The unseasonably warm weather some parts of Canada have experienced this year – may deprive some areas of their trademark rich fall colours.

Sean Thomas, a professor of forest ecology at the University of Toronto says the dazzling red leaves that draw crowds of tourists to areas of Ontario and parts of Quebec – are triggered by bright sunshine combined with cold temperatures – as trees start breaking down chlorophyll in their leaves – and draw out nutrients – to store over the winter.

Thomas says chlorophyll is what gives leaves their green colour – and as its  broken down – other pigments such as red, yellow and orange are revealed – but that process can produce other chemicals that damage plant tissues – if they’re exposed to UV radiation.

He says the the red pigments of sugar maple trees and others – emerge as a type of “leaf sunscreen” under optimal conditions.