A four-day heatwave across western Europe that killed seven people began to ease slightly on Sunday, as temperature alerts were cut back and wildfires slowly brought under control.

Water scarcity and heat are threatening two of Switzerland's main agricultural products: milk and cheese. But the shortage affects far more than cows — Swiss glaciers also feed Europe's major rivers.

Mediterranean countries long ago adapted their farming practices to little rain, but this year it is the north of Europe confronting a widespread drought that could see farmers having to send much of their herds to slaughter due to a lack of feed.

Farmers in around a dozen countries across northern Europe — from Ireland to the Baltics — are grappling with a once-in-a-generation drought.