When developing the A-bomb, the US realized that the plausible size of plutonium bombs (Fat Man) demanded bigger planes to deliver them. This and other needs drove development of the B-29s, which in fact delivered Fat Man. No other airplane could.
When time counts, carving R away from D is generally a mistake. Especially when you don't know the real timescale when you'll need the technology. Gregory Benford On Thu, Aug 4, 2011 at 8:17 PM, Mike MacCracken <mmacc...@comcast.net>wrote: > Hi Ken—If you had said we don’t need a global geoengineering research > program, which is what I think you are talking about, your position would > seem perhaps plausible, although I think we do need to figure out what the > potential is. > > However, I think we do really need to be doing research on the potential > for applying various of the techniques to limit particular regional impacts, > as I suggested in my abstract for the IPCC meeting (copy attached for those > who have not seen it). There are already serious impacts occurring that > might be addressed (the Arctic, some shifts in storm tracks, etc.), and it > seems to me we should be working rapidly to see if there are real > possibilities for taking action. > > Mike MacCracken > > > > > On 8/4/11 7:10 PM, "Ken Caldeira" <kcalde...@carnegie.stanford.edu> wrote: > > I believe my intentionally provocative title will not endear me to some > folks on this email list, so I present it here with some trepidation. > > My guess is those who think of SRM as a fitting subject for research will > find my comments copacetic. Those who think we should be in the phase of > developing deployment systems are likely to be irritated by my remarks. > > A key sentence is: *There appears to be little need for new overarching > research structures or institutions at this time for activities for which > there are no plans for deployment. > * > Also below is another abstract on climate sensitivity with some relevance > to this group. > > ----------- > > *CONTROL ID: * 1207083 > *TITLE: * We Don’t Need a “Geoengineering” Research Program > *PRESENTATION TYPE: * Assigned by Committee (Oral or Poster) > *CURRENT SECTION/FOCUS GROUP: * Union (U) > *CURRENT SESSION: * U20. Geoengineering Research Policy > *AUTHORS (FIRST NAME, LAST NAME): * Ken Caldeira1 > *INSTITUTIONS (ALL): * 1. Dept. of Global Ecology, Carnegie Institution, > Stanford, CA, United States. > *ABSTRACT BODY: * Most approaches commonly labeled as ‘geoengineering’ can > be divided into two categories: approaches that attempt to reduce the change > in atmospheric composition caused by anthropogenic emissions (commonly > labeled CDR, for Carbon Dioxide Removal), and approaches that attempt to > reduce the change in climate caused by changes in atmospheric composition > (commonly labeled SRM, for Sunlight Reflection Methods or Solar Radiation > Management). > > CDR is relatively uncontroversial (apart from ocean fertilization), and the > primary issues are typically cost, effectiveness, local environmental > consequences, and verification. In contrast, SRM has provoked much > controversy, because large-scale SRM deployments necessarily would affect > everyone on this planet. > > Several proposals have been tabled for SRM-specific or > geoengineering-specific research and governance structures, treating SRM or > geoengineering research as a thing apart. We should instead view CDR and SRM > research as part of a broader continuum of activities aimed at understanding > Earth system dynamics and reducing risks associated with climate change. The > scope of existing research efforts should be broadened so that CDR and SRM > approaches are, at this stage in development, treated as an extension of > what we are already doing. > > What is ‘geoengineering research’? A primary need at this time is for > expansion of scope of and funding for existing climate-related research > efforts. For examples: Scientists studying the role of aerosols in clouds or > stratospheric processes can expand the domain of concern to consider effects > of intentionally introduced aerosols (and not just natural aerosols and > aerosols we introduce as a byproduct of civilization’s normal functioning). > Scientists studying effects of land-surface change on global and regional > climates can expand the domain of concern beyond inadvertent effects to > consider effects of land-surface changes undertaken with the intent to > affect these climates. Research programs aimed at removing carbon dioxide > from power plant flue gases can be broadened to consider industrial > approaches to remove carbon dioxide that has already been released to the > atmosphere. There appears to be little need for new overarching research > structures or institutions at this time for activities for which there are > no plans for deployment. > > Defining the scope of reference of ‘geoengineering’ and related terms (eg, > ‘geoengineering experiment’) is a linguistic distraction and a waste of > time. We should focus instead on substantive issues of primary concern. If > our goal is to reduce risk from scientific experiments, then let’s develop > approaches aimed at governing risky experiments. Governance efforts can be > aimed at eliminating unjustified risk independently of whether some people > might want to apply labels like ‘geoengineering’ to those activities. > > We do not need ‘a geoengineering research program’. We need to expand > existing research programs to consider a broader range of activities and > conditions. We do not need efforts to govern ‘geoengineering experiments’ > although we may need efforts to govern scientific experiments that pose > unjustified risks. Let’s focus on gaining knowledge and managing risks, and > not let our brains be addled by emotionally-charged language. > > ------------ > > *CONTROL ID: * 1209062 > *TITLE: * Radiative Forcing and Climate Response: From Paleoclimate to > Future Climate > *PRESENTATION TYPE: * Assigned by Committee (Oral or Poster) [Invited] > *CURRENT SECTION/FOCUS GROUP: * Paleoceanography and Paleoclimatology (PP) > > *CURRENT SESSION: * PP10. Earth System Sensitivity To Radiative Forcings: > Lessons From Earth History > *AUTHORS (FIRST NAME, LAST NAME): * Ken Caldeira1, Long Cao1 > *INSTITUTIONS (ALL): * 1. Dept. of Global Ecology, Carnegie Institution, > Stanford, CA, United States. > *Title of Team: > ABSTRACT BODY: * The concept of radiative forcing was introduced to allow > comparison of climate effects of different greenhouse gases. In the classic > view, radiative forcing is applied to the climate system and the climate > responds to this forcing, approaching some equilibrium temperature change > that is the product of the radiative forcing times the ‘climate sensitivity’ > to radiative forcing. > > However, this classic view is oversimplified in several respects. Climate > forcing and response often cannot be clearly separated. When carbon dioxide > is added to the atmosphere, within days, the increased absorption of > longwave radiation begins to warm the interior of the troposphere, affecting > various tropospheric properties. Especially in the case of aerosols, it has > been found that considering rapid tropospheric adjustment gives a better > predictor of “equilibrium” climate change than does the classic definition > of radiative forcing. > > Biogeochemistry also provides additional feedbacks on the climate system. > It is generally thought that biogeochemistry helps diminish climate > sensitivity to a carbon dioxide emission, since carbon dioxide tends to > stimulate carbon dioxide uptake by land plants and the ocean. However, there > is potential to destabilize carbon locked up in permafrost and at least some > possibility to destabilize methane in continental shelf sediments. > Furthermore, wetlands may provide a significant methane feedback. These and > other possible biogeochemical feedbacks have the potential to greatly > increase the sensitivity of the climate system to carbon dioxide emissions. > > As time scales extend out to millennia, the large ice sheets can begin to > play an important role. In addition to affecting atmospheric flows by their > sheer bulk, ice sheets tend to reflect a lot of energy to space. If carbon > dioxide remains in the atmosphere long enough, there is potential to melt > back the large ice sheets, which would add additional warming to the climate > system. It is likely that these millennial time-scale feedbacks could double > climate sensitivity over that estimated by century-scale models. The > inclusion of these feedbacks may be one reason why paleoclimate studies seem > to indicate a much higher climate sensitivity than do the current generation > of climate models that focus on the physics of century-scale climate change. > > What is the relevance of “equilibrium” climate change on a dynamic planet? > Each gas or aerosol has a different time evolution in the atmosphere, so > the time evolution of the climate response to a methane release, an aerosol > release, and a carbon dioxide release would be very different, even if they > had the same initial radiative forcing (or radiative forcing integrated to > some time horizon, as is done in Global Warming Potential calculations). > Furthermore, the climate response to emissions of these radiatively active > substances will depend, to some extent, on the state of the climate system > into which these substances are introduced. Changes in continental positions > and altitudes can affect snow and glacier feedbacks. Changes in ocean heat > transport can affect cloud properties and the distribution of sea-ice. > > For many applications, it may be more fruitful to focus on the > time-evolution of the climate response to emissions and abandon the concept > of climate sensitivity to radiative forcing. > ___________________________________________________ > Ken Caldeira > > Carnegie Institution Dept of Global Ecology > 260 Panama Street, Stanford, CA 94305 USA > +1 650 704 7212 kcalde...@carnegie.stanford.edu > http://dge.stanford.edu/labs/caldeiralab @kencaldeira > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To post to this group, send email to geoengineering@googlegroups.com. > To unsubscribe from this group, send email to > geoengineering+unsubscr...@googlegroups.com. > 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. 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