Len and list:
Thanks for continuing the discussion on the Davis etal paper. It would appear that we are in substantial agreement. One place I would disagree with your draft article (cite given below, p4) is where you say: "Anaerobic conversion of 'bio-waste' to 'bio-char', and burying it in soil has promise, but is very difficult to manage efficiently on a large-enough scale." I believe you are seriously misreading that technology's growth path - with much larger corporate investments than I have seen in any other geoengineeering area - either SRM or CDR. I think the profit motive, coupled with a lot of private citizen and soil scientist enthusiasm will drive biochar faster than you are apparently projecting. The drive is much more on the energy and soil sides than the atmospheric side, but there is zero conflict between the soil and atmosphere motivations. Everything I read in your paper, which nicely supports the concept of many (>8?) wedges of CDR available from the biosphere, will go well with biochar. I would like your opinion on whether the Davis paper is now covering anything you have written. To others, Dr. Ornstein has a very nice presentation in his paper (cited below) on the concept of "draining the bathtub" - that I have yet to discern as being central in the Davis paper . As a minor editorial comment, I urge replacing "bio-char" in your paper with "biochar" . The former is not picked up in searches for the much more common latter form. I need to do more research on both of the biomass proposals in your cited draft. Re bringing water to the desert for new forests, my previous reading put some very high prices on this approach. I shall re-read your earlier papers on this topic, but fear the huge investments needed are gong to make this one a tough sell. But more irrigation is clearly a needed investment - maybe more for annually harvested grasses than forests.. Before bringing water to the Sahara, we can do a lot with land much closer to the oceans. Re RIL and SENCH, these also sound worthy of more R&D on our part. For reasons of largest possible NPP, I lean towards stands of something that can be coppiced annually - perhaps miscanthus. I agree we need the extra wedges possible with what you are proposing here - but think we have lower cost alternatives available today - when so little CDR is taking place anyway.. Ron ----- Original Message ----- From: "[email protected] Ornstein" <[email protected]> To: [email protected] Sent: Sunday, January 13, 2013 9:35:18 PM Subject: [geo] Re: Those darn wedges Ron: See "Thermostatting the Earth" http://www.pipeline.com/~lenornst/ThermostattingTheEarth.pdf There I note that virtually all discussions of dealing with AGW virtually completely ignore the potential for very large contributions to lowering the atmospheric concentration of CO2 to pre-industrial levels - that is by 8 or more wedges - by applying Irrigated Afforestation o! large, subtropical deserts, and by sustainable, eco-neutral, conservation harvest (SENCH) in 'virgin' tropical forests (both open source 2009 papers on these subjects are cited therein)! The general subject of large scale drawdown of atmospheric CO2 needs to be brought into all discussions of how to deal with AGW! Len Ornstein On Friday, January 11, 2013 1:56:27 PM UTC-5, Greg Rau wrote: Anyone for GE? - Greg Environmental Research Letters Volume 8 Number 1 Steven J Davis et al 2013 Environ. Res. Lett. 8 011001 doi:10.1088/1748-9326/8/1/011001 Rethinking wedges OPEN ACCESS Steven J Davis 1,2 , Long Cao 2,3 , Ken Caldeira 2 and Martin I Hoffert 4 Show affiliations [email protected] [email protected] [email protected] [email protected] 1 Department of Earth System Science, University of California, Irvine, Irvine, CA 92697, USA 2 Department of Global Ecology, Carnegie Institution of Washington, Stanford, CA 94305, USA 3 Department of Earth Sciences, Zhejiang University, Hangzhou, Zhejiang Province, 310027, People's Republic of China 4 Department of Physics, New York University, New York, NY 10003, USA Tag this article Full text PDF (586 KB) Abstract Stabilizing CO 2 emissions at current levels for fifty years is not consistent with either an atmospheric CO 2 concentration below 500 ppm or global temperature increases below 2 °C. Accepting these targets, solving the climate problem requires that emissions peak and decline in the next few decades, and ultimately fall to near zero. Phasing out emissions over 50 years could be achieved by deploying on the order of 19 'wedges', each of which ramps up linearly over a period of 50 years to ultimately avoid 1 GtC y -1 of CO 2 emissions. But this level of mitigation will require affordable carbon-free energy systems to be deployed at the scale of tens of terawatts. Any hope for such fundamental and disruptive transformation of the global energy system depends upon coordinated efforts to innovate, plan, and deploy new transportation and energy systems that can provide affordable energy at this scale without emitting CO 2 to the atmosphere. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To view this discussion on the web visit https://groups.google.com/d/msg/geoengineering/-/sDxBIbyNf0IJ . To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
