[atbb (OP)]

Hello,
          I doubt if you will agree with the following.
All the Earth's problems from global warming, pollution, wars, shortage of water and food, housing, even to the care of the elderly could be solved by huge population reduction.
Total human removal would help all the other species best, but with a
greatly reduced population we could learn to manage the Earth with
greater care.
The human population needs a large reduction, and I do not mean
culling as we sadly do to other forms of life. I would not suggest bringing
about the death of any human being in any of the barbaric ways we
remove other unwanted species of life.
Even though we are the most voracious animals on this planet we do not
need take any human life to do this.
It should be done openly through a world summit to find the best way to
encourage all of human kind to be sterilised if they wish it. Those who would
like a family, let them, the population would still go down.
It should ignore all protest.
The United Nations could do this.
It is our only hope, it is the only chance of humans living with the Earth
and not against it. Science should be able to produce a simple oral tablet
to bring sterility. With education and many outlets for the product, people
would choose to do this voluntarily. Rewards could even be given. This would
in a few decades, leave a stable, content reduced population.
The many species of life, other than the thousands we have made extinct
may then be saved.
If we do not greatly reduce the human population, then in a few decades
we will completely perish and the sad part is we will take with us millions
of other species. When we remove one species, many others may die out
that relied on its existence.
In other words we can only remove so many before it escalates out of
control and then we follow.
The extinction of any species by our hands is a crime beyond all other
crimes, as who knows what that species would have developed into in time.
Within a few years it will be too late.
David.

newbielink:http://www.artbydecart.co.uk [nonactive]    
My theory of creation, my theory of the meaning of life, my propulsion idea, a scaled down Universe, my shipping idea, my train stop idea and my link page.

[another_someone]

Problems?  What problems?

Certainly, there are species that will benefit from the demise of the human species, but others that will suffer badly.  Humans have made substantial changes to their environment, and some species (e.g. grasses, domesticated animals, some rodents that have leaned to take advantage oif the resources humans provide) have benefited from the changes humans have made; while other species (hardwood trees, many large predators) have suffered because of those changes.  If humans were removed from the planet, grasses would lose out, but trees would win; sheep would lose, but big cats would win.

As for global warming, this is only seen as a problem within the human context (the planet has been much warmer in the past than anything we experience today, but there were no humans around to grumble about it) – but if we lose the human species, then where is the problem with a warmer planet?

Certainly, there have been many attempt at human sterilisation.  In India, Indira Ghandi instigated a policy of voluntary sterilisation, except there was some doubt that it was always as voluntary as it was suggested.  China had (and maybe still has) a one child one family policy.  In Europe, very few countries are actually having enough children to sustain their current population.  Whether any of this actually provides a solution – I doubt it.  My own suspicion is that it may make the total population numbers look like they are decreasing, but it will so skew the age distribution within the population as to ultimately lead to a catastrophic collapse of the population, simply because we will have lots of old people who are beyond reproduction age, and relatively few people young enough to reproduce, and when the old die off, the population will crash in a very dramatic and frightening way.

Ofcourse, the issue I keep raising is that while people look at the human population, and ask what resources the human animal uses, people still ignore the ever increasing number of machines created by humans.  For the most part, it is not the human animal, with their requirement for some food, clothing, and shelter, that utilise the greatest resources; but the machines, whether they be aeroplanes or factories run by robots, that really use the greatest amount of resources.  Even if we reduce the human population to 10% of its present size, if those 10% continue to leverage there output by using ever more machines to replace the 90% of human animals that no longer exist, then how would you expect any reduction in resource usage?

George

[science_guy]

As george was just saying, That would help nothing.  And even if we stop the machines, we would only speed up the inevitible.  Because of human activity (decaying corn and farting cows releasing methane) and more recently, burning of fossil fuels, we have retained much of our heat through global warming.  The truth is, Humans have forestalled the next ice age for 5000 years now.  In other words, The second Ice age would of started at b.c. 3000.  Scientists predict that as soon as we run out of fossil fuels, or stop using them, the temperature will begin to catastrophically drop.  We have, remaining to us, 120 years, at best, left on this planet.

Other than that, How was your day? [][]

_________________________________________________________________________________________

I would engage you in a battle of wits, but it is against my moral code to attack the unarmed.

[crandles]

Ruddimann's view of pre-industrial global warming is a minority opinion. See http://en.wikipedia.org/wiki/Global_warming

The more majority opinion is that the current interglacial was meant to be a long one so it wasn't supposed to have ended yet.

quote:as soon as we run out of fossil fuels, or stop using them, the temperature will begin to catastrophically drop. We have, remaining to us, 120 years, at best, left on this planet.

Says who??

CO2 levels are likely to stay at elevated levels for thousands of years after we stop using fossil fuels and I doubt we will have a sudden dramatic ceasation of use of fossil fuels. Even if that did happen the warmest period would be at least a decade or two later.

[another_someone]

quote:Originally posted by crandles
Ruddimann's view of pre-industrial global warming is a minority opinion. See http://en.wikipedia.org/wiki/Global_warming

The more majority opinion is that the current interglacial was meant to be a long one so it wasn't supposed to have ended yet.

What interglacial - we are not in an interglacial - we are still in a trelatively very cold climate in comparison to most of geological time.  There has been a slight rise in temperature above the minimum, but we are well short of being in a warm period.

quote:
CO2 levels are likely to stay at elevated levels for thousands of years after we stop using fossil fuels and I doubt we will have a sudden dramatic ceasation of use of fossil fuels. Even if that did happen the warmest period would be at least a decade or two later.

How do you work out such a long period for CO2 recycling - I would have thought that given that even with the raised levels of CO2 in the atmosphere, they are still only a minute proportion of the amount of O2 (all of which is converted from CO2), that it should not take long at all for the any excess CO2 (of the very slight amount we talk about) to also be converted to O2.

Even the web site you quote (which certainly does not look like it is trying to underplay the impact of global warming) only talks abot 50 to 200 years to recycle the CO2, and I personally would be surprised if it took as long as that (although I claim no expertise for behind that opinion).

George

[crandles]

quote:Originally posted by another_someone

quote:Originally posted by crandles
Ruddimann's view of pre-industrial global warming is a minority opinion. See http://en.wikipedia.org/wiki/Global_warming

The more majority opinion is that the current interglacial was meant to be a long one so it wasn't supposed to have ended yet.

What interglacial - we are not in an interglacial - we are still in a trelatively very cold climate in comparison to most of geological time.  There has been a slight rise in temperature above the minimum, but we are well short of being in a warm period.

quote:
CO2 levels are likely to stay at elevated levels for thousands of years after we stop using fossil fuels and I doubt we will have a sudden dramatic ceasation of use of fossil fuels. Even if that did happen the warmest period would be at least a decade or two later.

How do you work out such a long period for CO2 recycling - I would have thought that given that even with the raised levels of CO2 in the atmosphere, they are still only a minute proportion of the amount of O2 (all of which is converted from CO2), that it should not take long at all for the any excess CO2 (of the very slight amount we talk about) to also be converted to O2.

Even the web site you quote (which certainly does not look like it is trying to underplay the impact of global warming) only talks abot 50 to 200 years to recycle the CO2, and I personally would be surprised if it took as long as that (although I claim no expertise for behind that opinion).

George

>What interglacial?

We are at the left hand side of http://en.wikipedia.org/wiki/Image:Ice_Age_Temperature.png

So we are warmer than most of the last 450,000 years.

If you go back more than 5 million years http://en.wikipedia.org/wiki/Geologic_temperature_record
yes we are colder than most of geologic time but I think the last 450,000 years is more relevant than what happened over 5 million years ago.

>How do you work out such a long period for CO2 recycling

Try http://www.realclimate.org/index.php/archives/2005/03/how-long-will-global-warming-last/

A couple of hundred years is a typical lifetime estimate. However there is a small proportion that takes a long time to disappear.

[another_someone]

quote:Originally posted by crandles
>What interglacial?

We are at the left hand side of http://en.wikipedia.org/wiki/Image:Ice_Age_Temperature.png

So we are warmer than most of the last 450,000 years.

Interesting how different sources give different answers (but it also depends upon how you define an ice age).

http://en.wikipedia.org/wiki/Ice_ages

quote:
An ice age is a period of long-term downturn in the temperature of Earth's climate, resulting in an expansion of the continental ice sheets, polar ice sheets and mountain glaciers ("glaciation"). Glaciologically, ice age is often used to mean a period of ice sheets in the northern and southern hemispheres; by this definition we are still in an ice age (because the Greenland and Antarctic ice sheets still exist). More colloquially, when speaking of the last few million years, ice age is used to refer to colder periods with extensive ice sheets over the North American and Eurasian continents: in this sense, the last ice age ended about 10,000 years ago. This article will use the term ice age in the former, glaciological, sense; and use the term glacial periods for colder periods during ice ages and interglacial for the warmer periods.
Many glacial periods have occurred during the last few million years, initially at 40,000-year frequency but more recently at 100,000-year frequencies. These are the best studied. There have been four major ice ages in the further past.

So it depends upon whether you regard an ice age as an absolute term, meaning that there is permanent ice somewhere on the planet (a situation that persists today), or a relative term, merely meaning that the era is colder than the periods of time before and after.

The problem with the relative aspect of it is which periods of time do you judge to be sufficiently significant to be regarded as a warmer of cooler period.  What about the mini-ice age of the 17th century – do you include that in your comparative assessment of an 'ice age'?

quote:Originally posted by crandles
If you go back more than 5 million years http://en.wikipedia.org/wiki/Geologic_temperature_record
yes we are colder than most of geologic time but I think the last 450,000 years is more relevant than what happened over 5 million years ago.

This is not completely true.

It is certainly true that the period over 5 million years ago was warmer, but:

http://en.wikipedia.org/wiki/Ice_ages

quote:
The earliest hypothesized ice age is believed to have occurred around 2.7 to 2.3 billion (109) years ago during the early Proterozoic Age.
The earliest well-documented ice age, and probably the most severe of the last 1 billion years, occurred from 800 to 600 million years ago (the Cryogenian period) and it has been suggested that it produced a Snowball Earth in which permanent sea ice extended to or very near the equator. It has been suggested that the end of this ice age was responsible for the subsequent Cambrian Explosion, though this theory is recent and controversial.
A minor ice age occurred from 460 to 430 million years ago, during the Late Ordovician Period.
There were extensive polar ice caps at intervals from 350 to 260 million years ago, during the Carboniferous and early Permian Periods, associated with the Karoo Ice Age.
The present ice age began 40 million years ago with the growth of an ice sheet in Antarctica, but intensified during the Pleistocene (starting around 3 million years ago) with the spread of ice sheets in the Northern Hemisphere. Since then, the world has seen cycles of glaciation with ice sheets advancing and retreating on 40,000 and 100,000 year time scales. The last glacial period ended about 10,000 years ago.

quote:Originally posted by crandles
>How do you work out such a long period for CO2 recycling

Try http://www.realclimate.org/index.php/archives/2005/03/how-long-will-global-warming-last/

A couple of hundred years is a typical lifetime estimate. However there is a small proportion that takes a long time to disappear.

There numbers are based upon an interesting assumption:

http://www.realclimate.org/index.php/archives/2005/03/how-long-will-global-warming-last/

quote:
Thus land-based plant sequestration should not be regarded as permanent.

While I accept that the simple argument that forests will convert CO2 to O2 is simplistic, because forests are a complex environment that is generally carbon neutral; but equally, one has to ask where did the oxygen come from – free oxygen does not come from CO2 that is dissolved in the oceans, nor CO2 that has been converted into carbonate, since neither of these means will free the oxygen back into the atmosphere.

They may be correct that this is not land based plants, but maybe marine algae that is doing this rather than land based plants, but they seem to disregard any aspect of photosynthesis at all in their calculations.  I agree with their assessment that it probably is not the forests, but to jump from that to dismissing all photosynthesis seems to me to be absurd.  The bottom line has to be that every mole of O2 in the atmosphere started some time as a mole of CO2 (with maybe a minute amount of O2 created from the reduction of metal oxides – if any at all), and that reduction of CO2 to O2 must come about through photosynthesis, thus to totally disregard all photosynthesis as irrelevant simply because the photosynthesis in a forest environment does not achieve the required function seems to be incomprehensible to me.

George

[crandles]

mini-ice age clearly indicates it is not a full ice age. I am not particularly interested in discussing the exact amount of warming to meet some idea of a relative warm period. I think I have explained what I meant about being in a warm period compared with most of the last 450,000 years.

Not sure what wasn't completely true :?


"Thus land-based plant sequestration should not be regarded as permanent." looks to me more like a conclusion than an assumption. It is in comment 8 not the article if anyone wants to look for it.

I disagree that it is ignoring photosynthesis. It just happens to be not very relevant. At equilibrium plant photosynthesis is matched by plant decay, animal respiration and soil decomposition. If you add a slug of new CO2 to the atmosphere, for a brief period the land takes up more carbon. However the amount of carbon that can be taken up by land is limited and a new equilibrium will be reached. This is small compared with the ocean uptake. Between land and ocean around 75% is taken up in a short period of a few hundred years. The remaining 25% takes much longer.

I don't see why you have to ask where the oxygen comes from. The oxygen in the atmosphere is a massive store that represents millions of years of turnover from O2 to CO2 and back. The turnover isn't important it is the net balance. It isn't the O2 we are interested in it is the carbon.

[another_someone]

quote:Originally posted by crandles
Not sure what wasn't completely true :?

You had stated that you accepted that “if you go back more than 5 million years yes we are colder than most of geologic time “ - I was merely saying that just as there were many times that we have been warmer (very much warmer) than we are today, there were also many periods when we were colder than we are today, and simply seeing the Earth's climate as a one way process (i.e. overall cooling) with some noise thrown in, is too simplistic.  There are wide swings in both directions, and always have been, and we are nowhere near either extreme at present.  Similarly, simply to say that we should ignore anything older the 450,000 years as being inherently different from today (although one can argue that history, even the Earth's climate, never quite repeats itself), seems an arbitrary distinction to make.

quote:
I disagree that it is ignoring photosynthesis. It just happens to be not very relevant. At equilibrium plant photosynthesis is matched by plant decay, animal respiration and soil decomposition. If you add a slug of new CO2 to the atmosphere, for a brief period the land takes up more carbon. However the amount of carbon that can be taken up by land is limited and a new equilibrium will be reached. This is small compared with the ocean uptake. Between land and ocean around 75% is taken up in a short period of a few hundred years. The remaining 25% takes much longer.

If you regard it as irrelevant, then you seem in effect to be justifying that it is ignored.  I certainly don't see it being taken into account.

quote:
I don't see why you have to ask where the oxygen comes from. The oxygen in the atmosphere is a massive store that represents millions of years of turnover from O2 to CO2 and back. The turnover isn't important it is the net balance. It isn't the O2 we are interested in it is the carbon.

A balance is only something we can ignore if we understand how that balance in maintained, and how it changes.
If humans are creating lots of CO2 through combustion, then they must in fact be using up lots of O2.  If you then make the assertion that O2 and CO2 are in permanent balance, then it must follow that there is a process where the O2 that the humans have used is somehow replenished, and this being from most probably by the reduction of that same CO2 back to O2 (through photosynthesis).  If the CO2 is not converted back to O2, then the O2/CO2 cycle is not in balance.
The absorption of CO2 by the oceans and by carbonate rocks does little to maintain the balance between O2 and CO2 (the processes are happening without regard to the levels of O2 in the atmosphere, excepting insofar as you may judge that in the extreme, an anoxic environment would not support shellfish and other living forms that convert CO2 to carbonates).
It has to be remembered that the only significant means of creating free oxygen on this planet is through photosynthesis, and so one must see the creation of free oxygen as a direct measure of the rate of photosynthesis, and the amount of free oxygen on the planet as a store of historic CO2 that has been converted to O2.  Clearly, the turnover is critical in any assessment of the pricess, since it indicates how responsive the system may be to environmental changes.

George

[crandles]

I said "yes we are colder than most of geologic time" I didn't say colder than all of geologic time over 5 million years ago.

I also said "I think the last 450,000 years is *more* relevant than what happened over 5 million years ago". I didn't say the last 450,000 years is relevant and over 5 million years ago is irrelevant. Therefore I don't think I did say ignore the periods over 5 million years ago. As to whether it is more relevant, note that the post I was answering mentioned having only 120 years left.

quote:A balance is only something we can ignore if we understand how that balance in maintained, and how it changes.

Fair enough and I guess there is some room for disagreement over how well all the processes are understood. Some are known better than others and we know more about situation similar to the present than about situation different from present. But generally I thing the processes are known well enough that intellegent estimates are good enough to make reasonable models that are far from perfect but good enough to be useful.

quote:
If humans are creating lots of CO2 through combustion, then they must in fact be using up lots of O2. If you then make the assertion that O2 and CO2 are in permanent balance, then it must follow that there is a process where the O2 that the humans have used is somehow replenished

Why would anyone make that assertion? We are trying to see what happens to CO2 so assuming a permanent balance seems very odd. If the O2 stock was changing significantly maybe that would have an effect on the processes of O2 to CO2 and CO2 to O2. However the stock of O2 is so huge
it is changing but not changing significantly.

quote:

The absorption of CO2 by the oceans and by carbonate rocks does little to maintain the balance between O2 and CO2 (the processes are happening without regard to the levels of O2 in the atmosphere, excepting insofar as you may judge that in the extreme, an anoxic environment would not support shellfish and other living forms that convert CO2 to carbonates).
 

As O2 is not in balance but staying practically constant, any change in ratio of CO2 to O2 is due to changes in CO2. If ocean absorbtion is taking up 75% of the extra CO2 we are producing, how do you decide that is doing "little to maintain the balance"?

I still don't see the relevance of O2.

quote:
It has to be remembered that the only significant means of creating free oxygen on this planet is through photosynthesis, and so one must see the creation of free oxygen as a direct measure of the rate of photosynthesis, and the amount of free oxygen on the planet as a store of historic CO2 that has been converted to O2. Clearly, the turnover is critical in any assessment of the pricess, since it indicates how responsive the system may be to environmental changes.

So

I still don't see the relevance of O2.

[science_guy]

quote:CO2 levels are likely to stay at elevated levels for thousands of years after we stop using fossil fuels and I doubt we will have a sudden dramatic ceasation of use of fossil fuels. Even if that did happen the warmest period would be at least a decade or two later.

part of the reason the temperature will drop is because of the lack of heat from the combustion of fossil fuels.  The reactions do produce heat, and that is part of what has kept this planet warm.  Without that, the temperature will fall, because the orbit that alters the earth enough to cause the ice age, is well into the cycle and it will not have the immediate benifit of hot sun.

_________________________________________________________________________________________

I would engage you in a battle of wits, but it is against my moral code to attack the unarmed.

[another_someone]

quote:Originally posted by crandles

quote:
If humans are creating lots of CO2 through combustion, then they must in fact be using up lots of O2. If you then make the assertion that O2 and CO2 are in permanent balance, then it must follow that there is a process where the O2 that the humans have used is somehow replenished

Why would anyone make that assertion? We are trying to see what happens to CO2 so assuming a permanent balance seems very odd. If the O2 stock was changing significantly maybe that would have an effect on the processes of O2 to CO2 and CO2 to O2. However the stock of O2 is so huge
it is changing but not changing significantly.

quote:

The absorption of CO2 by the oceans and by carbonate rocks does little to maintain the balance between O2 and CO2 (the processes are happening without regard to the levels of O2 in the atmosphere, excepting insofar as you may judge that in the extreme, an anoxic environment would not support shellfish and other living forms that convert CO2 to carbonates).
 

As O2 is not in balance but staying practically constant, any change in ratio of CO2 to O2 is due to changes in CO2. If ocean absorbtion is taking up 75% of the extra CO2 we are producing, how do you decide that is doing "little to maintain the balance"?

I still don't see the relevance of O2.

I shall be brief, but merely try and clarify the following point:

Atmospheric O2 is 209,460 ppmv
Atmospheric CO2 is 381 ppmv
If 0.18% of the O2 in the atmosphere is converted to CO2, that is a 100% rise in CO2.  If all of the CO2 in the atmosphere were to be converted to O2, it would only represent 0.18% change in the volume of O2 in the atmosphere.
Are we sure that the volume of O2 in the atmosphere has remained constant to within 0.1% (i.e. less that 1 part per thousand change in total volume, or more accurately, in the number of moles, since volume can also vary because of changes in temperature and pressure) tolerance over geological time (or even within recent times)?

George

[crandles]

quote:Originally posted by science_guy

quote:CO2 levels are likely to stay at elevated levels for thousands of years after we stop using fossil fuels and I doubt we will have a sudden dramatic ceasation of use of fossil fuels. Even if that did happen the warmest period would be at least a decade or two later.

part of the reason the temperature will drop is because of the lack of heat from the combustion of fossil fuels.  The reactions do produce heat, and that is part of what has kept this planet warm.  Without that, the temperature will fall, because the orbit that alters the earth enough to cause the ice age, is well into the cycle and it will not have the immediate benifit of hot sun.

The reactions produce heat but it is negligible. It is the carbon dioxide and other greenhose gasses' effect on radiative balance that matters.

See http://www.climateprediction.net/board/viewtopic.php?t=2723

Orbital cycles take thousands of years so you should expect changes to be slow. If you are interested in what happens in the next 100 years or so then it is the greenhouse gas levels that matter. I see little chance of 60% cuts in greenhouse emissions in the next 30 years so greenhouse gas levels will keep rising for at least that long and the warmest period will be well after the peak greenhouse gas levels.

[science_guy]

the orbit cycles are entirely my point.  The orbit cycle started to enter the ice age at b.c. 3000.  That means the orbit has had 5000 years to change.  Sure the burning of fossil fuels is negligible, but even negligible amounts can add up to be a dominating resource.  The point is that humans will no longer be able to survive on the planet for very much long, regardless of how it happens.

_________________________________________________________________________________________

I would engage you in a battle of wits, but it is against my moral code to attack the unarmed.

[crandles]

quote:Originally posted by another_someone

I shall be brief, but merely try and clarify the following point:

Atmospheric O2 is 209,460 ppmv
Atmospheric CO2 is 381 ppmv
If 0.18% of the O2 in the atmosphere is converted to CO2, that is a 100% rise in CO2.  If all of the CO2 in the atmosphere were to be converted to O2, it would only represent 0.18% change in the volume of O2 in the atmosphere.
Are we sure that the volume of O2 in the atmosphere has remained constant to within 0.1% (i.e. less that 1 part per thousand change in total volume, or more accurately, in the number of moles, since volume can also vary because of changes in temperature and pressure) tolerance over geological time (or even within recent times)?

George

Why do we want to be sure that the moles of O2 has remained constant to with .1%? That would hardly have much effect on CO2 to O2 or on O2 to CO2.

If it was varying more than .1% what would that mean? Well it would probably be to do with other reactions other than the O2 to CO2 and CO2 to O2 reaction. Why? because we know CO2 has not changed by 50% or more recently.

So what has this got to do with what we are discussing?

[crandles]

quote:Originally posted by science_guy

the orbit cycles are entirely my point.  The orbit cycle started to enter the ice age at b.c. 3000.  That means the orbit has had 5000 years to change.  Sure the burning of fossil fuels is negligible, but even negligible amounts can add up to be a dominating resource.  The point is that humans will no longer be able to survive on the planet for very much long, regardless of how it happens.

Read my earlier reply. We are not sure that "The orbit cycle started to enter the ice age at b.c. 3000". If you start by assuming there is one 100,000 year cycle then it does look as if we are overdue for an ice age. However, it is more complex than that and it looks like that is a bad assumption. There are cycles at 41,000, 102,000 and 22,000 years. It looks like the 41,000 ought to be the dominant cycle but the proxy records show something more like a 100,000 year cycle. The majority view is that the current warm period is supposed to be long one and therefore the ice age is not overdue.

Even if it was overdue the effect is slow and perhaps it could be more than offset by greenhouse gas effects for at least a couple of centuries and perhaps for a whole 41,000 year cycle.

I think your posts are inappropriately doom laden. I don't see the tropics getting as cold as greenland or greenland getting hotter than the tropics. Therefore I believe the conditions for humans to survive will remain. It isn't clear that civilisation would survive dramatic changes.

I doubt the changes will be that dramatic enough to cause civilisation to collapse so I view that as an extreme possibility. By contrast, your posts say *will* not may and I think that is untenable.

[another_someone]

quote:Originally posted by crandles
Why do we want to be sure that the moles of O2 has remained constant to with .1%? That would hardly have much effect on CO2 to O2 or on O2 to CO2.

If it was varying more than .1% what would that mean? Well it would probably be to do with other reactions other than the O2 to CO2 and CO2 to O2 reaction. Why? because we know CO2 has not changed by 50% or more recently.

So what has this got to do with what we are discussing?

I was not suggesting that the change in volume of O2 was .1% or greater, I was suggesting that if we are not able to tell if the volume remained constant to with .1%, then clearly, even smaller changes are even less likely to have been noticed.
A change in volume of 0.06% would be enough to explain a 30% change in CO2 volume, or to absorb what might have amounted to a 30% change in CO2 volume (I believe that some there are some who consider that the increase in CO2 in the atmosphere since the levels in pre-industrial times to be in the order of 30%, and I would have no reason to contradict them).

George

[crandles]

This seems to have started with

quote:
While I accept that the simple argument that forests will convert CO2 to O2 is simplistic, because forests are a complex environment that is generally carbon neutral; but equally, one has to ask where did the oxygen come from

I am no nearer to understanding why 'one has to ask where did the oxygen come from'.



I think these numbers could be a little out of date. I think human fossil fuel use was 7GT several years ago so 5.5 looks a little on the low side. Despite this, I think we understand the processes well enough to make intelligent estimates of how the numbers will change as the CO2 level increases. Models suggest that the carbon in vegetation has been increasing but is likely to soon start decreasing.

If the best way of measuring the CO2 level is from ice cores then I don't see why you have to bother with an non optimal method of trying to measure the O2 level or worrying about where the O2 comes from.

[another_someone]

quote:Originally posted by crandles
I am no nearer to understanding why 'one has to ask where did the oxygen come from'.



I think these numbers could be a little out of date. I think human fossil fuel use was 7GT several years ago so 5.5 looks a little on the low side. Despite this, I think we understand the processes well enough to make intelligent estimates of how the numbers will change as the CO2 level increases. Models suggest that the carbon in vegetation has been increasing but is likely to soon start decreasing.

If the best way of measuring the CO2 level is from ice cores then I don't see why you have to bother with an non optimal method of trying to measure the O2 level or worrying about where the O2 comes from.

I, on the other hand, do not understand exactly what the image is trying to say (that a picture says a thousand words does not mean that the thousand words actually make any sense).

How, in that picture, would you extract a total figure for all of the CO2 that is converted to O2 through photosynthesis (maybe I am just not looking at the right bot to see the number, and am simply being a total fool, but I cannot see the number).

What are the margins of error for these figures?

George

[crandles]

quote:Originally posted by another_someone
I, on the other hand, do not understand exactly what the image is trying to say (that a picture says a thousand words does not mean that the thousand words actually make any sense).

How, in that picture, would you extract a total figure for all of the CO2 that is converted to O2 through photosynthesis (maybe I am just not looking at the right bot to see the number, and am simply being a total fool, but I cannot see the number).

What are the margins of error for these figures?

George

The figure for photosynthesis is 121.3. That figure is for the carbon cycle and the units are Gigatonnes of carbon per year. To convert to weight of CO2 you would multiply by 44/12.

Margins of error is a good question and I suspect some are quite large but there are lots of correlations in the errors:

A reason I introduced the pic was to show the different timescales involved. For carbon in the atmosphere only lasts 750/(121.3+.5+90) = 3.5 years. For Marine Biota 3/50=.06.

A similar calculation can be done for oxygen and I now think it looks like about 10,000 years (not millions as I said earlier sorry).

Clearly the timeframes are very different.

I would assume the figures are quoted to an appropriate number of significant figures. So a figure like 60 could be out by around 10. We may not know all these figures accurately. It is the net movement in the stores that are the important thing. So for marine biota 50-40-6-4=0 and we know that 0 is pretty close because if it was 0.1 that would represent doubling or completely disappearing in 30 years.

I therefore believe we know how the quantity stored in each form is changing far better than we know some of the figures in that pic.