When Southern California’s jacaranda trees all burst into bloom, it’s as if bluish-purple clouds are billowing above city streets. But last spring, Californians reported that some trees flowered up to four weeks early. According to Andy Pitman of the Climate Change Research Center at the University of New South Wales in Australia, a mild winter was likely to blame.

Jacaranda trees

Pitman: “In the same way that we go to bed at night to sleep, jacarandas and a range of other plants go to sleep in the winter.”

But when winters are unusually warm and clear, the jacarandas can get restless.

Pitman: “There’s more sunlight, and it’s actually worth the jacarandas bothering to get out of bed in the middle of winter to carry on taking in carbon dioxide and growing.”

Jacarandas are not the only plants reacting to changing climate conditions.

Pitman: “Plants are germinating earlier. Plants that used to die back in winter aren’t being killed off by frosts anymore, and a whole suite of pathogens – pests – that used to be killed in winter, aren’t being killed in winter.”

So those jacaranda blooms are not just eye-catching – they’re also attention-grabbing, like blue flags alerting us to the effects of drought and rising temperatures.

This segment of Climate Connections was produced in partnership with iSeeChange.

Reporting credit: ChavoBart Digital Media and iSeeChange/Molly Peterson (KPCC).
Photo: Jacaranda trees (copyright protected).

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Early bloomers a sign of abnormal conditions
Professor Andy Pitman

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