The analysis I did in my last post was quite enlightening. To grapple with the sheer scale of the issue of CO2 reduction, it was helpful to determine what year would have the equivalent emissions as a 40% reduction in 1990 levels (1959), and what year would have equivalent per capita emissions as a 40% reduction in 1990 levels in 2050 (1900ish).
Another analysis would be to take the per capita emission levels we are taking about and compare it to equivalent countries today. The point of this analysis shouldn't be misinterpreted. I am not suggesting that people's standard of living will become equivalent to the countries mentioned. However, I think this shows how substantial the changes need to be in order to meet the cuts required.
I determined that in 2050, in order to have emissions equivalent to 40% of 1990s levels, the world would need to average only 0.25 tons per person. The current average per capita emission rate now is approx 1.23 (2004 data). Looking at the list of countries we see that the country closest to this today is either Morocco (1.2 tons/person) or Colombia (1.3 tons/person). Now, if we need to reduce the emissions to 0.25tons/person, that would be equivalent to dropping the average world's emissions to the levels of Bangladesh (0.25).
I should note that I was confused when one of the sources I quoted mentioned tons of CO2 and the other mentioned tons of CARBON. I am going to assume that by "Carbon" it is meant CO2, otherwise this comparison isn't fair.
So, if the world's average country will have to go from Colombia to Bangladesh, I'm not sure if that tells us a lot. Mostly because I only have a really vague idea of what the CO2 emissions and standard of living is like in both Colombia and Bangladesh. So, the next useful thing is to try to equate US/Canada/Australia emissions. Let's assume that if the mean per capita emissions has to drop by a factor of five that we can safely scale *all* countries by a factor of five. This might be unrealistic, but maybe not. The countries with near zero per capita emissions would not change much and the ones with the most per capita emissions would change the most - maybe that's fair. So, if we take current U.S. per capita emissions, they are 19.8 tons. Reducing this by a factor of five becomes only 4 tons per person. Today, ironically, Mexico has 4 tons per person.
So, let's review. If the U.S. were going to match South Australia's requirement of a reduction in CO2 emissions to 40% of 1990s levels in 2050, this would result in a drop in emissions per person from what the U.S. has today to what Mexico has today. Or, put another way, if the U.S. does not want a massive drop in standard of living, there is a MASSIVE amount of clean energy that needs to be implemented to accomplish this.
Actually, there is a bit of a flaw - I'm assuming that the US will see a population growth rate equal to the growth rate of the rest of the world. However, this isn't likely to be the case as most developed countries are seeing a drop in population growth rates, but still, the irony of comparing the U.S. and Mexico was too good to not persue.