September 23, 1998 USGCRP Seminar: "Depletion and Recovery of the Ozone Layer: An Update of the Scientific Understanding"

Tony Socci tsocci at
Thu Sep 17 11:06:50 EDT 1998

                U.S. Global Change Research Program Seminar Series

                   Depletion and Recovery of the Ozone Layer:
                   An Update of the Scientific Understanding

What are the current and projected trends in stratospheric ozone-depleting
chemicals in the atmosphere?  Has the Montreal Protocol been effective in
reducing ozone-depleting chemicals in the atmosphere?  How severe is ozone
depletion at present?  Will ozone depletion worsen before it gets better?
Is ozone depletion confined solely to high latitudes?  Will the ozone layer
recover to its natural state, and if so, when?  Are there likely to be
surprises along the way?

                                                       Public Invited

                              Wednesday, September 23, 1998, 3:15-4:45 PM
                 TEMPORARY LOCATION - Longworth House Office Bldg., Room 1539
                                                       Washington, DC

                                                   Reception Following


Dr. David Goodrich, Executive Director, U.S. Global Change Research Program
Coordination Office, Washington, DC


Dr. Daniel L. Albritton, Director, National Oceanic and Atmospheric
Administration Aeronomy Laboratory, Boulder, CO


            State-of-Science Update: The Stratospheric Ozone Layer

The forthcoming United Nations Environment Programme (UNEP)
report,"Scientific Assessment of Ozone Depletion: 1998"  will be the newest
in a series of assessments providing an update on the state of scientific
understanding of the Earth's ozone layer.  The key scientific points and
conclusions contained within this report's Executive Summary are listed
below.  These key points were established and agreed upon at a peer-review
meeting held in early June, 1998, of the full assessment report.  Over 250
scientists from around the world participated in the writing and review of
the 1998 report, which will go to press later this year and will be
available in early 1999.

   Key Points of UNEP's Scientific Assessment of Ozone Depletion: 1998

 The total tropospheric abundance of ozone-depleting gases peaked in 1994
and is now (slowly)
starting downward, giving direct evidence that the Montreal Protocol is

 The springtime Antarctic ozone hole continues unabated, with the extent
of Antarctic ozone depletion essentially unchanged since the early 1990s.

 In the Arctic, six of the past nine winters have been cold and
protracted.  As predicted in the 1994 assessment, those winters have seen
lower-than-usual ozone levels in the region.  Ozone has declined during
some months by 25-30% below the 1960s average.

 Over the middle latitudes of both the northern and southern hemispheres,
the decadal ozone decline has slowed since about 1991.  The understanding
of how changes in stratospheric chlorine/bromine and aerosol loading affect
ozone suggests some reasons why a linear extrapolation of the pre- 1991
ozone trend to the present is not suitable.

 Ozone losses in the stratosphere may have caused part of the observed
cooling of the lower stratosphere in the polar and upper middle latitudes
(about 0.6 ƒC per decade since 1979).

 The Ozone Depletion Potential (ODP) of methyl bromide is now calculated
to be 0.4 [compared to 0.6 from the previous (1994) assessment], with the
change being largely the result of the recognition and better
quantification of removal mechanisms in soils and oceans.

 In the stratosphere, the peak in the abundance of ozone-depleting gases
is expected before the year 2000, and the ozone layer will be in its most
vulnerable state for the next decade or two. Detection of the start of the
ozone layer recovery may not be possible for perhaps another 20 years, due
to natural ozone variability and changing atmospheric conditions.

 There are not many remaining options for substantially hastening the
return to a natural ozone layer. The largest of these options are
associated with potential action regarding the halons, which would
typically lower the sum of the ozone depletion over the next 50 years by a
few to several percent.  Non-adherence to the Montreal Protocol could also
add to future integrated ozone depletion.


Dr. Daniel L. Albritton has directed the Aeronomy Laboratory of NOAA's
Environmental Research Laboratories in Boulder, Colorado since 1986.  The
research of the Laboratory is focused on understanding the chemistry and
dynamics of the atmosphere.  Several key environmental phenomena are being
addressed: stratospheric ozone depletion, regional tropospheric chemistry,
tropospheric ozone production, tropical ocean/atmosphere interactions, and
the climate system.  The Laboratory is staffed with approximately 115
scientists, engineers, and support personnel.

Personal Research:  Dr. Albritton joined the Aeronomy Laboratory in 1967
and conducted research on the laboratory investigation of atmospheric
ion-molecule reactions and theoretical studies of diatomic molecular
structure.  In later years, his research interest has been the field
investigation of atmospheric trace-gas photochemistry.  He has published
approximately 150 papers in these areas, has contributed numerous invited
review papers, and has lectured worldwide on these subjects.

NOAA National and International Research Planning:  Dr. Albritton was one
of two coordinators of the drafting of the initial research plan for the
U.S. Global Change Research Program.  He has been a member of review and
steering groups for the National Academy of Sciences, other-Federal Agency
and private-sector programs, and international research efforts such as the
International Global Atmospheric Chemistry Program.  He is the Science
Vice-Chair of the Air Quality Research Subcommittee of the Committee on
Environment and Natural Resources.  He also leads the Atmospheric Chemistry
Project of NOAA's Climate and Global Change Program and NOAA's "Health of
the Atmosphere" regional air quality research program.

Scientific Assessments of the Stratospheric Ozone Layer:  Dr. Albritton
serves as Co-chair of the United Nations Environment Programme's Ozone
Science Assessment Panel.  In this capacity, he provides scientific
information to the United Nations Montreal Protocol on Substances that
Deplete the Ozone Layer.  He has often been called upon to describe this
science to other governmental and industrial organizations and to the
public. He has also testified frequently before Congress on this topic.

Scientific Assessments of the Climate System:  He has served as a Lead
Author on the Intergovernmental Panel on Climate Change (IPCC) scientific
assessment reports.  He has been invited by numerous organizations to
summarize the current scientific knowns and unknowns regarding the climate

Recognition and Awards:  Dr. Albritton is a Fellow of the American Physical
Society and of the American Geophysical Union.  He has served on the
Editorial Advisory Board of the Journal of Molecular Spectroscopy and the
Journal of Atmospheric Chemistry, as well as serving as editor of the
latter journal.  Dr. Albritton has received several awards and honors for
outstanding performance in NOAA, including two Department of Commerce Gold
Medal Awards and two Presidential Rank Awards.  For his role in leading
scientific assessments of stratospheric ozone depletion, he has received a
1992 Special Award from the American Meteorological Society, the 1993
Scientific Freedom and Responsibility Award from the American Association
for the Advancement of Science, the 1994 U.S. Environmental Protection
Agency Stratospheric Ozone Protection Award, and a 1995 U. N. Environment
Programme Ozone Award.

The Next Seminar is scheduled for Monday, October 12, 1998

Tentative Topic: Status of Global Fish Stocks: Causes and Consequences

For more information please contact:

Anthony D. Socci, Ph.D., U.S. Global Change Research Program Office, 400
Virginia Ave. SW, Suite 750, Washington, DC 20024; Telephone: (202)
314-2235; Fax: (202) 488-8681 E-Mail: TSOCCI at USGCRP.GOV.

Additional information on the U.S. Global Change Research Program (USGCRP)
and this Seminar Series is available on the USGCRP Home Page at:  A complete archive of seminar summaries can also be
found at this site.  Normally these seminars are held on the second Monday
of each month.

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