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 Deep decarbonization of industry is possible with innovations
25.03.2019 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)

nachricht Five-point plan to integrate recreational fishers into fisheries and nature conservation policy
20.03.2019 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

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: The taming of the light screw

DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.

The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...

Im Focus: Magnetic micro-boats

Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.

The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Laser processing is a matter for the head – LZH at the Hannover Messe 2019

25.03.2019 | Trade Fair News

A Varied Menu

25.03.2019 | Life Sciences

‘Time Machine’ heralds new era

25.03.2019 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>