Ron -
Yes, the longterm effect of biochar on crop productivity is an important consideration. But NPP can't be directly equated with carbon sequestration: most will be re-cycled. What matters is whether soil carbon will be significantly increased, in addition to what's added via biochar - with a reasonable likelihood of stability, under future climate warming (there will be some). Information on such aspects is currently uncertain. Phil Williamson ________________________________ From: [email protected] <[email protected]> on behalf of Ronal W.Larson <[email protected]> Sent: 03 May 2016 21:49 To: Geoengineering Cc: Leo Hickman Subject: Re: [geo] Analysis: How much is the UK relying on 'negative emissions' to meet its climate targets? List cc Leo Hickman 1. This is to comment on the 15 April sixth report at the Carbon Brief site on NETs (mostly on BECCS) as provided to this list last Saturday. http://www.carbonbrief.org/analysis-how-much-is-the-uk-relying-on-negative-emissions-to-meet-its-climate-targets [http://assets.carbonbrief.org/wp-content/uploads/2015/04/stock-old-growth-forest.jpg]<http://www.carbonbrief.org/analysis-how-much-is-the-uk-relying-on-negative-emissions-to-meet-its-climate-targets> Analysis: Is the UK relying on 'negative emissions' to ...<http://www.carbonbrief.org/analysis-how-much-is-the-uk-relying-on-negative-emissions-to-meet-its-climate-targets> www.carbonbrief.org The Paris Agreement on climate change pledges to keep warming “well below 2C” and “pursue... Following that lead, I found an inaccuracy in reasoning that has caused BECCS to be the IPCC and Carbon Brief favorite. The CarbonBrief article references a 2010 report at this URL: http://www.metoffice.gov.uk/media/pdf/l/i/AVOID_WS2_D1_18_20100730.pdf where there is a fairly complete description of biochar (with BECCS and three other types of CDR). But those 2010 authors missed the key feature of biochar: out-year improved NPP benefits - not available with BECCS. 2. The unusual met office idea of biochar is seen in this half-truth sentence about biochar just below Table 8 on p 26 (emphasis added): " In addition compared to using the same biomass in BECCS complaint power stations, the net negative emissions are approximately half. “ 3. I use “half-truth” because this sentence is true only if one stops the analysis period upon placing the biochar in the soil. But it is grossly inaccurate to stop the analysis after placing char in soil - as one is entitled to do for BECCS. The vast majority of biochar publications are devoted to what happens in these out-years. Several biochar meta-studies suggest about a 25% average annual increase of NPP. The largest number I have seen reported is a 4x NPP increase (http://www.mdpi.com/2077-0472/5/3/723/htm). The Terra Preta (biochar) soils of Brazil are reported to (still, after 500 years) double NPP and perhaps triple the soil’s dollar valuation. 4. So I now fear that the Carbon Brief (and many other) comparisons of biochar and BECCS are still based on this non-appreciation of biochar’s out-year ever-increasing negative emissions. Or what am I missing? Ron One other comment below. On Apr 30, 2016, at 12:43 AM, Andrew Lockley <[email protected]<mailto:[email protected]>> wrote: 15 April 2016 8:52 Analysis: Is the UK relying on ‘negative emissions’ to meet its climate targets? ROZ PIDCOCK 04.15.16 <snip all but the last paragraph. I concur; a NET conversation/comparison is overdue> <snip> A conversation overdue Negative emissions technologies, typically BECCS, are now baked into the majority of the scenarios modelled by scientists showing how the world can avoid breaching the 2C limit. These models tend to assume a growing amount of BECCS being deployed globally from the 2040s onwards. The vision for the UK is no different. The CCC has confirmed to Carbon Brief that its own recommended “central scenario” for the UK’s carbon reduction pathway for the decades ahead also assumes a rising amount of BECCS from 2035 onwards. And yet research and development – let alone the commercial upscaling of a demonstration project – is still at a tentative, early stage. Given that there are still large uncertainties about the efficacy and scalability of BECCS – for example, the land-use implications; the choice of bioenergy crop; the safe, available storage of sequestered carbon – it seems that a conversation about negative emissions among scientists, policymakers and the public is overdue. -- 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]<mailto:[email protected]>. To post to this group, send email to [email protected]<mailto:[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.
