I have always believed that Britain benefits from its membership of the European Union, so these new problems haven’t required a change of mind. Climate change is a perfect example of the kind of challenge we need the EU to help solve.
Lisbon wouldn’t help us deal with any of them, though. It would change nothing of substance on climate change, it would damage our economies (see above) and it would constrain national governments’ flexibility to work together to fight the scourge of terrorism. We’d be much better off without it.