A few days ago I tried to get my head around the concept of 385 parts per million (here). Relating it to tangible things I can measure I calculated that it is equivalent to one drop of wine out of a 75cl bottle or a single 14-point letter "O" on a sheet of A4 paper. These are very very small proportions and, in my final substantive paragraph, I suggested that it casts doubt on the AGW Armageddon theory. As well as providing me a prime supporting role in the antipodes (here), my efforts also elicited comments from some of those who seem to have no difficulty in the concept of disaster springing from tiny increases in the already tiny quantity of carbon dioxide in the atmosphere. I am not a one to dismiss an argument without careful consideration, so I thought I should weigh their views and see whether they appear to have merit.
Nice Mr O'Dwyer observed that very small quantities of cyanide and polonium-210 are fatally toxic, presumably to illustrate that it is not the quantity per se that matters but the effect that quantity has on the things it affects. A perfectly fair point, as I would always expect from Mr O'Dwyer. But we must keep apples and oranges in their respective places or we will probably be in breach of an EU fruit purity directive. I have no difficulty with the concept of a tiny pinch of cyanide being enough to render my flabby frame lifeless and fit only to be turned into soap. The reason I can accept that concept is not because I have any scientific knowledge about what cyanide is or how it works, but because Agatha Christie said so many times. Equally, I don't need to understand the science in order to accept that ingestion of any substance in sufficient quantities can be fatal. The first rule of toxicology, or so I understand, is that it's all about the dose. Even apparently harmless substances can become deadly if consumed in bulk. Take my pint of choice, Gaymer's Olde English Cider. Three pints won't touch me, four and I'm ready for a drink, after five it starts to take effect, nine's a fair evening out and fourteen are likely to reappear all over the back seat of a taxi on the way home from the Dog and Duck. Yet put a sherry glass full in a baby's bottle and you're off to the big house for a well-deserved life sentence.
I'm no scientist, but I can be reasonably sure that even the nuttiest doomsayer does not rely on toxicology for his hysteria about atmospheric carbon dioxide. The case that is put is one of physics rather than chemistry. It is said that 280 parts per million by volume was good and natural and pure, whereas 385 places us on the verge of an abyss and 500 will result in world-wide disaster. It is said that this additional minuscule quantity will kick-start an unstoppable physical chain-reaction. My first question when faced with a physical argument like this is whether I can envisage such a physical (rather than chemical) reaction. That requires me to look at the actual stuff involved, including the quantity of it.
Another commenter, Mr W, suggested I might be helped by envisaging splattering 35 litres of paint around my kitchen (here). I initially thought the relevant quantity was actually 350 litres, but he has pointed out my error so I am happy to accept it is 35. In any event it does not matter to me because I cannot envisage the effect of either 35 or 350 litres of paint being sprayed more-or-less evenly throughout the air in my kitchen. He then added that I might find it useful to think of adding 15 litres of strong dye to a 40,000 litres swimming pool (here). The problem with both these suggestions is that they give rise to exactly the conceptual difficulty I was seeking to eliminate. I do not have the faintest idea what 15 litres of dye would do to a 40,000 litre swimming pool. Not only do I not have a swimming pool of that or any other size but I have no way of assessing the visual impact 15 litres of dye would make because the whole exercise is far outside my personal experience. If he spoke of one bladder of used cider emptied in a municipal pool, it would be easier but that probably wouldn't help much either.
Interestingly, the two examples Mr W gave illustrate not only the conceptual difficulty I was trying to overcome but also the misleading nature in which the proportion 385:1,000,000 can be expressed. 35 litres of paint! Oh my ears and whiskers! That's an awful lot of paint, imagine that being thrown around my kitchen, what a horror. Strong dye in a swimming pool! Sheer vandalism and a breach of goodness knows how many health and safety edicts. They appear to be nasty things because they are suggested for use in a manner for which they are not designed. Talk of 35 litres of paint when the bare plaster walls of a room need two coats of duck-egg blue emulsion and the nastiness disappears; as it does when 15 litres of black dye are used in a fabric factory.
The reason I tried to illustrate what 385 parts per million means in real things we can actually get our heads around was to eliminate hysteria and shock. As I said the other day, by my calculations it is one drop of Rioja out of a standard bottle. To ensure no one, especially Mr W, would be offended by my refusal to spray paint the air in my kitchen with emulsion and throw a couple of buckets of black gunge into the local swimming pool during pensioners' hour; I decided to experiment using the measures I find useful. So I took 75cl of water and put it in a clear jug, then I added a drop of Rioja (wasteful I know, but it's all in the name of science) and stirred well. My eyes are particularly astute where fine wine is concerned and you know what? The addition of 385 parts per million of deep purple wine to the water was completely unnoticeable. Not the teeniest hint of purple could be seen because the quantity was just so small. No doubt it would be detectable by a finely tuned scientific instrument but in real terms, terms understandable by even the cerebrally-challenged like me, it's not 35 litres of paint or two buckets of threatening black dye; it's a tiny tiny speck, a speck so small I cannot even see it when it is mixed into the bulk.
And in all this we must bear in mind that it is not the 35 litres of paint, the 15 litres of dye or the drop of fermented Tempranillo grapes that is the threat. We know this because 280 parts per million is good and wholesome, it is natural and pure and untouched by filthy human hand. Only when we get above that arbitrary, once in a world-time, number are problems said to arise. Assuming we blame naughty people for the whole of the next 105 parts per million (which, as I understand it, is not the position anyway); we find that the air in my kitchen is permeated by 25.6 litres of paint that is fine and good and only about 10 litres need to be added to represent human wickedness. We also find that the pristine swimming pool is already enjoying the benefit of 11 litres of black dye and suffering nothing but pleasure, all we have done is add 4 more. My jug of water already has almost two-third of a drop of Rioja in it and the result is unquestionably wonderful because it was added by Bacchus and not by me, only the remainder of the drop is tainted.
When asking what 385 parts per million is, I find it useful to equate it to quantities I can actually understand by relating them to real life - hence one drop of wine out of a bottle of wine and a 14-point letter "O" on a sheet of A4. Then, when asking how this tiny quantity, and/or an increase of up to one-third in this tiny quantity, can cause a physical reaction of unimaginable nastiness I find I need more than a little persuasion. That is not to say the AGW Armageddon theory is necessary bunkum, but it helps to explain why I find it unconvincing.
Addendum
Mr W left another very helpful comment (here). He questioned my Rioja and water experiment because only a small part of the wine has a colouring effect. That, of course, is true and might mean I wasted a whole drop for absolutely no benefit whatsoever. Nonetheless, my central point remains undisturbed, namely that 385 parts per million is a tiny weeny proportion of the whole and that trying to make it sound a lot is potentially misleading. Whether it is one drop of Rioja or eight drops of water, out of the total volume of a wine bottle it is minuscule.
How we little people approach a subject on which we have no technical knowledge is almost bound to be affected by how the subject is presented to us. In an area where radical politics and science overlap it is particularly important, in my view, to put things in terms the little people can understand. Tell people that humans release so-many giga-tonnes of carbon dioxide into the atmosphere each year and it sounds a daunting quantity, it is quite natural for people to consider that worrying and potentially dangerous because it can seem such a vast quantity that we infer it must cause a massive shift in the balance of the atmosphere as a whole. Tell them that the total volume of carbon dioxide in the atmosphere is equivalent to roughly one-twentieth of a level teaspoon in a volume of one pint and they might look at it differently. Then tell them that current annual human-induced emissions are equivalent in volume to just a few percent of that one-twentieth of a teaspoon and the whole game changes. Suddenly our emissions are so extraordinarily small that it is hard to see why there is any fuss at all.
Perhaps it is no more fair to play down emissions by reference to a tiny proportion of a small everyday measure of volume than it is to hype them by reference to incomprehensibly large multiples of big everyday measures of weight. If, in fact, they are causing a major problem it matters not that they are a small percentage by volume. However, for so long as the supposed problem is measured in parts per million by volume I think it is relevant to have a comprehensible reference point for the measurements because the little people still have the final say (at least in theory).
Nice Mr O'Dwyer observed that very small quantities of cyanide and polonium-210 are fatally toxic, presumably to illustrate that it is not the quantity per se that matters but the effect that quantity has on the things it affects. A perfectly fair point, as I would always expect from Mr O'Dwyer. But we must keep apples and oranges in their respective places or we will probably be in breach of an EU fruit purity directive. I have no difficulty with the concept of a tiny pinch of cyanide being enough to render my flabby frame lifeless and fit only to be turned into soap. The reason I can accept that concept is not because I have any scientific knowledge about what cyanide is or how it works, but because Agatha Christie said so many times. Equally, I don't need to understand the science in order to accept that ingestion of any substance in sufficient quantities can be fatal. The first rule of toxicology, or so I understand, is that it's all about the dose. Even apparently harmless substances can become deadly if consumed in bulk. Take my pint of choice, Gaymer's Olde English Cider. Three pints won't touch me, four and I'm ready for a drink, after five it starts to take effect, nine's a fair evening out and fourteen are likely to reappear all over the back seat of a taxi on the way home from the Dog and Duck. Yet put a sherry glass full in a baby's bottle and you're off to the big house for a well-deserved life sentence.
I'm no scientist, but I can be reasonably sure that even the nuttiest doomsayer does not rely on toxicology for his hysteria about atmospheric carbon dioxide. The case that is put is one of physics rather than chemistry. It is said that 280 parts per million by volume was good and natural and pure, whereas 385 places us on the verge of an abyss and 500 will result in world-wide disaster. It is said that this additional minuscule quantity will kick-start an unstoppable physical chain-reaction. My first question when faced with a physical argument like this is whether I can envisage such a physical (rather than chemical) reaction. That requires me to look at the actual stuff involved, including the quantity of it.
Another commenter, Mr W, suggested I might be helped by envisaging splattering 35 litres of paint around my kitchen (here). I initially thought the relevant quantity was actually 350 litres, but he has pointed out my error so I am happy to accept it is 35. In any event it does not matter to me because I cannot envisage the effect of either 35 or 350 litres of paint being sprayed more-or-less evenly throughout the air in my kitchen. He then added that I might find it useful to think of adding 15 litres of strong dye to a 40,000 litres swimming pool (here). The problem with both these suggestions is that they give rise to exactly the conceptual difficulty I was seeking to eliminate. I do not have the faintest idea what 15 litres of dye would do to a 40,000 litre swimming pool. Not only do I not have a swimming pool of that or any other size but I have no way of assessing the visual impact 15 litres of dye would make because the whole exercise is far outside my personal experience. If he spoke of one bladder of used cider emptied in a municipal pool, it would be easier but that probably wouldn't help much either.
Interestingly, the two examples Mr W gave illustrate not only the conceptual difficulty I was trying to overcome but also the misleading nature in which the proportion 385:1,000,000 can be expressed. 35 litres of paint! Oh my ears and whiskers! That's an awful lot of paint, imagine that being thrown around my kitchen, what a horror. Strong dye in a swimming pool! Sheer vandalism and a breach of goodness knows how many health and safety edicts. They appear to be nasty things because they are suggested for use in a manner for which they are not designed. Talk of 35 litres of paint when the bare plaster walls of a room need two coats of duck-egg blue emulsion and the nastiness disappears; as it does when 15 litres of black dye are used in a fabric factory.
The reason I tried to illustrate what 385 parts per million means in real things we can actually get our heads around was to eliminate hysteria and shock. As I said the other day, by my calculations it is one drop of Rioja out of a standard bottle. To ensure no one, especially Mr W, would be offended by my refusal to spray paint the air in my kitchen with emulsion and throw a couple of buckets of black gunge into the local swimming pool during pensioners' hour; I decided to experiment using the measures I find useful. So I took 75cl of water and put it in a clear jug, then I added a drop of Rioja (wasteful I know, but it's all in the name of science) and stirred well. My eyes are particularly astute where fine wine is concerned and you know what? The addition of 385 parts per million of deep purple wine to the water was completely unnoticeable. Not the teeniest hint of purple could be seen because the quantity was just so small. No doubt it would be detectable by a finely tuned scientific instrument but in real terms, terms understandable by even the cerebrally-challenged like me, it's not 35 litres of paint or two buckets of threatening black dye; it's a tiny tiny speck, a speck so small I cannot even see it when it is mixed into the bulk.
And in all this we must bear in mind that it is not the 35 litres of paint, the 15 litres of dye or the drop of fermented Tempranillo grapes that is the threat. We know this because 280 parts per million is good and wholesome, it is natural and pure and untouched by filthy human hand. Only when we get above that arbitrary, once in a world-time, number are problems said to arise. Assuming we blame naughty people for the whole of the next 105 parts per million (which, as I understand it, is not the position anyway); we find that the air in my kitchen is permeated by 25.6 litres of paint that is fine and good and only about 10 litres need to be added to represent human wickedness. We also find that the pristine swimming pool is already enjoying the benefit of 11 litres of black dye and suffering nothing but pleasure, all we have done is add 4 more. My jug of water already has almost two-third of a drop of Rioja in it and the result is unquestionably wonderful because it was added by Bacchus and not by me, only the remainder of the drop is tainted.
When asking what 385 parts per million is, I find it useful to equate it to quantities I can actually understand by relating them to real life - hence one drop of wine out of a bottle of wine and a 14-point letter "O" on a sheet of A4. Then, when asking how this tiny quantity, and/or an increase of up to one-third in this tiny quantity, can cause a physical reaction of unimaginable nastiness I find I need more than a little persuasion. That is not to say the AGW Armageddon theory is necessary bunkum, but it helps to explain why I find it unconvincing.
Addendum
Mr W left another very helpful comment (here). He questioned my Rioja and water experiment because only a small part of the wine has a colouring effect. That, of course, is true and might mean I wasted a whole drop for absolutely no benefit whatsoever. Nonetheless, my central point remains undisturbed, namely that 385 parts per million is a tiny weeny proportion of the whole and that trying to make it sound a lot is potentially misleading. Whether it is one drop of Rioja or eight drops of water, out of the total volume of a wine bottle it is minuscule.
How we little people approach a subject on which we have no technical knowledge is almost bound to be affected by how the subject is presented to us. In an area where radical politics and science overlap it is particularly important, in my view, to put things in terms the little people can understand. Tell people that humans release so-many giga-tonnes of carbon dioxide into the atmosphere each year and it sounds a daunting quantity, it is quite natural for people to consider that worrying and potentially dangerous because it can seem such a vast quantity that we infer it must cause a massive shift in the balance of the atmosphere as a whole. Tell them that the total volume of carbon dioxide in the atmosphere is equivalent to roughly one-twentieth of a level teaspoon in a volume of one pint and they might look at it differently. Then tell them that current annual human-induced emissions are equivalent in volume to just a few percent of that one-twentieth of a teaspoon and the whole game changes. Suddenly our emissions are so extraordinarily small that it is hard to see why there is any fuss at all.
Perhaps it is no more fair to play down emissions by reference to a tiny proportion of a small everyday measure of volume than it is to hype them by reference to incomprehensibly large multiples of big everyday measures of weight. If, in fact, they are causing a major problem it matters not that they are a small percentage by volume. However, for so long as the supposed problem is measured in parts per million by volume I think it is relevant to have a comprehensible reference point for the measurements because the little people still have the final say (at least in theory).
Posts
15 comments:
"bladder full of used cider"is this going to be added incognito from within the pool or devil may care from the top diving board???
and the pool full of dyed pensioners,presumably looking like the black and white minstrels.Hillarious,had me wandering around my hovel sniggering.
I do love your descriptions.
Nice post Mr. FatBigot.
Let me first make the point that there are 3 positions in the AGW debate, two that are based on ideology, and one that's based on science. Those of us tenaciously sticking to the science are reserved about making predictions on what the consequences of AGW will actually be.
Next, let me point out that by trying to equate what 385 parts per million is to quantities you can actually understand by relating them to real life you're inevitably creating false analogies, a bit like arguing that if an ant were as big as an elephant it could lift a house, sometimes things just don't scale in a meaningful way, perhaps you'd like to have a crack at determining the accuracy of special relativity (time dilation)by relating it to how things work in your everyday life?
Next, can I correct you on the 350 litres of paint thing, 385ppm is about 1 part in 2600, your kitchen has a volume of about 90,000,000cc, one litre is 1000cc. So 90,000,000/2600 = ~35000cc = 35litres.
Now, if we move on and look at your Rioja in water experiment you have made several errors, firstly (and this may come as a shock) Rioja is mostly water, and most of the rest of it (this won't be such a shock) is alcohol, so perhaps far less than 1% of what you added to the 750ml of water was a colouring agent, whereas 100% of the CO2 added to the atmosphere absorbs IR radiation. Also after testing the size of a drop of water with a syringe I got 28 drops/ml, if this figure can be applied to your Rioja you'll need to add 8 drops to make up the 0.288ml required and multiply this by at least 100 to actually add the equivalent of 1 part in 2600 of colouring agent, ie. add ~30ml of Rioja to your 750ml of water (I take no responsibility for the anguish wasting this much Rioja may cause you).
To continue to bring your experiment closed to reality (if that term can be applied to this test) you need to allow for the fact that the mass of atmosphere above your head is equal to 10 metres of water (this is why I used the swimming pool comparison) so you really need to be looking through a column of Rioja and water 10 metres long when you conduct the experiment. I suggest a 4" diameter tube filled with about 75 litres of water and 4 litres of Rioja.
Regards Andrew W.
Thank you for the correction about litres, Mr W. Silly me. It's these bloody foreign measurements buggering up my stodgy English brain again. I have corrected it in the article and added a chunk to explain where I stand on the other points you raise, for which many thanks.
"100% of the CO2 added to the atmosphere absorbs IR radiation"
As I understand this:
Firstly CO2 only absorbs a narrow band of possible IR radiation (and there's only so much of it, whereas there's lots of other IR in the spectrum)
Secondly, it does so with an efficiency that decreases logarithmically as CO2 levels rise.
In other words, and this was not clear from the original phrasing, it's perfectly possible to add CO2 to the atmosphere and have little, or even no, effect on the absorbtion of IR.
Catastrophic CO2-induced AGW is only possible when projected using positive feedback mechanisms of a type as yet unkown in nature.
Mr Ridson, we're getting off topic but I'd like to address the points you raise, and basically you're right. But, just because all the IR in a band is trapped by the atmosphere this does not mean that adding more GH gases has no effect, because the warmer gas then re-radiates the absorbed energy which is more likely to then be re-absorbed due to increasing GH gas concentrations.
The end result is that the rate that which IR energy is radiated from the Earth is slowed, things are only brought back into equilibrium (inward energy = outward energy) with a warmer troposphere.
Your argument is a bit like saying since 1 blanket traps heat another won't make any difference.
An important point to consider is that the natural GH effect lifts the temperature on the surface of this planet by about 33C, so the additional GH gases are only expected to add a little to this, perhaps 2-3C by doubling the concentration of the forcing GH gases (water vapour being a feedback).
Pogo, if you mean that there's no known mechanism in nature that could result in a positive feedback f>=1 you're right, but nobody is claiming that there is.
Mr FatBigot, while measuring CO2 in ppm is useful to understand what concentrations are doing, it's actually not a useful way to judge effect, perhaps knowing that the amount of CO2 over each sq metre of the Earths surface has increased from 4.2kg to 5.7kg would be more useful? Or Perhaps not.
Perhaps you're not really interested in the science, but prefer to be ideologically driven?
Kind regards, Andrew W
"Your argument is a bit like saying since 1 blanket traps heat another won't make any difference."
No, my point, not argument, was, as you accepted initially, correct. The two-blanket analogy does not hold; you'd have to take it further and say that when you have so many blankets on a bed that all the heat is trapped, adding more blankets will not make a difference.
In fact, with CO2, you have to strain the analogy even further and say that if enough strips of blanket are placed on top of each other across a couple of narrow parts of a bed, such that all heat from those narrow strips is trapped, then adding more strips will make no difference.
Heat will still radiate from the rest of the bed in the normal way.
"The end result is that the rate that which IR energy is radiated from the Earth is slowed, things are only brought back into equilibrium (inward energy = outward energy) with a warmer troposphere."
That's right - this was one of the predictions common to most climate models, as I understand it (I'm not claiming any great expertise here). The fact that, except on one rather strained proxy analysis, the troposphere has not warmed as predicted is a problem for these models.
"An important point to consider is that the natural GH effect lifts the temperature on the surface of this planet by about 33C"
This is indeed important. It's easy to get the idea that the greenhouse effect is a Bad Thing, whereas in fact it makes life possible on the planet.
However, CO2 is the least significant greenhouse gas. Water vapour is the most important, and both methane and nitrous oxide have per-unit effects that are many multiples of that of CO2.
There have been warmer periods in the planet's history, and they have been characterised by abundant life. There have also been colder periods and these have not been so fertile.
These two facts - that there have been both warmer and colder periods in the past - suggest there is in fact an overall negative feedback in the climate system. Movements in either direction tend to be drawn back to the centre.
The closest I can get to a claim of expertise is that I have built, on contract, several carbon profiling software tools (one is the main such for the UK government's land use analysis). I tend to agree with Carl Wunsch (and Benny Peiser) that we should adopt a pragmatic approach to this risk, rather like insurance.
But the current solar quiescence is a greater source of concern to me, right now, than carbon emissions. This is because the consequences of cooling beyond the sort of fluctuations we saw in two periods in the twentieth century are far more serious than would be the consequences of a couple of degrees of warming. The latter might even be coped with financially simply through the sort of growth developed economies can reasonably expect to see in the coming century.
Having said that, it's amazing how few people ever suggest that change is part of the normal cycle of the planet. Movement in any direction is always extrapolated to catastrophe. Since catastrophes are rare (not unknown), this is bizarre.
It's a bit like the cock-up or conspiracy question. Normally, it's cock-up. Normally, it's normal.
On reflection, I'm warming (as it were) to the blanket analogy. Say one blanket traps 50% of the heat, but you need ten to trap all of it. Plainly, adding a second blanket does not trap a second 50% of the heat. There are diminishing returns, just as there is with CO2.
I omitted the words "strips of" for economy.
"Andrew W": Pogo, if you mean that there's no known mechanism in nature that could result in a positive feedback, you're right, but nobody is claiming that there is.
But they are... Even the IPCC at its most extreme is only claiming that a doubling of CO2 would cause approximately 1C increase in the next century. All the AGW alarmists who're talking about "tipping points" base this idea on some form of positive feedback - a concept which is, as I said, based on something unknown in nature.
When it comes down to it, the GCM computer models don't include clouds in their computations as they still can't decide whether they contribute a negative or positive feedback...
Mr Ridson,
your "strips" analogy is reasonable, but you must remember that most of the bed is already covered with strips of blanket, where CO2 isn't covering part of the bed it is likely to be covered by CH4, NO2, H2O, so heat isn't freely escaping from most of the bed as you claim.
Next you need to keep in mind that the atmospheres ability to support water vapour increases with increasing temperature, so slight initial warming from GH forcing gases results in more strips of blanket going onto the bits covered by WV.
It's understood that the process is logarithmic in nature.
"CO2 is the least significant greenhouse gas."
Wrong, it's the strongest of the forcing GH gases, it is weaker in terms of per-unit of additional molecules mainly as a result of its comparitively high concentrations and the diminishing returns that you mention.
"the troposphere has not warmed as predicted is a problem for these models."
Wrong.
"the current solar quiescence is a greater source of concern to me, right now."
Why? There is nothing exceptional about it to date.
Pogo: "All the AGW alarmists who're talking about "tipping points" base this idea on some form of positive feedback - a concept which is, as I said, based on something unknown in nature."
My bad, I was thinking in terms of a runaway GH effect, rather than, for example, the well established positive feedback ice melt (tipping point) that occurs during each glacial to inter-glacial transition. And the mini version of it that we are likely to see with the decline of existing Arctic sea-ice over the next few decades.
Whether the transition to an ice-free summer Arctic ocean would be "catastrophic" I don't know.
The science can only let us see so far, claims that AGW is certainly fiction, along with claims that AGW will certainly be catastrophic (a relative term), are founded in ideology, not science.
Mr FatBigot, it's a serious question (note the question mark) Do you see yourself as looking objectively at the issues, or are you swayed by the "political" issues involved, as I think most involved in bog debates are? One thing is certain, no matter how much it suits peoples ideologies as to what the effects of AWG are, their wishes ain't going to change the physics.
Regards, Andrew W
Mr W, you answered a comment I made and then deleted because I felt it could be construed as rude or petulant. You were very quick, it was only up for a minute or two.
My answer to your question cannot readily be contained within a comment, so I intend to write a piece about it in the not too distant.
280 ppm of CO2, CO2 is a trace gas. 385 ppm, CO2 is still a trace gas. A very important one for plants of course.
Setting this aside, during the Ordovician period CO2 was 8 to 20 times more plentiful in the atmosphere than now. the ordovician was charachterised for a very very protracted ice age. So it's not a simple tale of CO2. It's much more complex and much more complex than the models being used to predict climate change, especially when such models discount the medieval warm period and the mini iceage when the sun had bugger all spots for 200 plus years.
Chalcedon, the Ordovicia period was about 450 million years ago, conditions on the planet were very difference from now (Little land life, one super continent, such things markedly effect atmospheric circulation and climate) most of the period was noted for its warm GH conditions and absence of glaciation, the period ended with a mass extinction, rapid cooling, falling sea levels and increasing glaciation (the bit you refer to) What caused this rapid change? I'd suggest a sharp drop in sunlight reaching the Earth's surface through who-knows-what-cause.
The Maunder minimum lasted about 70 years, and occurred in the middle of the LIA, it's likely the two are related. This may surprise you but solar variations are taken it to account when causes of climate change are investigated.
Andrew W
i have a question. which is since plants absorb carbon dioxide and use it to grow, why isn't a big car engine, for instance, praised as a thing which helps plant growth?
just a thought.....
First my 2 cents worth. The effects of CO2 may be logarithmic, but that's obviously just a rough approximation based on current levels of CO2. If doubling CO2 increased the temperature by 1.2C, then halving CO2 concentrations should reduce CO2 levels by 1.2 C,
reducing levels to 1/2^40 would reduce temperatures by 1.2*40 = 48C, lower than NO greenhouse effect.
Post a Comment