http://www.earth-syst-dynam-discuss.net/esd-2016-42/esd-2016-42.pdf
Abstract"The rapid rise of global temperature that began about 1975 continues at a mean rate of about0.18°C/decade, with the current annual temperature exceeding +1.25°C relative to 1880-1920.Global temperature has just reached a level similar to the mean level in the prior interglacial25 (Eemian) period, when sea level was several meters higher than today, and, if it long remains atthis level, slow amplifying feedbacks will lead to greater climate change and consequences. Thegrowth rate of climate forcing due to human-caused greenhouse gases (GHGs) increased over20% in the past decade mainly due to resurging growth of atmospheric CH4, thus making itincreasingly difficult to achieve targets such as limiting global warming to 1.5°C or reducing30 atmospheric CO2 below 350 ppm. Such targets now require “negative emissions”, i.e., extractionof CO2 from the atmosphere. If rapid phasedown of fossil fuel emissions begins soon, most ofthe necessary CO2 extraction can take place via improved agricultural and forestry practices,including reforestation and steps to improve soil fertility and increase its carbon content. In thiscase, the magnitude and duration of global temperature excursion above the natural range of the35 current interglacial (Holocene) could be limited and irreversible climate impacts could beminimized. In contrast, continued high fossil fuel emissions by the current generation wouldplace a burden on young people to undertake massive technological CO2 extraction, if they are tolimit climate change. Proposed methods of extraction such as bioenergy with carbon capture andstorage (BECCS) or air capture of CO2 imply minimal estimated costs of 104-570 trillion dollars40 this century, with large risks and uncertain feasibility. Continued high fossil fuel emissionsunarguably sentences young people to either a massive, possibly implausible cleanup or growingdeleterious climate impacts or both, scenarios that should provide both incentive and obligationfor governments to alter energy policies without further delay." GR A)$104-570 could prove to be a bargain or B) maybe with a serious search for and practice of "technological" CDR options we can drive the cost and risk down and the feasibility up, just as we did with the first $7000 light bulb and the first multi $M computer. And why is risk and uncertain feasibility "unarguably" constrained to "technological" solutions when increasing the terrestrial biosphere CO2 sink (why ignore the ocean biosphere?) doesn't appear to be any non-technological walk in the park either??? Anyway, given our track record on emissions reduction, do we really have the option of not seriously pursuing CDR, whatever the "burden" might look like at this early stage of development? -- 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.
