Tag Archives: ozone

Significant ozone hole remains over Antarctica

Significant ozone hole remains over Antarctica.

Ozone levels in the atmosphere above the South Pole dropped to a seasonal low of 102 Dobson Units Oct. 9, tied for the 10th lowest in the 26-year record. The ozone layer helps protect the planet's surface from harmful ultraviolet radiation. Every year, an ozone hole forms above the Antarctic for several weeks, because of environmental conditions and the presence of ozone-depleting chemicals. (Credit: NOAA)

ScienceDaily (Oct. 20, 2011) — The Antarctic ozone hole, which yawns wide every Southern Hemisphere spring, reached its annual peak on September 12, stretching 10.05 million square miles, the ninth largest on record. Above the South Pole, the ozone hole reached its deepest point of the season on October 9 when total ozone readings dropped to 102 Dobson units, tied for the 10th lowest in the 26-year record.

The ozone layer helps protect the planet’s surface from harmful ultraviolet radiation. NOAA and NASA use balloon-borne instruments, ground instruments, and satellites to monitor the annual South Pole ozone hole, global levels of ozone in the stratosphere, and the humanmade chemicals that contribute to ozone depletion.Watch movie online The Transporter Refueled (2015)

“The upper part of the atmosphere over the South Pole was colder than average this season and that cold air is one of the key ingredients for ozone destruction,” said James Butler, director of NOAA’s Global Monitoring Division in Boulder, Colo. Other key ingredients are ozone-depleting chemicals that remain in the atmosphere and ice crystals on which ozone-depleting chemical reactions take place.

“Even though it was relatively large, the size of this year’s ozone hole was within the range we’d expect given the levels of manmade, ozone-depleting chemicals that continue to persist,” said Paul Newman, chief atmospheric scientist at NASA’s Goddard Space Flight Center.

Levels of most ozone-depleting chemicals are slowly declining due to international action, but many have long lifetimes, remaining in the atmosphere for decades. Scientists around the world are looking for evidence that the ozone layer is beginning to heal, but this year’s data from Antarctica do not hint at a turnaround.

In August and September (spring in Antarctica), the sun begins rising again after several months of darkness. Circumpolar winds keep cold air trapped above the continent, and sunlight-sparked reactions involving ice clouds and humanmade chemicals begin eating away at the ozone. Most years, the conditions for ozone depletion ease by early December, and the seasonal hole closes.

Levels of most ozone-depleting chemicals in the atmosphere have been gradually declining since an international treaty to protect the ozone layer, the 1987 Montreal Protocol, was signed. That international treaty caused the phase out of ozone-depleting chemicals, then used widely in refrigeration, as solvents and in aerosol spray cans.

Global atmospheric models predict that stratospheric ozone could recover by the middle of this century, but the ozone hole in the Antarctic will likely persist one to two decades beyond that, according to the latest analysis by the World Meteorological Organization, the 2010 Ozone Assessment, with co-authors from NOAA and NASA.

Researchers do not expect a smooth, steady recovery of Antarctic ozone, because of natural ups and downs in temperatures and other factors that affect depletion, noted NOAA ESRL scientist Bryan Johnson. Johnson helped co-author a recent NOAA paper that concluded it could take another decade to begin discerning changes in the rates of ozone depletion.

Johnson is part of the NOAA team tracks ozone depletion around the globe and at the South Pole with measurements made from the ground, in the atmosphere itself and by satellite. Johnson’s “ozonesonde” group has been using balloons to loft instruments 18 miles into the atmosphere for 26 years to collect detailed profiles of ozone levels from the surface up. The team also measures ozone with satellite and ground-based instruments.

This November marks the 50th anniversary of the start of total ozone column measurements by the NOAA Dobson spectrophotometer instrument at South Pole station. Ground-based ozone column measurements started nearly two decades before the yearly Antarctic ozone hole began forming, therefore helping researchers to recognize this unusual change of the ozone layer.

NASA measures ozone in the stratosphere with the Ozone Monitoring Instrument (OMI) aboard the Aura satellite. OMI continues a NASA legacy of monitoring the ozone layer from space that dates back to 1972 and the launch of the Nimbus-4 satellite.

Climate change set to increase ozone-related deaths over next 60 years, scientists warn

Climate change set to increase ozone-related deaths over next 60 years, scientists warn.

ScienceDaily (Sep. 27, 2011) — Scientists are warning that death rates linked to climate change will increase in several European countries over the next 60 yrs.

A new study, which is being presented at the European Respiratory Society’s Annual Congress in Amsterdam, predicts that Belgium, France, Spain and Portugal will see the biggest climate-induced increase in ozone-related deaths over the next 60 years.

The research is part of the Climate-TRAP project and its health impact assessment lead by Prof Bertil Forsberg from the Umea University in Sweden. The aim is to prepare the health sector for changing public health needs due to climate change.

According to the World Health Organization (WHO), climate change that has occurred since the 1970s caused over 140,000 excess deaths annually by the year 2004. In addition to its impact on clean air, drinking water and crop production, many deadly diseases such as malaria and those which cause diarrhea are particularly sensitive to climate change.

In this new research, the scientists used emission scenarios and models to assess the health impacts of a changing climate. They took projections from two greenhouse gas emission scenarios, A2 and A1B, and two global climate models, ECHAM4 and HADLEY, to simulate how the various future ozone levels are affected by climate change.

They compared four periods: baseline period (1961-1990); the current situation (1990-2009); nearer future (2012-2050); and further future (2041-2060).

The findings revealed that since 1961, Belgium, Ireland, The Netherlands and the UK have seen the biggest impact on ozone-related deaths due to climate change. The results predicted that the biggest increase over the next 50 yrs is likely to be seen in Belgium, France, Spain and Portugal, who could expect an increase of between 10 and 14%. However, Nordic and Baltic countries are predicted to see a decrease over the same period.

Dr Hans Orru, air pollution expert from the Umea University and University of Tartu in Estonia, explains: “Ozone is a highly oxidative pollutant, linked with hospitalisations and deaths due to problems with the respiratory system. Ground-level ozone formation is due to rise as temperatures increase with climate change. The results of our study have shown the potential effects that climate change can have on ozone levels and how this change will impact upon the health of Europeans.”

Professor Marc Decramer, President of the ERS, said: “Outdoor air pollution is the biggest environmental threat in Europe. If we do not act to reduce levels of ozone and other pollutants, we will see increased hospital admissions, extra medication and millions of lost working days. As part of the European Respiratory Roadmap, which was launched last month, the ERS is calling for a collaborative approach between health professionals and policy makers, to protect vulnerable populations from the damaging effects air pollutants can have.”

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by European Lung Foundation, via EurekAlert!, a service of AAAS.


Arctic ozone loss at record level

BBC News – Arctic ozone loss at record level.


The Arctic ozone hole lay over over populated regions for parts of winter and spring

Ozone loss over the Arctic this year was so severe that for the first time it could be called an “ozone hole” like the Antarctic one, scientists report.

About 20km (13 miles) above the ground, 80% of the ozone was lost, they say.

The cause was an unusually long spell of cold weather at altitude. In cold conditions, the chlorine chemicals that destroy ozone are at their most active.

It is currently impossible to predict if such losses will occur again, the team writes in the journal Nature.

Early data on the scale of Arctic ozone destruction were released in April, but the Nature paper is the first that has fully analysed the data.

“Winter in the Arctic stratosphere is highly variable – some are warm, some are cold,” said Michelle Santee from Nasa’s Jet Propulsion Laboratory (JPL).

“But over the last few decades, the winters that are cold have been getting colder.

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Why [all this] occurred will take years of detailed study”

Michelle Santee JPL

“So given that trend and the high variability, we’d anticipate that we’ll have other cold ones, and if that happens while chlorine levels are high, we’d anticipate that we’d have severe ozone loss.”

Ozone-destroying chemicals originate in substances such as chlorofluorocarbons (CFCs) that came into use late last century in appliances including refrigerators and fire extinguishers.

Their destructive effects were first documented in the Antarctic, which now sees severe ozone depletion in each of its winters.

Their use was progressively restricted and then eliminated by the 1987 Montreal Protocol and its successors.

The ozone layer blocks ultraviolet-B rays from the Sun, which can cause skin cancer and other medical conditions.

Longer, not colder

Winter temperatures in the Arctic stratosphere do not generally fall as low as at the southern end of the world.

Polar stratospheric clouds Ozone destruction takes place within polar stratospheric clouds, with chlorine the main culprit

No records for low temperature were set this year, but the air remained at its coldest for an unusually long period of time, and covered an unusually large area.

In addition, the polar vortex was stronger than usual. Here, winds circulate around the edge of the Arctic region, somewhat isolating it from the main world weather systems.

“Why [all this] occurred will take years of detailed study,” said Dr Santee.

“It was continuously cold from December through April, and that has never happened before in the Arctic in the instrumental record.”

The size and position of the ozone hole changed over time, as the vortex moved northwards or southwards over different regions.

Some monitoring stations in northern Europe and Russia recorded enhanced levels of ultraviolet-B penetration, though it is not clear that this posed any risk to human health.

While the Arctic was setting records, the Antarctic ozone hole is relatively stable from year to year.

This year has seen ozone-depleting conditions extending a little later into the southern hemisphere spring than usual – again, as a result of unusual weather conditions.

Chlorine compounds persist for decades in the upper atmosphere, meaning that it will probably be mid-century before the ozone layer is restored to its pre-industrial health.

Related Stories

Mysteries of ozone depletion continue 25 years after the discovery of the Antarctic ozone hole

Mysteries of ozone depletion continue 25 years after the discovery of the Antarctic ozone hole.

ScienceDaily (Aug. 29, 2011) — Even after many decades of studying ozone and its loss from our atmosphere miles above 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 in Denver Colorado on May 29. She also discussed chemistry and climate change, including some proposed ideas to “geoengineer” 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 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 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.

Arctic Ozone Loss

Arctic Ozone Loss : Image of the Day.

Arctic Ozone Loss

Posted March 30, 2011

Arctic Ozone Loss

Color bar for Arctic Ozone Loss
download animation (4 MB, QuickTime) acquired March 19, 2011
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Recent observations from satellites and ground stations suggest that atmospheric ozone levels for March in the Arctic were approaching the lowest levels in the modern instrumental era. What those readings mean for the remainder of the year is unclear. But what they mean for the long-term is that the recovery from human-induced ozone depletion is an uneven climb.

These maps of ozone concentrations over the Arctic come from the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite. The left image shows March 19, 2010, and the right shows the same date in 2011. March 2010 had relatively high ozone, while March 2011 has low levels. The large animation file (linked below the images) shows the dynamics of the ozone layer from January 1 to March 23 in both years.

In mid-March, scientists from Germany’s Alfred Wegener Institute announced that Arctic ozone levels had been cut in half in the waning weeks of winter, according to a network of 30 ozone sounding stations spread around the region. Data from OMI (shown above) also confirmed a depletion. OMI is a spectrometer that measures the amount of sunlight scattered by Earth’s atmosphere and surface, allowing scientists to assess how much ozone is present at various altitudes, particularly the stratosphere.

Ozone is destroyed when chlorine- or bromine-based compounds—especially chlorofluorocarbons (CFCs) —break into their free atoms and combine with the oxygen. That process is amplified when the stratosphere is especially cold, which it has been in recent weeks.

“This depletion is not necessarily a big surprise,” said Paul Newman, an atmospheric scientist and ozone expert at NASA’s Goddard Space Flight Center. “The ozone layer remains vulnerable to large depletions because total stratospheric chlorine levels are still high, in spite of the regulation of ozone-depleting substances by the Montreal Protocol. Chlorine levels are declining slowly because ozone-depleting substances have extremely long lifetimes.”

The concentration of ozone in the Arctic atmosphere varies greatly from year-to-year, and ozone “holes” do not form consistently like they do in Antarctica. “Last winter, we had very high lower stratospheric temperatures and ozone levels were very high; this year is just the opposite,” Newman said. “The real question is: Why is this year so dynamically quiet and cold in the stratosphere? That’s a big question with no good answer.”

Scientists will be watching in coming months for possible increases in the intensity of ultraviolet radiation (UV) in the Arctic and mid-latitudes, since ozone is Earth’s natural sunscreen. “We need to wait and see if this will actually happen,” Newman said. “It’s something to look at but it is not catastrophic.”

On a global scale, the ozone layer is still on a long-term course for recovery. But for decades to come, there remains a risk of major ozone losses on yearly or regional scales.