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 > > -- > 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 https://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. -- 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 https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
