(This was sent out at 7:15 or so, but wasn't posted on FW.)
Keith,
Mount Pinatubo, according to the USGS, emitted 20 million tonnes of
cloud, less than Tambora in 1815, and less than Krakatua in 1883. Your
figures were possibly correct about Iceland, but way off for Pinatubo in
1991. The global CO2 per cap tonnage was at 4 in 2005, and world
estimate was placed at 27 billion tonnes.
The first thing that struck me about your reply was comparing natural
emitting volcanic eruption to anthropogenic CO2 emissions. Wiki has some
fast answers. They say that only about 57% of man-made CO2 emissions are
removed by the biosphere. Coal and petroleum are the leading cause, then
deforestation, then change of land use.
I understand that ice core measurements can be unreliable for studying
past centuries, millennia, and that Somata (plant fossils) and S. pole
air flasks are far more realistic in their evaluations. However, though
the average pre-industrial p.p.m. numbers may have averaged 260-340 ppm,
depending on how many volcanoes erupted (a /constant /of 280 ppm was
unrealistic as Nature is unpredictable), and therefor resulted in a
likely pre-1750 average of about 305 ppm, the/three/ indicators seem to
agree on the increments from 1957. 40 years ago, the steady increase was
0.9%/yr. Since 2000, the increase has been 1.9% annual elevation, and
today we are at about 2.2% or more.
It's the steady recent increase that's most worrisome. That and the fact
that the CO2 is way more toxic than mere volcanic emissions. It only
takes 3% of natural emissions to tip the balancing effects of sinks, and
we've more than tipped it. So, when a volcano does go off, we're setting
the world up for a more impacting effect.
We not only have to stop anthropogenic CO2 emissions, we have to scrub
the air of what's there that shouldn't be.
Natali_*A*_
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