Here is some real climate science ...

[Injunear]

I don't have any reason to think that the AGW theory is accurate, but let us suppose for a moment that atmospheric CO2 is causing climate change.

What is the source of the "extra" CO2 that is "forcing" the climate?

The Climate Alarmists will say that it is the fault of people burning fossil fuels. I have seen a range of possible estimates for how much CO2 is "added" to the atmosphere by fossil fuel burning. I would be interested to know of any reliable estimates but for the sake of this discussion let us take a figure that I have seen quoted of 29 Gigatonnes of CO2 per year, where a gigatonne is 10 to the power 9 (that is 1 with nine zeroes following).

Wow- that seems like a lot, doesn't it. But consider this:

The average human exhales about 5 litres of breath 12 times a minute. That exhaled breath contains about 5% CO2. That means that in one year a single human exhales about 12x5x60x24x365x0.05 = 1.6 million litres of CO2 per year. (1.6 x 10 to the power 6).

The density of CO2 is about 2 kilograms per cubic metre. A kilogram is 1 thousandth of a tonne (a tonne is 1000 kilograms). A litre is one thousandth of a cubic metre, so converting for units the density of CO2 is about 2 millionths of a tonne per litre (2 x 10 to the power -6).

So a single individual exhales about 3.2 tonnes of CO2 per year.

Now the population of the planet has risen from 1.9 billion in 1900 to 6 billion by 2000 and its still rising. In other words the contribution to CO2 "added" to the atmosphere from human breathing has risen from about 6 Gigatonnes (3.2 x 1.9 x 10 to the power of 9) per year to about 19 Gigatonnes per year, or 66% of the amount estimated to be "added" from fossil fuel burning.

Now if we are successful at replacing fossil fuels then CO2 emissions from that source will come down. But CO2 emissions from people breathing will still be going up and will soon replace the CO2 emissions from fuel burning. What then?

So my practical advice to all of you who are concerned about CO2 emissions is this - don't wait! The situation is critical! We are approaching a tipping point! The future of the planet is at stake! Stop breathing now!

[quelquod]

Perhaps those people who believe most strongly that anthropogenic CO2 is the driver of warming would volunteer to do the decent thing to save the rest of us?

[XFool]

"Here is some real climate science..."?

It's pretty obvious there isn't going to be any "climate science" on here. So I can't help wondering (but not a lot...) what the point of the thread is.

[AJC5001]

The average human exhales about 5 litres of breath 12 times a minute. That exhaled breath contains about 5% CO2. That means that in one year a single human exhales about 12x5x60x24x365x0.05 = 1.6 million litres of CO2 per year. (1.6 x 10 to the power 6).

I don't know about you, but in order to exhale 'about 5 litres of breath 12 times a minute' I would expect to inhale an equivalent 'about 5 litres of breath 12 times a minute'.

How much CO2 is there in the air inhaled?

The only extra CO2 produced by my metabolism is the difference between that in the air inhaled and exhaled.

Perhaps you need to recalculate?

Adrian

[wheypat]

We are, of course, wiping out vast numbers of other animal species - helping to keep the total weight of animals on the planet about the same. We have removed huge swathes of trees so that we can farm cows and pigs . The route cause of the extra CO2 is a combination of the extra people, food animals and burning of fossil fuels.

This estimate suggests that cows may be the second (or joint first) largest mass of single species on Earth at around 500 million tonnes. Cows fart, a lot. Each cow produces 70 to 120 kilos of methane a year. Methane is 23 times a more potent greenhouse gas than CO2.

People are the route cause. Because there are too many of us and we are irresponsible. We burn too much fossil fuels. We keep too many cattle. We all want and aim for a western standard of living.

https://en.wikipedia.org/wiki/Biomass_(ecology)
https://en.wikipedia.org/wiki/Cattle

[tjh290633]

I should point out that water vapour is still a higher absorber of infra-red radiation than either CO2 or Methane. When the temperature of the oceans rises, the amount of water vapour in the atmosphere increases.

This always seems to be a neglected factor.

TJH

[modellingman]

The average human exhales about 5 litres of breath 12 times a minute. That exhaled breath contains about 5% CO2. That means that in one year a single human exhales about 12x5x60x24x365x0.05 = 1.6 million litres of CO2 per year. (1.6 x 10 to the power 6).

I don't know about you, but in order to exhale 'about 5 litres of breath 12 times a minute' I would expect to inhale an equivalent 'about 5 litres of breath 12 times a minute'.

How much CO2 is there in the air inhaled?

The only extra CO2 produced by my metabolism is the difference between that in the air inhaled and exhaled.

Perhaps you need to recalculate?

Adrian

I concur. The OP seems to have used lung capacity (5 litres) instead of tidal volume, the average volume of air inhaled and exhaled in each breath, which is around 500 ml. This reduces by a factor of 10, the OPs estimate of the impact of human breathing.

"Here is some real climate science..."?

It's pretty obvious there isn't going to be any "climate science" on here. So I can't help wondering (but not a lot...) what the point of the thread is.

I concur. Back-of-tab-packet calculations are useful aids to get an initial feel for the numbers but the OP's calculations fall far short of of even an approximate analysis of the impact of human "living" activity on the carbon cycle. Perhaps the OP was writing with his tongue firmly stuck in his cheek. Where does all that exhaled carbon come from? A moment's reflection leads to the thought that as well as breathing humans also eat and, ultimately, what we eat is based on a food chain that involves plants and photosynthesis.

[tjh290633]

I should point out that water vapour is still a higher absorber of infra-red radiation than either CO2 or Methane. When the temperature of the oceans rises, the amount of water vapour in the atmosphere increases.

This always seems to be a neglected factor.

TJH

What the warmists don't seem to be able to explain though - Does increased water vapour (as clouds) in the atmosphere trap more heat underneath it? Or reflect more heat back to space above it? I have never seen an answer to this, or several other seemingly simple questions either.

The main effect of cloud is to prevent radiation reaching the surface of the earth during daylight hours. It will be absorbed by the water droplets and vapour and possibly make the air even more unstable, leading to bigger clouds. It's a long time since I did meteorology, but the adiabatic lapse rate is the main factor leading to instability, as I recall.

The other effect occurs at night, when the cloud layer prevents loss of radiation to space, as compared with a clear sky. The first time I went to the USA I was in West Virgina in February, during an anticyclone, and the temperature at daybreak was +4°F rising to +70°F at lunchtime, showing what the absence of cloud can do.

TJH

[woolly]

To save myself a lot of typing, can I refer you to this link? https://www.skepticalscience.com/human- ... ssions.htm

It summarises in simple terms how natural CO2 cycles all cancel each other out, while burning fossil fuels (and destroying forests and so on) leads to a net increase in atmospheric CO2.

The net effect of all the hot air generated by climate change discussion is of course not factored in...

[Injunear]

The first time I went to the USA I was in West Virgina in February, during an anticyclone, and the temperature at daybreak was +4°F rising to +70°F at lunchtime, showing what the absence of cloud can do.

Actually what this illustrates is not what clouds do, it illustrates what the sun does.

Not that clouds are unimportant to temperatures experienced on the surface, but clouds do not generate energy, though they can reflect, absorb, store (temporarily) and re-emit it.

[Injunear]

It summarises in simple terms how natural CO2 cycles all cancel each other out, while burning fossil fuels

It summarises rather too simply unfortunately.

Natural CO2 cycles do not all occur in the same rhythm or at the same place on the planet, so they cannot directly "cancel each other out". Nor are they identical every year or every season, which also means that they cannot "cancel each other out". Alarmists like to dismiss anything which doesn't fit within their theory so of course any natural emissions of CO2, like say a lagging emission from oceans, has to be ignored.

Unfortunately the AGW hypothesis does not explain how a modest natural variation in the carbon cycle has no effect on climate whilst all "man-made" carbon has catastrophic consequences.

BTW in what way is burning fossil fuels not part of the natural carbon cycle? Fossil fuels are simply plant sequestered carbon that was not immediately re-released into the atmosphere.

[Injunear]

What the warmists don't seem to be able to explain though - Does increased water vapour (as clouds) in the atmosphere trap more heat underneath it? Or reflect more heat back to space above it?

I think I can help you here even if warmists can't. I think you will find, pretty much everywhere on the planet, that surface temperatures are higher in the absence of clouds during the day, and higher in the presence of clouds during the night.

Therefore it seems reasonable to conclude, without the invention of magical properties of CO2, that clouds both reflect and absorb radiation during the day time incidence of the sun's energy and reflect (from the surface) and emit (downwards and upwards) radiation during the period of absence of the sun's energy.

Mind you I'm not a "climate scientist" with published peer reviewed articles in the appropriate blessed journals so this might not be the official view. Then again as a hypothesis it is verily falsifiable and, to my knowledge, has not yet been, so it seems to pass the test of being science.

[XFool]

If only everything was a simple as some imagine it to be then, who knows, even bods on bulletin boards could 'do' climate science.

https://en.wikipedia.org/wiki/Cloud_feedback

[Injunear]

I feel I should apologise to all of you who took this post seriously and thank you to all of you who have posted about the errors of assumption in my calculation.

I stand corrected re tidal volume, though I note that this is "at rest" which we cannot assume we are all the time.

Another addition to the science might be to calculate the additional CO2 that all the domesticated animals that we have and will have, to feed the additional population, would add. Much fun yet to be had ...