Record stratospheric ozone loss in the arctic in spring of 2011
Record
stratospheric ozone loss in the arctic in spring of 2011
Geneva, 5 April
2011 GENEVA 5 APRIL 2011 (WMO) — Depletion of the ozone layer- the shield that
protects life on Earth from harmful levels of ultraviolet rays – has reached an
unprecedented level over the Arctic this spring because of the continuing
presence of ozone-depleting substances in the atmosphere and a very cold winter
in the stratosphere. The stratosphere is the second major layer of the Earth’s
atmosphere, just above the troposphere.
The record loss
is despite an international agreement which has been very successful in cutting
production and consumption of ozone destroying chemicals. Because of the long
atmospheric lifetimes of these compounds it will take several decades before
their concentrations are back down to pre-1980 levels, the target agreed in the
Montreal Protocol on Substances that Deplete the Ozone Layer.
Observations from
the ground and from balloons over the Arctic region as well as from satellites
show that the Arctic region has suffered an ozone column loss of about 40% from
the beginning of the winter to late March. The highest ozone loss previously
recorded was about 30% over the entire winter.
In Antarctica the
so-called ozone hole is an annually recurring winter/spring phenomenon due to
the existence of extremely low temperatures in the stratosphere. In the Arctic
the meteorological conditions vary much more from one year to the next and the
temperatures are always warmer than over Antarctica. Hence, some Arctic winters
experience almost no ozone loss, whereas cold stratospheric temperatures in the
Arctic lasting beyond the polar night can occasionally lead to substantial ozone
loss.
Even though this
Arctic winter was warmer than average at ground level, it was colder in the
stratosphere than for a normal Arctic winter.
This animation
shows, from 20 February until 4 April, the ozone abundance in the lower
stratosphere where ozone depletion is most intense. The smaller globe shows
values reached in a more common year (2010). One sees that this “ozone hole”
reached Scandinavia at the end of March .
The data comes from ECMWF and is generated for the European project MACC, in
which BIRA-IASB is in charge of the stratospheric ozone service. These results
combine several satellite instruments within a new “chemical weather” model
named IFS-MOZART and developed by ECMWF and the Jülich Research Centre. The 3-D
fields were then interpolated to the 470K isentropic level in order to follow
the vertical movements of the air masses in the lower stratosphere.
Unprecedented but not unexpected
Although the
degree of Arctic ozone destruction in 2011 is unprecedented, it is not
unexpected. Ozone scientists have foreseen that significant Arctic ozone loss is
possible in the case of a cold and stable Arctic stratospheric winter.
Stratospheric ozone depletion occurs over the polar regions when temperatures
drop below -78°C. At such low temperatures clouds form in the stratosphere.
Chemical reactions that convert innocuous reservoir gases (e.g. hydrochloric
acid) into active ozone depleting gases take place on the clouds particles. The
result is rapid destruction of ozone if sunlight is present.
Ozone depleting
substances such as chlorofluorocarbons (CFCs) and halons, once present in
refrigerators, spray cans and fire extinguishers, have been phased out under the
Montreal Protocol. Thanks to this international agreement, the ozone layer
outside the polar regions is projected to recover to its pre1980 levels around
2030-2040 according to the WMO/UNEP Scientific Assessment of Ozone Depletion
(see link below). In contrast, the springtime ozone layer over the Antarctic is
expected to recover around 2045-60, and in the Arctic it will probably recover
one or two decades earlier.
Without the
Montreal Protocol, this year’s ozone destruction would most likely have been
worse. The slow recovery of the ozone layer is due to the fact that
ozone-depleting substances stay in the atmosphere for several decades. In the
polar regions the drop in ozone depleting gases is 10% of what is required to
return to the 1980 benchmark level.
Global Atmosphere Watch
“The Arctic
stratosphere continues to be vulnerable to ozone destruction caused by
ozone-depleting substances linked to human activities,” said WMO
Secretary-General Michel Jarraud. “The degree of ozone loss experienced in any
particular winter depends on the meteorological conditions. The 2011 ozone loss
shows that we have to remain vigilant and keep a close eye on the situation in
the Arctic in the coming years,” he said.
“WMO’s Global
Atmosphere Watch Network has many stations in the Arctic and helps us to obtain
an early warning in case of low ozone and intense UV radiation.”
If the ozone
depleted area moves away from the pole and towards lower latitudes one can
expect increased ultraviolet (UV) radiation as compared to the normal for the
season. As the solar elevation at noon increases over the next weeks, regions
affected by the ozone depletion will experience higher than normal UV radiation.
The public is recommended to stay informed through national UV forecasts.
It should be
pointed out, however, that the UV radiation will not increase to the same
intensity as one suffers in the tropical regions of the globe. The sun is still
relatively low in the sky, and this limits the amount of UV radiation that
passes through the atmosphere.
UV-B rays have
been linked to skin cancer, cataracts and damage to the human immune system.
Some crops and forms of marine life can also suffer adverse effects.
Background
The stratosphere is the second major layer of the atmosphere, above the
troposphere and below the mesosphere. The stratosphere starts at about 10 km
altitude and reaches up to an altitude of about 50 km. About 90% of the ozone in
the atmosphere is found the stratosphere with the remaining 10% in the
troposphere. The ozone in the stratosphere is called the ozone layer, which
absorbs ultraviolet light and protects life on earth from harmful ultraviolet
radiation from the sun. The ozone in the troposphere, and especially close to
the ground, is unwanted because it is a corrosive gas that causes damage to
vegetation and can harm lung function and irritate the respiratory system in
humans and animals.
Increased
amounts of greenhouse gases lead to higher temperatures at the surface of the
earth, but models show that the stratosphere at the same time will get colder.
Therefore ozone scientists have foreseen that significant ozone loss can happen
in the Arctic stratosphere. If the cold temperatures persist into spring, i.e.
when the sun comes back after the polar night, ozone destruction speeds up. In
Antarctica such conditions prevail every winter/spring season, whereas in the
Arctic the variability from one year to the next is much larger. Large ozone
loss is therefore not an annually recurring phenomenon in the Arctic
stratosphere. While increased amounts of longlived greenhouse gases, such as
carbon dioxide and methane, are expected to cause some cooling of the
stratosphere in the long term, it cannot explain the large variations in
temperature that is observed from one year to the next in the Arctic
stratosphere.
Both
satellite observations and coordinated launches of ozonesondes carried by
weather balloons show us at which altitudes the ozone loss takes place. These
measurements show that the ozone loss takes place between 15 and 23 km above the
ground with an ozone minimum around 19-20 km. This coincides with the region of
low temperatures below -78°C. In this region more than 2/3 of the ozone has been
destroyed so far. Measurements from the SCIAMACHY satellite instrument show
record high amounts of the molecule OClO, a compound that takes part in ozone
destruction. Satellite measurements of total ozone from OMI, GOME-2 and
SCIAMACHY show a region of low ozone above the Arctic regions. As of late March
the ozone poor region is shifted away from the pole and covers Greenland and
Scandinavia.
The Vienna
Convention to Protect the Ozone Layer came into force in 1985. Two years later
the Montreal Protocol to phase out production and consumption of ozone-depleting
products was signed. The Montreal Protocol has been reinforced on several
occasions after 1987.
Images of
total ozone column and vertical ozone profiles around the pole on March 30,
developed by Finnish Meteorological Institute using satellite and ground based
data
The 2010
WMO/UNEP Scientific Assessment on Ozone Depletion is available at
http://www.esrl.noaa.gov/csd/assessments/ozone/
with more details about the current state of the ozone layer and projections for
the future.
For more
information, please contact:
Carine Richard-Van Maele, Chief,
Communications and Public Affairs, Tel: +(41 22) 730 8315;
Clare Nullis, Press Officer,
Communications and Public Affairs, Tel: +(41 22) 730 8478;
e-mail: cnullis[at]wmo.int
14 March
2011: Arctic on the verge of record ozone loss – Arctic-wide measurements
verify rapid depletion in recent days
Potsdam/Bremerhaven, March
14th, 2011. Unusually low temperatures in the Arctic ozone layer have
recently initiated massive ozone depletion. The Arctic appears to be heading for
a record loss of this trace gas that protects the Earth’s surface against
ultraviolet radiation from the sun. This result has been found by measurements
carried out by an international network of over 30 ozone sounding stations
spread all over the Arctic and Subarctic and coordinated by the Potsdam Research
Unit of the Alfred Wegener Institute for Polar and Marine Research in the
Helmholtz Association (AWI) in Germany.
“Our
measurements show that at the relevant altitudes about half of the ozone that
was present above the Arctic has been destroyed over the past weeks,” says AWI
researcher Markus Rex, describing the current situation. “Since the conditions
leading to this unusually rapid ozone depletion continue to prevail, we expect
further depletion to occur.” The changes observed at present may also have an
impact outside the thinly populated Arctic. Air masses exposed to ozone loss
above the Arctic tend to drift southwards later. Hence, due to reduced UV
protection by the severely thinned ozone layer, episodes of high UV intensity
may also occur in middle latitudes. “Special attention should thus be devoted to
sufficient UV protection in spring this year,” recommends Rex.
Ozone is lost
when breakdown products of anthropogenic chlorofluorocarbons (CFCs) are turned
into aggressive, ozone destroying substances during exposure to extremely cold
conditions. For several years now scientists have pointed to a
connection between ozone loss and climate change, and particularly to the fact
that in the Arctic stratosphere at about 20km altitude, where the ozone layer
is, the coldest winters seem to have been getting colder and leading to
larger ozone losses. “The current winter is a continuation of
this development, which may indeed be connected to global warming,” atmosphere
researcher Rex explains the connection that appears
paradoxical only at first glance. “To put it in a simplified manner,
increasing greenhouse gas concentrations retain the Earth’s thermal radiation at
lower layers of the atmosphere, thus heating up these layers. Less of the heat
radiation reaches the stratosphere, intensifying the cooling effect there.” This
cooling takes place in the ozone layer and can contribute to larger ozone
depletion. “However, the complicated details of the interactions between the
ozone layer and climate change haven’t been completely understood yet and are
the subject of current research projects,” states Rex. The European Union
finances this work in the RECONCILE project, a research programme supported with
3.5 million euros in which 16 research institutions from eight European
countries are working towards improved understanding of the Arctic ozone layer.
In the long
term the ozone layer will recover thanks to extensive environmental policy
measures enacted for its protection. This winter’s likely record-breaking ozone
loss does not alter this expectation. “By virtue of the long-term effect
of the Montreal Protocol, significant ozone destruction will
no longer occur during the second half of this century,” explains Rex. The
Montreal Protocol is an international treaty adopted under the UN umbrella in
1987 to protect the ozone layer and for all practical purposes bans the
production of ozone-depleting chlorofluorocarbons (CFCs) worldwide today. CFCs
released during prior decades however, will not vanish from the atmosphere until
many decades from now. Until that time the fate of the Arctic ozone layer
essentially depends on the temperature in the stratosphere at an altitude of
around 20 km and is thus linked to the development of earth’s climate.
Notes for
Editors:
Contacts at
Alfred Wegener Institute
Your contact
at the Potsdam Research Unit of the Alfred Wegener Institute is Dr Markus
Rex (tel.: +49 (0)174 311 8070, +49 (0)331 288 2127; e-mail:
Markus.Rex(at)awi.de). Your contact in the Communications and Media
Department is Ralf Röchert (tel: +49 (0)471 4831-1680; e-mail: [email protected]).
The Alfred
Wegener Institute conducts research in the Arctic, Antarctic and oceans of the
high and middle latitudes. It coordinates polar research in Germany and provides
major infrastructure to the international scientific community, such as the
research icebreaker Polarstern and stations in the Arctic and Antarctica. The
Alfred Wegener Institute is one of the seventeen research centres of the
Helmholtz Association, the largest scientific organisation in Germany.
This is a joint statement of the following institutions.
The persons mentioned in each case are also at your disposal
as contacts.
Belgium Hugo De Backer, Royal Meteorological Institute of
Belgium, +32 2 3730594, [email protected]
Canada Tom McElroy, Environment Canada, +1 416 739 4630,
Tom.McElroy(at)ec.gc.ca
David W. Tarasick, Air Quality Res. Div., Environ. Canada, +1 416 739-4623,
david.tarasick(at)ec.gc.ca
Kaley A. Walker, Univ. Toronto, Dep. of Physics, +1 416 978 8218,
kwalker(at)atmosp.physics.utoronto.ca
Czech Republic Karel Vanicek, Solar and Ozone Observatory, Czech Hydromet. Inst., +420
495260352,
vanicek(at)chmi.cz
Denmark Niels Larsen, Danish Climate Center, Danish Meteorological Institute,
+45-3915-7414,
nl(at)dmi.dk
Finland Rigel Kivi, Arctic Research Center, Finnish Meteorological Institute, +358
405424543,
rigel.kivi(at)fmi.fi
Esko Kyrö, Arctic Research Center, Finnish Meteorological Institute, +358
405527438,
esko.kyro(at)fmi.fi
France
Sophie Godin-Beekmann, Gerard Ancellet, LATMOS CNRS-UPMC, +33 1442747 67 / 62, [email protected],
gerard.ancellet(at)latmos.ipsl.fr
Germany
Hans Claude, Wolfgang Steinbrecht, Deutscher Wetterdienst Hohenpeißenberg, +49
8805 954 170 / 172,
hans.claude(at)dwd.de,
wolfgang.steinbrecht(at)dwd.de Franz-Josef Lübken, Leibniz-Institut für
Atmosphärenphysik, +49 38293 68 100,
luebken(at)iap-kborn.de
Greece Dimitris Balis, Aristotle University of
Thessaloniki, +30 2310 998192, [email protected] Costas Varotsos, University of Athens, +30 210 7276838,
covar(at)phys.uoa.gr Christos Zerefos, Academy of Athens, +30 210 8832048,
zerefos(at)academyofathens.gr
Great Britain Neil Harris, European Ozone Research Coordinating Unit, University of
Cambridge, +44 1223 311797,
Neil.Harris(at)ozone-sec.ch.cam.ac.uk
Norway Cathrine Lund Myhre, NILU – Norwegian Institute for Air Research,
+47-63898042,
clm(at)nilu.no
Russia Valery Dorokhov, Central Aerological Observatory , +7 499 206 9370,
vdor(at)starlink.ru Vladimir Yushkov, Central Aerological Observatory +7 495 408-6150,
vladimir(at)caomsk.mipt.ru
Natalya Tsvetkova, Central Aerological Observatory +7 495 408-6150,
nat(at)caomsk.mipt.ru Spain Concepción Parrondo, Manuel Gil , INTA, +34 91 5201564, [email protected],
gilm(at)inta.es
Switzerland René Stübi, Federal Office of Meteorology and Climatology, MeteoSwiss, +41
26 662 62 29,
rene.stubi(at)meteoswiss.ch Geir O. Braathen, World Meteorological Organization, +41 22 730 82 35,
GBraathen(at)wmo.int USA Ross J. Salawitch, Univ. of Maryland, MD, +1 626 487 5643,
rjs(at)atmos.umd.edu Francis J. Schmidlin, NASA/GSFC/Wallops Flight Facility, +1 757 824 1618,
francis.j.schmidlin(at)nasa.gov
The total ozone maps are based on
ground-based measurements available from the
World Ozone and Ultraviolet Radiation Data Centre. Preliminary near
real-time data from ground-based observations were also used for the most
recent maps. Total ozone values are given in
Dobson Units. The numbers represent observations taken from ground
stations situated at the bottom left corner of the number.
Maps of
deviations represent total ozone deviations from the
1978-1988 level estimated using Total
Ozone Mapping Spectrometer (TOMS) data for all areas except the Antarctic
and from the pre-1980 level estimated using Dobson data over the Antarctic.
Over
areas with poor data coverage adjustments are made according to
TOMS
on Nimbus-7, Meteor-3, ADEOS and Earth Probe satellites. Over the polar night
area Dobson and Brewer moon observations and/or
NOAA’s TIROS Operational Vertical Sounder (TOVS) satellite data are used.
TOVS data are also used when the more reliable TOMS data are not available. The
mapping algorithm is similar to those used by the
WMO Ozone Mapping Centre.
