David Keith

Large animals have substantial carbon emissions. A horse emits an average of two tonnes of carbon emissions a year [1], comparable to that of a car [2]. The full picture gets complicated when you account for vehicle fuel, horse diet, age of vehicle/horse, land use, storage etc. But in general it's fair to say that horses are broadly similar to cars in carbon impact. Compare both with pedal bicycles, where impacts are effectively negligible [3] [1] https://www.yourhorse.co.uk/news/agria-hoofprint-calculator/ [2] https://www.ageco.co.uk/useful-articles/car/what-are-the-co2-emissions… [3] https://keith.seas.harvard.edu/blog/climate-impacts-biking-vs-driving

There's an interesting blog post about this topic: https://keith.seas.harvard.edu/blog/climate-impacts-biking-vs-driving

> They are the most energy efficient form of transportation. If the cyclist is vegan or even an average diet, yes. If the cyclist is paleo, a Prius with 2-person occupancy may actually be more carbon-efficient: https://keith.seas.harvard.edu/blog/climate-impacts-biking-vs-driving

social-engineering, geo-engineering, bio-engineering, post cold war is interestingly fun to witness As early as the 80's for climate engineering https://keith.seas.harvard.edu/files/tkg/files/26.keith_.2000.geoengin… Social engineering became clear during Facebook era and the NSA drama And we now living the bio engineering with the supposed COVID that originated from a supposed lab It reminds me of the mosquito virus in Brazil, that one was suspicious

This has some data: https://keith.seas.harvard.edu/blog/climate-impacts-biking-vs-driving According to Table 1, a meat eating biker emits more CO2, than a double-occupancy Prius. I suspect an EV would completely tip the table in favor of driving.

https://keith.seas.harvard.edu/blog/climate-impacts-biking-vs-driving It doesn't count the manufacturing of each. It's still a valid comparison without it, cause most Americans who have a bike probably also have a car that they need for trips that aren't bike-able, and also cause it helps to separate fixed and marginal costs anyway.

Can you share the source, or the derivation, of the figure for lower bound on extracting CO2? I've had trouble finding the relevant information before. I just searched again and found this: https://keith.seas.harvard.edu/files/tkg/files/116.cherry.heidel.capco…

Link to the original research: https://keith.seas.harvard.edu/publications/climatic-impacts-wind-powe…

It's also interesting to consider this calculation from a carbon emission perspective. From Climate impacts of biking vs. driving : http://www.keith.seas.harvard.edu/blog/climate-impacts-of-biking-vs-dr… If you eat a lot of meat and bike, you could potentially have a bigger carbon footprint than a very fuel efficient vehicle.

Bloomberg News reports[1] that David Keith, a Harvard professor of applied physics and public policy, used to be a solar power skeptic but has reexamined the economics of current solar power and now expects solar power to be important because the economics have changed. Professor Keith's recent essay on solar power, "Cheap Solar Power,"[2] shows the facts and calculations to explain why solar power now beats several other sources of primary electricity for many applications. It is very likely that many industries will move to places where solar power is especially abundant and inexpensive. [1] http://www.bloomberg.com/news/articles/2016-05-04/harvard-scientist-a-… [2] http://www.keith.seas.harvard.edu/blog-1/cheapsolarpower

http://keith.seas.harvard.edu/papers/148.Holmes.Keith.ContactorForLarg… is probably the most advanced current geoengineering proposal currently; the estimated cost is US$60 per tonne of CO₂ removed, proposing to spend C$140M to construct a facility that removes 1 megatonne of CO₂ per year. (One of the authors constructed a small-scale prototype a few years earlier.) If this is correct, a facility to remove all of the 29 billion tonnes of CO₂ emitted by human activities annually would cost C$4 trillion to build (about one month of global GDP) and cost US$1.7 trillion per year to operate (about 5% of global GDP, comparable to the total amount currently being spent on energy.) That is, unless Keith's analysis is wrong, low-risk geoengineering to completely remediate current CO₂ emissions is clearly economically feasible, but not as a skunkworks project — it's a project of a size comparable to the entire existing energy industry, so it would need to be supported by the full influence of the current Establishment. It clearly cannot be done as a market-driven project. These costs, already somewhat pessimistic, should come down a bit as energy becomes cheaper with the proliferation of photovoltaic farms. Indeed, much of the operating cost is the energy used, which would have to come from non-carbon-burning sources. Many of the other geoengineering approaches mentioned — cloud doping, ocean fertilization, stratospheric acid, space mirrors — would probably be…

Unfortunately The Paper [1] is closed source. I can't find much information; no comparison with existing, chemical synfuels processes (like methanol via syngas [CO]). There's a serious problem with the general idea: "clean" CO2 is hard to get. You can get concentrated (>10%) CO2 streams from a power plant, which could work for synfuels, but ultimately that's still transferring fossil carbon into the air (if more efficiently). The "nice" idea is to capture CO2 from the atmosphere (I think they are implying this?); this gives you a carbon-neutral cycle (CO2 => fuel => CO2). This is difficult because CO2 in the air is so dilute -- 0.04% vol., or 0.8 grams/meter^3. Can you get CO2 from the air? There's research in this; the APS assessment [2] thinks it could be done at around $600-800/tCO2, which translates to e.g. $7/gallon gas equivalent of methanol, just for the carbon. The process uses an inorganic base (NaOH) to scrub CO2, so maybe you'd think you could genetically-engineer superbacteria to do better. But the absorbent is not the bottleneck -- it's the extreme volume and flow of air that needs to be brought to the absorbent, over an insanely large surface area. The scale is visualized in [2] figure 1.2 (http://i.imgur.com/Y0D2f.png): a very small, 10^6 ton CO2/year capture plant is designed as a 1km * 1km grid of rows of giant, sucking fans. And the NaOH process isn't particularly inefficient -- it captures 50% of the CO2 in air. Some more about atmosperic CO2 capture…