On May 15, 2:40 pm, "ozonb" wrote:
"Fran" wrote in message

...
On May 14, 5:33 pm, netvegetable wrote: On Thu, 14 May 2009 12:39:54 +1000, ozonb wrote:
Huh?
Who said oxygen was in short supply?
Not me!

I agree that oxygen is life-giving and that too much could kill you, but
I never said it was in short supply as CO2 is!

I think she's putting to you is pretty simple, and you should be able to
grasp it. You claim that current CO2 levels are "Current CO2 Levels Are
Way Too Low" on the sole basis that they have been higher in the past.

Oxygen levels have been higher in the past too, and yet you don't make
the same claim about oxygen. Why is that?

Because he wants to repeat specious talking points that seem
impressive to people with limited knowledge and time to reflect on the
matter.
======================================

BECUASE ...

Current oxygen levels are probably about right because there are no known benefits in
having more.


Current CO2 levels are too low because there are well known benefits, even for carbon
crackpots, in having more.

N'est ce pas?

You've moved the goalposts. Whether there are known benefits in having
more was never one of your criteria for determining whether CO2 was a
pollutant. It began and ended with past concentrations and possibly,
with it being "a life-giving substance".

If you want the new criterion to be "there are benefits in having
more" then you are going to have to state how much more CO2 would be
beneficial and offer some good science to support that. There isn't
any good modelling to suggest that in net terms, extra CO2 would be
beneficial to plant growth in ways that would help us. there would be
winners and losers and some of the "wins" wouldn't be that valuable,
and also, conditional on getting more water to cope with the greater
heat.

You are also going to have to stop trying to refute the idea that CO2
can't be a pollutant because at some concentration you would have to
acknowledge that all of the benefits of extra CO2 had been exhausted,
after which point CO2 would be a pollutant on your definition.

You're also wrong that there are no known benefits from having more
oxygen in the air. With more oxygen we humans would be able to work a
little harder at high altitude. There were some pretty impressive
plants and animals when oxygen was around 35%. It's just that 35%
would provoke some serious health problems in the places where most
humans live, which is a separate question. And of course in nitrogen
in the air fell by that amount (to about 64%), all plants C4 pathway
plants would suffer.

Fran