[Bored chemist]

The 400ppm or so of CO2 in air should be referred to as a mixing ratio, rather than a  concentration.
The units are wrong for a concentration which would be in mass (or moles) per unit volume.
It's a terminology thing, familiar enough to those who study atmospheric physics.

"That would explain a decrease in CO2 level. It doesn't explain an increase. Plants do not exhale carbon dioxide."
Actually, they do.
When there's not much sunlight about they metabolise differently and produce CO2.

[alancalverd]

Which would make the graph all the more mysterious. As the amount of sunlight increases, so does the amount of CO2!

[damocles]

From Alancalverd (#201)

Which would make the graph all the more mysterious. As the amount of sunlight increases, so does the amount of CO2!

***

From damocles (#183)

Quote from: alancalverd on 04/07/2013 09:45:03
Reverting to Mauna Loa, they do publish an annual CO2 cycle with the underlying trend removed.  I'm baffled as to why the CO2 level rises whilst the trees are growing, reaches a peak in summer, and decreases as photosynthesis shuts down.  When I was a lad, we were taught that photosynthesis extracts CO2 from the atmosphere, so I'd expect exactly the opposite behaviour if your model is correct (and they haven't moved Hawaii!). Where does the summer CO2 come from? Certainly not human activity, unless you Aussies have found some way of exporting your winter barbie smoke across the equator and halfway round the world.


Alan please check this diagram and tell me if that is the graph you are referring to: http://commons.wikimedia.org/wiki/File:Mauna_Loa_Carbon_Dioxide.png

If so, then you must appreciate two things:
firstly that the maximum and minimum are in May and October respectively, not June and December.
secondly that the amount of photosynthetic activity is reflected in the rate of change (slope) of the mixing ratio graph rather than the mixing ratio per se.

The months of maximum negative gradient (high photosynthetic activity) are June and July -- summer months -- while those of maximum negative gradient (low photosynthetic activity) are December, January, and February, the winter months.

***
Been there , done that, not really up for another lap!

[alancalverd]

OK, let's make it simple.

Long before humans evolved, plants extracted CO2 from the atmosphere. The atmosphere is finite, but the amount of CO2 in the atmosphere sometimes increased and certainly never decreased to the extent that the plants died.

What mechanism recycled the carbon, previously extracted by plants, back into the atmosphere?

(Hint: all animals generate energy by converting carbon componds to carbon dioxide.)

[damocles]

Hint to you alan: If animals generate energy by converting carbon to CO2, what about plants and microorganisms?

http://vro.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/soilhealth_organic_carbon-cycle

plants ~50%, microorganisms ~45%, animals ~5%

[alancalverd]

Intriguing thought that living plants lose half of the carbon they acquire - I thought it was less than 10%. Nevertheless, the loss is a "business expense" and the overall tendency is for plants to sink carbon when the sun shines, as evidenced by the fact that trees start small and get bigger every year until they die.

So as far as I am concerned, the point is proved. Microorganisms that convert plant material to CO2 count as "animals by definition" in the simple scheme of things, so as the temperature rises, so the wee beasties become more active and recycle carbon to the atmosphere, completely explaining the shape of the seasonal curve.   

I'll concede a free kick on yeasts. Neither plants nor animals, but they metabolise plant sugars. That said, they do not need sunlight to do so, and are temperature-sensitive, so the mechanism stands: in the absence of volcanic or human activity, the concentration, mixing ratio or whatever you want to call it of CO2 in the atmosphere depends on the competitive balance between plant and non-plant metabolism, which is determined by temperature and insolation. This gives us a plausible relationship between cause and effect that consists with observation: long-term, the CO2 graph lags behind the temperature curve, and short-term [CO2] increases as the temperature rises, until plant activity catches up.

[MoreCarbonOK]

henry@alan

anyway, as I had been saying all along, more carbon is OK, in fact it is better....

http://wattsupwiththat.com/2013/07/08/deserts-greening-from-rising-co2/

[alancalverd]

Nothing new here, then. Local market gardeners burn diesel fuel to increase the CO2 level in their greenhouses (they sell the electricity as a byproduct - the profit margin is in the salad!) and have to ventilate the greenhouse before it's safe for humans to harvest.

There is however an upper limit beyond which it seems that plants shut down, but in answer to the original question, it's well above 400 ppm, and 40,000 ppm is considered long-term tolerable for humans.

So we can expect the jungle to flourish for a while.

[Bored chemist]

henry@alan

anyway, as I had been saying all along, more carbon is OK, in fact it is better....

http://wattsupwiththat.com/2013/07/08/deserts-greening-from-rising-co2/

Most people don't live in deserts so greening them is of marginal benefit to people
On the other hand, a lot of people live on coastlines.
Sea level rises are bad for them.

I think Alan has shown the falsehood of your idea when he said
"...have to ventilate the greenhouse before it's safe for humans to harvest. "

Anyway, the point is easy to settle.
If you think more CO2 is better- just sit in a room full of it for a while.
Until you have done that, please don't make the false statement again.

[alancalverd]

Oh come on, BC!

There's a huge difference between 400 ppm and 40,000 ppm, and the mammalian breathing reflex doesn't work in the complete absence of CO2 (which is why we have re-breathing bags on oxygen supplies).

The Israeli economy was built on greening deserts. The US economy nearly collapsed when overcultivation turned parts of the Midwest into a dustbowl. History suggests that the Sahara was largely manmade: its fringes certainly support a fair number of people, and anything we can do to keep it in check, or even reverse desertification, would be welcome. 

Not that I have any sympathy with "most people". The world would be a much nicer place with a smaller human population. 

[Bored chemist]

Oh come on, BC!

There's a huge difference between 400 ppm and 40,000 ppm

Yes, there is.
Which is why the unqualified statement that "more is better" is obviously nonsense.
So, it's a shame that he keeps saying it- but he does.
Perhaps you can persuade him to stop. I have tried several times but he keeps on saying it even though it has been explained repeatedly, and at length, that it's not true.

Also, whatever the merits of wiping out a few billion people (and I can think of some who we could start with) it would be impossible to do it without killing a lot of innocent animals and that's not fair.


Also, things like
"The US economy nearly collapsed when overcultivation turned parts of the Midwest into a dustbowl."
Suggest that trying to grow too much, without regard for the other resources available is a bad thing.
If you raise the CO2 but not the supply of fixed nitrogen or the potassium or and (most importantly of all) the water, how long will this greening last? Perhaps as long as the early Midwestern corn belt.

Perturbing balanced systems is inherently risky; why advocate doing more of it on the biggest scale in history.
As you say, the Sahara, the Midwest and Israel are examples of what happens if you get it wrong. At least those were localised.
You seem to think it's a good idea to mess with the whole world in that way.
Are you sure that's a good idea?

[alancalverd]

AFAIK, Israel continues to export fruit and vegetables from a greened desert. At least the stuff I bought last week. The recent CO2-greening of the Australian desert and other areas appears to be entirely in equilibrium: I don't see massive changes in agriculture over the entire planet, just natural vegetation being its opportunistic self. And IIRC, increased vegetation tends to increase rainfall and wild forests incorporate their own nitrogen fixers.

Curious, isn't it, that any time anyone mentions reducing the human population, someone starts talking about killing. Seems to be an inherent defect in the human brain. Killing is a pointless, ethically complicated, and ludicrously expensive way of doing it. People die, quite naturally, at the rate of about 1.5% per annum. Now if we simply reduce our birthrate, the one ecological variable over which we have absolute and orthogonal control, we can reduce the population and make the world a better place by doing nothing at all! (As I recall, making babies involves doing quite a bit.) 

[damocles]

Alan, the "recent CO2 greening of the Australian  Desert" is no such thing. It is a water greening based around a few successive seasons of exceptional rainfall in the centre. It is an extreme form of a phenomenon that is not unprecedented, and can probably be attributed to climate change, which may or may not be an indirect consequence of CO2 mixing ratio change.

There is a form of farming in Australia called "opportunity cropping". When there is an inland flood a lot of the lakes fill up. The soil becomes waterlogged around the lakes. But there is a significant zone in a ring around any lake where the soil has just the right moisture content to support a crop and not to bog the farm machinery. The following year that ring will be a little smaller, and it will gradually shrink in towards the lake until the soil becomes too salty. At that stage cropping is abandoned until the next flood.

[alancalverd]

Just to quote a bit of the article that MCOK referenced:

In findings based on satellite observations, CSIRO, in collaboration with the Australian National University (ANU), found that this CO2 fertilisation correlated with an 11 per cent increase in foliage cover from 1982-2010 across parts of the arid areas studied in Australia, North America, the Middle East and Africa, according to CSIRO research scientist, Dr Randall Donohue.

“In Australia, our native vegetation is superbly adapted to surviving in arid environments and it consequently uses water very efficiently,” Dr Donohue said. “Australian vegetation seems quite sensitive to CO2 fertilisation.

 

Doesn't sound like opportunity cropping to me, unless that Yanks and everyone else have had exceptional rainfall every year since 1982 - which rather questions the meaning of "exceptional"! And I wouldn't class CSIRO and ANU among the evil atheistic capitalist deniers of AGW. I smell science rearing its sceptical head.

[MoreCarbonOK]

BC says
Which is why the unqualified statement that "more is better" is obviously nonsense
henry says
I wonder why you keep saying that I make unqualified statements.
I did my own research because clearly I cannot trust anyone of you here?
FYI I will repeat it to you again
I first studied the mechanism by which AGW is supposed to work. I will spare you all the scientific details. I quickly figured that the proposed mechanism implies that more GHG would cause a delay in radiation being able to escape from earth, which then causes a delay in cooling, from earth to space, resulting in a warming effect. 

It followed naturally, that if more carbon dioxide (CO2)  or more water (H2O) or more other GHG’s were to be blamed for extra warming we should see minimum temperatures (minima) rising faster, pushing up the average temperature (means) on earth.

I subsequently took a sample of 47 weather stations, analysed all daily data, and determined the ratio of the speed in the increase of the maximum temperature (maxima), means and minima. Here you can see the results.

http://blogs.24.com/henryp/2013/02/21/henrys-pool-tables-on-global-warmingcooling/

You will find that if we take the speed of warming over the longest period (i.e. from 1973/1974) for which we have very reliable records, we find the results of the speed of warming, maxima : means: minima

0.036 : 0.014 : 0.006 in degrees C/annum.

That is ca. 6:2:1. So it was maxima pushing up minima and means and not the other way around. Anyone can duplicate this experiment and check this trend in their own backyard or at the weather station nearest to you.

Having found no evidence of CO2 induced global warming, and finding only benefits, of more CO2 causing more greenery and increased crops (remember in the dutch greenhouses where they add CO2 to 1500 ppm?)

I say more CO2 is better,

Now who does not understand that?

If you BC, want to maintain your current viewpoint, you must qualify why you say that more CO2 is not better?

[Bored chemist]

henry says
I wonder why you keep saying that I make unqualified statements.

Because you said
"more carbon is OK, in fact it is better."
without qualifying it. In doing so, you made an unqualified statement.
Evidence that, in some cases more CO2 may be beneficial to some things is utterly beside the point.
And repeating it by saying "I say more CO2 is better, " just shows that you don't even understand why you are wrong.


I wonder why you don't find out what the phrase means.

[MoreCarbonOK]

henry@BC
to be able to make qualified statements you have to do your own research.

which is where?

[damocles]

From alancalverd:(reply #213, following on from 211 and 212)

Just to quote a bit of the article that MCOK referenced:

Quote
In findings based on satellite observations, CSIRO, in collaboration with the Australian National University (ANU), found that this CO2 fertilisation correlated with an 11 per cent increase in foliage cover from 1982-2010 across parts of the arid areas studied in Australia, North America, the Middle East and Africa, according to CSIRO research scientist, Dr Randall Donohue.

“In Australia, our native vegetation is superbly adapted to surviving in arid environments and it consequently uses water very efficiently,” Dr Donohue said. “Australian vegetation seems quite sensitive to CO2 fertilisation.

11% hardly represents "greening of the Australian desert", especially compared to a 200+% greening associated with a few seasonal floods! The headline on the article henry linked is a blatant overstatement, and might well cause confusion in readers other than myself!
Especially in the light of a few nature documentaries that have recorded the spectacular blossoming of the Australian desert in response to recent floods.

11% greening in response to 15% CO2 increase over the same period is hardly unexpected in desert plants that are not water-limited in their photosynthetic response. Fact is that most plants, including over 90% of food crops, are water-limited.
 

[alancalverd]

Never mind the article - I have little respect for journalism. I'm interested in the numbers quoted from CSIRO and ANU. 11% increased foliage over 18 years is a significant change in arid vegetation, and it's not just flood cropping in Austraila that they studied, but arid regions worldwide. If the figures are honestly reported, that looks to me like a signficant and unsurprising trend, in keeping with all we know about plant growth.

[Bored chemist]

I don't know about the other members of this forum, but I'm not a plant.
What's good for plants in some arid areas may well not be good for me, or for the planet as a whole.
Rapid changes in climate are generally bad for people- whichever direction the change takes.