Hmmm! Now you come to mention it what contribution have all the nuke tests had on the climate? Lots of those tests were in the oceans. Heat is lost from the ocean currents very slowly thats why the UK basks in warm gulf-stream waters from 3500 miles away, it takes weeks for that water to make its way across to us and it doesn't lose much heat on the way. Imagine the heat injected by a large underwater nuclear explosion. How long would it take to dissipate into the atmos'? Many years?? Not to mention the CO2...oops! Too late!

A few minutes searching came up with this, interesting little snippet of info.

http://www.llnl.gov/str/Duffy.html

The trapped methane is an unknown quantity in any future analysis too. That does worry me because its impossible to measure, so it remains one of those spooky unknown factors that could tip the balance well and truly over the edge. Hey Adriannem just think of all that Dino-methane...no comet or asteroid required just a rapid global meltdown caused by all that flatulence! It would also explain the disappearance of the ocean dwellers at the time of the mass extinction! A methane rich ocean would be a bit of a deadly environment. Would it not poison anything with gills?