Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Volcanic aerosols, not pollutants, tamped down recent Earth warming

01.03.2013
Dozens of sulfur-dioxide-spewing volcanoes could be the reason that Earth warmed less than scientists expected between 2000 and 2010, a new study has found.

The research indicates also that industrial sulfur dioxide emissions from India and China, which were suspected of tempering the warming, did not play a significant role, said lead study author Ryan Neely, who led the research as part of his University of Colorado Boulder doctoral thesis.

Small amounts of sulfur dioxide emissions from Earth’s surface eventually rise to 19 to 32 kilometers (12 to 20 miles) into the stratosphere, where chemical reactions create a mist, or aerosol, of sulfuric acid droplets and water droplets that reflects sunlight back to space, cooling the planet.

Neely said previous observations suggest that increases in stratospheric aerosols since 2000 have counterbalanced as much as 25 percent of the warming scientists blame on human greenhouse gas emissions. “This new study indicates it is emissions from small to moderate volcanoes that have been slowing the warming of the planet,” said Neely, a researcher at the Cooperative Institute for Research in Environmental Sciences, a joint venture of CU and the National Oceanic and Atmospheric Administration.

A paper on the subject has been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union. The new project was undertaken in part to resolve conflicting results of two recent studies on the origins of the sulfur dioxide in the stratosphere, including a 2009 study led by the late David Hoffman of NOAA, which indicated aerosol increases in the stratosphere may have come from rising emissions of sulfur dioxide from India and China.

In contrast, a 2011 study led by Jean Paul Vernier of NASA’s Langley Research Center in Hampton, Va. -- who also provided essential observation data for the new GRL study -- showed moderate volcanic eruptions play a role in increasing particulates in the stratosphere, Neely said. The new study relies on long-term measurements of changes in the stratospheric aerosol layer’s “optical depth,” which is a measure of transparency, Neely said. Since 2000, the optical depth in the stratospheric aerosol layer has increased by about 4 percent to 7 percent, meaning it is slightly more opaque now than in previous years.

“The biggest implication here is that scientists need to pay more attention to small and moderate volcanic eruptions when trying to understand changes in Earth’s climate,” said Brian Toon of CU-Boulder’s Atmospheric and Oceanic Sciences Department, a co-author of the new study. “But overall theses eruptions are not going to counter the greenhouse effect. Emissions of volcanic gases go up and down, helping to cool or heat the planet, while greenhouse gas emissions from human activity just continue to go up.”

The key to the new results was the combined use of two sophisticated computer models, including the Whole Atmosphere Community Climate Model, or WACCM, Version 3, developed by the National Center for Atmospheric Research in Boulder and is widely used around the world by scientists to study the atmosphere. The team coupled WACCM with a second model, the Community Aerosol and Radiation Model for Atmosphere, or CARMA, which allows researchers to calculate properties of specific aerosols and which has been under development by a team led by Toon for the past several decades.

Neely said the team used the Janus supercomputer on campus to conduct seven computer “runs,” each simulating 10 years of atmospheric activity tied to both coal-burning activities in Asia and to emissions by volcanoes around the world. Each run took about a week of computer time using 192 processors, allowing the team to separate coal-burning pollution in Asia from aerosol contributions from moderate, global volcanic eruptions. The project would have taken a single computer processor roughly 25 years to complete, said Neely.

The scientists said 10-year climate data sets like the one gathered for the new study are not long enough to determine climate change trends. “This paper addresses a question of immediate relevance to our understanding of the human impact on climate,” said Neely. “It should interest those examining the sources of decadal climate variability, the global impact of local pollution and the role of volcanoes.” While small and moderate volcanoes mask some of the human-caused warming of the planet, larger volcanoes can have a much bigger effect, Toon said.

When Mount Pinatubo in the Philippines erupted in 1991, it emitted millions of tons of sulfur dioxide into the atmosphere that cooled the Earth slightly for the next several years. The research for the new study was funded in part through a NOAA/ ESRL-CIRES Graduate Fellowship to Neely. The NSF and NASA also provided funding for the research project. The Janus supercomputer is supported by NSF and CU-Boulder and is a joint effort of CU-Boulder, CU-Denver and NCAR.

Title:
“Recent anthropogenic increases in SO2 from Asia have minimal impact on stratospheric
aerosol”

Authors:
R. R. Neely III: Department of Atmospheric and Oceanic Sciences, University of Colorado,
Boulder, Colorado, USA; NOAA, Earth System Research Laboratory, Boulder, Colorado, USA;

and Cooperative Institute for Research in Environmental Sciences, Boulder, Colorado, USA;

O. B. Toon: Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder,
Colorado, USA; and Laboratory for Atmospheric and Space Physics, University of Colorado,

Boulder, Colorado, USA;

S. Solomon: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute

of Technology, Cambridge, Massachusetts, USA;

J. P. Vernier: Science Systems and Applications, Inc., Hampton, Virginia, USA; and NASA,

Langley Research Center, Hampton, Virginia, USA;

C. Alvarez: NOAA, Earth System Research Laboratory, Boulder, Colorado, USA; and
Cooperative Institute for Research in Environmental Sciences, Boulder, Colorado, USA;

J. M. English, M. J. Mills, and C.G. Bardeen: Earth System Laboratory, National Center for

Atmospheric Research, Boulder, Colorado, USA;

K. H. Rosenlof and J. S. Daniel: NOAA, Earth System Research Laboratory, Boulder, Colorado,

USA;

J. P. Thayer: Department of Aerospace Engineering Sciences, University of Colorado, Boulder,

Colorado, USA.

Contact information for the authors:
Ryan Neely: Phone: +1 (336) 302-4244, Email: Ryan.Neely@colorado.edu
Brian Toon: Phone: +1 (303) 492-1534, Email: Brian.Toon@colorado.edu

Kate Ramsayer | American Geophysical Union
Further information:
http://www.agu.org

More articles from Earth Sciences:

nachricht NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center

nachricht Steep rise of the Bernese Alps
24.03.2017 | Universität Bern

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>