The figure for 2015 represents a fourfold rise on the total last year.

Adding to the pressure is a fourfold rise in the price of cans, Mir-Razavi said.

There has been a fourfold rise in cohabitation between 1996 and 2006.

Interest in holidays in Australian and New Zealand is forecast to treble, while a fourfold rise in trips to the polar regions is foreseen.