I don’t think that the paper is so excellent. They forgot to mention that nature has always removed almost all the CO2 that was emitted by volcanoes by the weathering of basic minerals, in particular olivine. That CO2 was sustainably stored in limestones, which contain about 1 million times more safely stored CO2 than a;ll the seas, the atmosphere and the biosphere together. If you apply enhanced weathering, these Boysen limits disappear, Olaf Schuiling
From: geoengineering@googlegroups.com [mailto:geoengineering@googlegroups.com] On Behalf Of Ronal W. Larson Sent: vrijdag 19 mei 2017 1:20 To: Ronal W. Larson Cc: Geoengineering; Andrew Lockley Subject: Re: [geo] Potentials, consequences and trade-offs of terrestrial (CDR): Strategies for climate engineering List: This is a followup. Yesterday, a third paper based on Dr. Boysen’s thesis was released - to be found (no-fee) at http://onlinelibrary.wiley.com/doi/10.1002/2016EF000469/full. The full title and author list is: Citation: Boysen, L. R., W. Lucht, D. Gerten, V. Heck, T. M. Lenton, and H. J. Schellnhuber (2017), The limits to global-warming mitigation by terrestrial carbon removal, Earth’s Future, 5, dos:10.1002/2016EF000469. I like this paper. The final sentence of the Summary states: “Although we find that this strategy of sequestering carbon is not a viable alternative to aggressive emission reductions, it could still support mitigation efforts if sustainably managed.” I think there has been too little credit given to the added out-year benefits of biochar, so I put this paper into a pro-CDR category - and hope for more modeling efforts of this high caliber. Ron On Apr 25, 2017, at 9:38 PM, Ronal W. Larson <rongretlar...@comcast.net<mailto:rongretlar...@comcast.net>> wrote: List: cc Andrew The cite given below by Andrew is for a 20 MB full thesis - which my server couldn’t handle. I’d greatly appreciate anyone able to suggest a work-around so we can all view the full document. The author, (now Dr.) Lena Boysen alerted me to this non-fee initial (out of 3) part of the thesis: “Impacts devalue the potential of large-scale terrestrial CO2 removal through biomass plantations” http://iopscience.iop.org/article/10.1088/1748-9326/11/9/095010/meta;jsessionid=325AACE0FC1BCA551F5ABFF7BC15679E.ip-10-40-2-108 I still need to re-read it, but I am impressed by the depth and breadth of what I have read so far. A little on biochar (fortunately “a little”, as I think biochar doesn’t suffer from the concerns she raises [see final sentence in the abstract below]) - but mostly this seems more related to BECCS (as in AR5). Much larger land areas and annual sequestration possibilities discussed than normal. Dr. Boysen has given us much to discuss - from the point of view of land-use modeling - mostly for RCP4.5. Ron On Apr 24, 2017, at 4:04 AM, Andrew Lockley <andrew.lock...@gmail.com<mailto:andrew.lock...@gmail.com>> wrote: Boysen Potentials, consequences and trade-offs of terrestrial (CDR): Strategies for #climate engineering https://t.co/knfig3fTn9 Abstract For hundreds of years, humans have engineered the planet to fulfil their need for incre- asing energy consumption and production. Since the industrial revolution, one conse- quence are rising global mean temperatures which could change by 2◦C to 4.5◦C until 2100 if mitigation enforcement of CO2 emissions fails.To counteract this projected glo- bal warming, climate engineering techniques aim at intendedly cooling Earth’s climate for example through terrestrial carbon dioxide removal (tCDR) which is commonly per- ceived as environmentally friendly. Here, tCDR refers to the establishment of large-scale biomass plantations (BPs) in combination with the production of long-lasting carbon products such as bioenergy with carbon capture and storage or biochar. This thesis examines the potentials and possible consequences of tCDR by ana- lysing land-use scenarios with different spatial and temporal scales of BPs using an advanced biosphere model forced by varying climate projections. These scenario simu- lations were evaluated with focus on their carbon sequestration potentials, trade-offs with food production and impacts on natural ecosystems and climate itself. Synthesised, the potential of tCDR to permanently extract CO2 out of the atmos- phere is found to be small, regardless of the emission scenario, the point of onset or the spatial extent. On the contrary, the aforementioned trade-offs and impacts are shown to be unfavourable in most cases. In a high emission scenario with a late onset of BPs (i.e. around 2050), even unlimited area availability for tCDR could not reverse past emissions sufficiently, e.g. BPs covering 25% of all agricultural or natural land could delay 2100’s carbon budget by no more than two or three decades (equivalent to ≈550 or 800 GtC tCDR), respectively. However, simultaneous emission reductions and an ear- lier establishment of BPs (i.e. around 2035) could result in strong carbon extractions reversing past emissions (e.g. six or eight decades or ≈500 or 800 GtC, respectively). In both cases, land transformation for tCDR leads to high “costs” for ecosystems (e.g. biodiversity loss) and food production (e.g. reduction of almost 75%). Restricting the available land for BPs by these trade-off constraints leaves very small tCDR poten- tials (well below 100 GtC) despite a near-future onset (in 2020). Similarly, simulated tCDR potentials on dedicated BP areas defined in a commonly used and published low emissions scenario stay below the aimed values using current management practices. Some potential may lie the reduction of carbon losses from field to end-products, new management options and the restoration of degraded soils with BPs. This thesis contradicts the assumption that tCDR could be an effective and envi- ronmentally friendly way of complementing or substituting strong and rapid mitigation efforts. -- 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 geoengineering+unsubscr...@googlegroups.com<mailto:geoengineering+unsubscr...@googlegroups.com>. To post to this group, send email to geoengineering@googlegroups.com<mailto:geoengineering@googlegroups.com>. Visit this group at https://groups.google.com/group/geoengineering. 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