The combination of last year's drought [exceptional] and the severe frosts and heavy rains of this winter [also exceptional] has had a devasting effect on hundreds of miles of Britain's coastline.
(The combination of last year's drought [exceptional] and the severe frosts and heavy rains of this winter [also exceptional; has had; a devasting effect on hundreds of miles of Britain's coastline)
The combination of last year's drought [exceptional] and the severe frosts and heavy rains of this winter [also exceptional
has had
a devasting effect on hundreds of miles of Britain's coastline