'With climate activity, countless factors interact with each other, and lots of explanations are possible. Using models it has been shown that this special mechanism could function that way. But that does not mean in any way that it is the deciding factor' -- Can the cause of the cold winters be identified? HvS: 'One has to ask why are such explanations first found after the event appears. It indeed would have been much nicer if someone had said already in the year 2000: By the way, you have to expect harder winters in Europe because the Arctic ice is retreating in the summer. This claim today then would have been far more convincing. But it was the other way around: We noticed that something strange had happened, and then an explanation was constructed. Other explanations would also be possible'