Greg and list (adding 4 ccs [authors]) 1. Thanks for bringing this new wedge paper to our attention. A short informal version - comments by the lead author (Davis) - are also at: http://ess.uci.edu/news/news-11012
2. My man concern on the article is that the concept of wedges providing carbon negativity or CDR is barely mentioned. The only exception I found (emphasis added) is:: " Most model scenarios that allow CO2 concentrations to stabilize at 450 ppm entail negative carbon emissions , for example by capturing and storing emissions from bioenergy [11]." [11] Clarke L et al 2009 International climate policy architectures: overview of the emf 22 international scenarios EnergyEcon. 31 S64 I presume that there is agreement that a natural metric for CDR is a wedge (Giga tonnes C/yr)? I don't know this cite, but it doesn't sound like one for bioenergy . The term "decarbonization" and power/energy are often used - and I don't associate these with CDR. Most CDR proponents don't think in terms of stopping at 450 ppm. 3. Thus, this is to ask the authors if the paper's intent was or was not to include CDR as a wedge concept. The final conclusion could/should be more positive if CDR were fully analyzed. For instance, Jim Hansen employs afforestation in multi-wedge amounts to achieve substantial CDR towards 350 ppm. 4. On this list, I think it also important to have some discussion on how SRM fits into the paper's conclusions. Needless to say, the four authors' thoughts on the practicality of large amounts of CDR should be impacting their thoughts on SRM. So, briefly - was CDR being modeled in this paper? If so, how can we determine the magnitudes assumed? Nothing on this in the Suppemental Information. Ron Ron ----- Original Message ----- From: "Greg Rau" <[email protected]> To: [email protected] Sent: Friday, January 11, 2013 11:56:27 AM Subject: [geo] Those darn wedges 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 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.
