Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Clouds caused by aircraft exhaust may warm the U.S. climate

29.04.2004


NASA scientists have found that cirrus clouds, formed by contrails from aircraft engine exhaust, are capable of increasing average surface temperatures enough to account for a warming trend in the United States that occurred between 1975 and 1994.

"This result shows the increased cirrus coverage, attributable to air traffic, could account for nearly all of the warming observed over the United States for nearly 20 years starting in 1975, but it is important to acknowledge contrails would add to and not replace any greenhouse gas effect," said Patrick Minnis, senior research scientist at NASA’s Langley Research Center in Hampton, Va. The study was published April 15 in the Journal of Climate. "During the same period, warming occurred in many other areas where cirrus coverage decreased or remained steady," he added.

"This study demonstrates that human activity has a visible and significant impact on cloud cover and, therefore, on climate. It indicates that contrails should be included in climate change scenarios," Minnis said.



Minnis determined the observed one percent per decade increase in cirrus cloud cover over the United States is likely due to air traffic-induced contrails. Using published results from NASA’s Goddard Institute for Space Studies (New York) general circulation model, Minnis and his colleagues estimated contrails and their resulting cirrus clouds would increase surface and lower atmospheric temperatures by 0.36 to 0.54 degrees Fahrenheit per decade. Weather service data reveal surface and lower atmospheric temperatures across North America rose by almost 0.5 degree Fahrenheit per decade between 1975 and 1994.

Minnis worked with colleagues Kirk Ayers, Rabi Palinkonda, and Dung Phan from Analytical Services and Materials, Inc., of Hampton, Va. They used 25 years of global surface observations of cirrus clouds, temperature and humidity records from the National Centers for Environmental Prediction (NCEP) reanalysis dataset. They confirmed the cirrus trends with 13 years of satellite data from NASA’s International Satellite Cloud Climatology Project.

Both air traffic and cirrus coverage increased during the period of warming despite no changes in the NCEP humidity at jet cruise altitudes over the United States. By contrast, humidity at flight altitudes decreased over other land areas, such as Asia, and was accompanied by less cirrus coverage, except over Western Europe, where air traffic is very heavy.

Cirrus coverage also rose in the North Pacific and North Atlantic flight corridors. The trends in cirrus cover and warming over the United States were greatest during winter and spring, the same seasons when contrails are most frequent. These results, along with findings from earlier studies, led to the conclusion that contrails caused the increase in cirrus clouds.

"This study indicates that contrails already have substantial regional effects where air traffic is heavy, such as over the United States. As air travel continues growing in other areas, the impact could become globally significant," Minnis said.

Humidity is the amount of water vapor in the air and determines how long contrails remain in the atmosphere. Contrails that persist for an extended period of time are most likely to impact the climate.

Contrails form high in the atmosphere when the mixture of water vapor in the aircraft exhaust and the air condenses and freezes. Persisting contrails can spread into extensive cirrus clouds that tend to warm the Earth, because they reflect less sunlight than the amount of heat they trap. The balance between Earth’s incoming sunlight and outgoing heat drives climate change.

NASA’s Earth Science Enterprise funded this research. NASA’s Earth Science Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather, and natural hazards using the unique vantage point of space.

Julia Cole | EurekAlert!
Further information:
http://www.larc.nasa.gov/
http://www.nasa.gov/home/index.html

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

nachricht Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

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: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Subaru Telescope helps pinpoint origin of ultra-high energy neutrino

16.07.2018 | Physics and Astronomy

Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides

16.07.2018 | Life Sciences

New research calculates capacity of North American forests to sequester carbon

16.07.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>