Raul wrote > But it did have a link to a page with an estimate of carbon in the atmosphere of 720 gigatons: https://en.wikipedia.org/wiki/Atmospheric_carbon_cycle
I guess I ought to be satisfied with that. My estimate is 622 gigatons (6.222E11 ton) which is within 20%. This reassures me that TABULA isn't injecting errors involving many orders of magnitude (e.g. swapping giga for mega). And my model assumes the atmosphere is homogeneous (which it isn't). It also reassures me that my manual method of copying data from web to uuc.ijs isn't losing digits on the way. That would tend to cause tenfold or 100-fold errors. It's that sort of thing I'd mainly like to detect and correct, and if possible guard against. > I did find https://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_atmosphere which indicates that CO2 levels have been relatively low for millenia, but if you go back far enough, they have been much, much higher than what we're seeing now. CO2 concentrations maybe. But actual CO2…? Before the Great Oxygenation Event and the Carboniferous, there was far less oxygen in the atmosphere. Which indicates there wouldn't have been an ozone layer either. Also if there was far less nitrogen too (…where did that all come from?) then CO2 concentrations may have been much higher, without there having been any more atmospheric CO2 than at present. A bit like Mars. The thin atmosphere may have been *mostly* CO2. My guess (with no supporting evidence since I took my degree in Physics) is that CO2 molecules absorb solar photons to make their contribution to the greenhouse effect. That would make global heating depend on the total mass of CO2 and not on its ppm. The Little Ice Age is an intriguing phenomenon, and one suggested cause is provocative (sorry, no links, going from memory here). At its commencement in the 1500s, the Americas suffered massive depopulation due to smallpox and other diseases wiping out some 60 million farmers, whose land reverted to forest. This significantly depressed CO2 levels due to new growth, lowering global temperature until the 1800s, with its massive burning of coal and oil. But determining the actual link between global temperature and CO2 ppm is very much a work-in-progress. Not mine to conjecture here. Except to stress to the hypothetical class of 14-18 year-olds that we don't want to extract *all* the CO2 from the atmosphere. Also that "pre-industrial levels" may prove to be rather too cool for comfort. I'll settle for the 1960's. It was nice back then in England. Though we did get 8ft snowdrifts. Haven't seen more than a smear of snow around here for decades. Ian Clark On Fri, 7 Jun 2019 at 23:30, Raul Miller <[email protected]> wrote: > I was trying to find a profile of how CO2 is distributed with > altitude, and I didn't find that. > > I did find > https://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_atmosphere > which indicates that CO2 levels have been relatively low for millenia, > but if you go back far enough, they have been much, much higher than > what we're seeing now. > > But it did have a link to a page with an estimate of carbon in the > atmosphere of 720 gigatons: > https://en.wikipedia.org/wiki/Atmospheric_carbon_cycle > > CO2 has a molecular weight of 44g/mol and O2 has a molecular weight of > 32g/mol, and C has a molecular weight of 12g/mol. If "carbon" here was > C rather than CO2, that would mean that the change in mass of CO2 > since 1960 would be about > > 80*44*7.2e11%12*410 > 5.15122e11 > > But running through your calculations with the change in mass > contributed by CO2 being 15.049 g/mol (44.01-28.96) gives a total mass > of CO2 change since 1960 of 2.162e11 and I have reason to believe that > that number is too high.. > > So if that 720 gigaton number is right, it probably represents a > weight of CO2 and not a weight of bare C. This gives weight of CO2 > change in atmosphere somewhere near > > 80*7.2e11%410 > 1.40488e11 > > Which better fits what I would expect after thinking about the base > numbers you presented. > > (Assuming the 720 number was correct - it's very easy to make mistakes > and people tend to be sloppy with labels -- assuming that everyone > knows what they were thinking.) > > Thanks, > > -- > Raul > > > On Fri, Jun 7, 2019 at 5:25 PM Raul Miller <[email protected]> wrote: > > > > Ok... working through the numbers. > > > > If 28.96 is the current molecular weight of air, then there is no > > increase from CO2 - instead, you would subtract from that weight to > > find the molecular weight of air in 1960. > > > > If currently, CO2 represents 410ppm of air, then I would expect that > > the total molecular weight of air has a g/mol contribution of > > 44*410%1e6 > > 0.01804 > > > > Note however that when I read up on the molecular weight of air, > > people make pains to mention that their numbers represent the dry > > weight of air, and sometimes talk about how this changes due to H2O. > > It would probably be worth understanding the details they provide as > > there's some subtle things going on here. > > > > Anyways, we don't just add the weight of the CO2 molecules - they are, > > roughly speaking, replacing other averaged molecules. So it's roughly > > the difference between the previous average weight and the CO2 average > > weight that's going to give us the increase in weight. > > > > So the change in atmospheric molecular weight would be less than the > > values currently listed on {4} and {5}. Still... your lines {4} and > > {5} look to be roughly within an order of magnitude or two for the > > change in average molecular atmosphere weight due to increased CO2 > > since 1960. > > > > But then we get to the mass of the atmosphere, and I think you've > > oversimplified: https://en.wikipedia.org/wiki/Atmosphere_of_Earth > > describes the structure of the atmosphere. Since CO2 is heavier than > > some other components (oxygen, nitrogen), it's not going to rise as > > much as the lighter gasses. Still, we could use the number on line > > {7} as an upper bound... > > > > I don't understand your lines {8} and {9} so I'll stop here. > > > > Thanks, > > > > -- > > Raul > > > > On Fri, Jun 7, 2019 at 12:18 PM Ian Clark <[email protected]> wrote: > > > > > > The addons math/tabula and its parent addons math/cal and math/uu have > been > > > largely rewritten and are now far stabler than they were. > > > > > > The main way to get to grips with TABULA is via studying the built-in > > > t-tables ("TABULA-tables") SAMPLE0--SAMPLE9… > > > > > > https://code.jsoftware.com/wiki/TABULA/samples > > > > > > The last one, SAMPLE9, is particularly noteworthy. See this page for > > > details… > > > > > > > https://code.jsoftware.com/wiki/TABULA/samples/cost_to_capture_atmospheric_CO2 > > > > > > Atmospheric CO2 concentration has been rising steadily since 1960, > when it > > > first began to be measured regularly at Mauna Loa, HI. At that time it > > > stood at <320 ppm (parts-per-million). Now it stands at >400 ppm, an > > > increase of over 80 ppm. > > > > > > This observed level of atmospheric carbon is gaining wider acceptance > as > > > having a damaging effect on the world's climate. Whether it does or > not, a > > > British Columbia-based firm called Carbon Engineering has built a > plant to > > > capture CO2 from the atmosphere, at a cost of <$100 per metric ton (100 > > > USD/t). They have attracted $68 million investments from Chevron, > > > Occidental and coal giant BHP. > > > > > > https://www.bbc.co.uk/news/science-environment-47638586 > > > > > > I don't want to take sides over this. Nor to invite the taking of > sides in > > > this thread. Rather it's my aim to develop tools to help the rest of us > > > explore the figures for ourselves, whatever side we're on. Relying on > > > specialists to do the calculations is simply to promote a new world > > > religion, with applied mathematicians as its priesthood. > > > > > > So I thought I'd take Carbon Engineering's current price and use > TABULA to > > > calculate what it would cost to restore atmospheric concentration to > 1960 > > > levels. > > > > > > The cost comes out rather high: around 57 times the projected USA > budget > > > deficit for FY2020, would you believe? > > > > > > This raises vital questions for me: > > > > > > ++ are the input figures reliable? I used Google to track them down, > but > > > have I copied them over correctly? > > > > > > ++ is TABULA doing it right? I'm terrified of orders-of-magnitude > errors, > > > which can so easily arise with a misplaced prefix 'k' (kilo-) or 'G' > > > (giga-). > > > > > > Would anyone fancy checking my calculations? > > > > > > Ian Clark > > > ---------------------------------------------------------------------- > > > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
