Nature's Atmospheric Cleanser Needs Closer Look

TERRADAILY

Researchers have found that on average, from 1978 to 2000, the concentration of OH in the southern hemisphere was about 14% higher than that of the northern hemisphere. Globally, OH increased from 1978 until around 1988 and then declined.

Cambridge - May 8, 2001
Levels of our atmosphere's main cleansing agent -- the hydroxyl radical (OH) -- have first risen and then fallen substantially since 1978, an international team of researchers led by a Massachusetts Institute of Technology atmospheric scientist report in the May 4 on-line issue of Science. This chemical destroys air pollutants and many gases involved in ozone depletion and the greenhouse effect.

These fluctuations, plus the fact that the chemical's levels are higher in the southern hemisphere than in the more industrialized northern hemisphere, are puzzling to researchers. "Neither of these types of changes over space and time are expected from current theory. The results are a surprise," said Ronald G. Prinn, TEPCO Professor, head of MIT's Department of Earth, Atmospheric and Planetary Sciences and the study's lead author.

Prinn warns that the new data should serve as a wake-up call, not only to atmospheric scientists, but also to policy makers, who depend on information about this chemical when considering legislation that would affect the global warming potential of many gases, including methane. "If we don't understand how OH is going to behave in the future, we can't decide how to factor it in to discussions on global warming," he said.

The hydroxyl radical (OH) is "by far the most important chemical species in the lower atmosphere," Prinn said. OH exists only fleetingly in the lower atmosphere and it cannot presently be measured directly at the regional to global scale. But its levels can be inferred from long-term global measurements of a man-made gas that it obliterates.

"If our current analysis is correct, it implies that present understanding of OH chemistry, and hence the capacity of the atmosphere to remove many anthropogenically and naturally produced trace gases, is incomplete," write the researchers. "This has important implications for mitigation of air pollution and climate change."

"These variations imply important and unexpected gaps in current understanding of the capability of the atmosphere to cleanse itself," writes Prinn and colleagues from the University of California at San Diego; Georgia Institute of Technology; Commonweath Scientific and Industrial Research Organization of Victoria, Australia; University of Bristol, United Kingdom; and Cape Grim Baseline Air Pollution Station in Tasmania, Australia.

The researchers found that on average, from 1978 to 2000, the concentration of OH in the southern hemisphere was about 14% higher than that of the northern hemisphere. Globally, OH increased from 1978 until around 1988 and then declined.

There are several possibilities that would explain the results. Prinn suggests that researchers look at the role of aerosols -- tiny particulates -- that could be reacting with and removing OH and its related molecules from the atmosphere. The tiny particles also may be reflecting and absorbing the sun's ultraviolet radiation, which would in turn lower OH production rates.

Because the changes in the global concentration of OH are dominated by changes in the northern hemisphere, where most of the world's industrialization and emission of human-made gases occurs, the variations in OH are probably driven more by human-made than natural causes, the researchers note. A changing mix of air pollutants in the northern hemisphere such as nitrogen oxides and carbon monoxide, along with aerosols, may be implicated.

Prinn said that more precise global measurements of short-lived air pollution gases around the world is needed for greater understanding of OH levels over time. The researchers call for additional global long-term measurements that match the timeframe in the study published in Science.

TERRADAILY

Natural Heat Vent Could Help Earth Let Off Steam

Greenbelt - Feb. 28, 2001
The tropical Pacific Ocean may be able to open a "vent" in its heat-trapping cirrus cloud cover and release enough energy into space to significantly diminish the projected climate warming caused by a buildup of greenhouse gases in the atmosphere.

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.