Actual Carbon Emissions vs. IPCC Scenarios - how far away is safety?

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23. It's actually not a compliment to the species that we survived Toba.

There are two reasons for that.

The first is that Toba wasn't a large-scale extinction event. If very few other species died out, it's no great miracle that we survived. There was nothing special about us that would have enabled us to survive where few others perished. Claiming there was amounts to bravado.

The second is that there is some serious question as to whether there was even a bottleneck. Some paleontologists assert that our population was very low to begin with, was not reduced much if at all by the event, and simply underwent a bit of a population explosion in the tens of millennia afterwards:

http://en.wikipedia.org/wiki/Toba_catastrophe_theory

The work done on Neanderthal sequencing (Green 2007) has identified little evidence of Neanderthal contribution to humans, moreover it describes an effective size of the population when humans and Neanderthals split was about 3000 individuals. Taken in the light of Schaffner's and Takahata's effective populations sizes, 3000 < Ne, female < 6000 and 2000 < Ne, male < 4000 does not appear to represent a magnitude shift downward from the average size. Taking a null hypothesis, prior to and after the mtDNA MRCA population sizes appear to reflect long-term small population structure up until 70,000~150,000 years ago, not a brief constricting bottleneck, but a long period of constrained size followed by an expansion.

It doesn't seem to me that Toba provides much evidence of human exceptionalism.

If we were to actually trigger a true extinction event like PETM, we should expect humans to be as subject to it as any other species.