Dear Ken,
Yes. The Aurora study and ours were both theoretical studies about the
cost of taking sulfur to the stratosphere. But the technology does not
exist. There are no planes with sulfur tanks and sprayers. There are
no hoses and balloons. There is no artillery. If you wanted to start
stratospheric geoengineering tomorrow you could not do it.
In theory, such technology could be constructed, but the procedures for
dealing with very dangerous sulfur compounds, SO2 or H2S or sulfuric
acid have not been developed. Nozzles to spray the chemicals and try to
produce aerosols of the desired size have not been developed. There is
no supply chain for the different sulfur compounds you might want to use
ready to be loaded onto planes. And there is certainly no squadron of
planes waiting to do this. That is what I meant.
By the way, there actually were a few errors in the story. The Pinatubo
cloud lasted about 2 years, not 2 months. And I disagree with Lynn's
characterization of CO2 emission as geoengineering. Geoengineering
requires intent to control climate.
Our study was:
Robock, Alan, Allison B. Marquardt, Ben Kravitz, and Georgiy Stenchikov,
2009: The benefits, risks, and costs of stratospheric geoengineering.
/Geophys. Res. Lett./, *36*, L19703, doi:10.1029/2009GL039209.
//http://climate.envsci.rutgers.edu/pdf/2009GL039209.pdf
Alan
Alan Robock, Distinguished Professor
Editor, Reviews of Geophysics
Director, Meteorology Undergraduate Program
Department of Environmental Sciences Phone: +1-848-932-5751
Rutgers University Fax: +1-732-932-8644
14 College Farm Road E-mail: [email protected]
New Brunswick, NJ 08901-8551 USA http://envsci.rutgers.edu/~robock
http://twitter.com/AlanRobock
Watch my 18 min TEDx talk at http://www.youtube.com/watch?v=qsrEk1oZ-54
On 9/8/2013 10:57 PM, Ken Caldeira wrote:
Jeff Bezos's rag has a story about "geoengineering":
Alan, were you quoted correctly here? Did you really say "No
technology exists to do solar radiation management"? If so, how do
you square this position with the results of the Aurora report
(http://www.keith.seas.harvard.edu/Misc/AuroraGeoReport.pdf)
Justin McClellan, David W Keith, Jay Apt. (2012). Cost analysis of
stratospheric albedo modification delivery systems. /Environmental
Research Letters/, doi:10.1088/1748-9326/7/3/034019. (PDF
<http://www.keith.seas.harvard.edu/papers/159.McClellan.2012.CostAnalysisOfStratosp.e.pdf>)
http://iopscience.iop.org/1748-9326/7/3/034019
Note that the abstract of this paper states "We evaluate existing
aircraft cost of acquisition and operations, ... " This does not
sound like "No technology exists ..."
http://www.washingtonpost.com/national/health-science/scientists-studying-solar-radiation-management-as-a-way-to-cool-planet/2013/09/08/cfb9def8-170c-11e3-be6e-dc6ae8a5b3a8_story.html
Scientists studying solar radiation management as a way to cool planet
Arlan N.Aeg/AFP/Getty Images - This picture, taken June 12, 1991,
shows a giant mushroom cloud of steam and ash exploding out of the
Mount Pinatubo volcano during its eruption as seen from inside a
former U.S. air base in the Philippines.
By Lenny Bernstein
<http://www.washingtonpost.com/lenny-bernstein/2011/02/24/ABHUJyI_page.html>,
Updated: Sunday, September 8, 7:25 PM E-mail the writer
<mailto:[email protected]?subject=Reader%20feedback%20for%20%27Scientists%20studying%20solar%20radiation%20management%20as%20a%20way%20to%20cool%20planet%27>
The 1991 eruption of Mount Pinatubo
<http://pubs.usgs.gov/fs/1997/fs113-97/>, a volcano in the
Philippines, blasted enough fine particles and sulfur dioxide gas into
the atmosphere to envelop the Earth in a high-altitude cloud for the
better part of two months. When scientists checked in 1992, they
determined that the cloud had deflected enough sunlight to cool the
planet by about 1 degree.
Now, with the planet warming inexorably and the threat of long-term
climate change looming, some experts are wondering whether the time
may one day come when humans want to deliberately attempt such "solar
radiation management." The idea is being investigated by, among
others, the National Academy of Sciences, which is conducting research
funded by the CIA, NASA and the National Oceanic and Atmospheric
Administration. The academy has invited experts to discuss the idea
Tuesday.
But even considering such an endeavor raises many practical,
economical, political and ethical questions, experts said, including
what the effects on global and regional climates would be.
"I'm not in favor of doing it today. I'm agnostic about whether we
should ever do it," said Alan Robock, a distinguished professor of
environmental sciences at Rutgers University. "We don't have enough
information and, in any case, we don't have the technology."
But Robock said additional research should be conducted despite
concerns that determining the feasibility of such "geoengineering"
might encourage a government or wealthy individual to try it, and
could lessen efforts to curb greenhouse gases such as carbon dioxide.
"I don't think you can just ignore it and pretend it doesn't exist,
and sometime in the future, when someone becomes scared and wants to
do it, they don't even know whether they can do it," he said.
Mount Pinatubo's eruption sent an estimated 20 million tons of sulfur
dioxide and ash
<http://earthobservatory.nasa.gov/Features/Volcano/>into the
stratosphere, where the sulfur dioxide formed sulfate particles that
reflected sunlight back into space. Some believe this could be done
effectively and at relatively low cost by injecting an aerosol of
sulfur dioxide or some other gas into the atmosphere over a period of
time, either from aircraft or powerful missiles.
Ken Caldeira, a senior investigator for the Carnegie Institution for
Science, told a congressional committee in 2009 that such methods are
inexpensive, can be deployed quickly, and probably would cool the
Earth effectively. He stressed, however, that it is more important to
address the root cause of global warming by reducing the production of
greenhouse gases. Carnegie will host a panel discussion on the subject
Tuesday evening.
But Robock, in an interview, said the effort is "not feasible. No
technology exists to do solar radiation management. There are no
airplanes, or hoses or missiles that exist to get sulfur up into the
stratosphere."
A more limited variation of the idea is to spray sea salt into clouds
over the ocean, probably from ships, to form more water droplets in
the clouds and make them whiter, said Lynn Russell, a professor of
atmospheric chemistry at the Scripps Institute of Oceanography, which
is part of the University of California at San Diego. The brighter
clouds would reflect more sunlight.
_______________
Ken Caldeira
Carnegie Institution for Science
Dept of Global Ecology
260 Panama Street, Stanford, CA 94305 USA
+1 650 704 [email protected]
<mailto:[email protected]>
http://dge.stanford.edu/labs/caldeiralab@kencaldeira
--
You received this message because you are subscribed to the Google Groups
"geoengineering" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/geoengineering.
For more options, visit https://groups.google.com/groups/opt_out.
