If Mike's chart were more fine grained, would it be able to indicate the 'rate of emission growth' by the steepness of curve? Or is another value on the chart needed?
Growth rate can be roughly inferred by looking at the chart. It's not the slope of the curve alone, though, that indicates growth rate; you need to look at the slope of the curve at a given point relative to the height at that point.
Or in other words, you would want to look at year-over-year growth, expressed as a percentage of the previous year.
Looking at the chart, for example:
Total emissions in 1975: 4.5 billion tons
Total emissions in 1980: 5.3 billion tons
Percent growth from 1975 to 1980: (5.3 - 4.5) / 4.5 * 100 = 17.7%Average yearly growth rate from 1975 to 1980
: 17.7% / 5 years = 3.6% per year
Total emissions in 2005: 8 billion tons
Total emissions (predicted) in 2010: 9 billion tons
Percent growth from 2005 to 2010: (9 - 8 ) / 8 * 100 = 12.5%Average yearly growth rate from 2005 to 2010
: 12.5% / 5 years = 2.5% per year
So to HFat's point, even though CO2 emissions are growing faster than ever before in absolute
terms, the growth rate
is considerably less now than it was 30 years ago.