Any option involves pros and cons, but it is curious to refer to SAI as neither scalable nor reversible. For scalability, it is essentially the only option we know for sure can scale (as your own email suggests by choice of defining success). For reversibility, if you stop putting aerosols in, the effect goes away. Note that if you’ve been doing it long enough for it to matter, then the time constant of the effect going away is going to be mostly dominated by the response times of the climate system, not by the residence time of the aerosols. So it’s true that the termination shock would be a bit more abrupt for MCB than for SAI, but that’s probably not that big a deal. It would seem to me that if one wants to do a comparison between methods, then one ought to actually evaluate their impacts rather than arbitrarily dismissing them by throwing incorrect adjectives around.
From: [email protected] <[email protected]> On Behalf Of Oliver Sent: Thursday, November 11, 2021 5:06 AM To: [email protected] Cc: [email protected]; [email protected] Subject: Re: [geo] Exploration of a novel geoengineering solution: lighting up tropical forests at night Hello Michael, Absolutely agreed on your point about rich desert ecology, and that we need to be humble in the face of the complex earth system. In all likelihood, all goeengineering methods are in some way 'simplistic' because they intervene in processes which have evolved over time, in symbiosis with the Earth system's changing state, as driven from the outside by Milankovich cycles and tectonic processes. However, we are at the point now where we are looking for 'least worst' solutions rather than magic bullets which moderate global forcing with little impact on important ecosystem services, as they probably don't exist. Hence, there is a risk calculation where we may need to accept a limited amount of damage to achive the greater good, i.e., a reduction in glocal forcing to preserve as many ecosystems as possible. Saving every desert ecosystem with little biomass may be a luxury we cannot afford. Furthermore, I would argue that we need to shift away from a 'magic bullet' geoengineering paradigm to one which advocates a diverse mix or 'package' of smaller scale solutions which all together have a synergetic impact on forcing, e.g., a mixture of regional aforestation, white roofs, marine cloud brightening, cirrus thinning, enhanced weathering, CCS and so on (these must be scaleable, sustainable and quickly reversible). By doing this, we retain the option to assess these pathways and then emphasize or deemphasize individual options over time as their impacts on society and environment become apparent. In consequence, one must redefine 'geoengineering' in a way that removes the requirement that any one single method needs to have a measurable impact on global forcing. An example of this is instead is to call methods 'regional geoengineering'. We would also need to refine our notion of what success is for these solution. In other words, a reduction in forcing of 0.01 W m-2 might be called a success, instead of requiring 0.2 W m-2 or similar as a benchmark (arbitrary numbers). Research would need to reflect this complex mix instead of writing paper after paper on the impacts of e.g. global reforestation alone, or global SAI alone, and so on. However, in my opinion SAI should be thought of in a different catgory to geoengineering. Recreating Pinatubo or Krakatoa is neither scaleable, or easily reversible and hence gives the rest of geoengineering proposals a bad name. On the other hand, marine or cirrus cloud seeding and its meteorological impacts can be stopped much more rapidly (of course, feedbacks with vegetation may be much slower). Regards Oliver -- Dr. Oliver Branch Inst. for Physics and Meteorology (120) University of Hohenheim Garbenstr. 30 D-70599 Stuttgart phone: 0711 - 459 -23132 On 10/11/2021 23:52, Michael Kleeman wrote: Irrespective of the benefits or risks of solar radiation management the ecosystem impacts are real. And for reference deserts have a rich life and are sensitive to light, pressure, vibration and general disruption. Different from forested area but no less alive in their own way We need to be humble in the face of complex systems and not propose simplistic interventions that make assumptions based on too little data. On Nov 10, 2021, at 12:55 PM, Oliver <[email protected]><mailto:[email protected]> wrote: Do you not think this is rather a kneejerk reaction? Is it as awful an idea as injecting thousands of tons of silver dioxide or similar materials into the stratosphere? An action which will influence the global weather for a minimum of 4 years if done at the equator. Now that is a truly awful idea. On the other hand, I would say that the consequences of lighting forests are more predictable, and the idea is scalable and can be stopped easily. In any case perhaps with some adjustment the idea may have merit. How about lighting desert plantations in marginal areas, not in pristine forest where delicate flora and fauna exist. Solar power can recharge batteries or lighting. Or extreme northern boreal forest, where few other animal forest species exist in large numbers. In areas of low radiation such a light boost may be just what it takes to increase productivity. Oliver -- Dr. Oliver Branch Inst. for Physics and Meteorology (120) University of Hohenheim Garbenstr. 30 D-70599 Stuttgart phone: 0711 - 459 -23132 On 10/11/2021 17:52, Jessica Gurevitch wrote: This is a truly awful idea. These authors are apparently totally ignorant of, or uninterested in, the natural world of ecological communities and of biodiversity. Many, many organisms in tropical forests depend on nighttime darkness to survive and function. The "unintended (or uninformed) consequences" of this are horrifically mind blowing. Jessica ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Jessica Gurevitch Distinguished Professor and Co-Chair Department of Ecology and Evolution Stony Brook University Stony Brook, NY 11794-5245 USA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ On Wed, Nov 10, 2021 at 1:54 AM Geoeng Info <[email protected]<mailto:[email protected]>> wrote: https://esd.copernicus.org/preprints/esd-2021-85/ Exploration of a novel geoengineering solution: lighting up tropical forests at night Xueyuan Gao, Shunlin Liang, Dongdong Wang, Yan Li, Bin He, Aolin Jia Abstract. Plants primarily conduct photosynthesis in the daytime, offering an opportunity to increase photosynthesis and carbon sink by providing light at night. We used a fully coupled Earth System Model to quantify the carbon sequestration and climate effects of a novel carbon removal proposal: lighting up tropical forests at night via lamp networks above the forest canopy. Simulation results show that additional light increased tropical forest carbon sink by 10.4 ± 0.05 petagrams of carbon per year during a 16-year lighting experiment, resulting in a decrease in atmospheric CO2 and suppression of global warming. In addition, local temperature and precipitation increased. The energy requirement for capturing one ton of carbon is lower than that of Direct Air Carbon Capture. When the lighting experiment was terminated, tropical forests started to release carbon slowly. This study suggests that lighting up tropical forests at night could be an emergency solution to climate change, and carbon removal actions focused on enhancing ecosystem productivity by altering environmental factors in the short term could induce post-action CO2 outgassing. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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