The one proposed "fix", seeding the seas with iron, seems not to be an option -
http://news.bbc.co.uk/1/hi/sci/tech/7959570.stm- indeed many think that the idea would be very dangerous and counter-productive.
Basically engineers have a very simplistic view of life: all processes can be reduced to simple formulae .... whereas life-processes are very different, complex and not really understood, even by the best of ecologists. Which is why biologists would urge caution - and drown all engineers in the sea!
