still have much to learn,
even after studying ozone for so long.”
The ozone layer is crucial to
life on Earth, forming a protective shield high in the atmosphere that blocks
potentially harmful ultraviolet rays in sunlight. Scientists have known since
1930 that ozone forms and decomposes through chemical processes. The first hints
that human activity threatened the ozone layer emerged in the 1970s, and
included one warning from Paul Crutzen, Ph.D., that agricultural fertilizers
might reduce ozone levels. Another hint was from F. Sherwood Rowland, Ph.D., and
Mario Molina, Ph.D., who described how CFCs in aerosol spray cans and other
products could destroy the ozone layer. The three shared a 1995 Nobel Prize in
Chemistry for that research. In 1985, British scientists discovered a
“hole,” a completely unexpected area of intense ozone depletion over
Antarctica. Solomon’s 1986 expedition to Antarctica provided some of the
clinching evidence that underpinned a global ban on CFCs and certain other
ozone-depleting gases.
Evidence suggests that the ozone
depletion has stopped getting worse. “Ozone can be thought of as a patient in
remission, but it’s too early to declare recovery,” said Solomon. And
surprises, such as last winter’s loss of 40% of the ozone over the Arctic
still occur due to the extremely long lifetimes of ozone-destroying substances
released years ago before the ban.
Solomon also took listeners on a
tour of gases and aerosols that affect climate change and described how these
substances can contribute to global warming.
“On the thousand-year
timescale, carbon dioxide is by far the most important greenhouse gas produced
by humans, but there are some other interesting — though much less abundant
— gases such as perfluorinated compounds that also last thousands of years and
similarly affect our climate for millennia,” said Solomon.
Increases in atmospheric
“greenhouse gases” such as carbon dioxide trap heat in the atmosphere,
causing the Earth’s temperature to creep upward. Global warming is causing
ocean levels to rise and could lead some regions to become dry “dust bowls.”
Dealing with global warming has
prompted a lot of interesting research on how to reduce greenhouse gas
emissions, how to adapt to a changing climate and on the possibility of
‘geoengineering’ to cool the climate.
“Recent studies on
‘geoengineering’ the Earth’s climate involve stratospheric particles of
different sorts,” she said. “Most of these schemes involve sulfate
particles, but other types have been proposed.”
The talk took place on Monday,
August 29, from 5:30 to 6:30 p.m., Mountain time in the Wells Fargo Theater at
the Colorado Convention Center.
Sponsored by The Kavli
Foundation, a philanthropic organization that supports basic scientific
research, the lectures are designed to address the urgent need for vigorous,
“outside the box” thinking by scientists as they tackle the world’s
mounting challenges, including climate change, emerging diseases, and water and
energy shortages.
“We are dedicated to advancing
science for the benefit of humanity, promoting public understanding of
scientific research, and supporting scientists and their work,” said Kavli
Foundation President Robert W. Conn in a statement. “The Kavli Foundation
Innovations in Chemistry Lecture program at the ACS national meetings fits
perfectly with our commitment to support groundbreaking discovery and promote
public understanding.”
The Kavli lectures debuted at the
Anaheim meeting in March during this
International
Year of Chemistry and will continue through 2013. They will address the
urgent need for vigorous, new, “outside-the-box”- thinking, as scientists
tackle many of the world’s mounting challenges like climate change, emerging
diseases, and water and energy shortages. The
Kavli Foundation,
an internationally recognized philanthropic organization known for its support
of basic scientific innovation, agreed to sponsor the lectures in conjunction
with ACS in 2010.
The
American Chemical Society is a nonprofit organization chartered by the U.S.
Congress. With more than 163,000 members, ACS is the world’s largest
scientific society and a global leader in providing access to chemistry-related
research through its multiple databases, peer-reviewed journals and scientific
conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.
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