On 2006-06-29, Matt Barrow wrote:
Which is a good thing. CO2 makes plants and trees grow.

And cars and power plants are way down on the list compared to natural
sources.

Human CO2 is something like only 3% of global CO2 emissions.

It's not absolute quantities in this context that are important - it's
the relative addition of man made CO2. If (as an example) the Earth's
system could keep a steady concentration of CO2 for a natural output of,
say, 100 units - and man made sources then started adding just 1 unit,
instead of a steady concentration (all things being equal) you start to
get an increase of 1 unit per unit of time.

The evidence is conclusive that recent rises in CO2 concentrations (from
280ppm in 1900 to 320ppm now) are entirely caused by human activity. We
can see that CO2 levels have only varied between 270 and 290ppm for a
good 10,000 years prior to this point. Carbon dating the CO2 in the
atmosphere shows that the recent additions of CO2 (i.e. the change from
~280ppm to 320ppm) are from the burning of fossil fuels.

It may all be well if we increased the carbon dioxide sinks by 3% also,
but generally the kind of activity that leads to the burning of fossil
fuels also leads to a reduction in the CO2 sinks.

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