How much greenhouse gases does Earth expel naturally to atmosphere (CO2 eq. ton)? and how much do humans?
Answer:
The Earth - about 770.3 Gigatonnes. (The .3 is volcanoes).
Man - about 26 Gigatonnes.
That's not the whole story of course. The Earth absorbs about 780 Gigatonnes, leaving an increase of about 16 Gigatonnes yearly. And it's coming from fossil fuels.
How do we know that? Isotopic ratios. The stuff from burning fossil fuels has different amounts of C13 than natural CO2. Measurements of the atmosphere show this different C13 ratio. Nature is quite good at recycling it's own inputs. Ours - not so much. Details here:
http://environment.newscientist.com/chan...
http://www.realclimate.org/index.php?p=8...
and lots of peer reviewed scientific papers.
Well compare the two graphs:
An 80ppm increase of CO2 concentrations linked to the solar variation done over a short period of 2000 years:
http://en.wikipedia.org/wiki/image:vosto...
Ok so far for "mother nature"
Now look at what we can do:
http://en.wikipedia.org/wiki/image:co2ma...
The same increase of 80ppm in 40 years (from 1960 to 2000).
But that´s only a modest beginning. Once China and India which have almost no energy source except for coal will reach higher energy consumption level per capita, we might be able to triple the rate of emissions we had in 1960.
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