Ozone losses may be speeding up at higher latitudes, according to U. of Colorado study

May 28, 2002

New findings by University of Colorado at Boulder researchers indicate ozone losses due to the breakdown of chlorofluorocarbons, or CFCs, occur much faster than previously believed at higher latitudes roughly 10 miles above Earth.

Associate Professor Darin Toohey of the Program in Atmospheric and Oceanic Sciences said scientists have known for several decades that chlorofluorocarbon-derived compounds can deplete stratospheric ozone. More recently, some have proposed that adverse chemical reactions caused by man-made compounds occurring just seven to 10 miles in altitude could lead to additional ozone losses.

While such chemical reactions at lower altitudes may be occurring, "What we see is that ozone-depleting reactions of chlorine and bromine compounds are occurring rapidly at high latitudes in winter," he said. The winter chemical reactions are occurring in an atmospheric region where the air can readily mix with air at mid-latitudes like the skies over Reno, Denver and Philadelphia.

PAOS researchers and students have used balloons and aircraft to show that ozone-gobbling chlorine "free radicals" produced by the breakdown of CFCs are more concentrated at high latitudes than previously believed. During winter and spring, the reactions appear to be accelerated from about 50 degrees to 60 degrees in latitude - roughly from Vancouver, B.C., north to Great Slave Lake in the Northwest Territories -all the way to the North Pole.

These chemical reactions occur in regions where there are ice clouds, based on measurements of CU-Boulder Professor Linnea Avallone of PAOS and the Laboratory for Atmospheric and Space Physics, said Toohey.

Toohey presented his research at the Spring American Geophysical Union Meeting on May 28 in Washington, D.C.

The invisible ozone layer, which shields Earth from harmful ultraviolet radiation, is produced naturally in the stratosphere -- 10 miles to 30 miles above Earth's surface. Until several decades ago, the equilibrium of the layer has been maintained by several competing chemical reactions among naturally occurring oxygen and hydrogen molecules.

"This ozone-depleting chemistry is important because it occurs outside the region where large amounts of ozone depletions have previously been reported, such as the poles and at higher altitudes," said Toohey.

While ozone losses at higher altitudes inside the polar vortex are thought to be confined to the high latitudes, it is possible that transport and mixing of lower-altitude air is having a wider influence on ozone abundance at lower latitudes.

In addition, new studies from Boulder scientist Stephen Reid of the National Oceanic and Atmospheric Administration suggest climate change could alter the motion of air in the lower stratosphere.

"These results raise the possibility that halogen chemistry occurring at high latitudes is more important for ozone trends at mid-latitudes than was previously believed," said Toohey.
Darin Toohey

Jim Scott
The AGU Press Room telephone number is 202-371-5016

University of Colorado at Boulder

Related Ozone Articles from Brightsurf:

Investigating the causes of the ozone levels in the Valderejo Nature Reserve
The UPV/EHU's Atmospheric Research Group (GIA) has presented a database comprising over 60 volatile organic compounds (VOC) measured continuously over the last ten years in the Valderejo Nature Reserve (Álava, Basque Country).

FSU Research: Despite less ozone pollution, not all plants benefit
Policies and new technologies have reduced emissions of precursor gases that lead to ozone air pollution, but despite those improvements, the amount of ozone that plants are taking in has not followed the same trend, according to Florida State University researchers.

Iodine may slow ozone layer recovery
Air pollution and iodine from the ocean contribute to damage of Earth's ozone layer.

Ozone threat from climate change
We know the recent extreme heat is something that we can expect more of as a result of increasing temperatures due to climate change.

Super volcanic eruptions interrupt ozone recovery
Strong volcanic eruptions, especially when a super volcano erupts, will have a strong impact on ozone, and might interrupt the ozone recovery processes.

How severe drought influences ozone pollution
From 2011 to 2015, California experienced its worst drought on record, with a parching combination of high temperatures and low precipitation.

New threat to ozone recovery
A new MIT study, published in Nature Geoscience, identifies another threat to the ozone layer's recovery: chloroform -- a colorless, sweet-smelling compound that is primarily used in the manufacturing of products such as Teflon and various refrigerants.

Ozone hole modest despite optimum conditions for ozone depletion
The ozone hole that forms in the upper atmosphere over Antarctica each September was slightly above average size in 2018, NOAA and NASA scientists reported today.

Increased UV from ozone depletion sterilizes trees
UC Berkeley paleobotanists put dwarf, bonsai pine trees in growth chambers and subjected them to up to 13 times the UV-B radiation Earth experiences today, simulating conditions that likely existed 252 million years ago during the planet's worst mass extinction.

Ozone at lower latitudes is not recovering, despite Antarctic ozone hole healing
The ozone layer -- which protects us from harmful ultraviolet radiation -- is recovering at the poles, but unexpected decreases in part of the atmosphere may be preventing recovery at lower latitudes.

Read More: Ozone News and Ozone Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.