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 How does the loss of species alter ecosystems?
18.05.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Excess diesel emissions bring global health & environmental impacts
16.05.2017 | International Institute for Applied Systems Analysis (IIASA)

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: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>