Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Atmospheric bromine, which attacks ozone layer, is decreasing

14.08.2003


Researchers have discovered that total bromine in the lower atmosphere has been decreasing since 1998 and is now more than five percent below the peak reached that year. Bromine is one of the most active destroyers of the stratospheric ozone layer, which forms an invisible shield around the Earth, protecting it from the biologically damaging ultraviolet rays of the Sun.



Stephen A. Montzka and colleagues from the National Oceanic and Atmospheric Administration’s Climate Monitoring and Diagnostics Laboratory in Boulder, Colorado, attribute the decline of total bromine primarily to international restrictions on industrial production of methyl bromide. Their report will be published August 15 in the journal Geophysical Research Letters.

"The decrease is driven by a large and rapid decline in methyl bromide, a brominated gas that is regulated internationally by the Montreal Protocol," said Montzka. The surprisingly large drop in atmospheric methyl bromide, about 13 percent since 1998, has more than offset the small increases still observed for bromine from fire-extinguishing agents known as halons. Bromine is about 50 times more efficient than chlorine at destroying stratospheric ozone.


"This is welcome news for stratospheric ozone because it means that less bromine and chlorine have been entering the upper atmosphere [stratosphere], where the ozone layer resides, for a number of years now," said Montzka. Furthermore, while chlorine’s decline in the lower atmosphere had been slowing in recent years, these new data suggest that the overall threat posed to stratospheric ozone from all halogenated gases continues to steadily diminish, Montzka said.

Methyl bromide is produced industrially for use as a fumigant in agriculture and in the shipment of commercial goods. It is unique among ozone-depleting substances regulated by the Montreal Protocol, in that it also has substantial natural sources, including the oceans, wetlands, some plants, and burning vegetation.

Global industrial production of methyl bromide has declined in recent years in response to restrictions outlined in the amended Montreal Protocol, say the researchers. The Montreal Protocol, which limits production of ozone-damaging compounds, was originally signed by 23 nations in 1987 and has been strengthened through revisions and amendments since then.

Methyl bromide and halons together account for nearly all of the human-released bromine that reaches the stratosphere. The NOAA scientists were able to discern the reversal in the long-term upward trend for bromine based on their ground-based measurements of methyl bromide and halons over the past eight years at 10 stations around the globe, including Cape Grim, Tasmania; the South Pole; Mauna Loa, Hawaii; and Barrow, Alaska.

The decrease in bromine is large compared to the decline documented earlier for chlorine. With this new result, the authors determined that overall ozone-depleting gases are declining faster than previously thought. International efforts to reduce industrial production of methyl bromide have had a noticeable impact on overall atmospheric levels of ozone-depleting substances, they say.

This good news must be tempered, however, because bromine from halons is still increasing slowly. But, says Montzka, "the surprisingly large decline observed for methyl bromide now dominates the overall trend for bromine." Full recovery of the ozone layer is still expected to take several decades, provided atmospheric levels of both bromine and chlorine continue to drop.

The researchers note that these encouraging trends could change. "Decreases in ozone-depleting substances are a direct result of international limits on production," said Montzka. "Without continued worldwide adherence to the restrictions outlined in the Protocol, these trends could slow and delay the recovery of stratospheric ozone."

The research was funded by NOAA.

Harvey Leifert | AGU

More articles from Earth Sciences:

nachricht Multi-year submarine-canyon study challenges textbook theories about turbidity currents
12.12.2017 | Monterey Bay Aquarium Research Institute

nachricht How do megacities impact coastal seas? Searching for evidence in Chinese marginal seas
11.12.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Long-lived storage of a photonic qubit for worldwide teleportation

12.12.2017 | Physics and Astronomy

Multi-year submarine-canyon study challenges textbook theories about turbidity currents

12.12.2017 | Earth Sciences

Electromagnetic water cloak eliminates drag and wake

12.12.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>