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 How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

nachricht Canadian glaciers now major contributor to sea level change, UCI study shows
15.02.2017 | University of California - Irvine

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Multicrystalline Silicon Solar Cell with 21.9 % Efficiency: Fraunhofer ISE Again Holds World Record

20.02.2017 | Power and Electrical Engineering

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>