John_Taverner wrote on May 8
th, 2015 at 5:42pm:
So what you're saying is that you're the better class of denialist, who realises that CO2 causes the greenhouse effect, but you question the extent of the negative (and positive ) feedbacks . Is that right?
So you distance yourself from the froth at the mouth (CO2 is a tiny amount) Soren types?
Two things to note, pal
CO2 is a tiny proportion of the athmophere.
But what is even more important is that human generated CO2 is a small percentage of that tiny proportion.
The consumption of terrestrial vegetation by animals and by microbes (rotting, in other words) emits about 220 gigatonnes of CO2 every year, while respiration by vegetation emits another
220 Gt.
These huge amounts are balanced by the 440 Gt of carbon dioxide absorbed from the atmosphere each year as land plants photosynthesise.
Similarly, parts of the oceans release about
330 Gt
of CO2 per year, depending on temperature and rates of photosynthesis by phytoplankton, but other parts usually soak up just as much - and are now soaking up slightly more.
http://www.newscientist.com/article/dn11638-climate-myths-human-co2-emissions-ar...So that's 550 Gt, on round figures.
Human emissions? 26.4 Gt (in 2007). Less than 5%.
Tiny is correct in every sense and from every angle.
But let's go back to the New Scientist:
How can we be sure that human emissions are responsible for the rising CO2 in the atmosphere? There are several lines of evidence. Fossil fuels were formed millions of years ago. They therefore contain virtually no carbon-14, because this unstable carbon isotope, formed when cosmic rays hit the atmosphere, has a half-life of around 6000 years. So a dropping concentration of carbon-14 can be explained by the burning of fossil fuels. Studies of tree rings have shown that the proportion of carbon-14 in the atmosphere dropped by about 2% between 1850 and 1954. After this time, atmospheric nuclear bomb tests wrecked this method by releasing large amounts of carbon-14.
D'oh. No evidence or explanation of how "we be sure that human emissions are responsible for the rising CO2 in the atmosphere."
To conclude:
Human CO2 IS A TINY amount when looked at as a proportion of all CO2 (iself a small part) in the athmosphere and nobody can or has explained how this tiny proportion of a tiny proportion makes all the huge, catastrophic difference.
And you know why?
Because nobody quite understands how the climate works.