Over the last 800,000 years Co2 levels have never been above 300 parts per million (ppm). Currently, the Co2 -equivalent level (i.e. including methane) is about 430 ppm. An increase of 30 ppm has never occurred in less than a thousand years but the last increase of 30 happened in just 17 years.
Co2 stays in the atmosphere for, on average, 5-200 years. But that's an average...there are some suggestions that it could be up to 1,000 years. So, even if we cut back now, there's still a chance of significant increases in temperature over time. In reality, because of "feedback effects" and the possibility of non-linear systems or "thresholds" we're not even sure in our projections of : i) how much Co2 there might be and ii) the damage it might cause. In short, we have a "cascade of uncertainty" (IPCC, 2007).
As the great natural philosopher once said: there are unknown unknowns.
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Just saw the beautiful film, Beasts of the Southern Wild.
Bought Yellow Birds from O'Hare. Looks good. A recent report out on sexual violence in the army. Second thought: is that so surprising? Glancing through Finley's Ancient Economy and the depressing thought strikes you: just how many people have been treated like chattel down the years or, alternatively, how few people have or had autonomous, decent lives?
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