Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rising height of atmospheric boundary points to human impact on climate

25.07.2003


A team of scientists, including several from the National Center for Atmospheric Research (NCAR), has determined that human-related emissions are largely responsible for an increase in the height of the tropopause - the boundary between the two lowest layers of the atmosphere. The research results, which will be published July 25 in the journal Science, provide additional evidence that emissions from power plants, automobiles, and other human-related (or anthropogenic) sources are having profound impacts on the atmosphere and global climate.



"Determining why the height of the tropopause is increasing gives us insights into the causes of the overall warming of the lower atmosphere," explains Tom Wigley, an NCAR senior scientist and co-author of the article. "Although not conclusive in itself, this research is an important piece in the jigsaw puzzle."

Benjamin Santer of the Lawrence Livermore National Laboratory is the lead author of the article, "Contributions of Anthropogenic and Natural Forcing to Recent Tropopause Height Changes." Wigley and four other NCAR scientists contributed to the article. NCAR’s primary sponsor is the National Science Foundation.


Although numerous past studies have pointed to human activities as a leading cause of global warming, this is the first to evaluate impacts on the tropopause. It also provides evidence that temperatures are rising in the troposphere, the lowest layer in the atmosphere.

The tropopause provides a unique window into atmospheric temperatures because it is situated at the upper boundary of the troposphere, where temperatures cool with increased altitude, and at the lower boundary of the stratosphere, where temperatures warm with increased altitude. Observations and climate models both show that the tropopause, which is about 5 to 10 miles (8 to 16 kilometers) above Earth’s surface depending on latitude and season, has risen by several hundred feet since 1979. Although this height increase does not directly affect Earth, it is important as an indication that the troposphere is becoming warmer and the stratosphere is becoming cooler. But until now, no study has looked into how much of the tropopause height increase could be attributed to natural causes and how much to human impacts on the atmosphere.

The research team looked at five variables--two natural and three human-related--that could contribute to the height increase: solar radiation, volcanic activity, emissions of greenhouse gases (such as carbon dioxide), emissions of sulfur dioxide, and levels of tropospheric and stratospheric ozone. The team used the NCAR/Department of Energy Parallel Climate Model to conduct a series of seven experiments. The first five analyzed each factor’s impact on the atmosphere in isolation. The sixth looked at the combined impact of the two natural factors, solar radiation and volcanic activity. The seventh assessed the impact of all the factors combined. The impacts were compared with observed changes in tropopause height, which were inferred from two sets of data--one from NCAR and the National Center for Environmental Prediction, and the other from the European Centre for Medium-Range Weather Forecasts.

The results showed that the depletion of stratospheric ozone combined with human emissions of greenhouse gases accounted for more than 80 percent of the rise in the tropopause. Ozone depletion (caused largely by human emissions of chlorofluorocarbons, or CFCs) was significant because it cooled the stratosphere, while greenhouse gases warmed the troposphere. The other factors had much smaller impacts. Solar activity made a small contribution to warming in the troposphere and stratosphere, while sulfur dioxide emissions from both human-related activities and volcanic eruptions slightly cooled the troposphere.

The study also gives support to scientists, including Wigley and Santer, who believe temperatures in the upper troposphere are increasing. Researchers have been at odds over whether satellite data indicate that atmospheric temperatures are rising or stable. But a new data set produced by researchers at remote sensing systems in Santa Rosa, California, and analyzed by Santer, Wigley, and other scientists in Science earlier this year indicates that global temperatures in the lowest several miles of the atmosphere rose by one-third of a degree Fahrenheit (about 0.2 degrees Celsius) between 1979 and 1999.

"The increase in the height of the tropopause appears to support the data set that shows the troposphere is warming," Wigley says.

Anatta | EurekAlert!
Further information:
http://www.ucar.edu/ucar

More articles from Ecology, The Environment and Conservation:

nachricht Emissions from road construction could be halved using today’s technology
18.05.2020 | Schwedischer Forschungsrat - The Swedish Research Council

nachricht When every particle counts: IOW develops comprehensive guidelines for microplastic extraction from environmental samples
11.05.2020 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Biotechnology: Triggered by light, a novel way to switch on an enzyme

In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".

Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...

Im Focus: New double-contrast technique picks up small tumors on MRI

Early detection of tumors is extremely important in treating cancer. A new technique developed by researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The work is published May 25 in the journal Nature Nanotechnology.

researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from...

Im Focus: I-call - When microimplants communicate with each other / Innovation driver digitization - "Smart Health“

Microelectronics as a key technology enables numerous innovations in the field of intelligent medical technology. The Fraunhofer Institute for Biomedical Engineering IBMT coordinates the BMBF cooperative project "I-call" realizing the first electronic system for ultrasound-based, safe and interference-resistant data transmission between implants in the human body.

When microelectronic systems are used for medical applications, they have to meet high requirements in terms of biocompatibility, reliability, energy...

Im Focus: When predictions of theoretical chemists become reality

Thomas Heine, Professor of Theoretical Chemistry at TU Dresden, together with his team, first predicted a topological 2D polymer in 2019. Only one year later, an international team led by Italian researchers was able to synthesize these materials and experimentally prove their topological properties. For the renowned journal Nature Materials, this was the occasion to invite Thomas Heine to a News and Views article, which was published this week. Under the title "Making 2D Topological Polymers a reality" Prof. Heine describes how his theory became a reality.

Ultrathin materials are extremely interesting as building blocks for next generation nano electronic devices, as it is much easier to make circuits and other...

Im Focus: Rolling into the deep

Scientists took a leukocyte as the blueprint and developed a microrobot that has the size, shape and moving capabilities of a white blood cell. Simulating a blood vessel in a laboratory setting, they succeeded in magnetically navigating the ball-shaped microroller through this dynamic and dense environment. The drug-delivery vehicle withstood the simulated blood flow, pushing the developments in targeted drug delivery a step further: inside the body, there is no better access route to all tissues and organs than the circulatory system. A robot that could actually travel through this finely woven web would revolutionize the minimally-invasive treatment of illnesses.

A team of scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart invented a tiny microrobot that resembles a white blood cell...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

International Coral Reef Symposium in Bremen Postponed by a Year

06.04.2020 | Event News

 
Latest News

New 5G switch provides 50 times more energy efficiency than currently exists

27.05.2020 | Information Technology

Return of the Blob: Surprise link found to edge turbulence in fusion plasma

27.05.2020 | Physics and Astronomy

Upwards with the “bubble shuttle”: How sea floor microbes get involved with methane reduction in the water column

27.05.2020 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>