Shop Windows to the Universe

Science, Evolution, and Creationism, by the National Academies, focuses on teaching evolution in today's classrooms. Check out the other publications in our online store.
Earth's ozone hole, shown here (in blue) in 2006, could be negatively affected by some efforts to mitigate climate change.
Click on image for full size
Courtesy of NASA

Injecting Sulfate Particles into Stratosphere Could Have Drastic Impact on Earth's Ozone Layer
News story originally written on April 24, 2008

A much-discussed idea to offset global warming by injecting sulfate particles into the stratosphere would have a drastic impact on Earth's protective ozone layer, new research concludes.

The study, led by Simone Tilmes of the National Center for Atmospheric Research (NCAR) in Boulder, Colo., warns that such an approach would delay the recovery of the Antarctic ozone hole by decades and cause significant ozone loss over the Arctic.

The study results are published today in the journal Science Express . The research was funded by the National Science Foundation (NSF), NCAR's principal sponsor, as well as by NASA and other agencies.

"Our research indicates that trying to artificially cool off the planet may be a perilous endeavor," Tilmes says. "While climate change is a major threat, this solution could create severe problems for society."

"The challenges of global warming mitigation are extremely complex," said Cliff Jacobs, program director in NSF's Division of Atmospheric Sciences. "Continued investment in basic research will allow the most cost-effective solutions--and those of the most benefit to society--to be found."

Climate scientists, concerned that society is not taking sufficient action to prevent significant changes in climate, have studied various "geoengineering" proposals to cool the planet and mitigate the most severe impacts of global warming.

One of the most-discussed ideas is to regularly inject large amounts of sun-blocking sulfate particles into the stratosphere. The goal would be to cool the climate, much as sulfur particles from large volcanic eruptions have cooling impacts.

Since volcanic eruptions temporarily thin the ozone layer in the stratosphere, Tilmes and her colleagues looked into the potential impact of geoengineering plans on ozone.

The new study concluded that, over the next few decades, artificial injections of sulfates could destroy between one-fourth and three-fourths of the ozone layer above the Arctic. This could affect a large part of the Northern Hemisphere because of atmospheric circulation patterns.

The sulfates would also delay the expected recovery of the ozone hole over the Antarctic by about 30 to 70 years, or until at least the last decade of the twentieth century, the authors warn. The ozone layer is critical for life on Earth because it blocks dangerous ultraviolet radiation from the Sun.

"This study highlights another connection between global warming and ozone depletion, which had been thought of as separate problems but are now increasingly recognized to be coupled in subtle, yet profoundly important, ways," says Science Express paper co-author Ross Salawitch of the University of Maryland.

To determine the relationship between sulfates and ozone loss, the authors used a combination of measurements and computer simulations.

They then estimated future ozone loss by looking at two geoengineering schemes--one that would use volcanic-sized sulfates, and a second that would use much smaller injections.

The study found that injections of small particles over the next 20 years could reduce the ozone layer by 100 to 230 Dobson Units. The average thickness of the ozone layer in the Northern Hemisphere is 300 Dobson Units. (A Dobson Unit is a common measure of ozone.)

For large particles, the loss would range from 70 to 150 Dobson Units. The larger figure is correlated with colder winters.

In the Antarctic, the sulfate injections would not significantly reduce the thickness of the already depleted ozone layer. Instead, they would significantly delay the recovery of the ozone hole.

The authors caution that the actual impacts on ozone could be somewhat different than estimated if atmospheric changes led to unusually warm or cold polar winters. They also warn that a geoengineering project could lead to even more severe ozone loss if a volcanic eruption took place at the same time.

"Clearly much more research needs to be conducted to determine the full implications of geoengineering before we may discuss seriously the injection of sulfate aerosols into the stratosphere," says co-author Rolf Müller of the Jülich Research Center in Germany.

Text above is courtesy of the National Science Foundation

Last modified May 29, 2008 by Becca Hatheway.

Shop Windows to the Universe Science Store!

Our online store includes issues of NESTA's quarterly journal, The Earth Scientist, full of classroom activities on different topics in Earth and space science, as well as books on science education!

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Effects of Climate Change Today

The world's surface air temperature increased an average of 0.6° Celsius (1.1°F) during the last century according to the Intergovernmental Panel on Climate Change (IPCC). This may not sound like very...more

Ozone - An Overview

The Ozone Hole. The Ozone Hoax. Pollution. Skin Cancer. The topic of ozone makes headlines on a regular basis, but why does a single molecule merit such media coverage? How important is the ozone in our...more

The Antarctic Region

What Will You Find There? South of the Antarctic Circle (at 66.5°S latitude) you will find the continent of Antarctica surrounded by the Southern Ocean, the geographic South Pole and the magnetic South...more

The Arctic: Earth's North Polar Region

North of the Arctic Circle (at 66.5°N latitude) you will find the Arctic Ocean surrounded by the northernmost parts of the continents of Europe, Asia, and North America. You will find the geographic North...more

What is Climate?

Climate in your place on the globe is called regional climate. It is the average weather pattern in a place over more than thirty years, including the variations in seasons. To describe the regional climate...more

Triggers of Volcanic Eruptions in Oregon's Mount Hood Investigated

A new study has found that a mixing of two different types of magma is the key to the historic eruptions of Mount Hood, Oregon's tallest mountain, and that eruptions often happen in a relatively short...more

Oldest Earth Mantle Reservoir Discovered

Researchers have found a primitive Earth mantle reservoir on Baffin Island in the Canadian Arctic. Geologist Matthew Jackson and his colleagues from a multi-institution collaboration report the finding--the...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA