OSLO: Early flowers, migrating swallows and sleepless bears are among signs that spring has arrived long ago in the northern hemisphere even as a record mild winter formally ends on Tuesday with a rare chill.

Spring officially starts on Wednesday at 0007 GMT when the sun passes north over the celestial equator, but scientists say the biological clocks of animals and plants are running ahead of time, perhaps upset by global warming.

Orange trees, olives and peaches are blooming weeks ahead of schedule in Greece, geese are cutting down on migrations in Canada and the United States and bears have been unable to hibernate in Bulgaria.

Red Admiral butterflies and swallows — usually a sign of summer after the birds spend the winter in Africa — have been spotted early in the Netherlands after the warmest Dutch autumn and winter since records starting in 1706.

“Springs have been getting earlier for the past 60 years. Plants have been getting incredibly confused, and birds have also been confused to some extent,” said Andre Farrar of Britain’s Royal Society for the Protection of Birds.

Winter in the northern hemisphere was the warmest since global records began in the late 19th century, spurred by a warming trend of recent decades and an El Nino warming of the Pacific, according to the US government’s weather agency.

Scientists say that weather is always chaotic but UN reports project that extreme events such as droughts, heatwaves and floods are likely to become more frequent because of a warming widely blamed on use of fossil fuels.

Among other swings, temperatures in Beijing were set to climb from a chilly 7C on Tuesday to 18C on Saturday.

One man in Cyprus got twin shocks from an early spring.

Picking wild asparagus in late February, he got bitten by a snake that had apparently woken early from hibernation.—Reuters