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CO2 direct air capture

Direct air capture using temperature-swing solubility
  (+3)
(+3)
  [vote for,
against]

Carbon dioxide capture from the air is a hot topic at the moment.

The two current technologies (amine-based or carbonate based) use either expensive synthetic chemicals to promote solvation, or energy-intensive chemicals to react with CO2.

Cost of CO2 direct-air-capture looks to be around £600 per tonne. To be a feasible climate change mitigation tool, this needs to come down to around £100 per tonne.

CO2’s solubility in water is strongly temperature dependent- much more so than nitrogen or oxygen. So it should be possible to extract CO2 from air using temperature cycles.

The problem is that CO2 solubility is related to partial pressure, and the concentration in the atmosphere is low (400 ppm)

Rather than a single cycle with expensive chemicals, a multi-stage thermal process with just water will enable separation of CO2 from air.

The first stage starts with chilled (say 10C) pure water. Sprayed in air, it will dissolve CO2, nitrogen and oxygen (and trace gasses) proportional to their partial pressure and solubility at that temperature. CO2, despite it’s low partial pressure, will dissolve preferentially over the other gasses.

The water/gas solution flows through a heater, where the gassed are released from solution. The water flows on to be chilled and re-circulated. The gas mixture, somewhat enriched in CO2, flows to the second stage.

The second stage repeats the process, again enriching the CO2 fraction of the resulting gas. The water is again cycled.

My calculations suggest that for 60 degree thermal cycles, CO2 is 99% after 4 cycles.

To increase efficiency, heat is recovered across heating/cooling cycles (using standard heat exchangers)

This would still require high flow-rates and heating rates in the first stage. Siting a plant next to a hydroelectric dam might make sense.

Frankx, Oct 01 2019

“Diesel made from CO2” https://www.bbc.com...nvironment-47638586
Greenwashing and environmental spin. Yes, if you extract CO2 from the atmosphere you can make hydrocarbon fuels from it. That’s not new. [Frankx, Oct 02 2019]

Differential solubility vacuum pump my me. An idea that was on my list for a couple of years; I was reminded to post it by this idea, which is related. [notexactly, Oct 03 2019]

xkcd - Earth temperature timeline https://xkcd.com/1732/
If you can't trust xkcd, who can you trust? [Loris, Oct 03 2019]

Berkeley Earth http://berkeleyeart...-temperatures-2017/
Independent analysis [Frankx, Oct 04 2019]

Temperature - CO2 correlation http://berkeleyeart...h-forcing-small.png
Berkeley Earth Temp/CO2 correlation, with 95% confidence intervals [Frankx, Oct 04 2019]

Metal Thunberg https://youtu.be/VVBy33ezwUc?t=58
[bigsleep, Oct 07 2019]

Black! https://www.youtube...watch?v=IIW9sL-Yf6Q
[bigsleep, Oct 07 2019]


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       //Cost of CO2 direct-air-capture looks to be around £600 per tonne.// I am prepared to sell you acorns at considerably less than £600 each.
MaxwellBuchanan, Oct 01 2019
  

       //acorns//   

       How about Juglans & Castanea sativa instead, edible too.   

       I know you 'can' eat acorns but not needing to bleach the nut first is a definite advantage.
Skewed, Oct 01 2019
  

       How does the energy cost per tonne look compared to the current processes? You should be able to do at least a rough calculation.
Even if you're using 'green' energy, the process needs to be as efficient as possible to function at scale.
  

       To understand why CO2 dissolves in the chilled water preferentially, I looked into it - here is some data for those interested:   

       gas, solubility at 10 degC, solubility at 60 degC
CO2, 2.5, 0.6
O2, 0.055, 0.023
N2, 0.028, 0.011
  

       These are estimates read from graphs, the units are grams gas per kilogram water. Also, these are for pure gasses at 1 atmosphere. One needs to consider only the fraction of the gas in a mixture.   

       The solubility graphs are steeper in the range 0..20 degrees C, particularly for CO2. It might make sense to chill the water (and incoming air) a bit further and heat less (for CO2, 0 degrees is 3.4 g/kg, and 40 degrees is 1.0 g/kg).   

       Given that electricity can be transported over some distance with only limited losses, it might make more sense to site the plant next to a source of diffuse CO2 - like a cowshed, or even combine it with ventilation for large buildings of people. This could increase the starting concentration a thousand-fold.
Loris, Oct 02 2019
  

       //site the plant next to a source of diffuse CO2// It might be logistically simpler to just bring coal or oil near to the plant and burn it there.
MaxwellBuchanan, Oct 02 2019
  

       // To increase efficiency, heat is recovered across heating/cooling cycles (using standard heat exchangers) //   

       Not only can you use heat exchangers to preheat/prechill and thereby reduce the requirements on the thing pushing heat in/pulling heat out, I believe you can also recycle that heat, by pumping it from a place you want to chill to a place you want to heat, and then letting the process gas transfer that same heat the other way, like a dehumidifier does.
notexactly, Oct 02 2019
  

       [MB] I agree that our number one priority in not f**ing up our lovely planet is to stop extracting geological carbon, burning it, and releasing CO2 to atmosphere. And that photosynthesis is a beautiful and brilliant way of capturing CO2 from the atmosphere- astonishingly good, given the low (400ppm) concentration - so I have ideas to post about biomass and sequestration.   

       This idea is partly in response to the recent “magic solution” press [link] touting a “new method” to extract CO2 from the atmosphere and convert it into fuel. Good marketing/greenwashing by the oil industry:   

       “It has now been boosted by $68m in new investment from Chevron, Occidental and coal giant BHP.   

       But climate campaigners are worried that the technology will be used to extract even more oil”   

       However. We face dramatic social change in response to our duty to look after our planet.   

       Our transport systems are heavily dependent on liquid hydrocarbon fuels. We can synthesise fuels from CO2 from the air (wasteful and frankly ridiculous that is, in energy terms), or we can try to convert our transport infrastructure to zero- emission energy very quickly.
Frankx, Oct 02 2019
  

       Apparently Tesla's electric semi trucks are out and in use now.
notexactly, Oct 02 2019
  

       //We face dramatic social change in response to our duty to look after our planet.//   

       That is undoubtedly true. For one thing, at some point when the bubble bursts all the climate "scientists" will be lynched. Greta Bloody Thunberg will have to watch out too.
MaxwellBuchanan, Oct 02 2019
  

       //at some point when the bubble bursts all the climate "scientists" will be lynched. Greta Bloody Thunberg will have to watch out too.//   

       Max, your views are often interesting and I hope you will expand on that.
Loris, Oct 03 2019
  

       [MB] - yes, what Loris said.
Frankx, Oct 03 2019
  

       //To be a feasible climate change mitigation tool, this needs to come down to around £100 per tonne [CO2].//   

       This equates to carbon capture of £27 ($33) per tonne by weight of carbon in CO2. Coincidentally $33 is the bulk price of coal per tonne, so the breakpoint would imply simply not digging up more coal as a method of carbon capture. I'm sure we can make use of the O2 bit.
bigsleep, Oct 03 2019
  

       //I hope you will expand // I have already expanded, and am taking metabolic uncouplers to try to reduce again.   

       More generally, we still don't have the first clue about how our climate works. I'm not saying that CO2 isn't warming the climate - it might be. But equally it might not be. Certainly the raw physics of it suggest not - you have to assume lots of synergistic and positive-feedback effects. Every single predictive model has failed by factors larger than the predicted effect. New models are based entirely on recent data - i.e., they are not models, they are just analyses. If this were done in any non-religious field of science, it would be howled out.   

       One question I've never seen answered satisfactorily is this. We are told that the recent warming is "unprecedented" in its speed. But all of the historical climate data (back beyond a few centuries) gives us temperatures which are averaged over hundreds or thousands of years.   

       In other words, what looks to us like a rise of (say) 3°C over a period of 1000 years back in the neolithic, could equally well have been a 3°C rise over 50 years - the data isn't fine-grained enough to say. So, we just don't know whether fluctuations like the one we're seeing today have happened once, twice or a hundred times in the past. And if temperatures had risen and then fallen within a single century, we probably wouldn't even know there'd been a change.   

       I am no longer completely convinced that anthropogenic global warming _isn't_ real. In case it is (and for other reasons) it probably makes sense to reduce CO2 emissions. But there is absolutely no genuine science to argue one way or the other.
MaxwellBuchanan, Oct 03 2019
  

       [MB], thank you, that’s a beautifully straightforward and cogent argument. I have so far found the anthropogenic warming argument convincing, but I certainly agree with some of your points. I’ll have to go away and do some more reading.
Frankx, Oct 03 2019
  

       //More generally, we still don't have the first clue about how our climate works. I'm not saying that CO2 isn't warming the climate - it might be. But equally it might not be. Certainly the raw physics of it suggest not - you have to assume lots of synergistic and positive- feedback effects. Every single predictive model has failed by factors larger than the predicted effect. New models are based entirely on recent data - i.e., they are not models, they are just analyses. If this were done in any non-religious field of science, it would be howled out.//   

       As I understood it, the physics of 'direct' CO2 influence on the climate are pretty settled, and accepted by essentially everyone. I haven't looked into the models at all, but I am supposing that the assumed positive-feedback effects you mention would be things which might happen in future, i.e. concerns about catastrophic rises (e.g. methane release from under-sea clathrates, bogs etc), rather than to fit historical data. Is that reasonable?
If so, I guess it's always going to be the case, just like vulcanologists don't know for definite that t'volcano is going to brew up.
  

       //One question I've never seen answered satisfactorily is this. We are told that the recent warming is "unprecedented" in its speed. But all of the historical climate data (back beyond a few centuries) gives us temperatures which are averaged over hundreds or thousands of years.//   

       I've linked to an xkcd comic, which shows a plot he generated for the last few thousand years.
You can see the line wang gradually up and down from about -4.5 to +0.5 (compared to an arbitrary point late 20th century). There's a comment a couple of pages down indicating how much error he thinks there is in the data, and it's not more than a degree for a short period, or about a quarter of a degree for longer. You could of course argue that the source data he used was totally wrong. But you'd have to claim that it had been misinterpreted, or become corrupted through processing somehow, you can't say there is no data.
And since the events he's written on are basically the extent of ice coverage, I think there's likely pretty good geographical evidence for them, and I'm certainly imagining that they match up.
But I don't think you're saying that - you're talking about not having data for time before that.
  

       So never mind ancient history. Looking at the last hundred years, which we have good records for. Anthropomogenic CO2 emissions have ramped up massively during that period, and this is just the point where suddenly the temperature line swings up faster than it had at any point previously (in the period covered).
All of that is I think consistent with what you said. It's just that you don't think the correlation implies causation?
(And also, you're nit-picking that "unprecedented" means since humans evolved, rather than during the mere duration of recorded human history, but whatevs.)
Loris, Oct 03 2019
  

       //the physics of 'direct' CO2 influence on the climate are pretty settled, and accepted by essentially everyone.// It's not quite that simple. The amount of re-radiated heat absorbed by an extra 300ppm (that's an extra 0.03% of the atmosphere) is minuscule, and a simple physics model (ie, change in energy budget) doesn't really predict a perceptible effect. Bear in mind that other gases (oxygen, nitrogen) also have a "greenhouse effect" - much less than that of CO2, but then they are present at 1000 times higher concentrations.   

       To get an effect for CO2 in the range we're talking about, you really need to pick a very special set of circumstances, and to ignore many other factors that could be orders of magnitude more important, but about which we know very little.   

       If you can find a physicist who hasn't been following the climate story, and ask them to work out the effect of an extra 0.03% CO2, they'll come back with zero.   

       Now, it might be that that "very special set of circumstances" does in fact apply, and that the other factors can indeed be ignored. But we simply do not know. What actually happened was that global temperatures started to rise (undeniable); we don't know if this is "normal" or not for Earth; and people started to look for reasons; and the CO2 story was qualitatively plausible and could be quantitatively _made_ plausible, after a lot of selective post-hoc reasoning.   

       //I've linked to an xkcd comic, which shows a plot he generated for the last few thousand years.// Yes, I've seen it - in fact that's the cartoon that prompted my argument. Yes, if there had been similarly large fluctuations in the very recent past we would know. But, going back over a _significant_ timespan, the very data that the cartoon relies on has an inherent smoothing in it - that's the limit of its resolution. What's drawn as a smooth curve with one sudden upturn could (up to a few centuries ago) have had multiple spikes that we would simply not be able to see. The year-by-year or decade-by-decade data can only be recovered for a short way back in time.   

       //So never mind ancient history.// But you _have_ to mind ancient history. There's no question that temperatures have gone up in the very recent past. What we desperately need to know is whether they've done so (and then dropped again) in the longer past. OK, imagine that we really did have year-by-year temperatures for the last 5000 years. Possibility 1: there has never been as rapid and large a rise as we're seeing now. We should be really worried, and there's a good chance that we are causing the current rise. Possibility 2: there were two similar rises and a couple of dips, both happening and then resolving over a couple of centuries. These happened 2200, 3300 and 3900 years ago. In that case, we should probably still be worried (climate change is disruptive), but it's much less likely that we're causing the current rise, and quite possible that we can't do much about it except to move people and animals around to help them ride it out.   

       My point is that we have no evidence to decide between the two possibilities.   

       //you don't think the correlation implies causation?// The problem is that we looked for a correlation, and we did it at the first time when we have had reliable temperature measurements of the planet. I am pretty sure I could produce very plausible correlations _over_the_ same_timescale_ based on, for instance:   

       (a) Total foliage-free land area. We've tarmacked or ploughed a lot more than 0.03% of the Earth's surface, greatly reducing its albedo. Give me a little feedback and following wind and I can make that one work.   

       (b) The ozone hole (very real, indisputably anthropogenic). We worried about UV, but the real impact was on algae and plankton in the top layers of the arctic oceans. I could make that work too, at a pinch.   

       (c) Direct heat generation by humans. Aside from CO2, we pump hundreds of terawatts of heat straight into the atmosphere. Not enough to change temperatures directly, but the concentrated heat around densely-populated areas leads to large scale convection which moves water vapour higher into the atmosphere, which in turn... you get the idea.   

       //Anthropomogenic CO2 emissions have ramped up massively during that period, and this is just the point where suddenly the temperature line swings up// Not quite. I don't want to nitpick, but the fastest temperature rise (taking a 2-decade moving average) happened in about 1910-1930, when CO2 rose by a minuscule 10ppm (as against a total rise, up to now, of 300ppm). Temperatures then plateaued in the 1940s-60s, just as CO2 levels started to take off. Then they started rising again, about as quickly as (not faster than) they had in 1910-1930.   

       So, overall, both CO2 and temperature have risen a lot in the last 100 years; but if you break that down into decades, they don't correlate - even if you try to assume a lag between the former and the latter. It's just not a nice picture.   

       [***BONUS CALCULATION***] Total human energy usage is about 5x10^20 Joules per year, all of which ends up as heat in the atmosphere. Given the mass of the atmosphere (5x10^21g) and the heat capacity of nitrogen (about 1J/g/ °K), it follows that if all that heat were added to the atmosphere, it would increase its temperature by 0.1°C per year. Now, of course, that's a very naive calculation for lots of reasons, but you can see that with a few "selected" conditions, we could hang global warming on direct heat production just as we do on CO2 emissions.
MaxwellBuchanan, Oct 03 2019
  

       I want to start out by saying that if I don't mention a part of your post it's probably because I agree, or at least don't disagree.
But to mention one part in particular:
[as a potential confounder]
//...Total foliage-free land area. We've tarmacked or ploughed a lot more than 0.03% of the Earth's surface, greatly reducing its albedo.//
I understood this to be a concern for measurements, which was why I said that the measurement data might be misinterpreted or corrupted. My memory of this was that the climate scientists were worried about the 'heat island effect', where measuring devices are in areas which became urbanised and hence warmer. One would hope that this sort of thing was accounted for. But I fully concede that this sort of issue will potentially give the calculation an undesirable number of degrees of freedom.
  

       I can't really comment on the physics of the insulating effect of CO2. I /thought/ it was clear, but will have to look into it later.
One thing which is typical in the more in-depth articles is that CO2 is not the only 'greenhouse' gas. Methane is more potent, for example, and SF6 is apparently 23,500 times worse! Fortunately that isn't released in large amounts.
At least part of anthropogenic methane release is due to fossil fuel extraction, so I don't have much inclination to make a big distinction for it as an alternate hypothesis. I know essentially nothing about SF6 use, and apparently it's not much, but if that were the real cause and we could just stop doing it, then ... well, we win.
  

       re: the xkcd cartoon:
//But, going back over a _significant_ timespan, the very data that the cartoon relies on has an inherent smoothing in it - that's the limit of its resolution. What's drawn as a smooth curve with one sudden upturn could (up to a few centuries ago) have had multiple spikes that we would simply not be able to see.//
As I said, there is an indication of the expected error within the diagram. He may have this wrong, but it does seem to have been considered.
  

       ////Anthropomogenic CO2 emissions have ramped up massively during that period, and this is just the point where suddenly the temperature line swings up// Not quite. I don't want to nitpick, but the fastest temperature rise (taking a 2-decade moving average) happened in about 1910-1930, when CO2 rose by a minuscule 10ppm (as against a total rise, up to now, of 300ppm). Temperatures then plateaued in the 1940s-60s, just as CO2 levels started to take off. Then they started rising again, about as quickly as (not faster than) they had in 1910-1930.//   

       I don't think it's nitpicking; if the correlation is important, we should look at the correlation!
This was interesting enough that I had a look at some data from ourworldindata.org, and I... don't see that. I took a 2-decade average for every year's global average temperature (in degrees C), and calculated each point's difference from that of the prior (non-overlapping) range, then sorted by value. The highest pre-1950 value was 1926-1945 vs 1906-1925 diff=0.25825 - in 19th place. The 1920-40s seem to have been about on par with the early 1980-2000s in terms of rise from 20 years prior.
  

       The first 10 values are:
1997-2016 vs 1977-1996 diff=0.3731
1998-2017 vs 1978-1997 diff=0.3703
1994-2013 vs 1974-1993 diff=0.36795
1995-2014 vs 1975-1994 diff=0.3654
1996-2015 vs 1976-1995 diff=0.3636
1990-2009 vs 1970-1989 diff=0.3606
1991-2010 vs 1971-1990 diff=0.35765
1993-2012 vs 1973-1992 diff=0.35395
1988-2007 vs 1968-1987 diff=0.3512
1987-2006 vs 1967-1986 diff=0.34955
  

       These are predominantly the most recent ranges, and this backs up a recent global temperature increase.   

       This is very much a discrepancy and I think we should try to get to the bottom of it. It may be that you're using a different dataset. But they shouldn't be that different. It's possible that the data I'm using hasn't been as aggressively massaged (to remove the heat-island effect, etc.) as yours.
I must also concede that I may have made a mistake in the spreadsheet somewhere, although I have checked it.
Loris, Oct 04 2019
  

       I find Berkeley Earth give a very balanced argument - they acknowledge many of the problems with the "scientific establishment" argument and set out to be independent, avoid the hidden assumptions, and assess the data objectively. And they use a number of methods to check and qualify their own assumptions.
Frankx, Oct 04 2019
  

       //there is an indication of the expected error within the diagram// I may be going mad or something, but I can't see it. He/she has a dashed line for temperature, and at the very bottom there are three diverging lines for predictions, but I can't see any indication of either (a) the error in the temperature shown or (b) the methods used to measure past temperatures (and hence the period over which they're effectively smoothed).   

       //This is very much a discrepancy// I just Googled image- searched "temperature versus CO2 graph", and found several plots that show both things plotted together. It's noticeable that no two plots are quite the same, which is indeed worrying. But I didn't come across any where the bumps and dips in CO2 matched the rate of temperature increase, either directly or shifted in time (which you'd expect to be the case). If you do the same search, you'll get the same sort of variety. (Note: a lot of the graphs extend back for millennia or more, and involve huge swings in both CO2 and temperature; there _is_ a clear correlation there but I'm talking about man-made CO2 changes.)   

       Bottom line is that (a) all the current models are post-hoc; as soon as a model has been around long enough, it fails to fit the new data (since it wasn't based on the new data), and gets replaced by a new up-to-date post-hoc model (b) climate change has become a religion, and the quality of the science is really poor (c) other anthropogenesis models not based on CO2 (as well as many non-anthropogenesis models) could be made to work just as well as the CO2 model.   

       It's _important_ to get the science right. Suppose, for example, that direct heating really is more important than people think*, and CO2 is much less important. In that case, our current policy of using low-emission technologies to reduce CO2, whilst not impacting total energy usage, are dangerously misguided.   

       *There are some papers pointing a finger at direct heating. They suggest it's accounting for 5-10% of the recent warming. But given the uncertainties in the whole business, it could be 1% or 90%.
MaxwellBuchanan, Oct 04 2019
  

       ////there is an indication of the expected error within the diagram//
I may be going mad or something, but I can't see it. He/she has a dashed line for temperature, and at the very bottom there are three diverging lines for predictions, but I can't see any indication of either (a) the error in the temperature shown or (b) the methods used to measure past temperatures (and hence the period over which they're effectively smoothed).//
  

       a) is embedded in the body, on the right between 16000 BC and 15500 BC.
b) Sources of the data are given at the top, in small writing down the on the right hand side of the image.
Loris, Oct 04 2019
  

       Temperature - CO2 correlation [link]   

       It's not quite as unequivocal as the classic hockey-stick graph, but does show the 95% confidence limits.
Frankx, Oct 04 2019
  

       [Loris] Ah yes, I see it now. He/she is saying brief spikes (a decade or so) would be smoothed out but longer ones (a century) would not. And, indeed, our current warming is longer than a decade or so. But, to be frank, I don't believe him/her. I haven't followed up his/her references for temperature data (and I can't, for journal articles he/she cites), but I would be very surprised if any/all of them have sub-century resolution going back more than a millennium or two.   

       [Frankx] I'm not sure what you're arguing from that graph. It doesn't show [CO2] and T over time; it's another post-hoc model showing "retrospectively predicted" versus actual temperatures. But, if you like that graph, you'll note that it shows violent _actual_ (?) temperature oscillations between 1775 and 1825. We're looking at oscillations on the order of 1-2 degrees per decade, back and forth - steeper than the more recent changes (although swinging back and forth on a shorter timescale).   

       If you want to argue that the oscillations from 1775 to 1825 are "man made" - good luck. If you want to argue that they are "just noise", it's very difficult to argue that a less-steep change for 2-4 times as long isn't also noise. Assuming it's a chaotic system, you would *expect* exactly that sort of behaviour.   

       I'm not quibbling for quibblement's sake, and arguments from either side based on one graph or one short period are spurious. But my point is that the whole thing is really, really messy and complicated. And that's _after_ it has all been strained through the filter of peer review, which I am pretty sure is not impartial. So, yes, I am saying I don't trust the sources.
MaxwellBuchanan, Oct 04 2019
  

       If there's one thing I think we can all agree on, it's that it's really messy and complicated.
Loris, Oct 04 2019
  

       There is one thing I would like to know*, and it is this: what data can the climate scientists imagine that would disprove the effect of anthropogenic CO2 on global temperatures? In other words, is it a falsifiable hypothesis? So far, it has simply been adapted to new data as new data becomes available; so what data would actually break the hypothesis?   

       (*This is clearly preposterous. For instance, I would like to know what tomorrow's lottery numbers will be, what happened to MH370, and exactly why the silver plating on teaspoons wears off long before that on forks.)
MaxwellBuchanan, Oct 04 2019
  

       //Temperature - CO2 correlation [link]//   

       The graph shows quite well the 1945 oddity. In the 5 years prior to 1945 world CO2 emissions would have gone up due to the war effort and yet post-war temperature actually dipped a bit. And if you look at the left side of the graph, CO2 actually lags temperature rise.   

       As they say - "correlation is not causation". If you find other graphs with sunspot numbers on them you'll also find correlations with temperature.   

       //what data can the climate scientists imagine that would disprove the effect of anthropogenic CO2 on global temperatures?//   

       What if CO2 did lag temperature i.e. temperature changes cause CO2 changes ? Temperature rise could just be a direct result of things being warmed by the sun or chemical processes like burning fossil fuel. Is heat output caused by human activity at a level similar to the energy variations from the sun due to sunspots ? CO2 could simply be an indicator of biological activity - stuff grows takes in CO2, it dies and rots and releases CO2. With more sunlight stuff grows faster and hence the average amount of CO2 - compost heap earth.   

       We are at a decades long sunspot minimum meaning solar irradiation has on average been higher so trees will grow faster if we take deciduous action.
bigsleep, Oct 04 2019
  

       I think there’s two useful things from the graph.   

       If you just take 1950 to present (and this is measured data, not modelled) atmospheric CO2 and temperature have been measured with high accuracy, and have both risen significantly. They are correlated, but I agree correlation is not causation. But we know for certain that human activity has released GTs of CO2 over that period, so it’s not unreasonable to link release of CO2 to atmospheric concentration, rather than look for the opposite causation (temp causes CO2)   

       Secondly, there is much more uncertainty in the older data (and more dependence on post-hoc modelling) which is reflected in the confidence bounds plotted - but it still supports a correlation between CO2 concentration and temperature.   

       Falsifiability: unfortunately difficult to implement. We could stop releasing CO2 for a decade, and look for a corresponding change in temperature. Or we could do the opposite. Or, if we found well validated temperature and CO2 proxies where a multi-decade CO2 increase coincided with a global temperature decrease (or vice-versa), that would be good counter-evidence. But I don’t see that in the data.   

       And I think finally: the precautionary principle. There is a hazard which could cause massive human social disruption, famine and death, and extinction of many other species. We can’t quantify the risk precisely, but we know it’s pretty high. So as a precaution, we should stop doing the things that might bring it about.
Frankx, Oct 05 2019
  

       // Falsifiability: unfortunately difficult to implement.// No, I'm not talking about an artificial experiment (like stopping CO2 emissions and seeing the result). I'm talking about a natural experiment - in other words, what climatic phenomena would disprove the hypothesis? Way back at the start, people were saying things like "an increase of X°C over the next Y years would support the hypothesis", but when the X°C rise didn't happen, the hypothesis was kept. When there was a brief pause in the warming, that was incorporated into the new post-hoc models, and therefore didn't disprove the hypothesis.   

       So, I'm asking the climatologists to put a flag in the sand and say "If _this_ happened, it would invalidate the hypothesis." And then stick to their word.   

       //it’s not unreasonable to link release of CO2 to atmospheric concentration// I agree, CO2 is rising rapidly and this is _almost_ certainly due to anthropogenic emissions. The question, of course, is whether that in turn is causing the current temperature increase.   

       I'd be very interested to know what the climatologists think caused the very violent (though only decade-long) oscillations around the end of the 18th century. (It's interesting, by the way, that as soon as have decent direct day-by-day temperature measurements back in the late 1700s, the first thing we find are rapid oscillations in temperature.)
MaxwellBuchanan, Oct 05 2019
  

       I think this is all connected to economics in the broadest sense, with energy budgets and human budgets and financial budgets all interacting in a very complex long-term way.   

       At the end of the day the laws of thermodynamics win anyway.
pocmloc, Oct 05 2019
  

       Why don't you let trees and grass capture the CO2. Focus on energy storage and generation.   

       And read about stock charts and correlations. In a field that, believe me, has been studied MUCH, MUCH, MUCH more carefully than climate science.   

       Turns out, most people making money on stock charts are people that are selling tools to analyze stock charts. People using stock charts can't beat the market.   

       Up on the hills, we call it weather.
theircompetitor, Oct 05 2019
  

       Thanks all for the valuable views. I’ll have to do some more research and go back to original data.
Frankx, Oct 05 2019
  

       //I think this is all connected to economics// I think it's all connected to asking climatologists what they think is going to end the world. If you'd asked a bunch of mycologists instead, we'd all be spending billions on fighting mushrooms.
MaxwellBuchanan, Oct 05 2019
  

       Ultimately we are an organism adapting to changing conditions, whether self imposed or environmental. Trying to seer the best bang for the buck is not really nature's way but rather work on all methods, that test to help should be the goal and see what settles out as the best.   

       Of course, a cheap, out of this well, organism pressure release would be my option for humanities widest survival.
wjt, Oct 06 2019
  

       There is x amount of potential energy stored as geological hydrocarbons. By the time of the heat death of the universe, that energy will have been liberated through burning or some analogous chemical process. There are also humans with needs, desires, and abilities. By the time of the heat death of the universe they will all be dead.
pocmloc, Oct 07 2019
  

       So where does X figure in this depressing take on the universe ?   

       //the time of the heat death of the universe//   

       [link]
bigsleep, Oct 07 2019
  

       I always thought oil was Earth's fat store and was destined for microbial inheritance or human's slavery of GM microbes for a cut of the generated resources.
wjt, Oct 09 2019
  

       // the precautionary principle //   

       Seemingly wise, but in fact extremely dangerous as it involves making decisions on the basis of limited facts and without proof - something politicians love, and therefore to be scrupulously avoided.
8th of 7, Oct 09 2019
  

       Agreed - there are costs and risks in the present policy of reducing CO2 emissions. First, it has a financial cost, and money=lives; money spent on wind turbines has to come from somewhere, whether it's policing, the NHS or whatever. Second, switching to renewable energy means that people can and will continue their current energy-intensive lifestyles; so, if CO2 isn't the culprit, eyes will be taken off other possibly more important balls.
MaxwellBuchanan, Oct 09 2019
  

       Talking of balls ...   

       Why aren't these climatologists incredibly wealthy ?   

       They are claiming, in effect, to ba able to predict the outcome of a football game from two or three adjacent frames, taken part-way through, with no a priori knowledge of the score, and having never previously seen a football match from beginning to end.   

       Your planet is 3.5 billion of your years old. 10kyears ago it was glaciated. Your direct climate records only go back 200 years, and are patchy at best for half that time. You have had planet-sensing satellites for about fifty years.   

       Everything else has to be inferred from tree rings and ice cores. Those don't reach back very far and there are wide error bands.   

       The underlying geologic processes - deep ocean gas diffusion, volcanism, phytoplankton blooms - are not understood, and therefore cannot be quantfied.   

       The Drake equation seems to involve fewer - and more quantifiable - assumptions ...
8th of 7, Oct 09 2019
  

       //Why aren't these climatologists incredibly wealthy ? // A few of them are. And, as a profession, the amount of money washing around has increased about 10-fold from 1990 to 2010 (as US government funding).
MaxwellBuchanan, Oct 09 2019
  

       Which begs the question "Cui bono ?" ...
8th of 7, Oct 09 2019
  

       Cher.
MaxwellBuchanan, Oct 09 2019
  

       I've never really looked into the earths orbital variations, but apparently they make a huge difference ... up to 25% difference in total solar irradiance. A Mr Milankovitch worked all this out a while ago. It's why the winter sun in the northern hemisphere is 6% hotter than the summer sun at the moment. In 10,000 years it will be summer sun that is 6% more powerful - phew! what a scorcher.
bigsleep, Oct 09 2019
  


 

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