Dear Andrew,
Those are your claims, not mine. A foam does not have to be air tight,
with a complete 100% cover of the water. Indeed, if one wanted to look
at this idea in more detail, such issues should be addressed. We just
changed the ocean albedo in certain regions without changing anything
else. It is best to change one thing at a time to examine responses.
Alan
Alan Robock, Distinguished Professor
Editor, Reviews of Geophysics
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 1/13/2017 12:46 PM, Andrew Lockley wrote:
To summarise a short side thread between Alan and myself:
Foams would potentially have a broad range of impacts, principally by
limiting gas exchange, eg:
* lower CO2 uptake (leading to higher atmos CO2,esp locally)
* reductions in NPP
* reduced DMS output (esp if bubbles don't burst), etc.
Good opportunity for further study.
Additionally, this reminds me a bit of the "plastic sheets in deserts"
idea, which turned out to be problematic
A
On 13 January 2017 at 13:15, Alan Robock <[email protected]> wrote:
Gabriel, Corey J., Alan Robock, Lili Xia, Brian Zambri, and Ben Kravitz,
2017: The G4Foam experiment: Global climate impacts of regional ocean albedo
modification. Atmos. Chem. Phys., 17, 595-613, doi:10.5194/acp-17-595-2017.
http://www.atmos-chem-phys.net/17/595/2017/
Abstract. Reducing insolation has been proposed as a geoengineering response
to global warming. Here we present the results of climate model simulations
of a unique Geoengineering Model Intercomparison Project Testbed experiment
to investigate the benefits and risks of a scheme that would brighten
certain oceanic regions. The National Center for Atmospheric Research CESM
CAM4-Chem global climate model was modified to simulate a scheme in which
the albedo of the ocean surface is increased over the subtropical ocean
gyres in the Southern Hemisphere. In theory, this could be accomplished
using a stable, nondispersive foam, comprised of tiny, highly reflective
microbubbles. Such a foam has been developed under idealized conditions,
although deployment at a large scale is presently infeasible. We conducted
three ensemble members of a simulation (G4Foam) from 2020 through to 2069 in
which the albedo of the ocean surface is set to 0.15 (an increase of 150 %)
over the three subtropical ocean gyres in the Southern Hemisphere, against a
background of the RCP6.0 (representative concentration pathway resulting in
+6 W m−2 radiative forcing by 2100) scenario. After 2069, geoengineering is
ceased, and the simulation is run for an additional 20 years. Global mean
surface temperature in G4Foam is 0.6 K lower than RCP6.0, with statistically
significant cooling relative to RCP6.0 south of 30° N. There is an increase
in rainfall over land, most pronouncedly in the tropics during the
June–July–August season, relative to both G4SSA (specified stratospheric
aerosols) and RCP6.0. Heavily populated and highly cultivated regions
throughout the tropics, including the Sahel, southern Asia, the Maritime
Continent, Central America, and much of the Amazon experience a
statistically significant increase in precipitation minus evaporation. The
temperature response to the relatively modest global average forcing of
−1.5 W m−2 is amplified through a series of positive cloud feedbacks, in
which more shortwave radiation is reflected. The precipitation response is
primarily the result of the intensification of the southern Hadley cell, as
its mean position migrates northward and away from the Equator in response
to the asymmetric cooling.
--
Alan
Alan Robock, Distinguished Professor
Editor, Reviews of Geophysics
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
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