Heinbloed, a good quote I heard springs to mind - "Like I always say, money's something you need in case you DON'T die tomorrow!.
Even taking your extreme example of WW2 and its effect on investments etc, even the most severely destroyed economies, ie Germany and Japan, had recovered and indeed had achieved unsurpassed levels of wealth by historical standards only 15 years later.
Somehow I think mankind will find a solution to the global warming issue, just like we've found solutions to every other allegedly catastrophic event about to wipe out our savings, future etc.
Plus, I wouldn't believe every scare story I read in the London Independent - with the exception of the Guardian its the most depressing, anti-business 'quality' paper out there.