"[for] Both questions assume these large quantities CO2 were dumped uniformly into our atmosphere on say Monday July 11 2005 within a period of 24 hours."

100 times CO2: So say there is around 2800 Gt* so that's 280,000 Gt of CO2.

In terms of volume 280,000,000,000,000 tonnes of liquid CO2 is about size of 60 km diameter sphere, whereas 10 times would about 30 km diameter sphere.

Obviously it would be hard to actually make this much CO2. Though a large comet impacting the ocean might generate this scale of quantity. [some small percentage of CO2 coming from the comet itself and heating the ocean- thereby release CO2 in ocean from impact energy, but it's all a bit complicated and unlikely].

*Upon checking, Wikipedia says there is about 2.7 × 10e12 tonnes of CO2 in our atmosphere [ http://en.wikipedia.org/wiki/Carbon_dioxide ]