If the Gulf Stream didn't exist, northern Europe would be colder of course. But what other effects might it have?
Would the Mediterranean be cooler and wetter? Would this be a net benefit or net detriment?
Also, if we place a butterfly net up to 1000 BC, 300 BC, 200 BC, or 100 BC, how would Europe, Africa, and Asia be affected then on?
Northern Europe... would it stay 'barbarian' forever?