Japanese authorities have declared the cherry blossom season open in Tokyo, with the flowers appearing seven days earlier than the area's average, and one day earlier than last year.

The country's meteorological agency, which reports on the closely-watched marker of spring each year, says the effects of global warming could be responsible.

Millions of Japanese wine and dine each year at parties under the cherry trees, whose delicate but short-lived blossoms have left centuries worth of poets pondering the ephemeral nature of beauty.