Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ozone recovering, but unlikely to stabilize at pre-1980 levels

04.05.2006


While Earth’s ozone layer is slowly being replenished following an international 1987 agreement banning CFCs, the recovery is occurring in a changing atmosphere and is unlikely to stabilize at pre-1980 levels, says a new University of Colorado at Boulder study.



The recovery is a result of the 1987 Montreal Protocol banning chlorine pollutants from the atmosphere, said Betsy Weatherhead, a researcher with the Cooperative Institute for Research in Environmental Sciences, a joint institute of CU-Boulder and the National Oceanic and Atmospheric Administration. But by the end of the century, ozone levels could be slightly higher or slightly lower than before 1980 because of high natural variability and human caused changes like warming temperatures, said Weatherhead.

A paper by Weatherhead and Signe Bech Andersen of the Danish Meteorological Institute in Copenhagen is featured on the cover of the May 4 issue of Nature.


"We now have some confidence that the ozone layer is responding to the decreases in chlorine levels in the atmosphere due to the leveling off and decrease of CFCs, and most of the improvements are in agreement with what we had hoped for with the Montreal Protocol in place," she said. "But we are not out of the woods yet, and the ozone recovery process still faces a number of uncertainties."

At high latitudes, for example, warmer temperatures at Earth’s surface can trigger colder conditions in the lower stratosphere and promote the formation of polar stratospheric clouds, which can contribute to severe ozone depletion. "During the next few years, ozone levels in the Arctic will be strongly influenced by stratospheric temperature, possibly resulting in delayed recovery or record-low observations," the authors wrote in Nature.

The new study shows a larger than expected recovery of ozone in the northern mid-latitudes in recent years, she said. The increase may be partially a result of natural variability, including shifts in air temperatures and atmospheric transport, the influences of the 11-year solar cycle and an absence of major volcanic activity on Earth. The 1993 eruption of Mt. Pinatubo in the Philippines, for example, caused ozone levels to backslide for several years, Weatherhead said.

Future ozone levels likely will be dominated by air temperature, atmospheric dynamics and an abundance of trace gases, she said. Trace gases include significant amounts of nitrous oxide, or N2O -- a result of fertilizer production on Earth -- and could lead to significant depletion of protective ozone molecules.

"In another 50 years CFCs won’t be the dominant factor controlling ozone," she said. "Instead, we think it will be factors like greenhouse gases, N2O and methane."

The Nature study, which shows ozone levels have stabilized or increased slightly in the past 10 years, used data from satellites and ground stations to compare changes in the ozone layer to past depletion levels. The researchers used data from 14 modeling studies published by scientific groups from around the world for the study.

The ozone data was collected by a suite of NASA and NOAA satellites and ground stations. The new study follows a 2005 study led by Weatherhead indicating the ozone layer was no longer in decline following nearly two decades of depletion from harmful chemicals.

While ozone depletion has been most severe at the poles, there has been a seasonal decline of up to 10 percent of ozone at mid-latitudes, the location of much of North America, South America and Europe. "Since the full recovery of the ozone layer is probably decades away, the amount of UV radiation reaching Earth is likely to remain elevated for some years," she said. "People still need to take precautions when spending time in the sun."

Scientific evidence indicates ozone was relatively stable over the past few thousand years, said Weatherhead. The Arctic is the only place in the world where indigenous people were spurred to develop protective mechanisms to shield their eyes from UV radiation, and fossil pigments of plants imply UV radiation has been stable for thousands of years. "It is the past few decades that have been unusual," said Weatherhead.

Now ratified by more than 180 nations, the Montreal Protocol established legally binding controls for nations on the production and consumption of halogen gases containing chlorine and bromine. The primary source of ozone destruction is CFCs, once commonly used in refrigeration, air conditioning, foam-blowing equipment and industrial cleaning.

About 90 percent of the ozone measured in the study, known as total-column ozone, is found between 10 miles to 20 miles above Earth’s surface in the stratosphere, Weatherhead said. The ozone layer protects the planet from the harmful effects of UV radiation, including skin cancer and cataracts in humans and damaging effects on ecosystems.

Betsy Weatherhead | EurekAlert!
Further information:
http://www.noaa.gov

More articles from Studies and Analyses:

nachricht Drone vs. truck deliveries: Which create less carbon pollution?
31.05.2017 | University of Washington

nachricht New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Supersensitive through quantum entanglement

28.06.2017 | Physics and Astronomy

X-ray photoelectron spectroscopy under real ambient pressure conditions

28.06.2017 | Physics and Astronomy

Mice provide insight into genetics of autism spectrum disorders

28.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>