More carbon dioxide fun (1)

It's always good to fight numbers with numbers.

The Warmenist will start off the debate by saying "Human activity emits 30 billion tonnes (aka 30 gigatonnes) of carbon dioxide every year."

To which the Skeptic counters "Those 30 gigatonnes only account for five per cent of all emissions, how come nobody's worried about the other 95%?"

Warmenist; "The natural world can cope with and absorb the other 95%, it's human beings who upset the natural balance. Carbon dioxide in the atmosphere has gone up by a third compared to pre-industrial levels"

Skeptic: "The natural world seems to be coping pretty well so far. Total carbon dioxide emitted each year is in the order of 600 gigatonnes, but the total amount of carbon dioxide in the atmosphere has only gone up by 500 gigatonnes since pre-industrial times. If nature couldn't cope, surely it would go up by 600 gigatonnes every year, and not by 500 gigatonnes over a century or two?"

Warmenist: "That's because nature can cope with the natural emissions. It's the extra industrial and human emissions that are leading to the increase"

Skeptic: "OK, maybe that's partly true. Since 1960, carbon dioxide levels have gone up from 320 to 390 parts per million, so that's an increase of 1.4 ppm every year. If we times that by the total weight of the atmosphere of 5 million gigatonnes, that's an increase of only about 7 gigatonnes a year, so nature is clearly dealing with three-quarters of human emissions."

Warmenist: "Exactly! And it's those extra 7 gigatonnes that will drive runaway global warming!"

Skeptic: "Do you go along with the general consensus that carbon dioxide and other greenhouse gases allow all the visible light from the sun straight through, which warms the surface of the earth, which in turn emits infra-red radiation (i.e. warmth), and that greenhouse gases somehow absorb and reflect this infra-red radiation back to the surface rather than letting it escape into space?"

Warmenist: "Yes. And?"

Skeptic: "I'll respond to that once MW has posted that chart from the IPPC's own report that shows that nearly all infra-red radiation from the surface already being reflected. I mean, how much more than 'nearly all' infra-red can a gas reflect?"