John I have trouble understanding why you think biochar would reduce the release of black carbon. Biochar IS black carbon and indeed the real world application of biochar appears to release a large quantity of black carbon particles into the air.
A preliminary report from a recent study here in Quebec, Canada reported that about 30% of the biochar (applied in granulated form) blew away during application.. (see Preliminary Evaluation of Biochar in a Commercial Farming Operation in Canada, BlueLeaf Inc, 2009, www.dynamotive.com/wp-content/themes/dynamotive/pdf/BlueLeaf_Biochar_Field_Trial_2008.pdf ) - some amazing images there of airborne biochar! Soil erosion in the months and years after application is a further way in which biochar is likely to become airborne. As you know airborne black carbon has a highly positive radiative forcing because it absorbs solar radiation and reduces albedo. How strong this effect will be depends on the size of biochar particles which are blown away – the lower end of the particle size of charcoal extends into the same range as that of soot, the submicron range. A report by CSIRO states: The size of biochar particles is relatively rapidly decreased, concentrating in size fractions <5μm diameter.” (Biochar, climate change and soil: A review to guide future research, CSIRO, Saran Sohi et al, February 2009, www.csiro.au/files/files/poei.pdf ) Scaled up to a large enough application to be considered geo- engineering there is an argument to be made based on teh Dynamotive trias that applying biochar could actually worsen warming through release of airborne black carbon rather than reduce it.. best Jim Thomas ETC Group. On Dec 14, 2009, at 4:55 PM, John Nissen wrote: > > Hi all, > > Saving the Tibetan glaciers must be high on the list of priorities > for action - but perhaps behind Amazon and the Arctic sea ice > because these have a higher short-term risk. As with the Arctic sea > ice, black carbon and organic carbon (BC and OC) reduction should be > part of the solution. (Explorers have pointed out how grubby the > Greenland glaciers look.) In the quest to reduce global warming > and ocean acidification by carbon dioxide removal, a major > advantage of the biochar process could be the avoidance of BC and OC. > > I've just received this from Jim Hansen: > > --- > Survival of Tibetan Glaciers: New PNAS paper on black soot & > Himalayan glaciers is available at > http://www.pnas.org/content/early/2009/12/07/0910444106.full.pdf+html > > A discussion of it is on the GISS web site at > http://www.giss.nasa.gov/research/briefs/hansen_14/ > --- > > The discussion is as follows: > > Survival of Tibetan Glaciers > By James Hansen — December 2009 > > Glaciers on the Tibetan Plateau, sometimes called Earth's "third > pole", hold the largest ice mass outside the polar regions. These > glaciers act as a water storage tower for South and East Asia, > releasing melt water in warm months to the Indus, Ganges, > Brahmaputra and other river systems, providing fresh water to more > than a billion people. In the dry season glacial melt provides half > or more of the water in many rivers. > > <figure1_s.gif> > Figure 1. Five ice cores were extracted from the indicated > locationson the Tibetan plateau. The white dashed line is the > northerly boundary of the Indian monsoon. (View larger image) > > Tibetan glaciers have been melting at an accelerating rate over the > past decade. Glacier changes depend on local weather, especially > snowfall, so glacier retreat or advance fluctuates with time and > place. Thus it is inevitable that some Tibetan glaciers advance over > short periods, as has been reported. But overall, Tibetan glaciers > are retreating at an alarming rate. > > Global warming must be the primary cause of glacier retreat, which > is occurring on a global scale, but observed rapid melt rates > suggest that other factors may be involved. To investigate the > possible role of black soot in causing glacial melt, a team of > scientists from Chinese research institutes extracted ice cores from > five locations on the Tibetan Plateau (Figure 1). > > Black soot, which includes black carbon (BC) and organic carbon > (OC), absorbs sunlight and can speed glacial melting if BC reaches > values of order 10 ng/g (nanograms per gram) or larger. The ice core > data revealed that BC reached values of 20-50 ng/g in the 1950s and > 1960s for the four stations that are downwind of European pollution > sources. BC and OC amounts decreased strongly in the early 1970s, > probably because of clean air regulations in Europe. > > However, the ice cores also reveal that in the past decade BC and OC > began to increase again, even on the Zuoqiupu glacier (Figure 2), > which is mainly subject to Asian sources. The data suggest that > increased black soot arises from Asian sources, especially the > Indian subcontinent. > > The measured concentrations of BC and OC refer to fresh snow. But as > the snow melts in the spring and summer the black soot > concentrations on the glacier surface increase, because the soot > particles do not escape in the melt water as efficiently as the > water itself. As a consequence, the soot noticeably darkens the > glacier surface during the melt season, increases absorption of > sunlight, and speeds glacier disintegration. > > <figure2_s.gif> > Figure 2.Black carbon (BC) and organic carbon (OC) concentrations in > the Zuoqiupu ice core for the monsoon (June-Sept) and non-monsoon > (Oct-May) seasons, and the annual mean. (View larger image) > > In a new paper by Xu et al., we concluded that black soot is > contributing to the rapid melt of glaciers in the Himalayas. And > continued, "business-as-usual" emissions of greenhouse gases and > black soot will result in the loss of most Himalayan glaciers this > century, with devastating effects on fresh water supplies in dry > seasons. > > But business-as-usual emissions are not inevitable. An alternative > scenario, which stabilizes the glaciers and has other benefits for > global climate and human health, requires a reduction of major human- > made climate forcing agents that have a warming effect — that means > greenhouses gases, especially carbon dioxide, as well as black soot. > > Quantitative policy implications have been defined: coal emissions > must be phased out over the next 20 years, and unconventional fossil > fuels, such as tar sands and oil shale, must remain undeveloped. > Combined with improved agricultural and forestry practices and > reduction of methane and black soot emissions, these actions would > avoid demise of the Tibetan glaciers. > > Not coincidentally, these policy actions are the same as those > required to stabilize Earth's energy balance and keep the climate > near the Holocene climate range in which civilization developed. The > question is whether the global community can exercise the free will > to limit fossil fuel emissions and move to clean energies of the > future — or is it inevitable that all fossil fuels will be burned? > > The conclusion is that prospects for survival of Tibetan glaciers > can be much improved by reducing black soot emissions. The black > soot arises especially from diesel engines, coal use without > effective scrubbers, and biomass burning, including cook stoves. > Reduction of black soot via cleaner energies would have other > benefits for human health and agricultural productivity. However, > survival of the glaciers also requires halting global warming, which > depends upon stabilizing and reducing greenhouse gases, especially > carbon dioxide. > > References > Xu, B, J. Cao, J. Hansen, T. Yao, D.J. Joswia, N. Wang, G. Wu, M. > Wang, H. Zhao, W. Yang, X. Liu, and J. He, 2009: Black soot and the > survival of Tibetan glaciers. Proc. Natl. Acad. Sci., doi: 10.1073/ > pnas.0910444106, in press. > > Hansen, J., Mki. Sato, P. Kharecha, D. Beerling, R. Berner, V. > Masson-Delmotte, M. Pagani, M. Raymo, D.L. Royer, and J.C. Zachos, > 2008: Target atmospheric CO2: Where should humanity aim? Open Atmos. > Sci. J., 2, 217-231, doi:10.2174/1874282300802010217. > > > > -- > > 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 > . Jim Thomas ETC Group (Montreal) [email protected] +1 514 2739994 -- 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]. 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